Category Archives: 1994

PeGASus Newsletter Issue #47 – April. 1994

  • Editorial Comments
  • In the Sky
  • Comet Crash Predictions
  • Supernova Adrenalin Rush
  • Observing Groups
  • Astronomy Day Thanks
  • Monthly Meetings
  • Rename the Planet

Prince George Astronomical Society Executive 1993/94

  • President Orla Aaquist 562-2131/964-9625
  • Vice President Bob Nelson 562-2131/563-6928
  • Secretary Jon Bowen 563-9869
  • Treasurer David Sundberg 562-5774/6655
  • Members at Large Ted Biech 562-2131/564-2838
  • Matthew Burke 964-3889

Nominated Positions

  • Technical Director Bob Nelson
  • Observing Director Jon Bowen
  • Promotional Director Orla Aaquist
  • PeGASus Editor Shannon Austman

The Observatory phone number is 964-3600. This is a party line, so if it rings busy, it does not imply that someone is at the observatory.


Editorial Comments

A supernova was discovered between March 31 and April in M51, the famous Whirlpool Galaxy, by several independent observers in Georgia, Wisconsin, California, and Japan. Alan Whitman also made an independent discovery about one week later at the PGAO. He has written an inspiring article for this issue which I hope will prompt all of the latent observers in our club to get out to the observatory and use it for what it was intended. Good work Al, and good luck tornado hunting!

The April 9th edition of the Sky and Telescope News Bulletin, left by some anonymous person in my mail box (gosh, couldn’t you attach your name?), reports that a bright comet McNaught-Russell is moving through the constellation Taurus. The comet is about 20′ across (almost the size of the full moon) with a integrated magnitude of 6.5, making it visible with binoculars. On April 10th it was at 5h 16m and +38.2 degrees; on April 14th it was at 5h 35m and +47.5 degrees. That’s all I know. Happy hunting.


In the Sky by Alan Whitman

he May sky offers a lot of viewing of solar system objects. this is very fortunate since serious deep-sky observing ends by mid-May at our high northern latitude as we tip towards the sun. On May 10th (the date of new moon) we still have 67 minutes of true night (when the sun is at least 18 degrees below the horizon and it is fully dark). After that, the tables for astronomical twilight in the Observer’s Handbook show only dashes until August 8th!

There is an annular eclipse of the sun on May 10th, the last central eclipse in North America until the Arctic event in 2008, if my memory serves me correctly. The moon is at apogee, its most distant position from earth in its monthly orbit, only 39 hours before the eclipse. Thus the apparent size of the moon’s disk is 94 percent of the diameter of the sun’s and a ring of bright sunlight (an annulus) remains visible around the black disk of the moon. An annular eclipse is not as dramatic as a total eclipse because such features as the solar corona and prominences are not visible. Nevertheless, having seen three total eclipses and never having seen an annular, I am looking forward to this one. I plan to be near the southern limit where the solar and lunar southern limbs will be in contact and the high mountains near the lunar sough pole will hopefully cause Bailey’s Beads as the sun shines down lunar valleys. The Beads were first seen at an annular eclipse, not a total.

The annular eclipse path is within a day’s drive for most of the population of Canada and the United States but Prince George is one of the most distant cities. The path of annularity runs from southern New Mexico (which has the best weather prospects), through El Pase, the Texas Panhandle, Oklahoma City (where this columnist just happens to have a jog chasing tornadoes in May), St. Louis, Detroit, Cleveland, Toronto (which has a 2 minute 55 second eclipse near the northern limit — did you say that you had to take a business trip to Toronto sometime soon?), upstate New York and northern New England, and Nova Scotia where Halifax enjoys a 5 minute 54 second eclipse on the centre line.

Prince George will have a partial eclipse beginning at about 8:24 AM PDT and ending at about 10:53 AM PDT. At maximum eclipse, at 9:35 AM PDT, the moon will cover 42 percent of the sun’s diameter. NEVER LOOK DIRECTLY AT THE SURFACE OF THE SUN WITHOUT A PROPER FILTER. For naked eye viewing, use a #14 shade rectangular welder’s glass, available for about $2 at most welding supply shops*. Do not use anything else, except for high-tech telescope filters. Look at the fat solar crescents projected on the ground by tree foliage. These natural pinhole images of the sun are probably the most attractive thing to see during a partial eclipse.

On May 24th, the evening before our monthly meeting, the full moon will rise at 9:10 PM PDT. It will be in a slight partial eclipse but will leave the earth’s dark umbral shadow at 9:23 PM. Some fainter penumbral shading should be visible for about another half hour. This is one of a great many lunar eclipses in the last decade or so which have ended in B.C. near moonrise or begun near moonset. C’est la vie!

On the 27th, 5th magnitude 21 Sgr reappears from a lunar occultation on the moon’s dark WNW limb at about 12:56 AM PDT. The moon is only 2 days past full, which considerably detracts from the attractiveness of the event and makes observing it difficult. Keep most of the moon out of the field of vies and try a polarizing filter. Normally I wouldn’t bother watching occultations near full moon BUT THIS OCCULTATION IS OF A FAIRLY CLOSE DOUBLE STAR WHICH MAKES IT INTERESTING. The stars are magnitudes 5.1 and 7.6, separated by 1.8 seconds of arc, and at position angle 286 degrees. The fainter star will reappear first; use a fairly high power to enhance its visibility.

Venus continues to be “the evening star” in evening twilight. The crescent moon is nearby on the evening of the 12th.

Jupiter is observable much of the night while Saturn rises about three hours before the sun. You will find that Saturn’s rings have closed up a lot since last summer. They will be edge-on in 1995.

If you have access to a 10″ or larger telescope, try finding Pluto as it is at opposition on May 17th. I’ve seen it in an 8″ several times but it is probably too far south now to be able to do that again during our lifetime from this far north. The PGAS has about a dozen of these at the observatory. Give someone on the executive a call if you would like to borrow one.


Comet Crash Predictions by Matthew Burke

During July 16-21 of this year the fragments of the Comet Shoemaker-Levy 9 will collide on the dark side of Jupiter. The burning question on everyone’s mind is,” What will we be able to see at the Prince George Observatory?”. For seeing direct impacts, the answer unfortunately is “Nothing”. The only fragment crashes during which Jupiter will be visible from Prince George are “C”, “M”, “R”, and “V”. They are minor fragments, which greatly diminishes our chances of seeing light echoes on Jovian Moons, or fireballs rising above the cloud tops. However it is my opinion that the energy released by the collision of Shoemaker-Levy 9, equivalent to millions of megatons of TNT (enough energy to destroy a planet) won’t go entirely unnoticed.

Despite our poor observing location (Earth) we still can watch for a variety of crash predictions. We can use the CCD Camera in conjunction with our 24″ Telescope to log the time during the “Great Comet Crash” and then compare each image for changes in the Jovian atmosphere. The crashes will be spread out over a weeks time (See Collision Chart). All the impact sights will be around -44 degrees latitude. Given that the Jovian day is about 10 hours, the impact sights should be strung around this latitude, possibly creating a new belt or series of storms.

During the first fragment crash on July 16, the Moon will be located 9 degrees directly below Jupiter in its First Quarter phase. During the successive days the moon will continue to drift at a rate of 1 hour in ascension per day. The brightness of the Moon and its location may hinder our observing attempts.

As the comet nears Jupiter, gravity will cause the fragments to accelerate away from each other. The nearest fragment to Jupiter will reach its top speed of 60 Km/sec. one week before the final fragment. Currently the “Comet Train” is approximately 893,000 Km long, with an arc length of 255 arc. sec. (see Comet Train Length Table). Just before the crashes the Comet Train length will be 4,907,000 Km. During the months leading to the crash, we can photograph the comet to track its separation.

