Central Bureau for Astronomical Telegrams
IAUC 5520: 4U 1543-47; N Cyg 1992; T Leo
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Read IAUC 5521
Circular No. 5520
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)
4U 1543-47
C. Chevalier and S. A. Ilovaisky, Observatoire de Haute
Provence, report: "Optical observations of the 4U 1543-47 x-ray
transient field obtained in 1989 May at the European Southern
Observatory with the 3.6-m and 1.54-m telescopes show that during
quiescence an apparently normal A-type star is located exactly (to
+/- 0".1) at the position of the 1983 transient (IAUC 3858). The
colors and magnitudes for the A star are V = 16.7 and B-V = +0.75.
In addition to the Balmer and the Ca II K lines in absorption, its
spectrum displays interstellar lines at 443.0, 577.8-578.0, and
628.4 nm, and a Na-D line that is mostly interstellar. Given its
brightness and location, this star contributes significantly to the
total optical flux measured during x-ray outburst. This contribution
can explain the small optical amplitude of the event (1.8 mag
in V) and the broad Balmer absorption seen in 1983 and also reported
on IAUC 5512. The derived magnitude and color for the disk during
the 1983 outburst are thus V = 15.1 and B-V = +0.6. For the A
star we derive a visual absorption of Av = 2.2 and a distance of 4
kpc. Assuming the 1983 outburst spectrum was reddened by a similar
amount, we derive for it Vo = 12.9 and B-V = -0.1. Full details
are given in Chevalier (1989), ESA SP-296, p. 341."
NOVA CYGNI 1992
D. Hanzl, F. Hroch, and E. Neureiterova, report the following
photometry of N Cyg 1992 made at the N. Copernicus Observatory
Planetarium, Brno, with a 0.4-m reflector (comparison star HD
195664, V = 7.39, B-V = +0.20, U-B = +0.17): Apr. 15.083 UT, V =
7.83 +/- 0.02, B-V = -0.06 +/- 0.02, U-B = -0.71 +/- 0.03; 18.074,
8.05 +/- 0.03, -0.07 +/- 0.04, -0.75 +/- 0.04; 20.078, 8.09 +/-
0.01, -0.02 +/- 0.04, -0.79 +/- 0.04; 21.079, 8.18 +/- 0.02, -0.03
+/- 0.02, -0.80 +/- 0.03; 27.067, 8.30 +/- 0.06, -0.05 +/- 0.07,
-0.70 +/- 0.07; 28.038, 8.32 +/- 0.01, -0.09 +/- 0.02, -0.71 +/-
0.03; May 2.077, 8.43 +/- 0.04, -0.09 +/- 0.05, -0.73 +/- 0.07;
5.051, 8.42 +/- 0.02, -0.19 +/- 0.02, -0.71 +/- 0.03.
T LEONIS
Visual magnitude estimates: May 3.90 UT, [13.6 (H. Dahle,
Oslo, Norway); 7.91, 10.8 (Dahle); 8.86, 10.8 (M. Verdenet,
Bourbon Lancy, France).
1992 May 11 (5520) Daniel W. E. Green
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