Central Bureau for Astronomical Telegrams
IAUC 6836: 1998U; 1987A
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Circular No. 6836
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
Phone 617-495-7244/7440/7444 (for emergency use only)
SUPERNOVA 1998U IN ANONYMOUS GALAXY
N. Regnault and O. Perdereau, on behalf of the EROS
collaboration (cf. IAUC 6760, 6762), report the discovery of an
apparent supernova (V about 20) on Mar. 3 (and confirmed on Mar. 4)
on images taken with the Marly 1-m telescope at the European
Southern Observatory (ESO). SN 1998U is located at R.A. =
11h36m32s.20, Decl. = -12o07'26".7 (equinox 2000.0), which is 2".4
west and 4".2 north of the host galaxy. Additional images of SN
1998U were obtained on Mar. 6 at the ESO 1.5-m Danish telescope.
SN 1998U was not present on a CCD frame taken on 1997 Feb. 2
(limiting mag 22).
SUPERNOVA 1987A IN THE LARGE MAGELLANIC CLOUD
A. Crotts, Columbia University; and S. Heathcote, Cerro Tololo
Interamerican Observatory (CTIO), report on data obtained with the
CTIO 4-m telescope on 1996 Dec. 5 and 1998 Feb. 17 UT (echelle
spectrograph), and on 1997 Sept. 23 (RC spectrograph): "The
increase in strength of the blue wing of the H-alpha emission line,
as reported on IAUC 6831, is difficult to confirm with certainty in
our data. Some weak emission lines have formed in the near-
infrared portion of the spectrum, particularly [Fe II] at 768.6,
889.1, and 905.1 nm, and appear offset to the northeast of the
supernova by about 0".5 (for the slit at p.a. 50o). (Stronger
lines due to [Fe II] at 715.5, 717.2, 738.8, 745.2, and 861.7 nm
are detected also in RC spectrograph data obtained on 1997 Jan. 15
by J. Maza and M. Phillips, while [Fe II] 768.6, 889.1, and 905.1
nm would have been detected at the strength found on 1997 Sept. 23,
but were not.) Previously detected lines over the range 570-1080
nm are the H I Paschen series (all terms 7 to 17); [Fe VII] 608.7
nm; [Ar III] 713.5 and 775.1 nm; [Ar V] 700.5 nm; [Cl II] 857.9 nm;
and [Ca II] 729.1 and 732.3 nm; [Ni II] 737.8 nm; [Cr II] 812.5,
822.9, and 830.8 nm; and perhaps [C I] 984.9 nm and [Ar IV] 723.7
and 726.2 nm. Also seen are the usual strong lines of [N II], He
I, [O I], [O II], [S II], [S III] and H-alpha. New, unidentified,
very weak lines are also seen at rest wavelengths 704.56, 710.37,
and 711.98 nm (with a typical accuracy of +/- 0.02 nm and
calculated for the supernova's redshift of 289 km/s). All of the
above lines have narrow components with velocity widths less than
about 100 km/s. This spectrum appears to be dominated by low-
density, low-ionization shock excitation, especially to the
northeast of the supernova (consistent in position with the
previously reported 'hot spot'; cf. IAUC 6665, 6710)."
(C) Copyright 1998 CBAT
1998 March 11 (6836) Daniel W. E. Green
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