A 2 Km object colliding with Jupiter would penetrate to a depth of 350 Km in 10 seconds, creating an atmospheric hole 200 Km wide at the cloud deck. Portions of Jupiter’s lower atmosphere (equal to the mass of each impactor) and disintegrated comet, could eject into Jupiter’s stratosphere changing its chemistry and possibly hazing over the lower hemisphere. Some dust could eject escape into the Jovian magnetic field, forming a glowing halo around the plant. Any fragments and cometary dust that miss Jupiter could create a faint ring around the planet.

Even though we will not see direct impacts of Shoemaker-Levy, we still will have many unusual phenomenon to look for


A n n o u n c e m e n t s

PUBLIC ACCESS TO THE PGAO

Starting May 13th, the PGAO will be open to the public every Friday and Saturday evening from 7:30PM to midnight. This is a good chance for PGAS members to come out and get involved with the club.Hope to see you there.

Science and Technology Week

Would anyone like to represent the PGAS on the Science and Technology Week committee. There is an initial organization meeting on the morning of April21 at the Fraser-Fort George Museum. Call Orla (964-9626) if you are interested. Last fall we had a successful display at the Pine Centre Mall under their banner.

WANTED

Brian Thair is looking for a 210 mm f/5.6 view cameralens with shutter. Image circle at f/22 not less than200 mm. (Fujinon, Nikon, Rodenstock or Schneider).Call 561-5848: CNC box 277

CLUB PHOTOGRAPHER NEEDED

The PGAS needs somone to take pictures at clubevents and of activities at the observatory. If you have a camera, we’ll supply the film. Call Orla at 964-9626.If you have anything to announce or advertise,consider this space of the PeGASus.


Supernova Adrenalin Rush by Alan Whitman

After 35 years of observing only for the aesthetic pleasure of viewing the sky’s showpieces or the
challenge of finding faint blurs, it seemed time to do something more serious in astronomy. I decided to begin systematic supernova searches this spring.

April 9th was only my seventh night of searching, five with the PGAO 24″ and two on my dark acreage with my 8″. When I arrived at the observatory after midnight on the 9th, the sky was only mediocre, degraded by high cirrostratus clouds. the second galaxy checked was M51, “The Whirlpool Galaxy”. The 120x view was atrocious, only the nuclei of the main galaxy and its companion were visible. I considered moving to a more transparent part of the sky but nowhere looked really promising and I started seeing glimpses of something which seemed out of place. So I killed over half an hour while wondering if I shouldn’t just give it up and roll into a cold sleeping bag.

At 1:44 AM the cloud thinned. The out-of-place object proved to be just a bright condensation on a spiral arm BUT there was a star within a minute of arc of the nucleus that definitely did not belong! This was my sixth detailed search of M51 in 26 days and I knew it intimately. The star was an interloper. It had to be either a supernova or a passing asteroid.

Adrenalin rush and doubts! How could I find a supernova on only my seventh night, and in the showpiece galaxy of the spring sky rather than some semi-anonymous NGC blur? Should I call it into the clearing centre for astronomical discoveries in Cambridge, Massachusetts now, or wait and see. I watched at 225x for half an hour; it neither brightened or moved. If I had a supernova, West Coast observatories had less than three hours of night left to put photometers and spectroscopes on it to catch the initial rise in brightness and the rapid early changes. It was only as bright as the 13th magnitude foreground star always seen with M51, rather faint for a supernova in a magnitude 8.1 galaxy.

I realized that I should call Skyline in Cambridge to see if anyone else had reported it but found that I did not have the number with me (that will never happen again). Home was a 40 minute drive, so I called and the phone twice rang twenty times. No one awoke. I tried directory assistance to call my old observing buddy in Kelowna, Jim Failes (one of the province’s most accomplished observers), so I could have him record the time of my discovery and also ask him for Skyline’s number. discovered that B.C. Tel doesn’t answer directory assistance at 2 AM. No problem. I dialed 0. Guess what? There isn’t an operator at 2 AM either, at least not in fifteen rings.

The round trip to home and back to the observatory would consume half of the remaining three hours of the night. I made the 40 minute trip home in 26 minutes. Called Skyline: “A magnitude 13 supernova was discovered in M51 April 2nd….”. It had been found a week ago! There was still some consolation. It had been an independent discovery and at least there was now no doubt that it really was what I had thought it was.

But hadn’t I checked M51 several times in the past week? I checked my observing log and found this entry for April 4th with the 24″: “M51 was very poor through cirrostratus (the bright superimposed star was barely visible)”. Well, the poor conditions explained that miss.

On April 5th I used my 8″ and recorded: “Superb view of M51 at 116x near the zenith–Instead of the ring effect, I could clearly trace both of the main spiral arms and the bright condensation on the inner arm which is on the same side at the outer arm leading to the satellite which was visible. I don’t remember ever having such a view with the 8″ before!” I had been ambivalent whether the 24″ with more light-gathering power or the 8″ which will find objects much faster was the proper tool for supernova gathering. The 8″ certainly failed on this one, not showing the supernova even on a very superior night when transparency was very good and seeing was excellent.

However, a negative observation with the 24″ on March 30th may be valuable in defining the light curve. A Japanese pre-discovery photograph was taken on the 31st showed the supernova when checked later. That photo must have been taken 6 to 12 hours after my negative supernova check at 10 PM on March 30th.

When I carefully checked M51, the transparency was very good although seeing was only fair. An excerpt from my journal follows: “At 120x M51 very well with the spiral arms quite distinct and several condensations along them, especially the innermost bright one of the same side as the star just outside the galaxy–fine view”. I am confident that the supernova would have been visible if no more than 1.5 magnitudes fainter on March 30th than it was on April 9th, given that it was very obvious in the 24″ through thin cloud on the 9th while my log shows “Transparency Very Good” on the 30th.

Orla Aaquist sent my March 30th negative report to Massachusetts on the College of New Caledonia e-mail system as it may help define the light curve immediately after the initial explosion. The supernova is a Type 1c so it should continue increasing in brightness for three weeks until about April 21st and then fade rapidly for a month, then more slowly. Type 1c objects only reach about a quarter of the brightness expected from a Type 1a.

Supernova-searching is an ideal use for our 24 ” and I would encourage others to give it a try. Many galaxies have foreground stars superimposed on them which over eager amateurs have reported as supernovas. Bob Nelson and I spent much of a night last October with the CCD camera checking out such a false report for M108. That galaxy is unusually speckled with stars and bright condensations which took three hours to check in the Ben Mayer photograph I had, due to the CCD camera’s tiny field of view (3′ by 4′). All were invisible visually as the galaxy was below the pole, low in the murk of the northern horizon almost hidden by the city lights.

The way to avoid making false reports is to get to know your regular galaxies so that interlopers will stand out just like new construction on your drive home would. Long exposure photographs taken with the telescopes in the 8″ range will give you a good idea of what you can see visually in the 24″. Professional observatory photographs, on the other hand, usually show the galaxies so brightly that foreground stars are invisible so these photos are seldom helpful for supernova searching.

Again, finding a supernova first would be a very positive thing for our observatory’s reputation. On the other hand, sending in a false alarm would hurt us. So please be sure that it really is an interloper and not just a foreground star or a HII region in a spiral arm. Feel free to wake me at any time of night to help you check it out if you think that you have a live one. I have several photos of all Messier objects available, as well as a pretty fair subconscious map of what each should look like. NGC galaxies are more of a problem. You could try sketching each of your regular galaxies, showing the stars normally visible. Sky Publishing once carried supernova- hunting charts but they are out of print.

