Central Bureau for Astronomical Telegrams
IAUC 7102: 1987A; 3C 279
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Circular No. 7102
Central Bureau for Astronomical Telegrams
INTERNATIONAL ASTRONOMICAL UNION
Mailstop 18, Smithsonian Astrophysical Observatory, Cambridge, MA 02138, U.S.A.
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SUPERNOVA 1987A IN THE LARGE MAGELLANIC CLOUD
P. Garnavich, R. Kirshner, and P. Challis, Harvard-Smithsonian
Center for Astrophysics, report on behalf of the Supernova
Intensive Study team: "Images of SN 1987A were obtained with the
Wide Field/Planetary Camera II (WFPC2) onboard the Hubble Space
Telescope on Jan. 7-8. The data show that the ring 'hotspot' (cf.
IAUC 6665, 6710) is continuing to brighten at wavelengths between
200 and 900 nm. The hotspot flux in the F656N filter (H-alpha + N
II 654.8-nm) is now 6.4 x 10E-15 erg cmE-2 sE-1, and the F675W
magnitude (similar to R band) is 20.65 +/- 0.05. The F675W light
curve over the past four years is well fitted by a line with a
slope of -0.0024 mag/day, more than doubling in brightness each
year. The hotspot is now easily detected in the F255W filter, with
a flux of about 3 x 10E-15 erg cmE-2 sE-1. The new F675W image
clearly shows evidence of the reverse-shock that had been detected
spectroscopically in Lyman-alpha and H-alpha (Michael et al. 1998,
Ap.J. 509, L117). The limb-brightened shock appears as two arcs
within the ring, east and west of the debris. Their separation is
measured to be 1".20 +/- 0".04 along the major axis of the ring.
Assuming spherical expansion and a maximum observed velocity of the
Ly-alpha emission of -12000 +/- 1400 km/s (Michael et al., with the
error based on the slit width), the distance to SN 1987A is 50 +/-
6 kpc. This is consistent with most distance estimates to the LMC.
The east arc is clearly brighter than the western arc by a factor
of about 1.5, mirroring the asymmetry found in the radio by
Gaensler et al. (1997, Ap.J. 479, 845) and calling into question
the assumption of spherical expansion."
3C 279
M. Villata, C. M. Raiteri, G. Sobrito, G. De Francesco, and L.
Lanteri, Osservatorio Astronomico di Torino; and R. C. Hartman,
Goddard Space Flight Center, for the CGRO/EGRET Team, write: "3C
279 is optically bright and active; CCD data taken with the Torino
1.05-m telescope from Jan. 14 to 26 show fast variations in R in
the range 13.78-14.50 (+/- 0.02; see
http://www.to.astro.it/Groups/Extragal/blazars.htm). Preliminary
results from EGRET observations show a flux (> 100 MeV) of about 2
x 10E-6 photon cmE-2 sE-1, with some evidence for time variation
over the first 4.5 days (Jan. 20.5-24.0 UT). From preliminary
analysis of data from RXTE, A. Lawson and I. McHardy report that
the x-ray flux is at an intermediate historical level, consistent
with the present EGRET flux. The RXTE PCA countrate (3-10 keV) is
very roughly 3 counts/s for 3 PCUs."
(C) Copyright 1999 CBAT
1999 February 1 (7102) Daniel W. E. Green
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