Central Bureau for Astronomical Telegrams
IAUC 7219: 1999da; GX 17+2
The following International Astronomical Union Circular may be linked-to from your own Web pages, but must not otherwise be redistributed (see these notes on the conditions under which circulars are made available on our WWW site).
Read IAUC 7220
.dvi or
.ps format.
Circular No. 7219
Central Bureau for Astronomical Telegrams
INTERNATIONAL ASTRONOMICAL UNION
Mailstop 18, Smithsonian Astrophysical Observatory, Cambridge, MA 02138, U.S.A.
IAUSUBS@CFA.HARVARD.EDU or FAX 617-495-7231 (subscriptions)
BMARSDEN@CFA.HARVARD.EDU or DGREEN@CFA.HARVARD.EDU (science)
URL http://cfa-www.harvard.edu/iau/cbat.html ISSN 0081-0304
Phone 617-495-7244/7440/7444 (for emergency use only)
SUPERNOVA 1999da IN NGC 6411
A. V. Filippenko, University of California at Berkeley (UCB),
reports that a CCD spectrum (range 330-1000 nm) obtained on July 9
UT with the 3-m Shane reflector at Lick Observatory reveals SN
1999da (cf. IAUC 7215) to be of type Ia, but similar to the
peculiar, subluminous type-Ia SNe 1986G or 1991bg (e.g., Filippenko
et al. 1992, A.J. 104, 1543). SN 1999da also appears to be
subluminous, and its host is an elliptical galaxy, consistent with
previous indications that such type-Ia events tend to occur in
early-type galaxies.
S. Jha, P. Garnavich, P. Challis, and R. Kirshner, Harvard-
Smithsonian Center for Astrophysics (CfA), report that a spectrum
of SN 1999da taken by M. Calkins on July 9.4 UT with the F. L.
Whipple Observatory 1.5-m telescope (+ FAST spectrograph) also
reveals it to be a type-Ia supernova that is likely subluminous.
The spectrum exhibits absorption from Ti II as well as a strong Si
II 580-nm feature typically seen in subluminous events such as SN
1998de (cf. IAUC 6980). Cross-correlation of the host-galaxy
spectrum with an absorption-line template yields a recession
velocity of 3830 +/- 40 km/s for NGC 6411.
GX 17+2
P. J. Callanan, University College, Cork; A. V. Filippenko,
UCB; and M. R. Garcia, CfA, write: "We have discovered a highly
variable K-band counterpart to the persistently bright x-ray
burster GX 17+2. Observations obtained with with the Near Infrared
Camera on Keck I during June 26.47 UT clearly resolve star 'TR'
(Tarenghi and Reina 1972, Nat. Phys. Sci. 240, 53; Naylor et al.
1991, MNRAS 252, 203) into two components, displaced in Decl. by
0".9. The southerly and northerly components have K-band
magnitudes of 14.5 and 14.9, respectively. The position of the
northerly component agrees well with the astrometry of Deutsch et
al. (1999, http://xxx.lanl.gov/abs/astro-ph/?9905174), and in
particular with their 'star A' identified with HST/NICMOS with an
H-band magnitude of about 19.8. For an H-band reddening of about 2
mag (ibid.), and an H-K color range of 0 to +0.3 (early O-late M),
this implies a K mag of about 18.5-18.8 during their observations,
and hence an amplitude of variability of about 3.5-4 mag at K. If
our counterpart is unrelated to 'star A' of Deutsch et al., then
the amplitude of variability is even higher. In any case, this
large degree of variability is surprising, considering the
persistently bright nature of the x-ray emission of GX 17+2."
(C) Copyright 1999 CBAT
1999 July 10 (7219) Daniel W. E. Green
Read IAUC 7220
.dvi or
.ps format.
Our Web policy. Index to the CBAT/MPC/ICQ pages.
