Vol. 29 No. 2 November 1999 http://physics.weber.edu/oas/oas.html
THE NOVEMBER MEETING
The November meeting of the Ogden Astronomical Society will convene on Thursday November 11, 1999 at 7:30 p.m. in the Ott Planetarium on the campus of Weber State University.
The Prez has arranged an interesting demonstration of four of the most popular astronomy software programs. We will have the opportunity to compare The Sky version 4, Starry Nights Deluxe, Red Shift, and Megastar. Any OAS members who would also wish to demonstrate their favorite program can contact president Ron Vanderhule at 544-9458 to make arrangements.
CALENDAR ORDERS ARE IN
OAS members who ordered the desk calendars from Alan Jensen
and/or the Astronomy wall calendars from Bob Tillotson will be able to pick them up at
Thursday's meeting. If you forgot that you had ordered, we've got your name.
THE PRESIDENTS PARSEC
Greetings Earthlings;
Wasn't life simpler before the astronomy bug bit you? Remember how your good your neighborhood looked at night when you would see how nice the houses looked with all the exterior lights shining so brightly? And wasn't it great if your house had a street light out front and you didn't have to leave your porch light on all the time?
There was a time when I didn't give a rip if the mall had shielded lights in the parking lot or giant smoking torches for illumination. I already had a enough brain freight to keep me occupied.
Now I find myself pacing the house fitfully on full moon nights and avoiding the well lit areas in town; (isn't this how Dracula got started)? Once, I was even thrown out of the theater for cheering Darth Vader and the "dark side".
Yes I know there is the perception that lighting is a deterrent to crime. And to a point I agree. Consider though how many malcontents, waiting in the shadows at night to commit whatever, will not have their perspective adjusted if there is Orion the Hunter posting watch overhead or the Northern Cross in Cygnus reminding them of lessons of right and wrong learned in Sunday school. Now that may seem a little whimsical but isn't there something about a star studded sky that solicits a little reverence? I mean I'm the kind of guy that puts on a Walkman to take the garbage out or shovel snow, but I have yet to hear the music suitable for observing while in the cosmic cathedral (oops, my "digress" alert just went off). Where was I now? Oh yeah, my dart board with Tom Edison's face on it and fear of excessive photons.
Life was simpler before astronomy, but the rewards are worth the aggravation. Knowing the correct way to deal with light pollution is certainly an asset. That is why this new moon I will sacrifice a Nagler to the Halogen god so I won't get a neighbor like I had at my last house and everything will be fine.
The PREZ
EARLY SPACE PROGRAM AND STAR TREK PHYSICS TO BE TOPICS AT WSU
Convocations next week, November 10th will be held on WEDNESDAY at 10 a.m. in the
Austad Auditorium. We will be hosting Homer Hickam whose story is told in the movie,
"October Sky." This movie is based on the true life story of Hickam in his
book "The Rocket Boys."
On December 2, 1999 the Convocations speaker will be Professor Lawrence Krauss a physicist
and the author of "The Physics of Star Trek." The talk will be held at 10:00
a.m. in the Browing Center's Allred Theater.
EXTRASOLAR PLANETS TO BE SUBJECT OF WSU's ANNUAL RITCHEY LECTURE
"The search for planets around other suns" is the title of the talk to be given on November 12, 1999 at the Lind Lecture Hall (room 125/126) at WSU. This room is just below and to the north of the planetarium. Dr. Steven Vogt will discuss recent searches for planets beyond our solar system. He is the researcher who built the spectrographs used to detect many of the new planetary systems recently discovered. Dr. Vogt will discuss the methods used to detect these planetary systems.
HALLOWEEN STORIES
OAS V.P. Dave Dunn Writes:
I put up 2 telescopes on Halloween and had a real good time. I had over 200 kids and
their parents come by and look at Alberio, Andromeda, Jupiter and Saturn. For most of the
people it was their first time looking through a telescope. A lot of the older kids really
enjoyed the images of Saturn and Jupiter. Some of them couldn't believe that they were
really looking at the planets, they thought I had a picture hidden somewhere. The viewing
was really good even though I have a street light across the street and live on a busy
street so cars were driving by all night. I found that there are several of my neighbors
that have telescopes.
