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IAUC 5073: PSR 1257+12 AND PSR 1534+12; DWARF N IN Pav

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                                                  Circular No. 5073
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

PSR 1257+12 AND PSR 1534+12
     A. Wolszczan, Arecibo Observatory, reports:  "I have discovered
two short-period pulsars, PSR 1257+12 and PSR 1534+12, during
the high-galactic-latitude (b > 30 deg) survey for millisecond
pulsars with the 305-m Arecibo radiotelescope at 430 MHz.  The data
were analyzed on the Cornell National Supercomputer Facility.  The
preliminary parameters for PSR 1257+12 are R.A. = 12h57m31s, Decl.
= +12 56'10" (equinox 1950.0); period, P, 6.218 ms; dispersion measure
10.1 +/- 0.2 pc cmE-3; flux density at 430 MHz, S about 15 mJy.
Preliminary parameters for PSR 1534+12 are R.A. =  15h34m47s, Decl.
= +12 05'37"; P = 37.904 ms; dispersion measure 11.6 +/- 0.2 pc
cmE-3; S about 8 mJy.  The accuracy of the coordinates is limited by
the 3' FWHM of the telescope beam at 1400 MHz.  The preliminary
timing results indicate that PSR 1257+12 is either an isolated pulsar
or it may be a member of a long-period binary system.  PSR 1534+12,
on the other hand, is in a fast binary system with orbital period
10.1 hr, full radial velocity amplitude 400 km/s, and eccentricity
0.27.  The mass function of the system, 0.32 solar units, suggests
that the pulsar's companion is another compact star.  Timing
observations to measure accurately the parameters of both pulsars are in

     J. Maza, Astronomy Department, University of Chile; and M.
Hamuy, Cerro Tololo Interamerican Observatory, report:  "M.
Wischnjewsky has discovered an apparent dwarf nova in Pavo.  The
object, which was recorded at estimated mpg = 14.5 on a 15-min
103a-O plate taken by Hamuy and L. Wells with the Curtis Schmidt
telescope on July 21.086 UT, coincides in position with a star of
mag 20 on the ESO Quick Blue Sky Survey plate:  R.A. = 19h11m33s.5,
Decl. = -62 41'10" (equinox 1950.0).  A spectrum (range 630-950 nm)
was obtained on July 26 by M. Phillips with the CTIO 4-m telescope;
the object had faded several magnitudes by this date and showed
broad H-alpha emission.  A search by S. Barros of plates obtained
between 1979 May and 1984 Sept. with the 0.70-m Maksutov camera at
the Cerro Roble Observatory revealed two previous outbursts.  The
first occurred on 1983 Sept. 1, when the object was observed at
estimated mpg = 14.5 for three consecutive nights; on plates taken a
month later, the object had disappeared (mpg >/= 20).  The second
outburst was recorded in a plate taken on 1984 Mar. 2, on which the
object was observed at estimated mpg = 16; on 1984 Mar. 4, the
object had again faded to mpg >/= 20."

1990 August 13                 (5073)             Daniel W. E. Green

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