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IAUC 5862: N Sgr 1993; 1987A; 1993J

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                                                  Circular No. 5862
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

     Independent photographic discoveries of an apparent nova have
been reported by Matsuo Sugano, Minami-Oda, Hyogo, Japan (via S.
Nakano, Sumoto), and by William Liller, Vina del Mar, Chile.  The
object is located at R.A. = 18h09m.7, Decl. = -29o30' (equinox
1950.0), situated approximately midway between, and slightly to the
north of, two stars of mag 10.  Magnitude estimates:  Aug. 27.02 UT,
[11.5 (Liller; Tech Pan film, orange filter); 14.508, 9.0 (Sugano;
Tri-X film); 16.043, 7.9 (Liller).

     J. Xu and A. P. S.  Crotts, Columbia University; and W. E.
Kunkel, Carnegie Observatories, report:  "We have discovered two
new (and possibly related) light echo structures from SN 1987A.
These are due to material more than twice as distant from the
supernova as any previously reported (IAUC 4561, 4733, 4739, 4791), at
3360 and 3470 lyr in the 'supernova foreground', corresponding to
radii of about 240" on 1993 May 1.  These first appeared in data
from 1991 Sept. 18, at 110 deg < p.a. < 140 deg and 3 deg < p.a. <
13 deg, respectively.  Since then, the second feature has brightened,
while the first brightened then later dimmed.  Their maximum
surface brightness is about 9.2 x 10E-19 erg sE-1 cmE-2 AE-1 arcsecE-2
(at 612 nm), and they can be easily detected only once background
stars and nebulosity have been subtracted from the image.
We also note that the outer prominent echo ring has become very
complex, particularly over its western half, with components ranging
from about 880 to 2060 lyr distance in the supernova foreground.
Further observations of these features are encouraged and would
help reveal their continued evolution and therefore their three-
dimensional structure."

     CCD photometry by X. Zhou, Y. Li, and H. J. Yan, obtained at
the Xing-Long station of Beijing Astronomical Observatory:  Sept.
4.41 UT, B = 14.90, V = 14.32, R = 13.46, I = 12.92; 4.44, 15.07,
14.49, 13.55, 12.91; 5.45, 14.91, 14.26, 13.49, 13.10; 5.49, 14.85,
14.22, 13.48, 12.91; 5.54, 14.78, 14.02, 13.43, 12.86; 5.58, 14.80,
14.13, 13.33, 12.85; 6.35, 14.96, 14.73, 13.97, 14.01; 6.38, 14.97,
14.29, 13.88, 14.16.

1993 September 16              (5862)            Daniel W. E. Green

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