For more reading on this subject, see Sky and Telescope magazine’s December, 1993 issue page 30 and the September, 1993 issue page 91.


Observing Groups by Jon Bowen

Well, now that summer has arrived, and we have actually been experiencing what’s known as clear weather, it is time to get a few observing groups up and running.

We currently have five different observing groups, each with it’s own group leader. The group leader is a contact person who is relatively experienced in his or her “field” of observing. They are as follows:

  • General Observing: Alan Whitman
  • Binocular Observing: Jon Bowen
  • Variable Stars: Bob Nelson
  • General Astro-photography: Gil Self
  • CCD Photography: Ted Biech

These people are here to help if you have any questions regarding equipment, methods of observing or what-ever. Also, if you would like to set up a Observing Night for your group, whether it is at your house, or the observatory, these are the people to contact.

If there is a type of astronomy that you are interested in, and would like to see it as an observing group, please give me (Jon Bowen) a call. Hope to see you out looking at the stars…


Astronomy Day Thanks

Thank you to the following club members who helped out at this year’s ASTRONOMY DAY: Ted Biech, Matthew Burke, Robb Fry, Les Griffiths,Dave Kubert, Mike Lancelot, Jon Bowen, Steve Bowen, Don Goldie, GillSelf, Bob Nelson, and Alan Whitman. Thanks to Cindy Rebman at the Fraser-Fort George Museum for letting us use their facility for our afternoondisplay. About 40 people visited us at the Museum, and 20 people visited theObservatory.


Monthly Meetings

The next meeting of the PGAS will be held at CNC in the Physics Laboratory (room 2-223) on April 27th starting 7:30 PM.

This month’s meeting will feature

Jennifer WhitmanFinding the speed of light using Roemer’s method & Orla Aaquist Measuring distances to stars(unless a more interesting topic comes along)
At next month’s meeting, Alan Whitman will talk about the Mount Kaubol star party. Last month’s meeting is somewhat of a blur to me. It seems that we spent nearly an hour talking about upcoming PGAS activities. They include

  • Astronomy Day on April 16
  • Science Council visit on April 28
  • Physics Articulation tour on May 6
  • AAPT tour on May 7
  • Public nights between May 15 and July 2
  • Joint star party sometime in mid-July.
  • The Q topic (was it put to rest?)

Afterwards, Bob Nelson made another Constellation of the month presentation, and we finally saw the completion of John Dobson’s Telescope Making video.


Rename the Planet by Orla Aaquist

According to the April 10th issue of our local newspaper, The Citizen, the Royal Astronomical Society of Canada, Vancouver Chapter, has proposed a contest to give the planet Uranus a new name. Why? Well, consider the following:

“What is the similarity between Star Trek’s USS Enterprise and toilet paper?” … “They both circle Uranus and wipe out Klingons!”

This poor planet has been treated with derision due to its pronunciation. Apparently, the contest is no joke. Are they being Sirius? There are various viewpoints we can take on this contest, but I hope that no one will seriously think that Uranus should be renamed because the name takes on other connotations in the English language. I speak Danish, and I know that the planet does not suffer
from a loss of dignity due to its pronunciation in this language, as is probably the case in other languages as well. Lets not make the same mistake of making English the centre of the universe. The Earth held that honour long enough, don’t you think?

I hope that the RASC gets a flood of silly suggestions, because silliness is the only logical interpretation of their contest. So send your suggestions to :

Name That Planet
c/o The Royal Astronomical Society of Canada, Vancouver Branch
1100 Chestnut St., Vancouver, B.C.
V6J 3J9


The Image Gallery

image3V6

Hubble image of COMET SHUMAKER – LEVY 9 See article this issueComet Crash Predictionsby Matthew Burke


PeGASus is published monthly by the Prince George Astronomical Society. Contributions to the newsletter are welcome.
Deadline for the May issue is Friday, May 13
Send correspondence to: The PGAS 3330 – 22nd Avenue Prince George, B.C. V2N 1P8 or Aaquist@cnc.bc.ca

PeGASus Newsletter Issue #46 – March. 1994

  • Editorial Comments
  • In the Sky
  • Monthly Meetings
  • Announcements
  • Science Fair Goodie Bag
  • Blind Spot Tester
  • Star on the Brink
  • The Image Gallery

Prince George Astronomical Society Executive 1993/94

  • President Orla Aaquist 562-2131/964-9625
  • Vice President Bob Nelson 562-2131/563-6928
  • Secretary Jon Bowen 563-9869
  • Treasurer David Sundberg 562-5774/6655
  • Members at Large Ted Biech 562-2131/564-2838
  • Matthew Burke 964-3889

Nominated Positions

  • Technical Director Bob Nelson
  • Observing Director Jon Bowen
  • Promotional Director Orla Aaquist
  • PeGASus Editor Shannon Austman

The Observatory phone number is 964-3600. This is a party line, so if it rings busy, it does not imply that someone is at the observatory.


Editorial Comments

Once again it is time for the editor come up with some new creative ideas as to how to fill these many pages with a small amount of text. This month, I have decided to increase the size of the margins; in some instances the size of the text had to be increased as well. I wonder what else we can increase the size of. Please send us your suggestions since we seem to be running out of words.


In the Sky by Alan Whitman

Venus dominates the western sky shortly after sunset. A slim two day old crescent moon will pass very close on the evening of April 12th. Both objects will be early crowd-pleasers on Astronomy Day, the 16th of April. By then the moon will have moved far above Venus as it will be just two days before First Quarter. This is when the moon is at its most impressive in a telescope.

Jupiter will be visible much of the night as it reaches opposition on the 30th. However, it is quite far south in Libra, at declination -14 degrees, so Jupiter will not climb high enough in the sky for fine seeing. consequently, for the next 4 or 5 years you cannot expect to see fine details like delicate festoons in Jupiter’s clouds. One exciting object orbiting Jupiter that experienced observers may want to try for is Comet Shoemaker-Levi. The April issue of Astronomy has a map and coordinates on page 57 — the comet is about 2 degrees SW of the planet and will require at least a 12 inch (30 centimetre) telescope and excellent conditions.

Spring features mainly galaxies. to view some interesting edge-on galaxies, see the article by Okanagan’s Ken Hewitt-White, also in the April issue of Astronomy. April normally has some of the best weather of the year in Prince George, so try to get out to the observatory and take advantage of it!


Monthly Meetings

At the last meeting of the PGAS after the usual discussions about the observatory progress:

Bob Nelson gave a detailed report on the astronomical observations and adventures of James Cook. Cooks attempted observations of the transit of Mercury were reproduced on PC Sky.

Orla showed some Hubble images recently obtained from the Space Telescope Science Institute via the electronic network, and demonstrated how the images are retrieved.

Next Meeting:

The next meeting of the PGAS will be held at CNC in the Physics Laboratory (room 2-223) on March 30th starting 7:30 PM. At this meeting, our plans for our Science Fair exhibit (April 8) and Astronomy Day activity (April 16) will be discussed.

Hopefully, Bob will give another excellent constellation of the month presentation, and Orla will finally get to reminisce about his experiences with his Amateur Telescope Making classes at the Calgary Centennial Planetarium.


Announcements

Setting Circles

Our new digital setting circles came and went. Bob noticed that the display elements were faulty, so they were sent back to the manufacturers.

