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IAUC 3952: 1984g; 2S 1254-690; V801 Ara; 1983v

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                                                  Circular No. 3952
Central Bureau for Astronomical Telegrams
Postal Address: Central Bureau for Astronomical Telegrams
Smithsonian Astrophysical Observatory, Cambridge, MA 02138, U.S.A.
TWX 710-320-6842 ASTROGRAM CAM    Telephone 617-495-7244/7440/7444

     J. Gibson reports his recovery of this comet on an exposure
with the 1.2-m Schmidt telescope at Palomar, as follows:

      1984 UT               R.A.  (1950.0)  Decl.         m1

      June  4.46051      2 22 01.74     +24 53 12.2       17

The indicated correction to the elements on MPC 8289 is Delta-T = +0.03
days.  Gibson also reports a series of observations made on 4 nights,
from June 8-11, with a CCD and the 1.52-m telescope at Palomar; frames
that were exposed for 60 s or longer show a gas tail, which was ~
50" long in p.a. 270 on a 60-s exposure centered at June 8.45885.

2S 1254-690
     T. J.-L. Courvoisier, A. Parmar and A. Peacock, European Space
Agency, report the discovery of a 3.9-hr period in the x-ray light
curve of the burst source 2S 1254-690.  EXOSAT observed the object
for 12 hr on May 15; three absorption dips were registered during
the observing session, indicating the above period.  The intensity
during the dips was approximately half of the normal quiescent
emission, and much more shallow than the dip observed during the
first EXOSAT measurement (cf. IAUC 3932).  No burst occurred during
the 12 hr of the second EXOSAT observing session.

     H. Pedersen, European Southern Observatory; J. van Paradijs,
University of Amsterdam; and W. H. G. Lewin, Massachusetts Institute
of Technology, write: "Photoelectric and CCD-camera observations
made during the past five years with the Danish 1.5-m telescope
at La Silla show that V801 Ara (= MXB 1636-53) is periodically
variable, with amplitudes up to 0.35 mag (V band).  An orbital
period of ~ 3.8 hr was suggested previously (Pedersen et al. 1981,
Nature, 294, 725; McClintock et al. 1983, Bull. A.A.S. 15, 1003).
Using all our data, we now find a period of 3.8134 +/- 0.0002 hr."

     Total visual magnitude estimates by C. S. Morris (0.25-m
reflector: Big Bear, CA):  May 26.24 UT, 12.0; 27.24, 12.2.

1984 June 14                   (3952)            Daniel W. E. Green

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