Central Bureau for Astronomical Telegrams
IAUC 7342: 1999gr; C/1999 S4
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Circular No. 7342
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)
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URL http://cfa-www.harvard.edu/iau/cbat.html ISSN 0081-0304
Phone 617-495-7244/7440/7444 (for emergency use only)
SUPERNOVA 1999gr IN MCG +5-29-24
G. M. Hurst, Basingstoke, England, reports the discovery by
Mark Armstrong, Rolvenden, of an apparent supernova on unfiltered
CCD images taken on 1999 Dec. 13 and 15 with a 0.30-m telescope in
the course of the U.K. Nova/Supernova Patrol. SN 1999gr is located
at R.A. = 12h09m11s.31, Decl. = +29o16'34".7 (equinox 2000.0),
which is 23" east and 8" north of the nucleus of MCG +5-29-24.
Hurst reports the following approximate magnitude estimates from
CCD images taken by Armstrong (Dec. 13 and 15) and by T. Boles,
Wellingborough (Dec. 19): Dec. 13.185 UT, 18.5; 15.166, 18.6;
19.173, 18.6. A CCD image obtained by M. Schwartz, Cottage Grove,
OR, obtained on 1999 Jan. 14 does not show the new object (limiting
mag about 18.5-19.0), and SN 1999gr is not visible on second
Palomar Sky Survey images (limiting mag about 20.5).
S. Jha, P. Challis, and R. Kirshner, Harvard-Smithsonian
Center for Astrophysics; and P. Garnavich, University of Notre
Dame, report that a spectrum of SN 1999gr, obtained by M. Calkins
on Jan. 5.46 UT with the F. L. Whipple Observatory 1.5-m telescope
(+ FAST spectrograph), shows it to be a type-Ia supernova, several
months after maximum light. Though of low signal-to-noise, the
spectrum exhibits broad emission features of [Fe II] and [Fe III],
observed at 470, 530, and 590 nm.
COMET C/1999 S4 (LINEAR)
D. G. Schleicher, Lowell Observatory, writes: "Narrowband
photometry of comet C/1999 S4 was obtained with the Hall 1.07-m
telescope at Lowell Observatory on 1999 Dec. 5, 28, and 30 UT (r =
3.57-3.28 AU). The only gas species definitively detected has been
CN, with a near-constant Haser production rate of log Q(CN) = 24.2;
C_2 was marginally detected in late December. The upper limit on
OH emission yields log Q(OH) < 27. The dust-production rates were
log [Af(rho)] = 2.4 on Dec. 5 and 2.2 on Dec. 28 and 30 (A is the
albedo of the grains, f is the filling factor of the grains, and
rho is the radius of the field-of-view; cf. A'Hearn et al. 1984,
A.J. 89, 579). This apparent decrease in dust production implies
either an earlier outburst or significant variability due to
rotation. Should the comet be dynamically new, the decrease in
dust production likely predicts behavior similar to that of comet
C/1973 E1 (Kohoutek), due to the continued dispersion of dust
released at much larger r."
(C) Copyright 2000 CBAT
2000 January 7 (7342) Daniel W. E. Green
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