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IAUC 5252: GALACTIC CENTER; 1953K; N Oph 1991

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                                                  Circular No. 5252
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

     T. Prince, California Institute of Technology; and G. Skinner,
University of Birmingham, report:  "We have been searching for
counterparts of the x-ray/gamma-ray source 1E 1740.7-2942.  The source
has recently been seen to flare at energies above 200 keV (IAUC
5140), and associations at 1.5 GHz and 115 GHz have been suggested
(IAUC 5211, 5228).  Observations by S. Kulkarni (Caltech) and Prince
with the Very Large Array in 1989 March detected two weak radio
sources within the Einstein IPC error circle of 1E 1740.7-2942.
Source 'A' (R.A. = 17h40m42s.99, Decl. = -29 43'25", equinox 1950.0)
has a flux of about 0.4 mJy at 4.9 GHz and is undetected at 1.5 GHz
at a level of about 1 mJy (95-percent confidence).  Source 'B' (R.A.
= 17h40m42s.45, Decl. = -29 43'05") has a flux of about 0.25 mJy at
4.9 GHz and 1.5 mJy at 1.5 GHz, and is possibly extended.  We suggest
that source A is the more likely counterpart to 1E 1740.7-2942
because of its pointlike nature at 4.9 GHz.  The observations at 1.5
and 4.9 GHz also show the radio source that is suggested in IAUC
5211 as a counterpart of 1E 1740.7-2942, but we note that it lies
well outside published x-ray error circles for 1E 1740.7-2942 and is
therefore not associated with the x-ray source.  J-, H-, and K-band
imaging at the U.K. Infrared Telescope by Skinner, and K- and L'-
band imaging at Palomar by K. Matthews and G. Neugebauer of Caltech,
detect no infrared sources at the position of source A, although
numerous stars are visible in the images."

     R. A. Fesen, Dartmouth College, reports his discovery on
Palomar Sky Survey prints of an apparent supernova (mag about 16) in
the galaxy IC 4536 (R.A. = 15h10m.4, Decl. = -17 57', equinox
1950.0).  The object is visible on both O and E prints (1953 May 18
UT) and is located 12" east and 3" south of the galaxy's center.  No
object is visible at this position to a limiting mag of 21 on R filter
CCD images taken on 1991 Apr. 14 with the Michigan-Dartmouth-MIT
1.3-m telescope.

     M. Watanabe, Toyama Science Center, and Y. Yamada, Yokohama
Science Center, forward the following pre-discovery photovisual
magnitude obtained by M. Yamamoto, Okazaki, Japan:  Apr. 9.739 UT, 9.8.

1991 April 25                  (5252)             Daniel W. E. Green

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