Aug. 13th occultation of 1 Trianguli by (89) Julia
Observed from 7 stations, Baja Calif. to Saskatchewan
Updated: 2005 Aug. 24
I've completed a first analysis of the observations of the occultation of 1 Trianguli = SAO 74880 = HIP 7948 by (89) Julia on August 13, by 7 observers from southern Baja California to Saskatchewan. For various reasons, only James Thompson video recorded the occultation, with all the other observations being visual timings except for Trina Ruhland, who recorded the occultation trail on a CCD drift scan. The observational data are in a plain text file here. There are a few problems with the data where some more information is needed and has been requested from the observers, so this should be updated as improved information is received. Below is just the first part of the above file only to indicate who observed the occultation. Ap cm is the aperture of the telescope or binoculars used to observe the occultation. Location Sta. E.Longitude Latitude Height Ap # Name, Location o ' " o ' " m cm 1 James Thompson, Eagle, CO -1064921.7 +393938.7 2179 10 2 Mark Vincent, w of Socorro, NM -1070934.9 +340745.7 2000 5 3 Mark Vincent, w of Socorro, NM -1070934.9 +340745.7 2000 5 4 Trina Ruhland, Miners View, CO -1060342.0 +392758.0 3609 36 5 Roc Fleishman, La Paz, BCS, Mexico -1102036.9 +240820.3 5 9 6 Richard Keen, Mt. Thorodin, CO -1052327.6 +395236.1 2725 32 7 Richard Huziak, Sleaford Obs., SK -1055513.0 +520504.0 479 32 8 Paul Maley, Pense, SK -1050344.1 +502347.4 637 4 I set up and prepointed my telescope at Station 1 2 hours before the event, using a star near alpha Andromedae; James Thompson stayed at the site and turned on the camcorder and other equipment a few minutes before the event, verified that the right star field was drifting through the field of view, and saw the occultation on the screen in real time near the center of the field. Pictures of the site and the equipment are here. Station 2 is the secondary occultation reported by Mark Vincent. The nearby chord at Station 4 is not consistent with a secondary occultation lasting as long as Vincent reported so it's most likely that the secondary extinction has a terrestrial explanation, as Vincent said it might. The elliptical fit solution was a little unstable in the east- west direction (length of long axis) until I gave higher weight (a little higher than video) to the easternmost and westernmost observations by Keen (Station 6) and Huziak (Station 7). That stabilized the solution to 174.4 +/-5.9 km for the long axis, 135.6 +/-2.6 km for the short axis, -66.5 +/-4.0 deg. for the PA of the long axis, -2838.7 +/-2.5 km for center X, and +1468.1 +/-1.5 km for center Y. You can see it here with also a Word version. Thanks to all the observers who supplied these observations, and to several others who tried but were clouded out (I was one of those myself). Prediction information about this event is here. 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