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IAUC 7159: 1999by; V364 Peg; V4334 Sgr; Corr

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IAUC number

                                                  Circular No. 7159
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
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SUPERNOVA 1999by IN NGC 2841
     P. Garnavich, S. Jha, and R. Kirshner, Harvard-Smithsonian
Center for Astrophysics, write:  "Spectra obtained by P. Berlind
with the 1.5-m Tillinghast telescope on May 6.2 UT confirm that SN
1999by is a type-Ia event, but the spectrum is peculiar.  The
580-nm Si II feature is very strong relative to the 615-nm Si II
absorption, suggesting that this is a subluminous type-Ia supernova.
The ratio of the depth of 580- to 615-nm lines correlates with the
decline rate (Nugent et al. 1995, Ap.J. 455, 147) and is found to
be 0.6 in SN 1999by.  This is similar to the ratio observed in SN
1991bg, the prototypical fast-declining, subluminous type-Ia
supernova.  In addition, the flux around 400 nm is depressed
relative to normal type-Ia events, consistent with Ti II absorption
also seen in subluminous events.  The minimum of the Si II
absorption, corrected for the redshift of NGC 2841 (638 km/s),
indicates a photospheric velocity of 10 800 km/s.  Spectra of SN
1999by can be found at

     Q. Y. Qiao, J. Y. Wei, Y. L. Qiu, and J. Y. Hu, Beijing
Astronomical Observatory (BAO), report their discovery in the
course of the BAO supernova survey of an outburst of the
cataclysmic variable in Pegasus that was previously reported on
IAUC 6746, 6772, 6982, and 7021.  The unfiltered CCD magnitude of
the star was 15.0 on May 5.82 UT.

     T. Geballe, Gemini North, Joint Astronomy Centre; S. Eyres,
Liverpool John Moores University; and A. Evans and B. Smalley,
Keele University, report on infrared (JHKLM) spectra obtained on
Apr. 22 and May 3 UT:  "There is now strong He I emission at 1.083
microns, in contrast to the strong absorption in this line in 1998
(cf. IAUC 6896; Eyres et al., MNRAS, in press).  No other emission
or absorption lines are obviously present.  There is also a strong
dust continuum, at temperature about 1100 K (cf. IAUC 7155).
Longward of 1 micron, the dust emission now completely obscures the
stellar photosphere, which was clearly visible in 1998."

     On the last two lines of IAUC 7158, the Apr. 13.675 and 16.662
observations attributed to SN 1999be actually belong to SN 1999bg
in IC 758.

                      (C) Copyright 1999 CBAT
1999 May 7                     (7159)            Daniel W. E. Green

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