Aug. 13th occultation of 1 Trianguli by (89) Julia, Video Observation by James Thompson at Eagle, Colorado
Easy to Use Telescope & Video Equipment was easily transported by plane
New: 2005 Aug. 24
This is just one of four telescope/video systems that I own and that James Thompson and I transported from the Washington, DC area to Colorado to observe the occultation of 1 Trianguli (89) Julia on August 13. Click here for more information about this event, including the data for all 7 successful observers and results (including ellipse fitted to the observations). The site, shown here in a photo taken several hours after the event by James Thompson, was in the parking lot of a small church at the edge of a large sink hole about 200m across (so there were no lights in the direction of the star for that distance). This was less than 100m from the Best Western motel in Eagle, CO where we stayed. It would have been all right as a remote site but James decided to stay there after I set up the equipment until the occultation occurred two hours later (I drove to a location about 40 km farther west, where I was clouded out shortly before the event). James needed to be there at least a little before the occultation to start the camcorder, which can only record for about 1 hour. At Eagle, the sky remained clear and dry, with temperature less than 10 deg. C., so it was fortunate that James had a sleeping bag loaned by Richard Dietz. The equipment is shown here in another photo by James. The telescope is an old 4" Meade ETX bought from a seller on Astromart with a 9 x 50 finder scope that I purchased from Orion. A Meade f/3.3 focal reducing lens is attached to the telescope, followed by a standard SCT eyepiece holder, a short 1.25" to video cylinder from Adirondack Video, and a PC164C camera from Supercircuits. The telescope was roughly polar-aligned and is shown pointing in the direction of the target star at the time of its occultation (the pointing was good; the occultation occurred near the center of the video field). I pre-pointed the telescope to this direction two hours beforehand using stars near alpha Andromedae that had the same declination as the target star. The white 12-volt "Universal battery" from Supercircuits, used to power the camera, is visible behind the telescope on the ground just under the eyepiece holder. A standard video cable connects the camera (with yellow RCA connectors) to a Sony digital camcorder to the left of the telescope using the yellow-jacketed RCA connector; the red and white wires were not used. Since the end of the PC164C camera is a male BNC, a female BNC to RCA connector from Radio Shack was used to connect it to the RCA cable. Behind and to the left of the camera you can see the Supercircuits PA3 microphone that was plugged directly into one of the audio input jacks of the camcorder, which was used only as a recording and display device, not for its own recording capability, which is not sensitive enough. Below the camcorder is a self-setting (using WWVB) travel alarm clock that allows knowing the time to the nearest second; its alarm was set to sound a few minutes before the occultation, to alert James to when everything needed to be reconnected and turned on, and James reset it to the minute of the occultation so that its alarm would be recorded, even though that time would be good to only a few tenths of a second, that's better than no calibration at all. Below it in the lower-left corner of the picture is the shortwave radio that was used for WWV time signals that were successfully recorded. On the ground are two large towels that allowed me to lay down to aim the finder scope and protect the video equipment from dirt; the telescope was wrapped in them for travel in the small suitcase to the right of the telescope. On top of the suitcase is an IOTA cap that was loosely put over the end of the telescope to prevent any dew from forming on the corrector plate, but it was dry enough that it probably wasn't needed (also not used was a folding dew cap that we had for each telescope). The rubber band that holds the finder scope snug in its mount broke, so pieces of paper were taped to the finder mount to serve that purpose, the white in the middle of the finder scope in the picture. For travel, the finder scope, its mount, the camera, focal reducing lens, and of course the three screw-in tripod legs were all removed so that everything fit in the small suitcase. David Dunham, IOTA, 2005 August 24, 19h UT e-mail home dunham@starpower.net office david.dunham@jhuapl.edu Phone home 301-474-4722; office 240-228-5609; car 301-526-5590