Central Bureau for Astronomical Telegrams
IAUC 4772: PSR 2127+11C; CAL 87; 1989B
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Circular No. 4772
Central Bureau for Astronomical Telegrams
INTERNATIONAL ASTRONOMICAL UNION
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
MARSDEN or GREEN@CFA.BITNET MARSDEN or GREEN@CFAPS2.SPAN
PSR 2127+11C
S. Anderson, P. Gorham, S. Kulkarni, and T. Prince, California
Institute of Technology; and A. Wolszczan, Arecibo Observatory,
write: "We report the discovery of a 30-ms binary pulsar in the
globular cluster M15 (NGC 7078). Observations were made with the
305-m Arecibo reflector at 430 MHz on 1988 Dec. 26. A 2E24 sample
time series representing 1.5 hr of observation was subject to a
pulse search, assuming a range of linear accelerations on the
Caltech NCUBE/10 supercomputer. The pulsar was best detected with
an assumed linear acceleration of 9.4 m/s2. The dispersion measure,
67.2 +/- 2 pc cmE-3, is consistent with that of the two known pulsars
in M15: the 110-ms pulsar 2127+11 reported by Wolszczan et al. (1989,
Nature 337, 531), and the 56-ms pulsar recently reported on IAUC 4762.
The new pulsar is within 2' of the center of the cluster. In the
1415-MHz Arecibo data taken one year earlier, the pulsar is detected
at the 6.5-sigma level with a frequency that is Doppler-shifted
relative to the 430-MHz detection by 95 km/s, and a best-fit linear
acceleration of 4.9 m/s2. The flux density of PSR 2127+11C is 1.6
+/- 0.2 mJy at 430 MHz."
CAL 87
A. P. Cowley and P. C. Schmidtke, Arizona State University;
and D. Crampton and J. B. Hutchings, Dominion Astrophysical Observatory,
write: "From six nights of photometric observations obtained at
Cerro Tololo Interamerican Observatory in 1988 Dec., we independently
found the 10.6-hr period announced by Naylor et al. (IAUC 4747).
Our recent observations, combined with additional photometry from
1985 and 1987, give an improved period of 0.442683 +/- 0.000006 days
with T_min = HJD 2447506.8022 +/- 0.0003. The full amplitude of the
V lightcurve is 1.2 mag. The phasing of the He II emission-line
velocity curve shows that the lines are associated with the accretion
disk of the degenerate star. If the F-star companion, partially
visible at minimum light, has a mass > 0.5 Mo, then the velocity
amplitude (40 km/s) implies that the collapsed star has a mass
> 3 Mo, suggesting that the source is probably an eclipsing
black-hole binary."
SUPERNOVA 1989B IN NGC 3627
Further visual magnitude estimates: Apr. 2.17 UT, 14.6 (A.
Hale, Las Cruces, NM); 7.40, 15.2 (R. Bunge, Mansfield, OH).
1989 April 12 (4772) Daniel W. E. Green
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