Central Bureau for Astronomical Telegrams

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IAUC 5162: 1989Z; PSR 0540-69; 1991a

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                                                  Circular No. 5162
Central Bureau for Astronomical Telegrams
Postal Address: Central Bureau for Astronomical Telegrams
Smithsonian Astrophysical Observatory, Cambridge, MA 02138, U.S.A.
Telephone 617-495-7244/7440/7444 (for emergency use only)
TWX 710-320-6842 ASTROGRAM CAM     EASYLINK 62794505

     M. Shaw reports his discovery of an apparent supernova in the
edge-on Sbc galaxy NGC 4013 (R.A. = 11h55m57s.6, Decl. = +44 13'40",
equinox 1950.0) in K-band (2.2 microns) imagery undertaken 1989 Dec.
30.64-30.67 UT with the U.K. Infrared Telescope on Mauna Kea.  The
apparent supernova lies within the northeast spiral arm, offset 10"
east and 4" north of the galaxy's center.  Relative photometry on
the frame within a 7".44-diameter aperture indicates that the
supernova is 0.03 mag brighter than the galaxy nucleus.  This relative
magnitude was measured from a single K band mosaic totalling 1200 s.

PSR 0540-69
     H. Ogelman, G. Hasinger, and J. Trumper, Max-Planck-Institut
fur Physik und Astrophysik and Institut fur Extraterrestrische Physik,
write:  "A very large glitch has been detected in the rotation
rate of the 50-ms pulsar in the Large Magellanic Cloud, PSR 0540-69.
X-ray observations with the ROSAT satellite covering the dates 1990
June 16.9-23.6 UT show that the fractional increase of the rotation
frequency and its derivative are at least (9 +/- 2) x 10E-6 and 0.23
+/- 0.06, respectively; the observations start after the discontinuity.
An additional ROSAT observation on 1990 July 19 shows that the
glitch has almost decayed to the extrapolation of the earlier GINGA
satellite results (Nagase et al. 1990, Ap.J. 351, L13), indicating
that the relaxation time was < 15 days.  This is the largest
fractional discontinuity observed in any pulsar.  Considering that PSR
0540-69 is similar to the Crab pulsar in age and period, it is
surprising that this glitch is about two orders of magnitude larger
than the largest Crab pulsar glitch."

     R. H. McNaught, University of Adelaide, reports that a 10-min
exposure taken Jan. 8.486 UT with the Uppsala Southern Schmidt
telescope shows the comet with a bright, narrow 1' tail and a much
fainter, narrow, 1.0 deg tail, both in p.a. 70 deg.  C. Grillmair
and McNaught note that this comet was situated within the field of a
U.K. Schmidt Telescope plate taken by M. Hartley on 1990 June 4.8;
nothing appears near the position predicted from the elements on
IAUC 5160, to a limiting magnitude of R about 19 for an asteroidal
image with the expected motion of comet 1991a.

1991 January 11                (5162)             Daniel W. E. Green

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