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IAUC 8005: 2002hh; V838 Mon

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                                                  Circular No. 8005
Central Bureau for Astronomical Telegrams
Mailstop 18, Smithsonian Astrophysical Observatory, Cambridge, MA 02138, U.S.A.
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SUPERNOVA 2002hh IN NGC 6946
     Further to IAUC 7906, W. Li reports the LOTOSS discovery of an
apparent supernova on unfiltered KAIT images taken on Oct. 31.1
(mag about 16.5) and Nov. 2.1 UT (mag about 16.3).  The new object
is located at R.A. = 20h34m44s.29, Decl. = +60o07'19".0 (equinox
2000.0), which is 60".9 west and 114".1 south of the nucleus of NGC
6946.  A KAIT image taken on Oct. 26.1 showed nothing at this
position (limiting mag about 19.0).  NGC 6946 has produced six
known supernovae:  1917A, 1939C, 1948B, 1968D, 1969P, and 1980K.
Observations of this potentially bright supernova are encouraged.

     U. Munari and S. Desidera, Asiago Astrophysical Observatory;
and A. Henden, Universities Space Research Association and U.S.
Naval Observatory (USNO), communicate:  "Photometry obtained with
the USNO 1.0-m telescope shows the central star of V838 Mon to be
constant in the blue around V = 16.05, U-B = -0.07, and B-V = +0.69
since September, while brightening by 0.012 and 0.020 mag/day in
bands R and I, respectively (from R = 14.43 and I = 10.93 on Sept.
25.5 UT to R = 14.00 and I = 10.22 on Oct. 30.5).  Spectroscopic
observations (range 360-774 nm at 0.32 nm/pixel) of V838 Mon were
obtained on Oct. 28 and 29 with the Asiago 1.82-m telescope (+
AFOSC).  The hot companion star reported on IAUC 7982 (confirmation
report on IAUC 7992) seems to resemble a normal B3 V star,
suffering from a reddening of E(B-V) = +0.9 that is consistent with
a law having R_V = A_V/E(B-V) = 3.1 (cf. Savage and Mathis 1979,
ARAA 17, 73), in agreement with earlier estimates based on the
intensity of Na I and K I interstellar lines (cf. IAUC 7812).
However, if the companion is a genuine B3 V star, V838 Mon lies
10500 pc distant and just 200 pc above the galactic plane, for
which such a low reddening is surprising, and the mass of the M-
giant progenitor should have been larger than 7 solar masses.  The
fact that the B3 V star is about 1 mag fainter in B than V838 Mon
in quiescence, and that the optical-infrared energy distribution of
the latter closely matched an F0 star (luminosity class III-II for
a distance of 10500 pc), suggests that the quiescent light could
have been dominated by the progenitor of the outbursting companion
or by circumstellar material in the form of a warm disk, or
something else.  The current spectrum of the cool component holds
identical to the 'later-than-M10' classification of one month ago
(cf. IAUC 7982)."

                      (C) Copyright 2002 CBAT
2002 November 1                (8005)            Daniel W. E. Green

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