Hubble Images Available

Dale Jepsen, one of CNC’s Astronomy students, has retrieved more images over the electronic network. In addition to more of the latest Hubble images from NASA, he has also retrieved some Magellan and Voyager images. The images are presently located on the PC in CNC’ physics laboratory. If you would like to see some of these images, or obtain GIF files of these images, give Orla a call at work (562-2131 local 307) or at home (964-9626).

Observatory Helpers Needed

Work at the observatory is progressing, but slowly. Bob Nelson has a crew out every Saturday trying to get our facility ready for upcoming events. If you have any time to spare on Saturdays, please come out and lend a hand. Contact Bob at 563-6928 for details.

WANTED

Brian Thair is looking for a 210 mm f/5.6 view camera lens with shutter. Image circle at f/22 not less than 200 mm. (Fujinon, Nikon, Rodenstock or Schneider). Call 561-5848: CNC box 277

Photographs Wanted

The PGAS needs photographs for our portfolio. If you have any which show the construction of the observatory or of our public activity, please contact Jon Bowen or Orla Aaquist.

If you have anything to announce or advertise, consider this space of the PeGASus.


Science Fair Goodie Bag by Orla Aaquist

Once a year the Central Interior Science Exhibition (CISE) committee organizes a regional science fair for the Central Interior school zones. This year the event will take place on April 8th and 9th at the College of New Caledonia. About 300 participants are expected, most of whom are at the elementary school level but also at the senior high school level. As part of the program, the CISE gives each participant a ‘goodie-bag’ as a token for taking part in the event. The ‘goodie-bag’ usually contains a number of small items such as a pencil, a note pad, stickers, bookmarks, small toys etc. donated by local businesses and organizations.

Although the PGAS does not have 300 items of anything to contribute, it is advantageous for us to make our presence known at such an event and have our name attached to some item which these young scientists can take home. Lacking ideas, I ran into Brian Thair (Dr. Bri the Science Guy) at the college and decided to tap his brain. It was easy! He has a very convenient release valve just below the left ear, and once you turn the knob a flood of information flows forth. He came up with a ‘Blind Spot Tester’. I promptly drew the design and put the PGAS logo on it (see the next page). Thanks, Brian for your contribution to the PGAS and the CISE.


Blind Spot Tester

blind_a


Star on the Brink credit: J. Hester/Arizona State University NASA PHOTO RELEASE NO.: STScI-PR94-09

The Image Gallery this month is a NASA Hubble Space Telescope “natural color” image of the material surrounding the star Eta Carinae, as imaged by the Wide Field Planetary Camera 2 (WFPC-2). Eta Carinae has a mass of approximately 150 times that of the sun, and is about 4 million times brighter than our local star, making it one of the most massive and most luminous stars known. Eta Carinae is highly unstable, and prone to violent outbursts. The last of these occurred in 1841, when despite its distance (over 10,000 light years away) Eta Carinae briefly became the second brightest star in the sky.

Pre-servicing mission HST observations taken with the WF/PC-I reveled new detail in the rapidly expanding shell of material which was ejected during the last century’s outburst. However, the earlier effects of HST’s spherical aberration obscured the structure of the material very near Eta Carinae itself. The clear view of Eta Carinae now provided by WFPC-2 dramatically demonstrates the ability of HST to reliable study faint structure near bright objects.

The picture is a combination of three different images taken in red, green, and blue light. The ghostly red outer glow surrounding the star is composed of the very fastest moving of the material which was ejected during the last century’s outburst. This material, much of which is moving more than three million kilometers miles per hour, is largely composed of nitrogen and other elements formed in the interior of the massive star, and subsequently ejected into interstellar space.

The bright blue-white nebulosity closer in to the star also consists of ejected stellar material. Unlike the outer nebulosity, this material is very dusty and reflects starlight. The new data show that this structure consists of two lobes of material, one of which (lower left) is moving toward us and the other of which (upper right) is moving away. The knots of ejected material have sizes comparable to that of our solar system.

Previous models of such bipolar flows predict a dense disk surrounding the star which funnels the ejected material out of the poles of the system. In Eta Carinae, however, high velocity material is spraying out in the same plane as the hypothetical disk, which is supposed to be channeling the flow.

This is quite unexpected. The WFPC-2 observations of Eta Carinae raise as many questions as they answer.

The Image Gallery

NASA Hubble Space Telescope “natural color” image of the material surrounding the star Eta Carinae, as imaged by the Wide Field Planetary Camera 2 (WFPC-2). PHOTO RELEASE NO.: STScI-PR94-09 credit: J. Hester/Arizona State University NASA See article ‘Star on the Brink’ in this newsletter.

carinae


PeGASus is published monthly by the Prince George Astronomical Society. Contributions to the newsletter are welcome.

Deadline for the April issue is Friday, April 15

Send correspondence to: The PGAS 3330 – 22nd Avenue Prince George, B.C. V2N 1P8 or Aaquist@cnc.bc.ca

PeGASus Newsletter Issue #45 – Feb. 1994

  • Editorial Comments
  • In the Sky
  • he Astronomical Observations of James Cook
  • Monthly Meetings
  • Announcements
  • DIAMONDS IN THE SKY
  • Picture Perfect
  • Astrology Survey
  • The Image Gallery

Prince George Astronomical Society Executive 1993/94

  • President Orla Aaquist 562-2131/964-9625
  • Vice President Bob Nelson 562-2131/563-6928
  • Secretary Jon Bowen 563-9869
  • Treasurer David Sundberg 562-5774/6655
  • Members at Large Ted Biech 562-2131/564-2838
  • Matthew Burke 964-3889

Nominated Positions

  • Technical Director Bob Nelson
  • Observing Director Jon Bowen
  • Promotional Director Orla Aaquist
  • PeGASus Editor Shannon Austman

The Observatory phone number is 964-3600. This is a party line, so if it rings busy, it does not imply that someone is at the observatory.


Editorial Comments

February is a short month and our second meeting of the year seems to fall on the heals of the first. Yet some exciting things have happened since the last newsletter.

The Hubble as been fixed. The image gallery this month illustrates the extent of the improvement. The three images were obtained directly from the JPL by Jon Bowen over the electronic network. We have commissioned a CNC student to retrieve all of the available images (or as many as our computer will hold) and they should be available by the next meeting.

Our long awaited digital setting circles arrived. They were tested by Bob, Jon, Matthew, Gill and Orla on a very cold February 2nd. Bob Nelson should be able to tell us more at the next meeting.

We have two rude cats. They wake me up every morning at 5:30 and demand food. The fat one sits on my shoulder and purrs. That wouldn’t be so bad if she didn’t also drool in my ear. The white amazon huntress almost rips my face off when she periodically (with a frequency of 1 per minute) dashes across the head of the bed, emitting a loud yowl in the process. I have tried to ignore them, but this is not possible because of the poor attitude of one white she-devil. So I am up at 5:30 every morning. This is a good time to give me a call if you want to chat.


In the Sky by Alan Whitman

Late in February Venus becomes visible very low in the south-west after sunset. It remains an evening star through to early October. On Sunday, March 13th, the thin two-day-old crescent moon will be about 10 degrees above the Venus. Jupiter continues to dominate the morning sky. By mid-March it rises before midnight.

