Central Bureau for Astronomical Telegrams
IAUC 3620: NEW OPTICAL CANDIDATES FOR GALACTIC X-RAY SOURCES; ASTROGRAM CAM /= Sat CAM
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Circular No. 3620
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
NEW OPTICAL CANDIDATES FOR GALACTIC X-RAY SOURCES
J. Grindlay, Harvard-Smithsonian Center for Astrophysics, reports
that preliminary precise values (~ 3"-5" 90-percent-confidence
error box radii) for positions of unidentified galactic x-ray
sources observed with the Einstein X-Ray Observatory and SIT vidicon
spectra obtained during May 6-8 with the 4-m telescope at Cerro
Tololo Interamerican Observatory have yielded the following candidate
source identifications:
2S 0918-549. Optical candidate ~ 5" south of the x-ray source position;
a faint star ~ 6" northeast of star 15 of Reid et al. (1980,
A.J. 85, 1062); V ~ 19.6; possible 464-465-nm emission.
2S 1417-624. Candidate ~ 8" +/- 3" south; star 8 of Apparao et al.
1980 A. & Ap. 89, 249); V ~ 17.0; strong (and variable?) H-alpha
emmision with full width at half maximum = 10**3 km/s.
4U 1744-26 = GX 3+1. 3" northeast; star 35 of Reid et al. (1980);
V ~ 19.0; no emission lines but appears to be normal G star.
4U 1813-14 = GX 17+2. 1".5 southeast; star 28 of Tarenghi and Reina
(1972, Nature Phys. Sci. 240, 53); V ~ 17.6; no emission lines
but appears to be normal G star.
4U 1822-00. 4" south; star F of Reid et al. (1980); V ~ 19.0; possible
465-nm emission.
4U 1916-05. 3" east; star 2 of Doxsey et al. (1977, Nature 269,
112); V ~ 16.3; no emission lines, appears to be normal G star.
The possible G star identifications are based on positional agreement
only but if correct would imply a new class of object associated
with galactic bulge/burster sources. Further optical studies
are needed, especially time-variability studies of the G star candidates
and the probable counterpart of 2S 1417-624, which is a
17.2-s x-ray pulsar (Kelley et al. 1981, Ap.J. 243, 251).
ASTROGRAM CAM /= SATELLITE CAM
Contributors are again reminded that messages to the Central
Bureau should be sent to TWX 710-320-6842 (answerback ASTROGRAM
CAM), not to the Smithsonian Astrophysical Observatory's telex.
The number and answerback can and should be included in telegrams
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center generally operates for no more than 10.5 hours per day and is
now closed from 21h15m UT on Saturdays to 11h30m UT on Mondays.
1981 July 31 (3620) Brian G. Marsden
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