Monthly Archives: March 1994

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.


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.


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


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.


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