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IAUC 7838: 2000ft; 2002ap

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                                                  Circular No. 7838
Central Bureau for Astronomical Telegrams
Mailstop 18, Smithsonian Astrophysical Observatory, Cambridge, MA 02138, U.S.A.
IAUSUBS@CFA.HARVARD.EDU or FAX 617-495-7231 (subscriptions)
URL http://cfa-www.harvard.edu/iau/cbat.html  ISSN 0081-0304
Phone 617-495-7440/7244/7444 (for emergency use only)

SUPERNOVA 2000ft IN NGC 7469
     L. Colina, Instituto de Fisica de Cantabria, Consejo Superior
de Investigaciones Cientificas (CSIC); A. Alberdi, Instituto de
Astrofisica de Andalucia, CSIC; J. M. Torrelles, Institut d'Estudis
Espacials de Catalunya, CSIC; N. Panagia, European Space Agency and
Space Telescope Science Institute; A. S. Wilson, University of
Maryland; and S. T. Garrington, Jodrell Bank Observatory,
communicate:  "The source RSN J230315+0852.4 in NGC 7469, first
detected at radio frequencies on 2000 Oct. 27 (see IAUC 7587) and
identified with a radio supernova (Colina et al. 2001, Ap.J. 553,
L19), has been monitored extensively over the past few months with
MERLIN.  The flux measured at 5 GHz for the last epoch (2001 Sept.
11) was 0.79 +/- 0.02 mJy, indicating that the radio flux emitted
by this source has dropped by about a factor of 2 since first
discovered.  Additional new data taken at 8.4 GHz with the Very
Large Array (VLA) on 2002 Feb. 8 indicate that the decline in flux
continues.  The observed variation in flux is typical of other
radio supernovae also identified as such in the optical, and
confirms the source RSN J230315+0852.4 as a radio supernova (and
the first not detected in the optical).  Radio monitoring with
MERLIN and the VLA is continuing."

     J. Danziger, Trieste Observatory; M. Della Valle, Arcetri
Observatory; E. Palazzi, Consiglio Nazionale delle Ricerche,
Bologna; and E. Pian, Trieste Observatory, report that high-quality
spectropolarimetry in the infrared bands J, H, and K were obtained
with the 3.6-m reflector (+ NICS) by the Telescopio Nazionale
Galileo staff at La Palma during inferior weather conditions on Feb.
6.9 UT.  Polarization measures in the range 1.0-2.4 microns fall in
the range 0.5-0.9 percent, but the 3-sigma error bars suggest this
could range from about 0 to about 2 percent.  The spectra reveal a
P-Cyg absorption feature near 1.0257 microns, which, if attributed
solely to He I 1.083-microns, leads to a velocity of 16 500 km/s.
Velocities of the blue-shifted absorption extend to 23 500 km/s.
Another broad absorption feature is measured at 1.5136 microns.
There appears to be a real abrupt drop in the level of the spectrum
between the H and K spectral regions.  Comparison with spectra of
SN 1998bw (Patat et al. 2001, Ap.J. 555, 900) reveals a similarity.
This apparent jump might plausibly be attributed to the presence of
(a) broad emission feature(s) spanning the range 1.5-1.9 microns.

                      (C) Copyright 2002 CBAT
2002 February 28               (7838)            Daniel W. E. Green

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