Observers' Forum

This is the place where you can share observing experiences, make suggestions, ask for advice, and sound off on any topic likely to interest other observers. Material for inclusion in the Observers' Forum can be sent to the Observers' Forum editor:

John Isles, 11105 Tremont Lane, Plymouth, MI 48170 e-mail: jisles@voyager.net

In this Observers' Forum we are pleased to have interesting contributions from Bob Gent, Jerry Knowles, Lew Cook, and John Gries‚.

The International Dark-Sky Assocation (IDA)

Congratulations to Jerry Knowles on 50 years of variable-star observing! What a superb achievement! Thanks for the compliment aimed at IDA. [Jerry wrote: "The work of the International Dark-Sky Association is exemplary."] We are making major progress in combating light pollution, and everyone's support is deeply appreciated. Last year, we had the wonderful reports in the September issue of Sky & Telescope, then David Levy wrote a timely article, "Our Wasted Light," in the November 22 issue of Parade magazine. That reached an estimated 85 million readers! A friendly news reporter hopes to publish an article about light pollution in USA Today. This will reach millions of readers.

1998 was a great year for the International Dark-Sky Association. Our membership is growing quickly, and many communities are now tackling the problems of energy waste, bad glare, light trespass, and destruction of our beautiful night skies. In addition to many cities passing new light-control initiatives, state-level governments are looking at the problem. Debates are currently under way in Texas, New Mexico, and several other states.

In other news, the IAU is now preparing for the UNISPACE III conference this summer. With any luck, there will be some excellent initiatives sent to the United Nations to help combat energy waste through light pollution. IAU's Commission 50 is now working to "Preserve the Astronomical Windows."

There is much that all of us can do. After all, the science of astronomy is at risk, and we are wasting an enormous amount of energy for no good reason! For more information, please visit http://www.darksky.org. And by all means, please consider joining IDA if you haven't already.

Two observing anecdotes

In college days I observed often with Edward K.L. Upton, now a retired UCLA Astronomy Professor. One summer I was on the road, while "Ned" worked for Harlow Shapley at Agassiz Station, Harvard, MA. In Margaret Mayall's absence, a telegram with an urgent message had reached "Ned." Someone had observed R CrB at magnitude 5.1, and was upset because she could not find the time of its predicted maximum in Sky & Telescope.

The saga of Lew's star

I have been working on building a CCD camera (the Cookbook CCD Camera) AND reworking one of my telescopes. CCDs require good drives. I have a 17.5-inch fork-mounted Newtonian which I used as a purely visual instrument for several years, and also left unused for several more while I took an extended holiday from observing. The mount, while equatorial, did have a sector drive, but I didn't often use the drive-I just observed visually, moving the 'scope manually, and the drive wasn't very precise anyway.

The larger part of the project has been the construction of a friction drive for the instrument. The moving mass weighs a couple of hundred pounds, and the new drive has been balky, especially when the instrument is off balance by several pounds or tens of pounds from one side to the other. The drive roller tends to slip then. It'll track fine and then it won't, but I keep trying one "improvement" after another until something works.

A tricky thing about the CCD cameras is they look at such a tiny piece of the sky, and star hopping wasn't possible at that stage of the work, as I had no slow motions on the 'scope yet. I could slew, but couldn't position the telescope finely. Nudge the button, and the 'scope would move a half degree, maybe less, maybe more. I'd point it in about the right place and then go through the process of seeing what the image on the screen was. Then I'd try to find a star pattern that matched it on the atlas. I had an atlas on the computer that went down fairly faint, and the CCD images were showing stars down to 14th magnitude as they popped up on the screen every 8 seconds. I could turn off the drive and let things drift into another area to find a recognizable grouping.

When I finally got the drive working to the point where I could do some imaging, the very first variable star field I looked at/for was AQ Eridani, a dwarf nova-fairly easy to find, too. My goal was to do photometry in Blue, Visual, Red and Infrared (BVRI). The photometric filters are expensive and as a first step, just to see what things were going to look like in various colors, I got ordinary filter material and made green and red filters. The green filter "looked right" for a V filter, but I didn't have any data on the transmission properties. One of the first fields I imaged near the variable AQ Eri mimicked the variable field, but something seemed odd, and I realized that I was off by a few minutes of arc.

The field there was recognizable, except one of the stars was really bright-like 9th magnitude. The atlas on the computer said the Guide Star Catalogue listed that star at magnitude 15.2. Maybe this was a variable? I dared not think I would find a variable star by accident, much less with the first star field I looked for! I took images of this field and then went over to AQ Eri, which was at minimum-something fainter than 16th magnitude-as faint as I could go with the short exposures.

I wanted also to pursue the strangely bright star. Perhaps it was a known variable. On Jan. 9, 1999, I posted a note on the AAVSO Discussion Group e-mail system asking if anyone knew about this star. Later that day, Brian Skiff from Lowell Observatory responded it was an IRAS star and had a red magnitude of 12.3 but not of any particular noteworthiness. Arne Henden of the U.S. Naval Observatory offered to check it in a week with his CCD system as he had some telescope time, and the next day I posted a page on my CCD camera project web site devoted to the question: "Is this star variable?" I marked and put an AAVSO chart on the page identifying the suspected variable on the AQ Eri chart.

