Central Bureau for Astronomical Telegrams
IAUC 4470: Millisec PULSAR IN M4; 1987M
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Circular No. 4470
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 617-495-7244/7440/7444
MILLISECOND PULSAR IN M4
A. Brinklow, A. G. Lyne, and J. D. Biggs, University of
Manchester, Jodrell Bank; and M. Ashworth, Regional Computer Center,
University of Manchester, telex: "A pulsar with a barycentric
period of 11.07571 +/- 0.00002 ms (epoch 1987 Oct. 13.2) has been
detected in the direction of the globular cluster M4. The first
observations were made with the 76-m Lovell radio telescope at
Jodrell Bank on June 19 with the 30'-diameter beam centered on the
cluster's core position. Outputs from 32 channels of 125-kHz
bandwidth near 610 MHz were recorded every 300 ms for 75 min and
processed on a Cyber 205 supercomputer in a periodicity and dispersion
measure search for pulses. The pulsar has a mean flux density of about
5 mJy at 610 MHz and a dispersion measure of 62 +/- 7 pc/cm3. The
latter indicates a distance of about 2 kpc, consistent with the
estimated distance to the cluster."
SUPERNOVA 1987M IN NGC 2715
A. C. Porter, California Institute of Technology, reports: "A
spectrum (range 380-770 nm, average resolution 0.9 nm) of SN 1987M
was taken with the Hale 5-m reflector (+ double spectrograph) at
Palomar Observatory by J. R. Mould and I. N. Reid on Oct. 2.5 UT.
Preliminary reduction of this spectrum confirms Filippenko's
classification of the SN as type Ib (IAUC 4459). The relative strengths
of the absorption features resemble those of the type-Ib SNe 1983I
and 1983V more than those of 1983N and 1984L. In particular, lines
at 570.0 and 639.6 nm are weaker relative to that at 617.2 nm.
Filippenko communicates that complete reduction of his Lick spectra
(range 310-1000 nm) confirms this, except that the second line is
somewhat stronger than in the Palomar spectrum and is centered at
637.2 nm. Moreover, the Ca II infrared triplet and O I (777.4 nm)
are present, and exhibit very strong P-Cyg profiles. Since Wheeler
et al. (1987, Ap.J. 313, L69) have suggested that SNe 1983I and
1983V were He-poor, O-rich type-Ib supernovae, persistent photometry
and spectrophotometry of SN 1987M would add considerably to our
understanding of the new subtype. The Lick and Palomar spectra
also show strong, narrow Na I D absorption due to gas in NGC 2715.
Dawn CCD images of SN 1987M were taken in the Gunn g and r
passbands with the Palomar 1.5-m reflector by S. Djorgovski on Oct.
3.5. Reduction by Porter gives magnitudes r = 15.2, g-r = +0.4,
and offset 5" east, 17" north from the nucleus."
1987 October 16 (4470) Daniel W. E. Green
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