Large Asteroid (790) Pretoria Occ'n Oct. 29 am, BC to MS
Updated: 2005 Nov. 28
2009 October 29, 5:59 am CDT (10:59 UT): Occultation of 10.8-mag. TYC 0216-01594-1 by the 170-km asteroid (790) Pretoria, visible from a path passing over Tulsa, OK, about 100 miles northeast of Stillwater. Click here and here for much prediction information. The occultation was successfully observed, mostly with video systems, by IOTA meeting attendees from 6 sites spanning from 40 km southwest to 65 km northeast of the predicted central line, with maximum chord lengths approaching 8 seconds; a 7th station at the predicted northern limit at 87 km northeast had no occultation. The observation at 65 km northeast was a remote station. Unfortunately, clouds approaching from the west ruined the view at Stillwater, and some observers who tried the event in the region were clouded out. A 7th chord near the predicted central line has been reported by Benny Roberts in Jackson, MS. More about the results of this occultation will be posted here later. ________________________________ Here was a plan to cover Saturday morning's (790) Pretoria occultation path; distances are in km from Steve Preston's central line, + for distances northeast, and - for distances southwest; this plan was followed approximately, but not exactly. Results are given after the distance: +, positive, occultation timed; -, negative, no occultation observed; c, clouded out. Dist., km +85 - David Dunham attended station +65 + David Dunham remote station +45 + Bob Sandy +27 + Chad Ellington +9 + Benny Roberts, Jackson, MS -5 c Roger Venable attended station -20 + Paul Maley -30 c Derald Nye near Tulsa (not sure; maybe +?) -40 + Richard Nugent -60 c Derek Breit with Roger Venable's 2nd station -80 c Rick Frankenberger -109 c Art Lucas at his observatory ______________________________________________ My observations: I've finally taken the time to determine accurate times for four asteroidal occultations that I've video recorded with GPS time insertion during the past two months. All of these were recordings made at unattended stations while I was at another place attempting another observation. For the October events, the time insertion was with a McAfee time inserter, and at the other location I video recorded a miss (no occultation of the star). 2005 October 29, occultation of 10.9-mag. TYC 0216-01594-1 by (790) Pretoria, both stations used 20mm-inch SCT's, attended station (no occultation recorded) at Fairland, Oklahoma at WGS84 long. 94 deg. 50' 14.6" W., lat. +36 deg. 45' 13.6", h 810 feet. Unattended station near Success, Oklahoma at WGS84 long. 94 deg. 58.9389' W., lat. +36 deg. 37.6400', h 256m: U.T. 10:58:17 Star drifted into field of view, start of observation 10:58:53.4 +/-0.3s Disappearance 10:58:57.2 +/-0.2s Reappearance 10:59:27 Star drifted out of field of view, end observation The target star appeared faint because the secondary was slightly out of optical collimation (since fixed), so the star could not be seen in single frames reliably, and the times were determined with a few plays of the tape using a stopwatch. A wind gust shook the telescope a little at the disappearance, making it less distinct. _____________________________________________________________ David Dunham