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Auburn Astronomical Society E-Newsletter November, 2000 In this Issue
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This month's meeting will be on Friday, November 3 at 8:00 PM, in room 215 of the Aerospace Engineering building, on the campus of Auburn University. Anyone from the Montgomery area wishing to car-pool, should meet at my house (518 Seminole Dr., Montgomery). We'll head for Auburn at 7:00PM. Our New Moon weekend falls on November 23, the Saturday after Thanksgiving. If you're not too full of left-over turkey sandwiches and if you've OD'd on football games, we'll have a star party to cleanse the soul. Location T.B.A. Dec. 1 Monthly Meeting -- Larry
Lee speaking on The Origins Of The Space Shuttle
Discount Magazine Subscriptions Sky & Telescope magazine and Astronomy magazine club subscriptions will be due this month. SKY & Telescope magazine will cost $ 29.95 (regular $ 39.95). We will need at least 5 subscriptions to qualify. SKY Publishing also gives a 10% discount on books and products to those in Club Plan. Astronomy magazine
will cost $ 29.00 (regular $ 39.95). Kalmbach Publishing Company gives
discount on their list of Kalmbach books:
You may bring your checks made payable to "Auburn Astronomical Society", to the November meeting or mail them to: John Zachry
If you have any questions, e-mail John at: jbzachry@mindspring.com CCSSC Telescope
Clinic
Secondly, I'm writing you to let you know about an event that we have coming up, and to see if anyone from your group might want to participate. Our event is called "So You Want To Buy A Telescope," scheduled for Sat. Nov. 4th (3:30 PM EST). It will be an informational workshop for those interested in buying telescopes at Christmas time. Discovery Telescopes is sponsoring the event and has donated an 8-inch Dob to be given away as a door prize. We anticipate a pretty good crowd. I thought it might be a good opportunity to promote your society. We could provide you a table and you could give out information (?), or whatever you'd like to do. Also after the workshop, we'll be having an observatory open-house, which (if y'all brought your 'scopes) you could join in on, as well. I've also invited the Atlanta group to come down. (Believe it or not, we don't seem to have an active club in town!) Anyway, if you're interested in participating, we'd love to have you. Even if you just want to direct some would-be telescope buyers this way, that would be great, too. As a note about future events, we're working on getting the Astronomy editor for the journal Nature (U.S. office in D.C.) down for a talk in January. He's a friend of mine, and we're just trying to work out the travel details now. If this comes about, I'll send you a note, in case you want to pass it on to your members. Thanks for your time!
As is typical for late October, the foliage along the way to McComb Mississippi and back was at its colorful peak. Hazy skies most of the way over there Wednesday gave little incentive to keep going but, as I've come to learn, weather is almost always unpredictable. The sky had cleared to a deep azure somewhere between Jackson and McComb. When I arrived at the observing field at 2:30 PM. I found the field nearly full of telescopes. So much so, that I elected to set up on the western edge of the field -- across the way from our traditional spot near the Mobile and Jackson clubs on the eastern side. Because of a prior commitment, I had to limit my stay this year to just Wednesday and Thursday nights. But, what glorious nights they were! Both nights were spent on an eclectic mix of old favorites and deep-sky challenges. The solar system was well represented with Uranus and Neptune early in the evening, followed by Saturn and Jupiter (in wonderful detail) a bit later. Wednesday night I swapped eyepieces and filters with Greg Thompson of the Mobile Astronomical Society, as he put his recently completed home-built 16-inch Dob (Gregg won 1st place in the home-made telescope competition) through its paces. Thursday was another gorgeous day -- shirt-sleeve temperatures during the day followed by sweat-shirt temperatures at night. Around midday, our old observing buddy, Rod Mollise, arrived for our annual reunion. Late Thursday afternoon, we adjourned en masse to "Mr. Whiskers" for catfish supper. Thursday night I filled in my observing gaps from the previous night until just after midnight. The only other delegate from AAS was Robert Rock, who didn't arrive until after I left. Reports I've read said that the seeing was at its best Friday night showing incredible detail on the gas giants. There was an incredible diversity of telescopes types -- no two quite the same. A virtual smorgasbord of hardware and expertise to draw on is to be had there. For those of you who have been before, you know what I mean. If you've never been -- well, I think you'd really enjoy it. DSRSG 2001 will be from October 17 to October 21. Keep up with all that's happening at at DSRSG at www.egroups.com/group/Deep-South-Regional-Star-Gaze PSSG 2001 Moved
to September
