Central Bureau for Astronomical Telegrams
IAUC 3039: X-RAY SOURCES; AN UMa; Poss. OPTICAL COUNTERPART FOR LMC X-4; SU Tau; NOVAE
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Read IAUC 3040
Circular No. 3039
Central Bureau for Astronomical Telegrams
INTERNATIONAL ASTRONOMICAL UNION
Postal Address: Central Bureau for Astronomical Telegrams
Smithsonian Astrophysical Observatory, Cambridge, MA 02138, U.S.A.
Cable Address: SATELLITES, NEWYORK Telex: 921428
Telephone: (617) 864-5758
X-RAY SOURCES
M. Ricketts and B. A. Cooke, Leicester University, report:
"The Ariel 5 sky-survey instrument has been observing flaring x-ray
activity from a source in the region of 3U 0042+32. This is the
first observation of this source by the ssi, although the source
has been scanned for a total of 50 days since Nov. 1974, during
which time the mean flux was less than 1.5 Uhuru cts/s. During
1977 Feb. 3-6 the flux was variable up to 25 Uhuru cts/s and during
Feb. 14-17 up to 50 Uhuru cts/s. The 90-percent-confidence region
is defined by R.A. = 0h42m, Decl. = +33o.5; 0h42m, +32o.6; 0h45m, +31o.5;
0h44m, +32o.2 (equinox 1950.0)."
P. J. N. Davison, University College, London, writes that the
Mullard Space Science Laboratory's experiment C on board Ariel 5
observed a turn-on of Her X-1 on Feb. 3d15h +/- 1h UT, the phase in the
1.7-day binary cycle being 0.28 +/- 0.02.
R. H. Becker, S. H. Pravdo, J. R. Saba and P. J. Serlemitsos,
Goddard Space Flight Center, report the discovery of an x-ray binary
pulsator, consistent in position and intensity with 3U 1538-52. The
source, detected by the cosmic x-ray spectroscopy experiment on OSO
8, has a pulsation period of 528s.96 +/- 0s.10 and a pulsed fraction of
0.5. Zero phase occurred on 1976 Aug. 25.8 +/- 10.1 UT.
J. McClintock, F. Li, J. Nugent and S. Rappaport, Massachusetts
Institute of Technology, report that the SAS-3 Group has discovered
a 272s.2 +/- 0s.4 periodicity in the x-ray intensity of GX304-1 = 3U
1258-61. The source was observed during Feb. 14.8-21.9 UT and was
variable with a mean 1-12 keV intensity ~ 0.02 that of the Crab
Nebula. A prominent flare in the 1-12 keV intensity was observed
to commence on Feb. 17.83328 UT; the duration of the flare was ~
100s and the peak intensity > 3 times the ambient source intensity.
W. H. G. Lewin, J. A. Hoffman and J. Doty, Massachusetts Institute
of Technology, report that the SAS-3 Observatory has detected
23 x-ray bursts between Feb. 6 and 11 from within 1o.5 of the direction
of the galactic center; this is a twofold increase over what
was observed a year ago (IAUC 2918). A unique transient event,
from a location at least 2o from the galactic center and having a
brightness comparable to that of the Crab, was observed at about
Feb. 7d20h01m25s UT. At low energies (1.3-5 keV) the risetime was
1s.5, and the decay took about 30 min; the hard x-rays (8-35 keV)
were delayed by about 1.5 min, after which they rose to a maximum
in an additional 2 min. The outburst was preceded by a precursor
(simultaneously in the range 1.3-35 keV) of comparable brightness;
the precursor started 9s before the onset of the main outburst at
low energies and lasted only 4s.
AN URSAE MAJORIS
W. Krzeminski and K. Serkowski, Lunar and Planetary Laboratory,
report that the circular polarization of the novalike object AN UMa
varies between -9 and -34 percent in the blue spectral region of
the UBV system, and the linear polarization varies between 0 and 11
percent. The circular polarization in U and V reaches -28 and -25
percent, respectively, halfway between the maxima of linear
polarization. The polarization changes with the same period, 1h54m45s,
derived from photometric observations by Shugarov and Mumford (1976
Inf. Bull. Variable Stars No. 1133). The object is similar to AM
Her (IAUC 2994) and should be examined at x-ray wavelengths.
POSSIBLE OPTICAL COUNTERPART FOR LMC X-4
V. M. Blanco, Cerro Tololo Interamerican Observatory, reports
that observations by W. A. Hiltner lend support to the suggestion
by Sanduleak and Philip (IAUC 3023) that the OB star 25" southeast
of Pakull's candidate (IAUC 3017) is the one associated with LMC
X-4. Approximate magnitudes and colors are V = 14.0, B-V = -0.1,
U-B = -1.1. However, there are variations of 0.15 magnitude from
night to night, possible variations of 0.05 magnitude in 3-4 hours
and an observed brightening by 0.15 magnitude in minutes.
SU TAURI
Several observers have noted that the brightness of this R CrB
variable is increasing. AAVSO Circ. No. 76 mentions brightening
from magnitude 15 in the middle of January to 13.5 at the end.
Recent visual estimates: Feb. 5.35 UT, 12.6 (C. E. Spratt, Victoria,
British Columbia); 8.15, 13.0 (E. Mayer, Barberton, Ohio); 12.10,
12.9 (J. Bortle, Brooks Observatory); 16.02, 12.7 (Bortle).
NOVAE
V1500 Cyg. Correction to IAUC 3031, line 6: for 0d.130, read
0d.138. Visual magnitude estimate 12.4 on Feb. 10.99 UT (Bortle).
NQ Vul. Visual estimates: Jan. 30.26 UT, 11.5 (G. M. Hurst,
Northampton, England); Feb. 4.54, 11.5 (J. Morgan, Prescott, Arizona);
10.54, 11.4 (Morgan); 14.53, 11.4 (Morgan).
Nova Sge 1977. Visual estimates: Jan. 30.2 UT, 10.9 (J. G.
Hosty, Huddersfield, England); Feb. 2.54, 10.4 (Morgan); 6.54, 10.4
(Morgan); 10.54, 10.0 (Morgan); 14.53, 10.4 (Morgan).
1977 February 23 (3039) Brian G. Marsden
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