Have you ever seen the zodiacal light? February and March are the best months to see it in the evening sky because of celestial geometry. You will need a fairly flat western horizon without any light pollution. The zodiacal light is not difficult to see. It’s brightest parts are actually brighter than the Milky Way, but it is a large softly glowing pyramid without definite boundaries. It is rather formless compared to the Milky Way, and so can be overlooked. Look for a triangular glow lying through Pisces and Aries (both zodiac constellations, of course) after the end of astronomical twilight. The broad base of the triangle is just above the western horizon while the vertex is farther south. Venus will indicate where the base of the zodiacal light will later appear (and fortunately, Venus will set before the end of twilight, so its brightness will not interfere). Look during the period from February 28th through March 12th when the early evening sky is moonless. The zodiacal light and its fainter extensions, the zodiacal band and the Gegen- schein, are unique in that they are only visible with the naked eye. They cannot be viewed in binoculars and telescopes because the field of view is too small to include the surrounding darker sky for contrast..


James Cook (The Astronomical Observations of James Cook) by Bob Nelson

In the summer of 1768 (Aug 26), Lieutenant (later Captain) James Cook, R.N., set sail from Plymouth, England in the barque Endeavour to make the first of his three great voyages of discovery into the Pacific. His ship was fully equipped for three years at sea and in James Cook, it had one of the foremost seamen and navigators of history. Also on board were three scientists: Charles Green, the assistant to the Astronomer Royal, Joseph (later Sir Joseph) Banks, the President of the Royal Society, and Dr. Solander, an able biologist.

The principal intention of the expedition was to observe the transit of Venus on 1769 June 3 from the Pacific (only the start of the event was visible from London). After the observation, Cook was to make whatever discoveries he could in the South Seas. As it turned out, Cook made the observation of the transit of Mercury in Tahiti, went on to discover New Zealand (making an observation of the transit of Mercury on 1769 Nov 9 near present-day Auckland), and continued on to explore the uncharted east coast of Australia.

What was so important about the transit of Venus? Also, what is a transit? To answer the second question first, a transit is the passage of a smaller object in front of a larger one. Only the planets Mercury and Venus can transit the Sun – Mercury transits about 13 times per century; Venus transits less often, only a couple of times per century. [There were transits of the Sun by Venus in 1874, 1888, none in this century, and there will be transits in 2004 June 8, and in 2012 June 6.]

To answer the initial question, one has to understand the determination of distances in the Solar System. Since the time of Copernicus, astronomers have known the relative distances of the planets from the sun (ie. a scale drawing could be made). However, the absolute distance between any two objects in Earth units (eg the kilometre) was much harder to obtain – only rough estimates could be made. Therefore the astronomical unit (the mean distance of the Earth from the Sun) was only approximately known. If one could determine precisely the distance between the Earth and another planet at closest approach, one could calculate all the other distances.

The transit of Venus was deemed to be a rare opportunity to determine such a distance precisely. Here’s how it was supposed to work: observers at different places on the Earth were to record the instant at which an edge of Venus touched the edge of the Sun (either externally or internally) to within a few seconds. If the distance between observers was around 6000 km or more, time differences of between 5 and 15 minutes (depending on the geometry of the situation) should be detected. By the appropriate calculations, it was hoped, astronomers would be able to determine the distance to Venus and hence, to the Sun.

In the event, unfortunately, James Cook’s chronometers were fast by about four minutes and the results were useless (just try to find a reference to the event in any astronomical text!). By fortunate circumstance, I have obtained a reprint of James Cook’s diary (published 1925) and, with the aid of Guide 2.0 software, I can accurately recreate both transits. In doing so, we can learn about the observations that James Cook and his scientific passengers made. A presentation will be made at the February meeting using the observatory’s computer and whatever else I can get together.


Monthly Meetings

Last Meeting

At the last meeting of the PGAS, Bob presented another excellent constellation of the month. Then, after some trouble with the video player, the first half of John Dobsen’s tape on Telescope Making was played. The cookies were enjoyed by everyone; lets hope that Orla remembers to buy some more for the next meeting.

At the start of the meeting, Orla summarized some of the activities that the club will be involved with this year: Among them were

  • Science Fair Tour/CNC Booth April 8
  • Astronomy Day April 16
  • AAPT/Articulation Tour May 6 & 7
  • Public tours May 1 to June 25
  • Canada Day Participation? July 1 & 2
  • Grand opening (the Q subject) August 17

Next Meeting

The next meeting will be held at CNC in the Physics Laboratory (room 2-223) on February 23rd. The meeting will start at 7:30 PM with a short business reports. Afterwards, Bob will give a more detailed report about the astronomical observations of James Cook, Jon will show some of the Hubble computer images recently obtained from JPL, and finally John Dobson will conclude their presentation on telescope making.


Announcements

Observatory

Our new digital setting circles have arrived. They are still being tested, and we may have some results by the next meeting. Hopefully, we will have pointing accuracy to within one field width in the near future.

Observatory Computer

When you go out to the observatory, please take care NOT to use the computer if the temperature is below freezing. Damage to the hard drive may occur. Thank you.

Hubble Images Available

Jon Bowen and Orla Aaquist have retrieved some of the latest Hubble images from NASA and various other places. The images are transferred to CNC via electronic mail from the public information area on the JPL computer. If you would like to see some of these images, or obtain GIF files of these images, give Orla a call at work (562-2131 local 307) or at home (964-9626).

Photographs Wanted

The PGAS needs photographs for our portfolio. If you have any which show the construction of the observatory or of our public activity, please contact Jon Bowen or Orla Aaquist.

Free Space for Announcements

If you have anything to announce or advertise, consider this space of the PeGASus.


DIAMONDS IN THE SKY by Matthew Burke

During the period between July 16, 1994 to July 22, 1994 the major fragments of the comet Shoemaker-Levy 9 will collide on the dark side of Jupiter. Pictures of the comet show specks of light travelling in a row resembling a string of diamonds. Depending on the size of the fragments, the collisions could be the most spectacular event ever witnessed by Astronomers.

The comet Shoemaker-Levy 9 was discovered by Carolyn Shoemaker, Eugene Shoemaker, and David Levy at the mount Palomar Observatory on March 25, 1993. This is the 9th comet the team has discovered. David Levy is credited with 19 comet discoveries which ranks him the second most successful living comet hunter, after Carolyn Shoemaker who has discovered 30 comets. Shoemaker-Levy 9 is a 13.8 magnitude object and was found on photographic plates taken using an 18″ Schmidt camera. The comet is believed to have been in orbit around Jupiter for 20 years, with the aphelion at about 0.33 AU (note one Astronomical Unit = 149,600,000 Km) and an eccentricity over 0.995. On July 7, 1992 it came 94,000 Km to the centre of the planet (within the Roche limit) tearing it apart into the 21 major fragments seen today. The progenitor comet size is believed to be 10 Km in diameter, although sizes of 20 Km – 2 Km are also speculated. The comet fragments are estimated to be between a fraction of kilometre up to 5 Km in diameter. More accurate observations by the Hubble Space Telescope will confirm the actual sizes.

The size of the fragments is very important because the kinetic energy released is equal to 1/2 of the mass times the velocity squared. At time of impact the speeds are estimated to be around 60 Km/sec. An object with a mass (in grams) of 10 to the eighth power will release energy at a peak rate of .02 megatons of TNT per second yielding an apparent visual magnitude of +10. While an object with a mass of 10 to the power of sixteen grams will release energy at a peak rate of 100,000 megatons of TNT per second yielding an apparent visual magnitude of -10 (Science – Vol. 262 – 15 October 1993).

