Central Bureau for Astronomical Telegrams
IAUC 6845: PSR 1744-1134; 1998S
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Circular No. 6845
Central Bureau for Astronomical Telegrams
INTERNATIONAL ASTRONOMICAL UNION
Mailstop 18, Smithsonian Astrophysical Observatory, Cambridge, MA 02138, U.S.A.
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PSR 1744-1134
W. Becker and J. Trumper, Max-Planck-Institut fur
Extraterrestrische Physik; and G. Hasinger, Astrophysikalisches
Institut, Potsdam, communicate: "We report the detection of the
isolated galactic millisecond pulsar PSR 1744-1134 in soft x-rays
with ROSAT. The pulsar was observed with the HRI at the focus of
the XRT during 1997 Sept. 3-24 for an effective exposure time of
61 238 s. The pulsar's net countrate (including background,
vignetting, and dead-time corrections) is (2.9 +/- 0.9) x 10E-4
count/s. Assuming a Crab-like spectrum and a column absorption of
N_H = 10E20 cmE-2, deduced from the radio dispersion measure (cf.
Bailes et al. 1997, Ap.J. 481, 386), we find an energy flux of 2 x
10E-14 erg sE-1 cmE-2 over 0.1-2.4 keV. The low number of recorded
source counts precluded any modulation testing at the 4.07-ms radio
period."
SUPERNOVA 1998S IN NGC 3877
P. Garnavich, R. Kirshner, and P. Challis, Harvard-Smithsonian
Center for Astrophysics, on behalf of the Supernova Intensive Study
team, report that the Space Telescope Imaging Spectrograph aboard
the Hubble Space Telescope obtained spectra (range 114-570 nm, via
three low-resolution gratings) of SN 1998S on Mar. 16.1 UT.
Longward of 300 nm, the spectrum shows primarily Balmer emission
with broad, shallow P-Cyg absorption troughs. The maximum velocity
measured in the H-beta absorption is -10 000 km/s. The continuum
peaks at 265 nm, and the flux estimated from the continuum around
440 nm corresponds to magnitude B = 12.3. Shortward of 300 nm, the
character of the spectrum changes radically. Deep, blended
absorption lines dominate the spectrum. The strongest lines show a
narrow P-Cyg emission (500 km/s FWHM), narrow absorption shifted by
-1100 km/s from the emission, and a broad, shallow absorption
extending to -10 000 km/s. Major lines include Mg II (280 nm), C
III (230 nm), C IV (154 nm), Si IV (140 nm), C II (134 nm), O I
(130 nm) and N V (124 nm), Lyman-alpha (122 nm), and C III (118 nm).
Spectra taken with the Fred L. Whipple Observatory 1.5-m telescope
on Mar. 19.5 by D. Koranyi and M. Calkins show H-alpha with a
profile similar to the ultraviolet lines, but with the narrow
absorption at a blue shift of only -415 km/s. The broad absorption
extends to -9000 km/s, with a minimum at -4700 km/s. H-alpha has a
redshifted emission tail extending to about +1600 km/s.
(C) Copyright 1998 CBAT
1998 March 21 (6845) Daniel W. E. Green
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