OAS Secretary Bob Tillotson Writes:
Each year I wonder if Halloween will be the fun event for we astronomers that it has been in years past. About the only thing that would keep me from setting up the 'scopes for the Trick-or-Treaters is bad weather. Who would think that we would be having early September weather in late October. No complaints from this end of the Peanut Gallery. Conditions were excellent for sky viewing on the 31st.
My neighborhood is getting older. All the kids have grown up and last year we only saw maybe 20 or 30 'Treaters. So this year, my daughter invited us to her family's house. It's a new subdivision full of young families. It was worth it. We had hordes of kids and parents and I don't think there were more than only a few, out of the two or three hundred that came by, who had ever looked through a telescope.
The activities started early. Even before the sun had set the little goblins and their parental escorts were grabbing up the Milky Ways, Mars Bars and Starbursts; good thing I had brought along the solar filter for the C-8. The sunspots were clear and well defined and even though I explained that they were great solar magnetic storms, one comment was that "they look like bugs".
It wasn't long before glowing Jupiter popped up over the eastern mountains. From my observing site in west Roy, we had an unobstructed eastern horizon so that, along with superb sky conditions, lead to an outstanding Halloween to remember. The kids and parents loved Jupiter and when Saturn came up about an hour later, I had the C-8 trained on it and the 4-inch refractor on Jupiter. That is where the 'scopes stayed all evening. So many folks came by, then came back again to look, I didn't have a chance to even think about changing the subject in the lenses. My son-in-law, Blake, got assigned to the C-8 and he was beaming. After briefing him on running the 'scope and a few statistics about the largest planet, he was answering questions and explaining telescope facts that he had never described before. People thought he was a seasoned astronomer and he loved it.
No matter how often we bring astronomy to the public, I am continuously amazed at the reactions of people when they put their face to the eyepiece for the first time. You know, wwwooooow and ooohhhhh coool and "that's Jupiter" or "that's Saturn"? This year I wasn't accused of putting a photograph in front of the telescope but they want to know how long I've "been doing this" and "how much does one of these cost" and all kinds of questions from silly to really good.
By 9:00 p.m. the crowds had thinned out a lot and my swollen ankle was screaming so we started to take things down. But I have to say, this was one of the best Halloween's I can remember. If you didn't do it this year, try setting up your telescope next Halloween. You won't regret it and keep your fingers crossed for good weather.
Minutes
Ogden Astronomical Society
October 14, 1999
The October meeting of the Ogden Astronomical Society was called to order at 7:30 p.m. in the WSU Ott Planetarium by club president Ron Vanderhule.
FY 1999-2000 membership stickers will soon be made available to members to affix to their cards. Deloy Pierce announced that Mr. Ken Crosswell will speak at the SLAS meeting next week. Dr. Sohl updated the members on the progress of the WSU observatory. Progress reports will soon be posted on the WSU Physics web site. The observatory blue prints were displayed. John reported that some of the neighbors have been complaining. The Ott Planetarium may soon purchase a new projector.
The Show and Tell meeting program offered:
Ron demonstrated the new solar filter material,
Doug Say described his 4-inch binoculars, THING,
Cliff Peterson described the Kendrick web site,
Wayne Sumner discussed the light pollution issue,
Jim Seargeant described his CCD imaging system,
Scott Crosby described his experience during a night at Mt. Wilson in California.
The meeting adjourned at 9:30 p.m.
Bob Tillotson, Secretary
Jim Seargeant's - Images
"Fuzzy Image"
"Sharp Image"
Getting Closer to High Resolution CCD Imaging
[Web editor's note: I have cropped and enlarged the original images that I was supplied with this article. You can click on the above images to see them as jpeg versions of the tiff files that I was given. You can also download the original tiffs by clicking on the following two links: fuzzy image and sharp image. JES]
So far I've been just taking snapshots with my CCD. Find an object, take a couple of pictures, then move on to the next. This has taught me how to operate the equipment and shown me the basics of image processing, but I haven't really tried to get the most out of my system. One person's web page showed me how to focus on high quality imaging.
Antonio Cidadao (http://www.astrosurf.org/cidadao) operates an observatory through the roof of his house in Oeiras, Portugal. Because of his location, he specializes in planetary and lunar imaging and has developed (and explained very clearly in his website) processes to make high resolution images. I've done my best to follow his examples and added my own methods of tuning the telescope and this picture of Jupiter is the best I've done so far.
