Central Bureau for Astronomical Telegrams
IAUC 4910: 1987A; N Sct 1989
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Circular No. 4910
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 or GREEN@CFA.BITNET MARSDEN or GREEN@CFAPS2.SPAN
SUPERNOVA 1987A IN THE LARGE MAGELLANIC CLOUD
A. R. Walker, Cerro Tololo Interamerican Observatory, telexes:
"I have obtained the following CCD photometry of the two stars (Nos.
2 and 3 of West et al. 1987, A.Ap. 177, L1) adjacent to SN 1987A,
from measurements made on four nights during Oct.-Nov. with the CTIO
0.9-m telescope: Star 2, V = 14.96, B-V = -0.04, U-B = -0.74, V-R =
-0.05, V-I = -0.10; Star 3, V = 15.82, B-V = +0.12, U-B = -0.80, V-R
= +0.25, V-I = +0.36. The V-R and V-I values for Star 3 cannot yet
be regarded as definitive, since SN 1987A is still more than a
magnitude brighter in the R and I bands. The bright and uneven
background in the immediate vicinity of the supernova also hinders
precision photometry, particularly in the R band. The reddening, from
UBV CCD photometry of 23 early-type stars in the field of SN 1987A,
is E(B-V) = 0.17 +/- 0.02 (Walker and Suntzeff, P.A.S.P., in press).
The colors of Star 2 are consistent with this reddening, or a value
just slightly larger. However, Star 3 appears to be heavily reddened,
with E(B-V) = 0.42 +/- 0.04. If this result is confirmed then it
has important bearing on the interpretation of optical photometry of
SN 1987A (separation of the two lines-of-sight is 0.4 pc at SN 1987A).
De-reddening using the above values together with a two-component
(foreground, 30 Dor) model for the extinction yields intrinsic colors
and absolute magnitudes for Stars 2 and 3 that correspond to spectral
classifications of B1 III and B0 V, respectively. This result appears
to be consistent with temperatures and gravities found by comparing
IUE spectra with model atmospheres (G. Sonneborn 1987, Fourth George
Mason Astrophysics Workshop). Optical classification spectra for
these stars would be of great interest. On 1989 Nov. 10.3 UT, SN
1987A itself had U = 14.77, B = 15.08, V = 15.10, R = 14.26, I = 14.26."
NOVA SCUTI 1989
Visual magnitude estimates (cf. IAUC 4893): Nov. 3.03 UT, 11.1
(G. Kronk, Troy, IL); 3.80, 11.1 (A. Pereira, Cabo da Roca, Portugal);
6.02, 11.7 (Kronk); 7.74, 11.0 (P. Schmeer, Bischmisheim, W. Germany);
10.74, 11.3 (A. Boattini, San Niccolo, Italy); 14.71, 12.1 (Boattini,
Florence, Italy); 16.72, 11.5 (E. Schweitzer, Strasbourg, France);
18.72, 11.9 (Schmeer).
1989 November 22 (4910) Daniel W. E. Green
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