The new impact estimates from Sekenina, Paul Chodas, and Donald K. Yeomans (of Jet Propulsion Laboratories) are located five to nine degrees behind the limb, – 44 degrees Jupiter latitude @ 67 degrees east (towards the sunrise terminator) from the midnight meridian. At this location any explosions reaching 1000 Km above the cloud tops of Jupiter will be directly observable. Although the impact locations are out of sight of earth bound eyes, the spacecraft Galileo @ 1.34 AU from Jupiter, Voyager 1 @ 52 AU, Voyager 2 @ 41 AU, and Ulysses will be in position to directly observe the impacts. Unfortunately software controlling the on- board cameras on both Voyager 1 & 2 has been deleted making imaging the impacts in the visual spectral range unlikely. The only Voyager instruments likely to observe the impacts are the ultraviolet spectrometers and planetary radio astronomy instruments. The Ulysses spacecraft will monitor the event in radio waves. Unfortunately Galileo’s antenna array is damaged, limiting its data transition rate at a pitiful 10 bits per second. Galileo will be the only spacecraft to directly image the impacts.

Comets are thought to be primordial balls of frozen gas, ice, and dust formed in the outer solar system and are often described as “dirty snowballs”. Generally they are composed of gases (ammonium, carbon dioxide, carbon monoxide, methane), water (70-80%), and dust: (20-30% metals & rocky material). Comets travel in highly elliptical orbits around the sun and can have orbital periods of tens of years to tens of thousands of years. Comet tails are formed by vaporized dust and gas swept back by the pressure of solar light and can be millions of kilometres long.

tres long. Jupiter is the largest plant in the solar system, with more mass than all other planets combined. It is composed of mostly hydrogen and helium with a bulk density slightly higher than water. Jupiter orbits at an average distance of 5.2 AU from the sun, and takes 12 earth years to orbit the sun. A day on Jupiter lasts 9 hours 55 minutes. The planet has an equatorial radius of 71,398 Km, and the second most extensive system of moons in the solar system with 16.

Stay tuned for next months issue when I report on detailed predictions of the collision effects, and local times of the collisions.

References Astronomy, Vol 22 Issue 1 Jan 1994 page 19 Astronomy, Vol 21 Issue 12 Dec 1993 page 18 Astronomy, Vol 21 Issue 9 Sep 1993 page 18 Nature, Vol 140 Issue 1898 Nov 6 , 1993 page 18-19 Nature, Vol 356 Issue 6448 Oct 21, 1993 page 731-733 Nature, Vol 363 Issue 6429 Jun 10, 1993 page 492-493 Science, Vol 262 Issue 5133 Oct 22, 1993 page 505 Science, Vol 262 Issue 5132 Oct 15, 1993 page 382-387 Science, Vol 261 Issue 5121 Jul 30, 1993 page 552 Scientific America, Vol 269 Issue 3 Sep 1993 page 26-30 Science News, Vol 143 Issue 26 Jun 26, 1993 page 410 Natural History, Vol 102 Issue 10 Oct 1993 page 40-42 Maclean’s, Vol 106 Issue 31 Aug 2, 1993 Page 42 Sky & Telescope, Vol 86 Issue 1 Jul 1993 page 38-39 World Book Information Finder (c) 1993 World Book Inc (Jupiter, Comet) Comet/Jupiter Collision FAQ Last Update 18-Jan-1994 page 1-7


Picture Perfect Photo release number: STScI-PR94-02 figure caption (modified)

The image below is of the spiral galaxy M100 obtained using the second generation Wide Field and Planetary Camera (WFPC-2), installed in the Hubble Space Telescope during the STS-61 Servicing Mission. The WFPC-2 contains modified optics to correct for the aberration of the Hubble’s primary mirror. The new optics will allow the telescope to tackle many of the most important scientific m100_aprograms for which the it was built, but had to be temporarily shelved with the discovery of the spherical aberration in 1990.

The picture shows a mosaic of the images taken with WFPC-2s four separate cameras. The three Wide Field cameras give HST its “panoramic” view of astronomical objects. The Planetary Camera, has a smaller field of view but provides better spatial resolution. The image shows the fields of view of the four cameras combined into a “chevron” shape, the hallmark of WFPC-2 data. The three wide field detectors in the camera reveal individual stars and filamentary dust lanes in the outer arms of the majestic spiral galaxy. The instrument’s planetary camera image (upper right) resolves complex structure in the core of the galaxy, which is the site of vigorous star formation. The image was taken on December 31, 1993. The field of view is about two and a half arc minutes across.

Though the galaxy lies several tens of millions of light-years away, modified optics incorporated within the WFPC-2 allow Hubble to view M100 with a level of clarity and sensitivity previously possible only for the very few nearby galaxies that compose our Local Group. Just as one does not learn about the diversity of mankind by conversing only with your next door neighbour, astronomers must study many galaxies in a host of different environments if they are to come to understand how our own galaxy, our star, and our earth came to be. By expanding the region of the universe that can be studied in such detail a thousand fold, the WFPC-2 will help the Hubble Space Telescope to fulfil this mission.

One of the greatest gains of the high resolution provided by Hubble is the ability to resolve individual stars in other galaxies. The new camera not only allows astronomers to separate stars which would have been blurred together at the resolution available from the ground, but also allows astronomers to accurately measure the light from very faint stars. The quantitative study of compositions, ages, temperatures, and other properties of stars and gas in other galaxies will provide important clues about how galaxies form and evolve.

In addition, the WFPC-2 will allow the Hubble Space Telescope to be used to attack one of the most fundamental questions in science: the age and scale of the universe. Astronomers have many ‘yardsticks’ for measuring the scale of the universe, but lack a good knowledge of how long these yardsticks really are. M100 is a member of the Virgo Cluster of galaxies. By allowing astronomers to resolve and measure individual stars in the Virgo Cluster (in particular a special type of star called Cepheid variables, which have well known absolute brightness values) HST observations are expected to provide a crucial measurement of this much needed scale. Only the Space Telescope can make these types of observations. Cepheids are too faint and the resolution too poor, as seen from ground-based telescopes, to separate the images in such a crowded region of a distant galaxy.


Astrology Survey

A York Astrology/Astronomy Survey (RASC Victoria SkyNews No. 149) reports that a survey of over 1500 first year university Arts and Science students reveals that approximately 40% “subscribe at least somewhat to the principles of astrology”, and over half are unable to distinguish between astronomy and astrology. The response from the Science students are not markedly different from the Arts students.


The Image Gallery

melnick34The three images below were retrieved from pubinfo@jpl.nasa.gov by Jon Bowen. The three panels show images of a very bright Wolf-Rayet star, Melnick 34, located in the Large Magellanic Cloud. In the background are a number of fainter stars that are comparable in brightness to our Sun. The first image is the best available ground-based image of the region. This image was taken under ideal atmospheric conditions (0.6″ resolution). The second image shows the spherical aberration which was present before the repairs were made. In particular, there is a 4″ skirt around the bright star which obscures the view of the sky in its vicinity. The last image was taken with the improved optics. As can be seen, the aberration is gone from the central star. Note that a large number of fainter stars also become visible. This is because their light is now concentrated in the star’s image rather than in a halo. This makes quantitative measurements of their brightness possible.


PeGASus is published monthly by the Prince George Astronomical Society. Contributions to the newsletter are welcome.

