Central Bureau for Astronomical Telegrams
IAUC 4944: 4U 1850-08; 1989c1; PU Vul
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Circular No. 4944
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
4U 1850-08
J.-L. Nieto, M. Auriere and E. Thouvenot, Observatoire
Midi-Pyrenees; J. Sebag, G. Lelievre and R. Foy, Observatoire de Paris;
J. Arnaud, Canada-France-Hawaii Telescope (CFHT); and A. Blazit,
Observatoire de la Cote d'Azur, report: "On 1988 Sept. 13 we obtained
one R and two B high-resolution (FWHM about 0".4-0".6) images of the
field of the x-ray source 4U 1850-08 in the globular cluster NGC 6712
with the Sub-Pupil Imaging technique at CFHT. The analysis reveals two
new stars (S and Z; B about 21), 0".3 apart and located 0".6-0".7
arcsec southwest of X (B about 20), the star proposed by Cudworth
(1988, A.J. 96, 105) as the optical counterpart of the x-ray source. S
and Z are therefore between X and KC 62 and as close as star X to the
position of the faint radio source of Machin et al. (IAUC 4818).
Clearly, the U object pointed out by Bailyn et al. (1988, Ap.J. 331,
303), whose centroid is 0".5 southwest of star X (Bailyn 1990, CfA
Preprint 3002, in agreement with our independent CCD U images), is a
blend of stars X, S and Z on these low-resolution (FWHM about 1".3)
images. Star Z is detected on only one B image, implying strong
variability (by about 1 mag). It is therefore a good candidate for the
optical counterpart of the x-ray/radio source, if this star and its
variability are confirmed (we fail to find any technical reason
suggesting a spurious effect). If not, the possible blueness of star S
(in B-R) and the blending revealed by the U images would make S the
most likely candidate.
COMET AUSTIN (1989c1)
M. Wallis, University of Wales, Cardiff, reports observations on
1989 Dec. 29 using the IUE satellite-borne telescope with Resident
Astronomer A. Talavera. The spectrum shows the usual OH, C2, CS and
290-300-nm molecular continuum. OH was unexpectedly strong, the
brightness (3.0 kR) translating to a production rate of more than 10**29
H2O molecules/s, similar to P/Halley postperihelion and 50 percent
higher than P/Halley preperihelion at a comparable heliocentric distance.
PU VULPECULAE
Visual magnitude estimates: 1989 July 29.9 UT, 10.5 (E. Schweitzer,
Strasbourg, France); Aug. 31.80, 10.5 (A. Boattini, Florence, Italy);
Sept. 27.00, 10.2 (A. Pereira, Cabo da Roca, Portugal); Oct. 26.77, 10.5
(Schweitzer); Nov. 23.86, 10.4 (Pereira); 29.70, 10.6 (Boattini).
1990 January 16 (4944) Brian G. Marsden
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