Central Bureau for Astronomical Telegrams
IAUC 3806: ANOTHER Millisec PULSAR; POTENTIAL BLACK-HOLE CANDIDATES; TENMA Obs OF Her X-1
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Circular No. 3806
Central Bureau for Astronomical Telegrams
INTERNATIONAL ASTRONOMICAL UNION
Postal Address: Central Bureau for Astronomical Telegrams
Smithsonian Astrophysical Observatory, Cambridge, MA 02138, U.S.A.
TWX 710-320-6842 ASTROGRAM CAM Telephone 617-864-5758
ANOTHER MILLISECOND PULSAR
V. Boriakoff, Cornell University; R. Buccheri, CNR-Palermo:
and F. Fauci, University of Palermo, report the discovery at Arecibo
of a millisecond binary radio pulsar inside the error box of
the gamma-ray source 2C G065+1. Preliminary parameters for the system
are: R.A. = 19h53m25s7, Decl. = +29deg00'42" (equinox 1950.0: VLA):
P = 6.13369 +/- 0.000019 ms (on 1983 Apr. 3.46 UT); dP/dt < 0.58 x
10**-15; dispersion measure = 104.5 +/- 0.3; orbital period = 120 +/- 4
days; a sin i = (0.92 +/- 0.08) x 10**7 km: e ~ 0.
POTENTIAL BLACK-HOLE CANDIDATES
N. E. White, European Space Agency; and F. E. Marshall,
Goddard Space Flight Center, write: " The HEAO-1 A2 all-sky x-ray
spectral survey reveals that six x-ray sources have ultrasoft x-
ray spectra (kT < 3 keV) similar to those of several black-hole
candidates in the high state (e.g., Jones 1977, Ap.J. 214, 856:
Ricketts 1983, A.Ap. 118, L3). These are LMC X-3, LMC X-1, 4U
0142+61, H1743-32, 4U 1755-33 and 4U 1957+11. The first two have
recently been identified as potential black-hole candidates from
radial-velocity measurements (e.g., IAUC 3791). There are no x-
ray eclipses associated with the 4-day binary period proposed for
LMC X-1. H1743-32 was a transient source, and five other transients
(A0620-00, H1705-250, 4U 1543-47, A1524-62 and 4U 1630-47)
also had similarly ultrasoft x-ray spectra. The sources H0845-33,
A1742-294 and 4U 1907+09 have spectra similar to either the blackhole
candidates in the low state or x-ray pulsars. Since the x-
ray spectra of these sources are very distinct from the majority
of galactic x-ray sources, we urge observers to concentrate on
them in order to elucidate their nature further."
TENMA OBSERVATIONS OF HERCULES X-1
Y. Tanaka, Institute of Space and Astronautical Science,
Tokyo, telexes: " The Japanese x-ray-astronomy satellite Tenma (cf.
IAUC 3787) will observe Her X-1 from about May 22 through early
June. Using the 0.064 m**2 gas scintillation proportional counter
array, Tenma will make both timing and detailed spectral observations
as a function of pulse phase. Correlated optical observations
of Her X-1 would be useful and desirable. Optical astronomers
who are interested in collaborating are invited to contact me
(telex Japan 24550 SPACETKY J) for a detailed schedule."
1983 May 11 (3806) Brian G. Marsden
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