Deadline for the March issue is Friday, March 18

Send correspondence to: The PGAS 3330 – 22nd Avenue Prince George, B.C. V2N 1P8 or Aaquist@cnc.bc.ca

PeGASus Newsletter Issue #44 – Jan. 1994

  • Editorial Comments:
  • In the Sky
  • Monthly Meetings
  • Announcements
  • Hubble News
  • What Lunar Eclipse?
  • Image Gallery

PeGASus – News Letter of the Prince George Astronomical Society – January 1994 Issue #44


Prince George Astronomical Society Executive 1993/94

  • President Orla Aaquist 562-2131/964-9625
  • Vice President Bob Nelson 562-2131/563-6928
  • Secretary Jon Bowen 563-9869
  • Treasurer David Sundberg 562-5774/6655
  • Members at Large Ted Biech 562-2131/564-2838
  • Matthew Burke 964-3889

Nominated Positions

  • Technical Director Bob Nelson
  • Observing Director Jon Bowen
  • Promotional Director Orla Aaquist
  • PeGASus Editor Shannon Austman

The Observatory phone number is 964-3600. This is a party line, so if it rings busy, it does not imply that someone is at the observatory.


Editorial Comments:

This is the first issue of 1994, and I know that all of you made a New Year’s resolution to contribute more to this newsletter. So I have left lots of room for your contributions. I am writing this on January 10, and there is still a whole week for you to submit your article. I am confident that you will ‘hit’ the keyboard some- time this week. I am sending you a psychic message to this effect. You long to pick up a pen and start writing something astronomical. If you don’t, I will start accepting astrological articles from Zelda. It’s almost the same thing, isn’t it? Just kidding, Bob.

For the last few months I have been sending our newsletter to various RASC centres in western Canada hoping for an exchange of newsletters. So far only the Victoria Centre has responded by putting us on their mailing list. THANKS VICTORIA! How about the other centres? We would like to receive a copy of your newsletter, too.

Oh, yes. Sorry for the brief newsletter last month. We’ll try to do better next Christmas.


In the Sky: by Alan Whitman

Saturn is leaving the evening sky this month, as the sun approaches. Meanwhile Mercury, which never gets very far from the sun, makes its best evening appearance of the year. It will be best placed on February 1st and will shine brightly at magnitude -1 during mid-twilight. If you find Mercury on the 1st, binoculars will reveal Saturn only 1.3 degrees to the south but two magnitudes fainter. Mercury is always easiest to see each year during the evening apparition closest to the spring equinox and this is the one–imagine that, a sign of spring already!

Mercury is not that difficult a target when it is this well placed and this bright (its magnitude varies far more than that of any other planet). However, you will need a flat WSW horizon. Try Highway 16 in the Beaverly area or Foothills Drive along the big hill near Ridgeview Drive. The last week of January and the first week of February is about the whole apparition.

Jupiter still rules the morning sky, rising by 1 AM at the beginning of February and is in the south during morning twilight. If you are still unhappy about being clouded out during the lunar eclipse, Jupiter’s system offers another chance. Did you know that eclipses of Jupiter’s moons can be watched two or three mornings a week! The smallest telescope will do the job.

Here are the times of a few events (PST):

  • Jan 31 5:22 AM Io eclipsed8:10 AM Ganymede eclipsed (two in one morning but this is only 7 minutes before sunrise so you must begin following Jupiter in your telescope by about 7:40)
  • Feb 2 3:14 AM Europa reappears from eclipse VERY CLOSE to Jupiter and disappears behind the planet only 11 minutes later
  • Feb 7 7:15 AM Io eclipsed
  • Feb 9 1:43 AM Io eclipsed (Jupiter is low in the SE) 3:27 AM Europa eclipsed 5:50 AM Europa reappears from eclipse
  • 6:00 AM Europa disappears behind Jupiter For more phenomena of Jupiter’s moons, consult Sky and Telescope magazine at the CNC library. You can also watch total solar eclipses as the shadows of the moons move across Jupiter’s disk with a good quality telescope (I’ve seen the shadows with a good 60mm refractor when the seeing was very good and Jupiter was unusually close, displaying a disk a full 50″ in diameter).
  • I’ve been struck by how many British Columbians go out in the winter. If you’re one, don’t forget your binoculars or a portable telescope. You can see many things that never rise this far north and over the course of the night half of the sky will wheel overhead. Going south in February, say to Hawaii or the Mexican Riviera? This will put you more than 30 degrees of latitude south of Prince George. Here’s a taste for late February:
  • 8 PM: Sirius, the brightest star, is more than halfway up the southern sky, instead of low in the south as we are used to. But there is a bright star low in the south right about where you usually see Sirius. Canopus! The second brightest star in the sky can never be seen from Prince George but in Hawaii it mimics Sirius, scintillating like Sirius does low in our winter sky.
  • 10 PM: The southern constellations Puppis, Carina, and Vela float across the south along with the Vela portion of the Milky Way.
  • Midnight: Crux, The Southern Cross, and Centaurus are rising in the SE. Leo’s Sickle is right overhead.
  • 2 AM: Crux is due south but it’s too low to see the Coalsack (save that for Australia). If you’ve brought your telescope and found a dark sky, the galaxies of Virga and Coma Berenices are overhead while the Sombrero Galaxy (M104) is 55 degrees up. (The Sombrero is fairly good from Kelowna but it just never gets high enough in Prince George).
  • 3 AM: Omega Centauri is the best globular cluster in the sky. It is unmistakeable in binoculars about 35 degrees below Spica and easily resolved in almost any astronomical telescope at 60X. Just 4 degrees to the north lies one of the finest galaxies in the sky, NGC 5128 with the most prominent dark lane of any galaxy (also known as Centaurus A).
  • 5 AM: This view is worth the price of the trip! One of the most attractive constellations in the sky is Scorpius and it even looks like a scorpion. From PG only the top half of Scorpius struggles above the horizon; from Mexico it is a curling splendour with ruddy Antares half way to the zenith! The Sagittarius Milky Way is high in the SE and from a dark site it looks like the photographs, not like the anaemic glow we see here. The real surprise is seeing that the Milky Way spreads far beyond the brightest portion in Sagittarius. From a dark southern site the glow bathes much of Scorpius and part of Ophiuchus (home of the big 7 degree long dark Pipe Nebula which is visible to the naked eye–a dark pipe (what else) against the bright Milky Way.) So if you go south for the winter for some summery weather, rising before dawn will also give you the summer stars and it will be a view that you will never forget. (The trick of course is to find a safe dark site).

Monthly Meetings:

Last Meeting

There was no meeting in December. Rather a few members met at Alan, Gretchen and Jennifer Whitman’s house for a PGAS Christmas party. Thank you for a wonderful time and the great food. Gerhard and Riva Bierman contributed a wonderful party tray of seafood morsels and the rest of us contributed hearty appetites.

Next Meeting

The next meeting will be held at the College of New Caledonia in the Physics Laboratory (room 2-223) on January 26th. As usual, the meeting will start at 7:30 with a short business report from the various executive and directors.

Bob Nelson will once again entertain us with the constellation of the month presentation. Then John Dobson will talk to us about telescope making. Both Bob and Orla have built telescopes in the past and they will attempt to add a lively commentary to this interesting video. If there are any club members who are interested in assembling their own telescope and grinding their own mirror, this meeting is a ‘must’.

We need your ideas to make our monthly meetings a success. What would you like to see happen at these meetings? What other activities would you like to see happen at these meetings? What other activities would you like to see our club participate in? What do you want out of the club?


Announcements

Observatory Bookings

The observatory is available to PGAS members for their personal observing projects. It is also open for special interest groups such as schools and cubs. If you want to book the observatory, contact the Observatory Director (Jon Bowen, 563-9869), before finalizing your observing plans to ensure that conflicts do not arise. Also, not all of our equipment is kept at the observatory at all times because of our activity with the Scientist in the School Program and The PeGASus Project.

Astrology

Get your computer generated horoscopes and detailed personality profile from Zelda.

