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Location: Chemistry/Physics Building, MUN
Time: 8:00 pm
1. Randy's Introduction. Randy gave some notes on the Society, what we are all about, what membership benefits were, and showed off our web site. Randy would like everyone to note that next month is our annual Christmas wine and cheese thing. It is important to note this will take place on the second Wednesday of the month in order to avoid the Christmas rush, so December will also be an exception to the normal third Wednesday of the month meeting time.
2. Observing. Gary Case went over the highlights of what would be visible for the next month. He touched on Saturn, the hijinks of Jupiter's moons, and Venus and Mars (both morning objects). This could possibly be the last good Leonid shower for 30 years or so. This shower is predicted to have a pretty high peak (not as strong as the last few times), but unfortunately the moon may dim some of the splendor. There will be two peaks, the first starting after midnight on Monday, the 18th, continuing into Tuesday morning, the second just before sunrise on Tuesday morning. We should emphasize that both peaks occur in Tuesday morning. Finally, on Tuesday night, from 8:20 to 12:15 am (now into Wednesday night), there will be a penumbral eclipse of the moon. It won't be the easiest to notice. More information on these events can be found at http://www.skyandtelescope.com .
3. Fred then introduced our speaker, Dr. Rajiv Gupta, RASC President. Fred touched on several contributions Dr. Gupta has made to the society over the years, including his current editorship of the Observer's Handbook and the increasingly popular Calendar (many images of which he has produced himself, using the methods of this talk). The talk will be on composite digital techniques for high-resolution astrophotography with film. Dr. Gupta has been active in the software area as well. Rajiv is a mathematics professor at the University of British Columbia. Fred also attempted to explain why it gets warmer in the night-time in Nfld., having to do with the dark side of the sun being warmer than the bright side....
4. Dr. Rajiv Gupta. Dr. Gupta began with a brief note about the Society, and how we have grown greatly in the recent past. We now have about 4500 members, and 26 Centres. For comparison, the only comparable national organisation in the United States, the Astronomical Society of the Pacific, has far fewer members, with ten times the population base to draw on! So, astronomy in Canada is doing well. During his tenure he hopes to add some emphasis to our observing and education mandates.
Dr. Gupta began photography over 8 years ago in much the same humble fashion as anyone else. After gradually learning some of the tricks of the trade, he came across the film technique of high-resolution photography. After seeing what could be done with various black and white, high-resolution films, he gave up on colour for a number of years. Nowadays, he has returned to colour in spectacular fashion, by using composite digital techniques to combine high-resolution black and white photographs with their colour cousins. In addition, the following digital techniques were to be demonstrated with his Registar software: stacking, LAB, tri-colour, mosaicking, and various hybrids of these techniques.
After showing us some of his early efforts with star trails, barn-door trackers, and piggy-backed cameras (on equatorial telescopes), we were treated to some pictures of his telescope. Dr. Gupta acquired an AstroPhysics refractor, along with a relatively primitive (but inexpensive) German equatorial mount. The mount does emphasize rigidity. Basically, he preferred to spend his money on optics, everything else could almost come from an episode of the Red Green show. Any exposures longer than 15 or so seconds required some manual corrections. One can only imagine the patience required for two and three hour exposures! Nowadays he has an autoguider (which uses a CCD) in order to automatically make drive corrections. He also updated to one of the later model AstroPhysics, a Starfire 5" f/6. He focuses using a hand made disc. Based on tests with his optical filters, measuring the temperature at the same time, he has a curve for his specific telescope. Given a particular temperature, filter (or none), he can dial in the focus position for the film. Unfortunately, the newer Starfire has some awful temperature characteristics, so in some ways it would be better to have the older one. Much like his drive and focuser, the camera itself is fairly primitive. Dr. Gupta does not employ vacuum curve-fitting, or for that matter, any special techniques. His first camera was largely made out of tupperware, electrical tape, and a few core metal parts! The Kodak Tech-Pan film (a high-resolution, medium format film) was stuffed in to fit over a trial and error surface made from scotch tape. [I think Red Green would be proud.] At this point we were treated to some Tech-Pan pictures and a direct comparison with lower resolution colour film pictures.
Dr. Gupta's next and latest camera is a somewhat fancier all aluminium job, but only as fancy as needed. Again, he uses medium format film (about 2 inches across). The amount of bending is again determined through trial and error exposures on sky objects. It can be noted that if an amateur were to spend about $10 000 on an SBIG ST-10E CCD, they would have the best in large detectors, but the size is still small compared with film, making for a small field of view, and the price would definitely not be small.
Hypering is also an important part in order to get film results of this calibre. The film is baked in hydrogen gas (actually, an 8% solution) at 50-60 degrees for one or two days. Hypered this way, as long as the film is kept very dry, the film should be ready to use many months down the road. Of course, home-made hypering gear was the way to go....
The final process is to make a standard 8x10 inch print and scan it in to your computer with a scanner. The scanner needs to handle about 4000 dpi, and the resulting files are often 1 GB in size. Getting a good scan can be an art form all in itself.
Finally, the talk ended with some practical demonstrations of image processing:
Finally, we were treated to a glimpse of a Calendar production run at the University of Toronto Press.
5. Coffee Break.
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