Central Bureau for Astronomical Telegrams
IAUC 7108: 1999aa; RINGS OF NEPTUNE
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Circular No. 7108
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 1999aa IN NGC 2595
Ron Arbour, South Wonston, Hants, U.K., reports his discovery
of an apparent supernova (mag about 15.5) in the galaxy NGC 2595 on
an unfiltered CCD image (limiting mag about 17.5) taken on Feb.
11.0166 UT using a 0.3-m f/6.3 reflector in the course of his
supernova patrol. M. Armstrong confirmed the new object's
existence via two exposures (the first at Feb. 11.0461 UT),
measuring its position as R.A. = 8h27m42s.03, Decl. = +21o29'14".8
(equinox 2000.0), which Arbour notes to be 1" east and 28" north of
the center of NGC 2595. Nothing is present at this position on six
images taken by Arbour in 1998 Feb. and Mar. (limiting mag about
17.5), nor is it present in the Digitized Sky Survey. Arbour notes
that a CCD image obtained by M. Schwartz with the Tenagra 0.35-m
patrol telescope on Feb. 12.07 yields an offset of 2" east, 27"
north, while an image by Schwartz obtained on 1998 Nov. 26.45 shows
no object at this location.
A. V. Filippenko, W. D. Li, and D. C. Leonard, University of
California at Berkeley, write: "CCD spectra (range 330-1000 nm)
obtained on Feb. 12 UT with the Lick Observatory 3-m Shane
reflector show that SN 1999aa is a peculiar type-Ia supernova, very
similar to SN 1991T (Filippenko et al. 1991, Ap.J. 384, L15). The
Si II absorption at 620 nm is very weak, but Fe III lines near 430
and 500 nm are prominent; unlike the case of SN 1991T, however, the
absorption trough centered at 375 nm (due to Ca II?) is strong.
Overall, the spectrum suggests an age of about 6 days before
maximum brightness. SN 1999aa is not visible in an unfiltered
image of NGC 2595 obtained on Feb. 5.3 (limiting mag about 19) with
the 0.8-m Katzman Automatic Imaging Telescope in the course of the
Lick Observatory Supernova Search (cf. IAUC 6627). The recession
velocity of the host galaxy, determined from narrow H-alpha and [N
II] emission, is 4400 km/s."
RINGS OF NEPTUNE
C. Roddier, F. Roddier, J. E. Graves, O. Guyon, and M. J.
Northcott, Institute for Astronomy, University of Hawaii (UH); and
B. Sicardy, Paris Observatory, report: "Infrared (1.72-micron)
images of Neptune taken on 1998 July 6 with the UH adaptive optics
system (Hokupa'a) mounted on the Canada-France-Hawaii 3.6-m
telescope have been studied further. In addition to the
observations of Neptune arcs reported on IAUC 7051, evidence is now
found for another ring structure even closer to Neptune. Its
radial distance is that of the Le Verrier ring. It is visible only
on the west ansa, and its brightness is roughly twice that of the
Adams arcs."
(C) Copyright 1999 CBAT
1999 February 12 (7108) Daniel W. E. Green
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