Central Bureau for Astronomical Telegrams
IAUC 3449: OPTICAL CANDIDATE FOR H0544-665; Cir X-1; P/SCHWASSMANN-WACHMANN 1
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Circular No. 3449
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
OPTICAL CANDIDATE FOR H0544-665
J. R. Thorstensen and P. A. Charles, Space Sciences Laboratory,
University of California at Berkeley, report that star 1 of
Johnston et al. (1979, Ap. J. 233, 514) is a strong candidate for
this LMC x-ray source. A spectrogram taken with the 4-m telescope
and R/C spectrograph at Cerro Tololo shows broad Balmer and He I
absorption features; the H-beta absorption is very weak and may show a
weak, sharp emission core. Photometry with the 0.91-m telescope on
1979 Dec. 24.130 UT gave V = 15.47 +/- 0.02, B-V = -0.23, U-B = -0.96,
indicating a spectral class near Bi and a luminosity near the main
sequence, assuming LMC membership. On Dec. 22.191 the star had V =
15.36 +/- 0.02, with very similar colors, suggesting that it is
slightly variable. Thus this object is apparently a Be star or
related object.
CIRCINUS X-1
G. D. Nicolson, Radio Astronomy Observatory, National Institute
for Telecommunications Research, Johannesburg, reports that
60-mm observations made at Hartebeeshoek over the last three
transitions of Cir X-1 have shown the following. On 1979 Dec. 13 there
was no flare above 150 mJy. On Dec. 30 there was a 400-mJy flare
for 12-24 hours. On 1980 Jan. 15-16 there was a 1-Jy flare,
starting on Jan. 15.18 UT and lasting 4-5 days; onset was 22.7 hours
prior to predicted x-ray transition (Kaluzienski and Holt, IAUC
3099) and 11.2 hours earlier than radio flares in early 1979
(Nicolson, Feast and Glass 1980, M.N. in press). This confirms
that the period is decreasing. The best estimated ephemeris, based
on radio flares during 1976-1980, is T = 1976 Oct. 25.263 UT +
N (16.588 - 0.000166 N). If the mean x-ray/radio period of 16.594
days derived for 1976-1977 is assumed, T = 1976 Oct. 25.263 UT +
N (16.594 - 0.00025 N).. The respective decreases in period are
-0.0036 and -0.0053 days per year. The latest results are consistent
with a periodicity of 330 days for the recurrence of strong
radio flares.
PERIODIC COMET SCHWASSMANN-WACHMANN 1
Visual observations by J. Bortle, Brooks Observatory (0.32-m
reflector, 65 x): Jan. 21.12 UT, m1 = 11.8, coma diameter ~ 2'.3,
extremely diffuse; 22.11, m1 = 11.6, coma diameter ~ 2'.3.
1980 January 30 (3449) Brian G. Marsden
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