After suffering through every spring trying to keep it away from Easter, close to the New Moon weekend and not too cold and not too warm, I polled all of you who went to the event with an on-line questionnaire last summer asking about having the event in the spring, September or October. With only one or two exceptions, the answer was for the New Moon weekend in September. Thus, it will be Thursday-Sunday, September 13-16, 2001. The featured guest will be Wil Tirion. We've received quite a few e-mail address changes:
Richard has done some astrophotography in the past and is telescope shopping now. We look forward to having Richard at the meetings and star parties. Rod Havens bbhavens@gte.net writes that he is recovering from oral surgery and looking forward to our next star party. Here's to a rapid recovery, Rod. The Apodizing
Mask
I thought this might be something of interest to the group. The topic (Apodizing Mask) came up recently within the StarMaster users group - some folks thought it was some sort of illegal hippie-era device!! Lacy (contributed by Mitch G., telemitch@aol.com, of the StarMaster (SM) user group; starmaster_scopes@egroups.com. ******************************************************************* Debbie Schermerhorn's site has an article about a "do it yourself" apodizong mask by Ken Florentino: http://www.pcisys.net/~astrogirl/tips1.htm complete with instructions to build your very own mask. BTW, the proper name for an apodizing mask is a "Lyot Stop". (contributed by Nick Taylor, ntaylor@iname.com, of the SM User Group. ******************************************************************** The masks are great for Jupiter, Saturn, Venus and Mercury. They kill off glare and give better contrast, especially on the details of Jupiter. Also good for some double stars. We call it the "60's mask" because it also causes psychedelic colored light rays all around the object you are viewing. They are easy to make and will fit right on the front of your scope with Velcro. (contributed by Ginger Mayfield, chikadee@earthlink.net, of the SM Users group. ********************************************************************* Apodizing=eliminating some of the results caused in the focal plane from diffraction within the scope. The Lyot stop screen is evidently intended to remove from the focal plane some of the diffraction caused to the incoming light at the tube rim and periphery of the primary optical element; thus the graded density of the screen, increasing toward the outer edge of the light path into the scope. Works well on planets as they have finite image size, not point light sources. however, the Lyot screen allows all the light diffracted at the secondary to enter the focal plane. The Hubble Space scope also has an "apodizer", but it is in/near the focal plane of the primary, and is intended to remove light diffraction being caused by the central obstruction and support 'arms' (secondary and spider supports). The Hubble apodizer can be switched in/out of use. In effect, it "shadows" from the focal plane, light which has passed the periphery of the central obstruction elements within the light path of the primary mirror as it looks back up and out of the main "tube". Note, this is in some ways similar to, but not the same , as an "occulting" disk, nor is the result the same. One of the earliest uses of the Hubble apodizer was during the imaging of the companion "planet" of Beta Pictoris. It was used to enhance resolution. Not sure what the central obstruction percentage is within the Hubble. In typical SCT scopes it is pretty high, around 25 to 30% or so, I believe. Some years ago experiments showed that reducing the obstruction percentage below 14 or 15% essentially eliminated diffraction problems from that source in the image plane. Some planetary reflector builders, f ratios up around 9 or 10, have 'downsized' the secondary to around 11%, claiming enhanced fine detail resolution as a result. Neither gadget should be of too
much use with the StarMaster designs, as the secondary has been downsized
by Rick to a very acceptable size so that diffracted light in the image
plane from the central obstruction is very low.
Leonids
2000
The Moon is heading for a close encounter with a Leonid debris stream on Nov. 17, 2000. For most stargazers, this year’s quarter Moon during the Leonid meteor shower will be a blazing nuisance. Bright moonlight will overpower many faint shooting stars as the Earth passes through the outskirts of three cometary debris streams during a 36-hour period spanning Nov. 17 and 18, 2000. But for some astronomers, the Moon itself will be the main event if a Leonid meteor storm erupts. "On Nov. 17 [around 0500 UT] the Moon will pass approximately four Earth-diameters from the center of a dust trail left behind by comet Tempel-Tuttle in 1932," says David Asher of the Armagh Observatory, an expert on Leonid debris filaments. "The Moon will be considerably closer to the trail than Earth," raising the possibility of vigorous Leonid activity there. For more information about the 2000 Leonids meteor
shower, stay tuned to http://spaceweather.com.
Hope to see everyone at the meeting,
Russell |