Coverage of the appulse of mu Geminorum by 752 Sulamitis on 2000 Nov. 20
Updated: 2000 Nov. 18, 0h U.T.This was certainly the most frustrating asteroidal occultation of my life. Known (to me) observational coverage of the event is indicated below, where first the distances of the observing stations from the central line of Martin Federspiel's November 11th prediction are given, then the location, coordinates, name, and height of the observers. Distances are measured perpendicularly to the height-corrected central line. Frac. is the fractional distance from the center to the edge, = dist./(0.5*width), where the width is the 69-km width of the predicted zone of totality. The partial occultation zone is about 30% greater, or about 2.6 half-widths. The "C" column is a code indicating the form of the coordinates, "D" or blank meaning that they are in degrees and decimals of a deg.; "M" meaning that they are in degrees, minutes of arc, and decimal minutes of arc; and "O" meaning that they are in degrees, minutes of arc, and seconds of arc. The asteroid subtended about 0.06", quite small, but we've had a better than 50% success rate in calculating these paths, using the accurate Flagstaff and Table Mtn. Obs. astrometry, to better than half a path-width. So this high-profile event turns out to have a larger prediction error than usual and shifts completely out of the expected path, where all of the mobile observers naturally congregated. So far, I know of no positive observations of this occultation. Maley at 1.37 km S recorded an approximately 10-sec. occultation of mu Gem, but eta Gem also disappeared during much of that time; clouds were clearly involved at his site, less than 500m from Degenhardt's site that recorded no occultation. The only other claimed dimmings of the star were at the close stations (within 500m) at Elliston, VA (J. Guerber) and 30 km s. of Ft. McMurray, AB (Alister Ling and Sharon Tansey). They both reported substantial dimmings, but Jeff's was over one minute before the predicted time of closest approach, while Ling and Tansey's event was at the predicted time; the times don't match. Like Maley, Ling and Tansey's site was affected by "herring-bone" clouds with thick parts; fortunately, the others of us in Alberta (except at Ft. McMurray, 40 km or 1.19 half-widths from the predicted central line; Brian Thachuk tried to observe there, but was completely clouded out) had thinner clouds that allowed us to monitor the star well throughout the 2 minutes around the time of closest approach. Guerber was observing with only binoculars in a brightly twilit sky (Sun alt. about -4 deg.), and lost the star altogether just after his marginal dimming; the others in Virginia used telescopes and had no trouble monitoring the star. For awhile, a possible positive observation was claimed by Jim Davison in Nashville, TN, but upon further review of his video, he noted that other stars dimmed at the same time, and is now rather confident that there was no occultation dimming at his site that was far south of the predicted path. Included in this list is the negative observation made within the south side of the predicted path of totality in Meadow Lake Park, Sask., where the sky was clear (the rest of us from Edmonton should have gone there instead of up the road to Ft. McMurray, but that didn't seem to be the best thing to do based on the weather forecast just before we had to leave Edmonton). Two negative observations from observatories in Saskatchewan (Sleaford) and Manitoba (Glenlea) compound the dilema of "where was the real path"? Bill Gray's prediction was a little over half a path-width north of Federspiel's, and Manek's was about 1.2 path-widths north of it, so maybe the path shifted north? I think that is most likely, with a shift of close to 1.0 path-widths north, since then the path could have fit between Glenlea and Anzac; also, the asteroid could have been smaller in the cross-track dimension. Did anyone besides Scott Young try to observe from Manitoba? In Alberta and most of Saskatchewan, there were no roads and thus no observers north of the expected path, and the weather was overcast over virtually all of the northern side of the path in the U.S. All of the observers listed below, with the already-discussed exceptions, reported no dimming of the star during several minutes surrounding the closest-approach times at their stations. Could the path have shifted south? Then either G. Bilecky should have recorded a dimming, or there should have been one at Sleaford Obs., but they both said no. The fit between these two stations is tighter than that between Glenlea and Anzac on the north side. My prediction, that agreed with Federspiel's, used only the Table Mtn. Observatory observations made during 4 nights the week before the occultation; I thought they should have the highest weight. But my prediction using the USNO-Flagstaff observations, only two of which were in November (1st and 8th, rather far before the event), indicated a path about a path-width south of Federspiel's. So as I said, this has been a very frustrating event. It's too bad the weather was bad over such a large, populous part of the path where the event occurred in a reasonably dark sky. Distance, Location C Latitude Longitude Sta. h, km Frac. # m 125.11N 3.680N GlenleaObsMBSYoungD 49.6454 -97.1208 206 208. 31.13N 0.916N Anzac AB M 5626.899 -11102.276 200 497. 24.24N 0.713N Glenvar VA O 371531.38-800957.30 213 402.3 19.17N 0.564N Elliston VA O 371415.6 -801321.5 212 387. 18.47N 0.543N 30k sFM AB A Ling M 5625.657 -11118.479 201 526. 3.17N 0.093N Christiansburg VA O 370819.4 -802135.0 211 681. 1.37S 0.040S 50kTsFM AB approx.M 5619.62 -11135.51 202 520. 1.82S 0.054S Harveysburg OH O 393003.06-835713.20 214 302. 10.56S 0.311S Radford VA - WHW O 370454.78-803046.92 208 608.1 13.50S 0.397S Radford VA - RLN O 370521.1 -803428. 210 570. 17.72S 0.521S 67k sFMAB M 5611.573 -11143.308 203 500. 17.92S 0.527S Newberry VA O 370433.7 -803757.1 209 609.6 21.43S 0.630S MeadowLakeParkSK D 54.55 -108.67 215 500. 32.09S 0.944S 83k sFMAB M 5605.064 -11151.828 204 738. 99.49S 2.926S Sleaford Obs SK O 520504. -1055513. 205 500. 449.4 S 13.22 S Nashville TN D 36.1 -86.8 216 500. Dist., Location Observer Sta. km # 125.11N GlenleaObsMBSYoung MPC729SCottYoungWin.RASC 206 31.13N Anzac AB David Dunham, video 200 24.24N Glenvar VA John Z Wetmore 213 19.17N Elliston VA Jeffrey R Guerber 212 18.47N 30k sFM AB A Ling A. Ling, S.Tansey 8in. 201 3.17N Christiansburg VA Peter Chen,Tina Dwyer 211 1.37S 50kTsFM AB approx. Paul Maley, video 202 1.82S Harveysburg OH Scott Degenhardt, video 214 10.56S Radford VA - WHW Wayne H Warren Jr 208 13.50S Radford VA - RLN Richard L Nugent, video 210 17.72S 67k sFMAB vis. Murray Paulson 203 17.92S Newberry VA Robert H Stewart, video 209 21.43S MeadowLakeParkSK 3.5in.videoRussSampson&+ 215 32.09S 83k sFMAB PC33C Gary Bilecky 204 99.49S Sleaford Obs SK 12.5in. R.Huziak,Saskatn 205 449.4 S Nashville TN Jim Davison video 216 David Dunham, 2000 December 1