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