Central Bureau for Astronomical Telegrams
IAUC 4995: Prob. N IN Sco; 1987A
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Circular No. 4995
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
PROBABLE NOVA IN SCORPIUS
W. Liller, Vina del Mar, Chile, reports his discovery with
PROBLICOM of a probable nova at R.A. = 17h50m57s, Decl. = -30 48.3
(equinox 1950.0). Magnitudes from 2415 film (+ red filter): Apr.
9.25 UT, [12; 17.19, 10.2. He adds that this may be a recurrence
of N Sco 1954 = NSV 09808 (IAUC 1471), though the position of that
object is poorly known (Duerbeck 1987, Space Sci. Rev. 45, 1).
SUPERNOVA 1987A IN THE LARGE MAGELLANIC CLOUD
N. Suntzeff, M. Phillips, J. Elias, D. Depoy and A. Walker,
Cerro Tololo Interamerican Observatory, report: ''We have continued
our multi-band observations (optical and near-infrared spectroscopy,
UBVRI CCD photometry, JHK imagery, and mid-infrared photometry) of
SN 1987A at CTIO. We find that the optical colors, based on PSF
fitting to the CCD data, have continued to slow their decline in
brightness compared to the data we presented on IAUC 4881. Over the
period from 939 to 1123 days since outburst, the UBVRI colors have
fallen with e-folding times of 180, 140, 160, 153, and 144 days,
respectively. The decline in brightness at 19 microns (Q) from days
600 to 1143 can be fitted by a simple exponential law with an e-folding
time of 133 +/- 9 days. At 10 microns (N), the decline was more
rapid from days 600 to 935, but since then the e-folding time for
the decline has been 144 +/- 7 days. The behavior of the mid-infrared
data is consistent with the cooling of the dust in the ejecta from
400 K at day 600 to 180 K by day 935 (Suntzeff and Bouchet 1990,
A.J. 99, 650) and constant temperature since then. The CTIO 10-
and 19-micron measurements, which were made through a 4".3 aperture,
are significantly fainter than the photometry reported by the ESO
group (IAUC 4839, 4933) for days 991 and 1054 and do not support
their conclusion that the bolometric lightcurve is rapidly leveling
off. Instead, our data indicate that the bolometric luminosity of
SN 1987A is leveling off more slowly and is now declining with an
e-folding time of roughly 155 days. For day 1143, we estimate that
the log10 luminosity (cgs units) is 37.55 +/- 0.07, where we have
integrated the flux based on the broadband magnitudes and
extrapolated the unobserved flux longward of 19 microns by fitting
a blackbody with T = 160 K to the data. At this temperature, half
the flux is being emitted longward of 19 microns, and the quoted
error only represents the error in the fit."
1990 April 18 (4995) Daniel W. E. Green
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