Correspondents (T), 1974-1996

              <LjuUT.
RTMENTOF ASTRONOMY
I September 1975
'l/Ef^
TO:   E. Bowel!, C. Cristescu, D. Cruikshank, D. Forbes, C. Lagerkvist,
G. Lustig, D. Minor, I. Nikoloff, J. Oliver, H. Schober, R. Taylor,
W. Wamsteker, V. Zappala
FROM: Edward F. Tedesco
Department of Astronomy
New Mexico State University
Box 4500
Las Cruces, New Mexico 88003
RE:   Global lightcurve coverage of Ceres
The purpose of this memo is to coordinate the worldwide lightcurve coverage
of Ceres by providing potential observers with specific nights and comparison
stars. The two comparison stars were chosen because of their brightness and
proximity to the opposition position of Ceres. The four nights on which our
major effort is being concentrated are those nights when Ceres passes closest
to the comparison stars.
Enclosed you will find a sheet describing these two comparison stars as well
as a chart adopted from the Hans Vehrenberg Atlas Stellarum chart number
130 Tau (chart center +20°, 4h20m).
Please note that the dates given are UT dates and not civil calendar dates.
Observers east of Greenwich are requested to begin their lightcurves on the
UT date preceding those listed here. All lightcurve observations should be
made in the V band of the UBV photometric system. The magnitudes and colors
of the comparison stars given on the enclosed sheet are approximate only.
It would be helpful if each observer made an independent determination of
the V, B-V and U-B of the comparison stars on each night a lightcurve is
obtained.
Although the major effort is directed toward the four dates given on the
enclosed sheet I would like to mention that V. Zappala (8° E longitude) and
myself (107° W longitude) will also be observing on 27 and 30 November and
9 December using these same comparison stars. I would appreciate receiving
reduced observations consisting of UT or UTC (please specify which)
uncorrected for light time or reduction to ET versus A V (in the sense
comparison star magnitude minus Ceres' magnitude) as soon as you have
reduced them. I will then combine the observations and circulate a copy
of our results. In addition to the lightcurve observations values of
comparison star V, (B-V) and (U-B) to three decimal places where warrented
and (B-V) and (U-B) colors of Ceres relative to the comparison stars would
also be of great use.