The inevitable kit posting

I thought I would take the time to post about the equipment I use for satellite tracking. One of the things that attracted me to satellite observing in the first place was the fact that unlike planetary observing, for example, an observer did not have to use a great deal of expensive kit.

For the record, I use:

• Synta 80mm f/5 "Short Tube 80" refractor, branded "Helios" with focus knobs from www.focusknobs.com and a Rigel QuickFinder 1-power reflex finder
• Meade 4000 series 32mm Plössl eyepiece, giving a magnification of 12.5 x
• Slik D400 heavy-duty photo tripod and fluid head
• Oregon Scientific stopwatch
• Panasonic CF-25 Toughbook laptop computer running Windows 98, 166 MHz Pentium processor
• Radio-controlled clock from Lidl controlled by a signal from DCF77 at Frankfurt am Main, Germany on 77.5KHz
• Rob Matson's SkyMap 6.0 for predictions; Ted Molczan's ObsReduce 1.3 for reducing points; a self-written spreadsheet in MS Excel (Splittime) for working out timings from the stopwatch

When I first started sat watching I used a pair of 7x50 binoculars as much of the literature (both published and online) suggested. This was fine though with the light-polluted skies of North-West Germany where I was living at the time, they were a bit limited. Later I bought a pair of Canon 10x30IS image-stabilised binoculars which were excellent for observing bright satellites such as the Lacrosse series or the ISS. The only problem with both these binoculars was that their realistic limit of visibility was around magnitude 8 or so which limited the number of background stars I could see. This was not much of a problem early on but as I began making positional observations I found that I could not see enough background stars to make many points. For a short while I used WW2-vintage 10x80 Flakfernröhr binoculars which I have on loan from a friend. These are excellent with huge wide-angle eyepieces and a very wide field of view and uncoated optics. The downside is that they are built like a tank and weigh 5kg (unsurprising considering they are military spec optics). This makes them heavy to move around on the tripod and even though the tripod is designed to take the weight, it was still difficult to move the binoculars around and take timings as well.

Eventually I settled on the telescope. I already owned it as I had bought it in October 2001 as a general-purpose astronomical telescope. I had bought the Short Tube 80 as it was quick to set up, light and had been given good reviews on various astronomical websites such as www.cloudynights.com . I had planned to begin variable-star observations which was why I bought a fast telescope; I was not much interested in high magnification. The other reason was that it was relatively cheap as it was made in China. The colour-fringing other users mentioned did not bother me as I planned to use it at low powers. The Short Tube came with a couple of Kellner eyepieces, a 45° correct-view diagonal and a 6 x 30 inverted-view finder scope - in other words all the basics. I soon bought some other eyepieces, a Meade Barlow lens and a 90° diagonal and other accessories including the QuickFinder and the aluminium focus knobs.

With the telescope I can leave it set up waiting for a pass of a faint satellite as predicted by SkyMap, while I consult the laptop or check the time. It is very light, and with the 32mm Plössl it can cover around 4° of sky. With 80mm of aperture, I can see down to around magnitude 9 or 10 under typical UK sky conditions. Using the arm of the photo tripod head, I can follow a satellite on its track very easily and it will reach almost as high as the zenith. The tripod allows for a adjusting the height of the scope so I can comfortably see satellites at high elevations; the short length of the scope also means that the eyepiece does not move too far as well, which is a problem for long focal-length telescopes.

Earlier this evening I experimented with using the Barlow for sat tracking, and used it for the 17:58 UTC pass on 2006 January 14 of Lacrosse 5 (05-016A). I had always avoided using it as I wanted as wide a FOV as possible. What prompted me to use the Barlow was a desire to obtain more accuracy from my observations. David Brierley kindly sent me some analysis of some points we (he, myself and Peter Wakelin) had made of the same pass of XSS-11 R/B (05-011B) around 06:15 UTC on 2006 January 12. I saw that my points were the least accurate. Now, I am prepared to admit that this would be because I am still new to this game, and Peter and David are veterans. I still have much to learn about satellite tracking. But until I can start using video technology for observing (a subject of a future posting) I can try to use more magnification in the quest for greater accuracy on my points. It will be interesting to see if using the Barlow does bring more accuracy by bringing out some fainter stars than I might otherwise had used for points.

The Short Tube 80 is an excellent telescope for satellite tracking work and I will continue to use it for the foreseeable future. I may one day buy a larger telescope (I like the look of the Short Tube's bigger brothers the 102mm and 120mm versions) but this is a nice setup.