There were three stages to preparing this picture - getting the telescope ready, taking the picture, and processing the resulting digital images. Taking the pictures was by far the easy part.
I took considerable care with the telescope. I wanted the largest image possible, so I attached the CCD to my Televue Big Barlow, giving a focal length of 240 inches at f/20. The key to getting the most out of a Schmidt-Cassegrain Telescope (SCT) ( really any telescope ) is collimation. In the past I've used a PC23C video camera to see the diffraction rings as I tweak the screws that control alignment of the SCT's secondary mirror. This gets collimation very close, but does not use the CCD camera that I'd be using to take the pictures. I felt that any change in the optical system might affect overall alignment, so I repeated collimation using the CCD. I set up a laptop computer on a ladder right next to the front of the telescope, so I could see the screen as I adjusted the screws. A three-hole Hartmann mask on the telescope gave me a triangular pattern of three stars if the focus was just a bit off. The three-star pattern did not seem symmetrical - it did not seem to an be equilateral triangle. Placing a hand over each hole in the mask in succession showed me which star was out of place gentle turns of the corresponding screw brought it into position. Carefully focusing the image with the mask in place gave me a tight round star that did not grow lumpy as the atmospheric turbulence shifted the image around the screen. The total adjustment was perhaps 10 degrees of turn on one of the collimation screws, but I could tell the difference
The SCTs are well known for the way the mirror flops around as the telescope slews around the sky. It's really only a tiny movement, but it's enough to shift the image around as the telescope moves from side to side. The previous night I had tried the procedure described above on a magnitude 7 star near Altair - at that time fairly far to the West - and then began imaging Jupiter and Saturn in the East. Saturn's moons showed a distinct seagull-shaped flair. Not good. The next night, I used a star just to the West of the meridian and near the ecliptic as the collimation reference and then waited until Jupiter crossed the meridian before shooting. This had the added advantage of pointing high in the sky and away from the mountains - through hopefully more stable air. It seemed to work.
I usually take care with focus, but lately some members of the Meade Advanced Products Users Group (MAPUG) have been commenting on how focus changes as the temperature changes. As the night cools, the aluminum telescope tube contracts, pulls the secondary and primary mirrors closer together, and changes focus. The answer to this is to re-focus just before every series of images.
As I said, taking the pictures was the easy part. The catch is, Antonio's procedure required a lot of images. The software that comes with my SBIG ST-7 automates multiple images, so I took several sets of 50 shots. (Rechecking focus after each set of 50.)
The reason for taking so many shots becomes apparent after reviewing them. As Antonio points out, even though the exposure times were as brief as possible - .11 second - about half the images would obviously be less sharp then the rest due to turbulence. I discarded those and adjusted contrast and brightness, then ran a sharpening filter and unsharp mask on the remainder. Another review of these images found six that were sharper than the rest. I paired them up and combined each pair into three images. Combining images like this through an averaging process tends to reduce noise in the image - noise is random and cancels out - and emphasizes features - features are repeatable between images and reinforce. The effect is to increase the signal-to-noise ratio. After combining pairs, I selected the best two of the three and combined them. Fifty exposures were winnowed down to four, which were combined to produce this picture. Everything else went into the bit bucket. Processing one set of 50 took about three hours. If I were doing color, three sets of 50 would have been required.
All of this produced a fairly good image, but not as good as Antonio posts on his web page. One difference is that he does shoot color, which shows makes the features on Jupiter more apparent. That advantage is less on the rather un-colorful Saturn. I'll see how my Saturn's compare with his after I find another three hours to process them.
Another difference is that I may have been pushing my telescope a bit too far by using the Big Barlow. Longer focal lengths magnify flaws in the optics and mount, and the effects of turbulence. The commercial SCTs are not known for their optical or mechanical excellence. I'll have to try again at f/10.
A final note. The amount of computing power we have available now is amazing. In two nights I accumulated over a gigabyte of images. In three hours I ran six megabytes of images - one set of 50 - through some very sophisticated processes. Through all of this, the computer spent more time waiting on my next keystroke than it did actually thinking about anything important. Remarkable.
Jim Seargeant