Central Bureau for Astronomical Telegrams
IAUC 4112: EXO 2030+375; 1982i; Corrs
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Read IAUC 4113
Circular No. 4112
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
EXO 2030+375
N. E. White, P. Ferri, A. N. Parmar and L. Stella, EXOSAT
Observatory and European Space Agency, communicate: "Further EXOSAT
observations of the transient x-ray source EXO 2030+375 (IAUC
4066) have shown the intensity of this source to have decayed
almost linearly from its discovery value of 700 mCrab on May 19 to
85 mCrab on July 10. After this the decline slowed such that on
July 25 the flux was 30 mCrab, on Aug. 13 it was 7 mCrab, and on
Aug. 25 the source became undetectable at < 1 mCrab. Measurements
of the pulse period showed it to be decreasing very rapidly.
Deviations from a quadratic fit to pulse periods obtained during the
linear decline can be well fit by Doppler variations caused by the
pulsar being in an eccentric orbit. The best-fit parameters are P
= 37.9 +/- 1.3 days, e = 0.31 +/- 0.02, T = 1985 June 8 +/- 2 days, a =
190 +/- 10 light seconds, longitude of periastron = 232 +/- 5 deg. The
mass function of 5 MO is consistent with the companion's being a
Be star (IAUC 4073, 4096). The spin-up timescale when the source
was at maximum brightness was ~ 30 yr, indicating a luminosity of
several x 10**31 J/s (i.e., a distance of order 10 kpc)."
PERIODIC COMET HALLEY (1982i)
S. Koutchmy and J. Lecacheux, Institut d'Astrophysique, Paris,
and Meudon Observatory, report good-resolution, 1-hr exposures on
Kodak 2415 hypered film obtained on Sept. 12-14 by F. Dossin and
Koutchmy with the 0.62-m f/3 Schmidt telescope of Haute-Provence
Observatory; the P/Halley images show a resolved central region
with an average FWHM of 5"7 (5"4 north-south, 6"6 east-west) with
an overall coma extension from the nucleus of 58" (65" westward).
The inner coma near the nucleus was V-shaped with arms 3"5 long at
p.a. 30 and 300. An additional faint, jet-like feature at p.a.
30, extending radially up to 15" from the nucleus, is apparent on
the picture (free of faint star trails) obtained on Sept. 12.094
UT; magnitudes measured by flux integration in circles of 10" and
120" diameter were V = 15.0 +/- 0.2 and 13.8, respectively.
CORRIGENDA
IAUC 4101, AC 211, line 12, for 14.6 during read 15.6 during.
IAUC 4103, Periodic Comet Giacobini-Zinner (1984e), line 11, for
arcmin read arcsec.
1985 September 23 (4112) Brian G. Marsden
Read IAUC 4113
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