Graze Profile Observed by Myself - New 2004 Dec. 20
I Video Recorded the Grazing Occultation of 7th-mag. ZC 3434 from 3 Stations around Valley Lee, MD on 2004 December 17/18
This is a preliminary report of my successful expedition to observe the grazing occultation of 7.5-mag. ZC 3434 16 deg. from the south cusp on the dark side of the 42% sunlit crescent Moon at Valley Lee, Maryland, last Friday evening, Dec. 17 at 8:04 pm EST (Dec. 18, 1:04 UT). I ran two remote telescopes as well as an attended one to record three lines across the lunar profile. They turned out to be optimally placed for this southern-limit graze, with the northern telescope recording a single occultation lasting about 1.5 minutes (I was at that station and didn't know how successful I had been until Sunday when I finally had time to play back the remote station tapes). The southernmost telescope recorded 3 occultations of the star, each only 1 - 2 seconds long, catching just the highest mountains on the profile. The middle station recorded 4 occultations of the star, with mostly fairly brief appearances in valley bottoms. During the 92-mile trip from my office in Laurel to Valley Lee, through some heavy rush-hour traffic but taking a route of lesser highways that minimized those delays, I stopped in a bank parking lot in Hughesville to record the disappearance of 4th-mag. psi 2 Aquarii about 25 min. after sunset; that star is possibly a close binary and I wanted to get a video record to try to confirm or deny that. If I hadn't done that, or if I didn't have to move one of my telescopes (I had received permission from a young resident, but her father later called my cell phone asking me to remove it), I probably would have had time to set up a 4th station, and even a 5th one if I had been able to leave my office earlier. For all of my previous remote-station graze observations, there were other observers who helped add to the observed profile. But this time, nobody else observed the graze, as far as I know. They missed perhaps the last "warm" (temperature about 4 deg. C. or 39 deg. F) graze of the season with clear sky and no wind; winter arrived in force in our area this morning with strong winds and a temperature of -13 deg. C or +9 deg. F. Wayne Warren did attempt an observation, setting up his telescope only a few hundred feet from my southernmost telescope, but he wasn't able to start observing until just after the graze had ended; he didn't allow enough time to get through the rush-hour traffic. Probably sometime in January, after 2005 predictions are distributed, etc., I'll determine times from the video tapes and prepare a reduction profile for the graze to post here. The telescopes were my usual old clock-driven Celestron Schmidt-Cassegrains (polar aligned with Polaris to within a couple of degrees, not real precise) with f/3.3 focal reducing lenses and PC-164C cameras, using camcorders for recording. Two of the telescopes were C8's and the middle one was a C5. I used a McAfee GPS video time inserter at the northern station (and used it to also record the position, and also recorded WWV time signals as a check). At the other stations, I didn't have time to record any time before the graze, but set them with WWVB-controlled clocks whose alarms were set to sound at 1:03:00 UT (a minute before the graze was expected to begin), and then also with some GPS time (and location) inserted several minutes after the graze with the video time inserter (which also then calibrated the clock on one of the camcorders, a digital one). I have also made some GPS time-inserted test tapes with some WWV minute tones and also alarms sounded from the WWVB-controlled clocks to see how accurate those are, but listening to them and watching the GPS time display, they seemed to be accurate to 0.1 second or so (again when I get a chance, I'll process the tape to measure the accuracy). Besides passing over southern Maryland, and Virginia including the western and northern suburbs of Richmond, the path for this graze also passed over western N. Carolina, s. Delaware, and s. New Jersey. Maps showing the southern Maryland area around Valley Lee (southwest of Lexington Park) and the Richmond area can be seen by clicking the links below. Overview of s. Maryland Maryland detailed map 1 - Valley Lee area Richmond, VA area This 2.8-meg Power Point file includes these maps and others. The scales of all of the maps can be gauged from the 0.6-mile-wide graze zone. Summary of the grazing occultation DATE Day EST Star Mag % alt CA Location Dec 17 Fri 20:04 ZC 3434 7.5 42+ 33 16S Valley Lee,MD & Richmond,VA _____________________________________ David Dunham, e-mail NOW dunham@starpower.net, 2004 December 20 Phone home 301-474-4722; office 240-228-5609; car 301-526-5590