Central Bureau for Astronomical Telegrams
IAUC 3746: NOTICE RE ASTROMETRIC Obs OF SNe; Occn OF BD +29 579 BY (93); Millisec PULSAR IN 4C 21.53
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Circular No. 3746
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
NOTICE CONCERNING ASTROMETRIC OBSERVATIONS OF SUPERNOVAE
Several astronomers, particularly those involved in making
ultraviolet, infrared and radio observations, have pointed out the
great need for accurate positions of supernovae. Discoveries of
supernovae are generally described on these Circulars in terms of
approximate offsets from what appears to be the nucleus of the parent
galaxy. In practice, these offsets have errors of the order
of +/- 10" . The discoverer or other optical observers are strongly
urged to make an accurate astrometric determination of the position
of a new supernova as soon as possible after the initial announcement.
Such a position should preferably be absolute, obtained using standard
astrometric procedures. If this is not possible, an acceptable
position, good to ~ 2" , might be obtained relative to a known bright
star in the vicinity. Timely astrometric observations of supernovae
published in these Circulars will not be subject to line charges.
OCCULTATION OF BD +29 579 BY (93) MINERVA
B. Sicardy, Observatoire de Meudon, reports that P. Laques,
J. Lecacheux and J. J. Vedere observed this occultation with the
2-m telescope at Pic du Midi. The event was recorded on video
tape, began on Nov. 22d03h31m31s8 +/- 0s2 UT and had a duration of
11.3 +/- 0.2 s. J. F. Leborgne, observing visually from 15 km north
of Pic du Midi, noted an occultation lasting 7.5 +/- 1.5 s. No
secondary events were recorded during 3h30m-3h50m UT.
Continuous visual monitoring of the star for 20 min beginning
at 3h24m UT by S. Baroni at Milan and by M. Cavagna and
C. Gualdoni from 40 km north of Milan revealed no occultation.
MILLISECOND PULSAR IN 4C 21.53
D. Backer, S. Kulkarni and C. Heiles, University of California,
Berkeley, report that timing observations of the millisecond pulsar
at Arecibo during Nov. 8-18 do not confirm the period derivative
reported on IAUC 3743. The new limit on the (dimensionless) period
derivative is 10**-15. The barycentric period during these observations
was 1.557807 +/- 0.000002 ms, and the dispersion measure was
75 (+/- 5) e pc cm**-3.
1982 November 29 (3746) Brian G. Marsden
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