Sky and Telescope Subscription

The club is eligible for a subscription discount to the magazine Sky and Telescope. As a member of the PGAS you can take advantage of this discount if we order the magazine through the club. If anyone wants to subscribe to the magazine, please give Alan Whitman a call or let us know of your interest at the next monthly meeting. We can probably get a subscription discount from Astronomy too. Let Orla know if you are interested.

Hubble’s Glasses Work

The Hubble telescope is now fixed and reports claim that its vision is ‘beyond anyone’s wildest dreams’.

Astronomy and Music

Astronomy is truly music of the spheres. If you don’t believe this, come down to the Fraser Fort George Regional Museum by 7:30 PM on January 20 and hear a presentation given by Orla Aaquist. This is a family event. Call the museum at 562-1612.

Astronomy Anyone?

Observing is not much good these days. If its not cloudy, its freezing cold, and if it isn’t snowing, its raining. How about some armchair astronomy in the warm comfortable setting of CNC to wait out the rest of the winter? Orla is willing to hold weekly evening astronomy classes for members if there is enough interest within the club. Give him a call at home (964-9626) or at work (562-2131 local 307). This would be strictly a non-algebra course, lots of discussion and absolutely no pressure to learn anything unless you want to.

No Heat at the Observatory

There will be no heat at the observatory this winter due to lack of funds. If you go out there, bring your own heat.

Observatory Computer When you go out to the observatory, please take care NOT to use the computer if the temperature is below freezing. Damage to the hard drive may occur. Thank you.


Hubble News

The following electronic mail was received from Chris Brougham at the editor’s office on January 15.

From: <brog@vanbc.wimsey.com>

Hi Orla, I thought you might be interested in this NASA/JPL Press Release (perhaps for inclusion in the newsletter?) as well as an offer from me to obtain any HST images that have recently been released. I have easy access to the site and a high speed modem to transfer the images to disc (or send them to you in a uuencoded format via e-mail). Let me know.

FOR IMMEDIATE RELEASE January 13, 1994

PUBLIC INFORMATION OFFICE JET PROPULSION LABORATORY CALIFORNIA INSTITUTE OF TECHNOLOGY NATIONAL AERONAUTICS AND SPACE ADMINISTRATION PASADENA, CALIF. 91109. TELEPHONE (818) 354-5011

Contact: Diane Ainsworth

NASA today announced the completion of its planned series of adjustments and tests of the cameras onboard the orbiting Hubble Space Telescope and released images showing that the telescope’s desired performance has been restored.

NASA today announced the completion of its planned series of adjustments and tests of the cameras onboard the orbiting Hubble Space Telescope and released images showing that the telescope’s desired performance has been restored.

The announcement was made at NASA’s Goddard Space Flight Center in Greenbelt, Md., by NASA Administrator Daniel S. Goldin and Sen. Barbara A. Mikulski (D-Maryland), chair of the Senate subcommittee responsible for appropriating NASA funding.

In successive news panels following the announcement, scientists, engineers and managers at NASA’s Jet Propulsion Laboratory expressed satisfaction that the space telescope’s Wide-Field and Planetary Camera-II was performing perfectly. The camera, designed and built at JPL, is the principal imaging instrument aboard the observatory and was used to take most of the images NASA released today.

The Hubble servicing mission, conducted in December 1993 aboard the space shuttle Endeavour, put in place a new JPL-built camera that incorporates correc- tive optics to compensate for a flaw in Hubble’s 2.4-meter (94.5-inch) diameter primary mirror. Shortly after launch, star images from the newly deployed telescope showed that the surface of the mirror was too flat by an amount equal to about 1/50th the width of a human hair and that images could not be brought to a sharp focus.

The corrective optics in the new camera have completely eliminated this blurring so that images are essentially in perfect focus, according to Dr. John Trauger of JPL, principal investigator of the new Wide-Field and Planetary Camera-II.

Once the new camera was installed, the original Wide-Field and Planetary Camera-I, also designed and built at JPL, was returned to Earth by the STS-61 astronauts for possible reuse at a later time. Except for the flaw in the telescope itself, the original camera had also performed perfectly, scientists reported, and was used to record most of the images obtained to date from the Hubble telescope.

In addition to the Wide-Field and Planetary Camera-II, the Endeavour astronauts also installed the Corrective Optics Space Telescope Axial Replacement, or COSTAR, a telephone-booth-sized instrument that carries corrective optics to offset the telescope flaw for three other science instruments aboard Hubble: the European Space Agency’s Faint Object Camera and the Goddard Space Flight Center’s High Resolution Spectrograph and Faint Object Spectrograph.

The astronauts replaced the telescope’s solar panels, used to generate electricity from sunlight to power the observatory, because the original panels were found to cause vibrations of the telescope when it passed into and out of Earth’s shadow. Replacement gyroscopes and an upgraded computer memory were also installed during the highly successful servicing mission in early December.

The refurbished Hubble Space Telescope is now capable of achieving the scientific objectives for which it was originally designed, scientists and engineers concurred at the news conference.

The images released today show, for example, that the telescope is for the first time able to see individual stars that are imbedded in galaxies at the distance of the Virgo cluster some 65 million light years away. These stars are of about the same brightness as Cepheid variable stars, which are used by astronomers to measure distances.

A key science program of the Hubble telescope to accurately calibrate the cosmic distance scale — currently uncertain to within a factor of about two — will also become possible for the first time.

Other images released today show how well the telescope will be able to produce clear, sharp images of the densely populated regions near the cores of galaxies and star clusters, previously thwarted by the telescope’s blurred imaging.

Images that were taken with the new Wide-Field and Planetary Camera-II reveal well-resolved shots of newly forming stars in the nearby Orion nebula. They also show previously unseen structure in the exploding star Eta Carinae, which is located in one of the Magellanic clouds just outside the Milky Way galaxy.

In one of the images, the expanding gas clouds around Eta Carinae have grown larger than they were when first observed by Hubble, as the result of the clouds’ expansion at a speed of about 1,000 kilometers per second.

The Wide-Field and Planetary Camera-II was designed and built by JPL for NASA’s Office of Space Science, Washington, D.C.

1-13-94 DEA # 9405


What Lunar Eclipse? by Orla Aaquist

It was not clear in Prince George for the lunar eclipse on November 28. The observatory was open for the event, and I thank the members who dropped by to help: the entire Bowen family (who brought hot chocolate and cookies), Matthew Burke and Bob Nelson. It has been a while, so I probably forgot someone. Sorry. Although we saw nothing of the moon, we did see an exciting episode of ‘Deep Space 9’ (thanks for the rabbit ears, Steve) and a video of John Dobson making a telescope.

Despite the clouds, two local families dropped by to have a look at our facility.

My parents in Edmonton saw the eclipse from their back steps. They are not astronomers. To them, astronomers are people who look up at the stars and waste the taxpayer’s money rather than doing something useful like digging ditches or being a doctor. My parents do not know the difference between a lunar eclipse and a solar eclipse and had never seen either one until November 28. So when I asked them to keep an eye on the moon on the evening of November 28, they asked me, ‘Which eye?’

Yes, they did have a look at the eclipse, several times during the evening, in fact. They were impressed. Now, I know I shouldn’t advertise this fact, but I have never seen a lunar eclipse, so I was curious what an eclipsed moon looked like. The photos in Sky and Telescope show a moon with an orange shading. However, they told me that the moon looked blue during the eclipse. Can an eclipsed moon look blue?


The Image Gallery

eagle_a

A CCD image of the Eagle Nebula in Serpens taken by Jack Newton. The exposure is 300 seconds.


PeGASus is published monthly by the Prince George Astronomical Society. Contributions to the newsletter are welcome.

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