Charles Scovil chided me about referring to charts in my e-mail notes without specifying the date of the chart, and Gary Walker cautioned me about using filters of unknown pedigree. Gary suggested the green filter-which I was calling a "pseudo V" filter-had a red leak and the star could be very red, not anomalously bright.

On January 13, Jan Hers looked at the star and estimated it at magnitude 14.2, while my most recent CCD image suggested it was as bright as ever-I even got some other green filter material (still of unknown transmission in the IR) and came up with the same result as before-the star was bright. I then looked at it visually-and couldn't see it-it was fainter than about magnitude 12. Arne Henden finally got an image of it and reported it was magnitude 13.55 with a color index (B-V) of 2.3-a very red star! So Gary turned out to be right-the green filters had red leaks! He even chased the clouds to try to get CCD images of the star, but missed. Another observer, Miroslav Komorous, also looked at the star on Valentine's Day and confirmed it was faint-14.0.

Arne later reported that the star was at magnitude 13.34 V-a full two-tenths of a magnitude brighter than almost 4 weeks previously, and therefore apparently a variable.

Arne left the task of following the star and making other reports on the type of variability up to me. All this action occurred in one month during my winter when it was rainy and difficult to observe (and the gremlins in the drive acted up again). It was an exciting and educational month!

I learned several valuable lessons from this experience:

1. If you see something that looks funny, investigate why-you may be onto something-don't pass it up.
2. Don't try to do photometry unless you have filters of known properties all across the spectrum that your detector can see. Just because you can't see a red leak doesn't mean it isn't there in the IR.
3. The AAVSO discussion group is a SUPER way of getting a question answered by people all over the world who will actually go out and observe a questionable star. The investigation spawned over 30 e-mail messages about this little red star.

For those interested in the latest updates on my CCD camera and telescope rebuild project, it is on the web at: http://www.geocities.com/CapeCanaveral/Hall/8449/lewccd.html. If finding and investigating one little variable star is this much fun, imagine how the folks who find them by the thousands feel!

Tales of telescopes and VSOing

John Isles kindly asked me to write about my observing experiences for the AAVSO Newsletter. I've been interested in astronomy since elementary-school days; a certain neighbor named Richard Perkin and his 24"-equipped backyard observatory helped. I started VSOing the summer of 1973 when I was introduced to the Stamford Observatory and Charles Scovil. He promptly took me under his wing and taught me how to observe variable stars with the 22" Maksutov, well known to all. I also met Clint Ford and joined the AAVSO that fall. Together, the two of them worked on me, as I eventually became a proficient observer. Except for college and travel, I have continued using the 22" and it feels like an extension of my body as well as an old friend. I pat the mirror cell after a night's work and tell it I will see it later. I always do this with telescopes as if they are living creatures. I guess to me they are.

In the summer of 1986 after chasing Halley's Comet in Australia, I was hired as an observer on the 20" Clark refractor at Wesleyan University's Van Vleck Observatory. You'll notice I used the word "hired"- yes, this job included money. My job was to take plates for parallax research but I got permission to use the 20" for variables. Soon thereafter, I was hired to observe on Van Vleck's other large telescope, a 24" Boller & Chivens classic reflector-indeed the very same one that had been in Dick Perkin's observatory. I did photometry on this one, but the equipment was removed each summer and I got permission to use it for VSOing. This certainly helped with my observing totals as I used the Stamford telescope on weekends and the 24" during the week. I did get a few observations with the 20" but it was maneuvered by brute force and the amount of work for each observation caused me to give this up.

Eventually, a CCD was placed on the 24", more students arrived, and my use of that telescope came to an end. However, we just had a CCD for the 22" donated to Stamford Observatory by a new member of the Fairfield County Astronomical Society, the society that meets at and operates the facility.

Through my travels, though, I've used some other large telescopes. While in Arizona, I sat in on an observing run with the 60" Catalina telescope built by NASA. David Levy and Steve Larson were using it to get CCD images of comets and I got an observation of X Leo at minimum!

I'm not very fast as an observer. It takes me 2 to 5 minutes or longer per observation. I try not to strain to get an observation but the moon can certainly make things difficult. I use circles and have memorized many fields. I try not to linger over any star longer than needed to get an observation and I don't do Mira stars. I have mild color blindness in red; this really shows up in observations of Miras. I stick to the CVs and other eruptive stars. Since my observing time is relatively limited, I try to be as efficient as possible, something we all strive for. So far I've amassed 20,000 observations and am working toward that 25,000 level. I am no John Bortle or Danie Overbeek and expect to be lucky to make 50,000 observations lifetime total. Currently I'm 43. Charles Scovil and Clint Ford have been wonderful mentors and I've tried to be a good mentor to others.