The 1993 October 9 occultation of 8.3-mag. SAO 128735 by (27) Euterpe was observed from 9 stations in Arizona, New Mexico, and the Texas panhandle. Unfortunately, many other observers farther east in the path were clouded out, and partly cloudy skies also caused some observations to be lost in Arizona. The observations can be fit well by a rather extreme ellipse with major axis 124.2 +/-1.7 km and minor axis 75.2 +/-1.7 km, as shown in this plot. The disappearances are on the right side and the reappearances on the left side. Fortunately, observations were made near both limits, so the nearest bracketing miss observations are probably too far away to add anything to the analysis. As far as I know, the closest miss observation on the north side was by Bob Millis west of Mesa, Arizona, and the closest one on the south was by Derald Nye and Rik Hill at Nye's observatory in Corona de Tucson southeast of Tucson. Their miss observations will be added to the plot later. In the meantime, please check the data for your station given below.
Stations for the 1993 Oct. 9th occultation of SAO 128735 by (27) Euterpe
Location Code Latitude Longitude Observer # Height
Coolidge, AZ O 325730. -1113915. Allen Morton, C14 video 6 450.
Florence, AZ - LW H 325135.9 -72455.19 Wasserman&Thompson C14pe 9 693.
Belen, NM - Alb. O 343120.2 -1065041.7Gen.NathanTwiningObs.41cmV 8 1558.
Socorro, NM O 340414. -1065454. Etscorn Obs.C14,NMIT 1 1423.77
Dumas, TX - PM&RN O 355115.6 -1015801.2PaulMaley&RichNugent,Md10 7 1116.
Tucson, AZ - JS O 322513.4 -1105752.2Jim Stamm 5 842.
Tucson, AZ - LW O 321948. -1105437. Larry Wilson 3 878.
Tucson, AZ - JB O 321610.3 -1105713.5Joe Bergeron 4 719.
Tucson, AZ - AV O 321735.3 -1104738.5Albert Vreeland 2 805.
Code specifies the form of the lat. and long. (negative w. of Greenwich):
O means that the form is +/-DDMMSS.S, or +/-DD deg. MM' SS".S
M means that the form is +/-DDMM.MMM, or +/-DD deg. MM'.MMM
D means that the form is +/-DD.DDDD, or +/-DD.DDDD deg.
The station number is given under #; if the number is in the 200's, a miss (no
occultation) was reported and the station is not shown on the plots. An F
following # indicates that the Height above sealevel is in feet; otherwise,
it is in meters (which is the case for all of these stations).
The stations are arranged as they are on the asteroid from north to south.
Timings for the 1993 Oct. 9th occultation of SAO 128735 by (27) Euterpe
B1950
Date U.T. R.A. Star Dec. Ev P.E. Identification, remarks #
YearMoDy h m s h m s d ' "
19931009.65910.1 02106.699 -04906.3141 Socorro, NM Etscorn Obs. 1
19931009.65921.2 02106.699 -04906.3142 Socorro, NM Etscorn Obs. 1
19931009.65956.3 02106.699 -04906.31 1 Tucson, AZ Al Vreeland 2
19931009.65956.5 02106.699 -04906.31 2 Tucson, AZ Al Vreeland 2
19931009.65954.2 02106.699 -04906.31 1 Tucson, AZ Larry Wilson 3
19931009.70000.4 02106.699 -04906.31 2 Tucson, AZ Larry Wilson 3
19931009.65956.4 02106.699 -04906.31 1 Tucson, AZ Bergeron appx 4
19931009.65959.4 02106.699 -04906.31 2 Tucson, AZ Bergeron appx 4
19931009.65952. 02106.699 -04906.31 1 Tucson, AZ Jim Stamm 5
19931009.70001. 02106.699 -04906.31 2 Tucson, AZ Jim Stamm 5
19931009.65956.8 02106.699 -04906.3141 Coolidge, AZ A. Morton 6
19931009.65958.7 02106.699 -04906.3142 Coolidge, AZ A. Morton 6
19931009.65824.0 02106.699 -04906.3141 Dumas, TX Maley&Nugent vid. 7
19931009.65834.6 02106.699 -04906.3142 Dumas, TX Maley&Nugent vid. 7
19931009.65907.3 02106.699 -04906.3141 Belen, NM TwiningObs. video 8
19931009.65916.1 02106.699 -04906.3142 Belen, NM TwiningObs. video 8
19931009.65950.75 02106.699 -04906.3141 Florence, AZ LHW & DT, p.e. 9
19931009.65959.78 02106.699 -04906.3142 Florence, AZ LHW & DT, p.e. 9
Ev is Event
1 = visual dis. with P.E. (personal equation, or reaction time) applied
2 = visual reappearance with P.E. applied
41 = video or photoelectric disappearance
42 = video or photoelectric reappearance
# is the observer's station number
Notes:
Station Weight for ellipse solution and remarks
1 Socorro - weight 0.5 because only the duration could be used; -5.8s has
been applied to the reported times, based on a PC that was
set to WWV several hours before the event (and unfortunately
with a large drift in the PC clock that was not determined at
the time). The chord was shifted so that its center matched
the center of the nearby video chord 7 (Dumas, TX).
2 Tucson AV - weight 0.3 because the observed time, reported to 1 sec.,
is about 3 seconds too early relative to the well-timed
chord 3 (Tucson - L. Wilson). A very short event, as
described, is probable at this southern-limit location, but a
further inquiry is needed to establish the true accuracy of
the timing.
4 Tucson JB - weight 0.5 because the event was timed only roughly, "Just
prior to midnight [local, 7h U.T.], approx. 2-4 sec. drop in
brightness". This short chord near the southern limit is
nevertheless useful, and I have assumed a 3-second duration
with the center of the chord adjusted to match the center of
chord 3.
1.0 was used for the weight for both timings at the other 6 stations.
David Dunham, IOTA, 1996 November 27
Joan and David Dunham (301) 474-4722
dunham@erols.com