Well-Observed Occultation by (530) Turandot Feb. 24
Please check your data listed here
First elliptical fit, 99 x 78 km +/-2 km
Updated: 2006 March 3
The target star was 7.9-mag. SAO 80107 (HIP 40832) in Cancer only 3 deg. from Saturn. Please check your position and timing data here. This first version of the data were used to generate this view of the observations projected into the plane of the sky at Turandot; a possibly easier to view and plot Word version of it is here. In the figure, disappearances are on the right and reappearances are on the left. You can gauge the time scale by the fact that the longest chords were 7.3 seconds long. Most of the visual timings were late (mostly because the reaction times were longer than estimated, common with these events, but you should double-check your times to be sure there was no additional error in their determination) and so most were given zero weight in this first analysis. After receiving any corrections, we will apply a correction to some of them to force them to match nearby video chords (that is, fix the reported duration) and include them in a later solution, but with reduced weight relative to nearby video observations. But we'll give full weight to Ballaron's lone observation so far north since it's location is important for the solution. Note that station 15's (Huziak's) "chord" is not an occultation. He said in his report that the sky was mostly cloudy up to 5 minutes before the event, when it unexpectedly cleared. He didn't quite have enough time to set up; by the time he did, the star was visible and remained visible. BUT he reported this start time as 7:32:00 UT, at which time, the plot and other observations show, the star was behind the asteroid and must have reappeared about 3 seconds later. So Richard, if you can (that is, have a tape recording you can play back), check the time when you first saw the star; I suspect it was after 7:32:03. If not, perhaps you located the wrong star in your rush to get on it? I don't have Tenho Tuomi's coordinates for his miss observation at Lucky Lake, SK here at my office, but I have them in his e-mail message on my computer at home; we'll add him to the plot with the next iteration. Click here to get our WinOccult .obs file for this event. Below is a brief summary of what I know about the event; there was a substantial north shift of the path (that is, the actual path was well north of the predicted one). Fortunately, we have a rather good distribution of observations across the path. Thanks to all for their effort, and to those not mentioned who tried, but failed, mainly due to clouds: Dist. (+ = north, actually northeast; - = south of center) from predicted central line, Sta. km # Location, Observer, Result +102 12 Eagle, WI Scott Jamieson, no occultation +83 5 Lake Villa, IL Steve Ballaron, 2.7s occultation +49 7 Gas City, IN Chuck Bueter with my C5 & video, 7.3s occultation +38 16 Darren Drake, Indian Head Park, IL, 7.4s occultation +30 8 Gaston, IN Dunham remote site, 4" SCT video, 7.3s occultation +28 11 Shirland, IL G.Samolyk & S.Diesso, 7s occultation +27 6 Pelham, NC Bob Oldham 7s occultation +23 3 Dodgeville, WI David Oesper, video 7.06s +1 15 Saskatoon, SK Richard Huziak (clouds, on star seconds late) +1 10 Harvest Moon Obs., Northfield, MN Steve Messner video -2 1 Cincinnati, OH Paul Maley & Gene Herrmann video 5s occ'n -20 9 Fisher, IN David Dunham, 2.3s occultation videotaped -21 4 Villa Hills, KY John Armor, 2.1s occultation -49 13 near Vilna, AB Mike Hoskinson no occultation -77 14 Loreburn, SK Garry Stone no occultation -101 17 Dark Sky Obs, w. NC, Dan Caton, no occultation -107 Lucky Lake, SK Tenho Tuomi, no occultation -121 2 Versailles, KY Otto Piechowski, no occultation -999?18 Martinez, CA Derek Breit, no occultation (not plotted) It was a long night for me (only got to sleep 6 - 9 am) and I had to work late Friday evening to catch up on a backlog of work at my office, after getting there from Indiana late in the afternoon. A preliminary report of my observations is below (unchanged from my previous posting of this on March 1): I give below accurate locations and preliminary times for the occultation of SAO 80107 = HIP 40832 by 530 Turandot on 2006 Feb 24 obtained with the three telescopes and recording systems that I transported to Indiana, by Southwest from Baltimore to Indianapolis (they are the only airline now with a 150-lbs. free baggage allowance), and then by rental car to locations northwest of Indianapolis near I-69. Everything worked, obtaining 3 beautiful video tapes of the occultation, but I nearly ran out of time, arriving at the southernmost station to attach a camcorder to the pre-set-up telescope only 4 min. before the occultation (more about that adventure later). All telescopes had f/3.3 focal reducing lenses and PC164C video cameras. More accurate times will be determined soon by single-frame playback of a VHS copy of the tapes; one will need time insertion with a Manly time inserter. The manually-determined times below are all U.T. 1. Near Gas City, IN, at long. 85 deg. 33.4752' W., lat. 40 deg. 28.4287' N., h 255m, 5-inch clock-driven SCT. Chuck Bueter, driving from the north from South Bend, met me at the I-69 exit, both of us arriving there within one minute of each other about 1.7 hours before the occultation. After locating the target star, I left the site 1.1 hours before the occultation, leaving Chuck to keep the target star in the field of view by making small corrections in declination to correct for polar misalignment, which was reasonably small. He recorded for about 2 minutes before and after the occultation, timed with a GPS Kiwi OSD time inserter: Disappearance: 7:29:22.3 Reappearance: 7:29:29.6 duration 7.3 seconds 2. Near Gaston, IN, at long. 85 deg. 33.6956' W., lat. 40 deg. 15.7366' N., h 274m, 4-inch stationary pre-pointed SCT. This was run as a remote station, with the Sony video walkman attached with the McAfee GPS time inserter and started recording about 50 min. before the occultation. Target star first appeared in video: 7:27:58 Disappearance: 7:29:21.2 Reappearance: 7:29:28.5 duration 7.3 seconds Target star exited field of view: 7:30:35 3. Fisher, IN, at long. 85 deg. 59' 43.3" W., lat. 39 deg. 57' 05.0" N., h 771 ft., 5-inch stationary pre-pointed SCT. I arrived back at this site 4 min. before the occultation but did not need to adjust the pointing (didn't even have time to check it), connected a camcorder to the PC164C, started recording only 11 seconds before the disappearance but saw the star on the camcorder screen several seconds before that, and connected a PA3 microphone and recorded WWV, loud and clear at 5 megahertz, for a few minutes starting about 20 seconds after the occultation: Start recording: 7:29:13 Disappearance: 7:29:24.5 Reappearance: 7:29:26.8 duration 2.3 seconds Target star exited field of view: 7:31:21 Extensive pre-event prediction & plan information is here. __________________________________________________ David Dunham, IOTA home dunham@starpower.net 301-474-4722 cell 301-526-5590 office david.dunham@jhuapl.edu 240-228-5609