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IAUC 5017: 1990c; OAO 1657-415; 1990a

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                                                  Circular No. 5017
Central Bureau for Astronomical Telegrams
Postal Address: Central Bureau for Astronomical Telegrams
Smithsonian Astrophysical Observatory, Cambridge, MA 02138, U.S.A.
Telephone 617-495-7244/7440/7444 (for emergency use only)
TWX 710-320-6842 ASTROGRAM CAM     EASYLINK 62794505

COMET LEVY (1990c)
     David H. Levy reports his discovery of a comet.  The
following visual observations are available:

   1990 UT            R.A. (1950) Decl.        m1      Observer
   May  20.44       23 54.3      +27 30        9.6     Levy
        21.426      23 55.07     +27 33.7     10.1     Hale
        21.442      23 55.0      +27 37       10.5     Morris
        21.462      23 55.10     +27 34.2              Hale

D. H. Levy (Tucson, AZ).  0.4-m reflector.  Tail 2' to southwest.
A. Hale (Las Cruces, NM).  0.41-m reflector.  Coma diameter about
  1', moderately condensed.
C. S. Morris (Pine Mountain Club, CA).  0.26-m reflector.  Coma
  diameter 1'.5, nearly stellar condensation.

OAO 1657-415
     S. Mereghetti, Centre d'Etudes Spatiales des Rayonnements
(CESR), Toulouse, communicates the following for the Granat Team
(CESR; Service d'Astrophysique, Centre d'Etudes Nucleaires de
Saclay, Gif sur Yvette; and Space Research Institute, Academy of
Sciences, Moscow):  "The x-ray pulsar OAO 1657-415 has been
observed by the SIGMA and ART-P telescopes onboard the orbiting
Granat observatory on Mar. 27-28.  The source was detected in the
x-ray band by ART-P, and at energies > 35 keV by the SIGMA hard
x-ray/gamma-ray telescope.  The pulse period at the solar system
barycenter was 37.853 +/- 0.002 s.  Since its discovery in 1978,
this source has been constantly spinning up, with (dP/dt)/P about
-1 to -5 x 10E-3 yrE-1.  The results obtained with Granat show that
a change in the accretion torque has recently occurred, causing the
source to enter a phase of period spin-down.  Comparison with the
previous Ginga measurement in 1988 Mar. yields (dP/dt)/P = 1.3 x
10E-3 yrE-1.  Other x-ray observations of OAO 1657-415 are urged."

     Total visual magnitude estimates:  Apr. 24.57 UT, 12.5 (J.
Kobayashi, Kumamoto, Japan, 0.31-m reflector); May 14.48, 13.0 (A.
Pearce, Scarborough, W. Australia, 0.41-m reflector); 21.22, 12.7
(A. Hale, Las Cruces, NM, 0.41-m reflector).

1990 May 21                    (5017)             Daniel W. E. Green

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