Central Bureau for Astronomical Telegrams

IAUC 5632: FG Sge; GRO J0422+32; 1992ba

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                                                  Circular No. 5632
Central Bureau for Astronomical Telegrams
INTERNATIONAL ASTRONOMICAL UNION
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
MARSDEN@CFA or GREEN@CFA (.SPAN, .BITNET or .HARVARD.EDU)


FG SAGITTAE
     E. F. Guinan, G. P. McCook, and T. A. Thrash, Villanova
University, report:  "UBVRI photometry of FG Sge has been carried out
on 86 nights since 1991 at Mt. Hopkins, AZ (0.8-m Automated
Photoelectric Telescope) and at Villanova (0.38-m reflector).  These
observations (plus those reported on IAUC 5604, 5609, 5610, and 5619)
indicate a sudden dimming of the star at all wavelengths, starting
in mid-August.  By early October, the star has decreased in brightness
to V about 12.1 and B about 13.6.  This is the faintest that
FG Sge has been observed since the 1890s, when its photographic
brightness was mpg about 13.1.  Observations prior to the recent
dimming show FG Sge to have low amplitude (about 0.2 mag at V),
quasiperiodic (about 110-130 days) light variations, and a mean
brightness of V about 9.1-9.2.  The current light loss episode
could be caused by the formation of dust in an ejected shell,
similar to light loss events observed in R CrB-type variables."


GRO J0422+32
     N. M. Shakhovskoj reports photometric and polarimetric data
obtained with the Crimean Astrophysical Observatory 1.25-m reflector:
Aug. 26.99 UT, U = 13.46, B = 13.83, V = 13.54, R = 13.16, I =
13.04; Sept. 28.06, 13.50, 13.92, 13.57, 13.16, 12.81; Sept. 29.06,
13.46, 13.89, 13.56, 13.15, 12.76; Sept. 29.91, 13.46, 13.88, 13.54,
13.15, 12.77.  Linear polarimetry in the specified bands:  Aug.
16.02, U, 1.7 +/- 1.6 percent, position angle 62 +/- 22 deg; B, 0.1
+/- 0.7, 108 +/- 40; V, 0.6 +/- 0.9, 8 +/- 27; R, 0.3 +/- 0.8, 13
+/- 36; I, 0.8 +/- 0.7, 155 +/- 22.  Aug. 26.99, U, 1.7 +/- 0.5, 65
+/- 9; B, 0.4 +/- 0.4, 77 +/- 23; V, 1.6 +/- 0.7, 68 +/- 12; R, 0.7
+/- 0.4, 86 +/- 16; I, 0.7 +/- 0.5, 116 +/- 19.  Sept. 28.07, U,
0.1 +/- 0.4, 9 +/- 35; B, 0.5 +/- 0.3, 84 +/- 15; V, 1.1 +/- 0.5,
165 +/- 13; R, 0.7 +/- 0.3, 87 +/- 10; I, 0.5 +/- 0.4, 156 +/- 19.
Sept. 29.06, U, 0.7 +/- 0.3, 76 +/- 12; B, 0.5 +/- 0.2, 90 +/- 10;
V, 0.9 +/- 0.4, 120 +/- 12; R, 0.7 +/- 0.2, 95 +/- 6; I, 0.6 +/-
0.3, 107 +/- 12.  On Aug. 29, the circular polarization was measured
in the R band with the 2.6-m Shajn telescope to be +0.10 +/-
0.08.


SUPERNOVA 1992ba IN NGC 2082
     R. H. McNaught, Anglo-Australian Observatory, reports that no
image appears on a U.K. Schmidt Telescope plate taken by A. Savage
on 1992 Sept. 17.7 UT to a limit of I = 19.  The comparison I
survey plates were taken in 1978 and 1982.


1992 October 8                 (5632)            Daniel W. E. Green

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