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IAUC 7879: 2002ch; Poss. N IN SAGITTARIUS; V4334 Sgr

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IAUC number

                                                  Circular No. 7879
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)

     T. Puckett and A. Langoussis, Mountain Town, GA, report the
discovery of an apparent supernova (mag 18.4) on an unfiltered CCD
frame taken with the Puckett Observatory 0.35-m automated supernova
patrol telescope on Apr. 16.14 UT (and confirmed on a frame taken
on Apr. 17.08).  The new object is located at R.A. = 11h14m31s.72,
Decl. = +33o48'18".3 (equinox 2000.0), which is 4".5 west and 3".0
south of the center of its apparent host galaxy.  SN 2002ch is not
present on images taken by Puckett on 2001 Feb. 25, Apr. 10, May 9,
and Nov. 20 (limiting mag about 20.5) or on Palomar Sky Survey
plates taken on 1990 Mar. 19 and 1992 Feb. 4 (limiting mag about
21.0) and on 1953 Mar. 9 (limiting mag about 20.0).

     W. Liller, Vina del Mar, Chile, reports his measurement for
the position of the possible nova reported on IAUC 7878:   R.A. =
17h59m59s.38 +/- 0s.08, Decl. = -30o53'21".9 +/- 1".0 (equinox
2000.0).  On Apr. 16.40 UT, a low-dispersion objective-prism CCD
spectrogram, taken by Liller with a 0.20-m Schmidt camera, showed
the object to have narrow H-alpha in emission with a strength about
2.5 times that of the surrounding continuum (FWHM approximately 800
km/s); H-beta is present but very faint, suggesting that the object
is considerably reddened.  The [Fe II] multiplet-42 lines also seem
to be present.  On Apr. 16.3814, Liller measured the star's
magnitude to be V = 9.84.  T. Kato, Kyoto University, reports that
K. Haseda (Aichi, Japan) found nothing to magnitude 13.1 on a T-Max
400 film taken on Apr. 12.79.

     F. Kerber, N. Pirzkal, and M. R. Rosa, Space Telescope
European Coordinating Facility, European Southern Observatory (ESO),
Garching, report the discovery of emission lines from V4334 Sgr,
indicating that the star has again left the asymptotic-giant branch
(AGB) only a few years after its final helium flash in 1996.
Spectra obtained with ESO's Very Large Telescope (+ FORS2) on 2001
June 17 and 22 show [N II] 654.8- and 658.3-nm, as well as [O II]
732.5-nm and [O I] 630.0-nm.  H-alpha is marginally detected at </=
20 percent of [N II] 658.3-nm.  Kerber et al. conclude that the
star has started to ionize the H-deficient matter in its
surrounding dusty envelope of ejecta, indicating that the star's
temperature has increased from about 5500 K in 1997 to >/= 20 000
K, and that the star is now retracing its post-AGB evolution toward
the planetary-nebula phase for a second time.

                      (C) Copyright 2002 CBAT
2002 April 17                  (7879)            Daniel W. E. Green

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