Central Bureau for Astronomical Telegrams
IAUC 3364: V1057 Cyg; 4U 1626-67
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Read IAUC 3365
Circular No. 3364
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
V1057 CYGNI
A. Winnberg and C. Walmsley, Max-Planck-Institut fur
Radioastronomie, report: "The unusual FU-Ori-type variable V1057 Cyg,
which increased in brightness by 6 magnitudes in 1969-70 (Welin
1971, Astron. Astrophys. 12, 312), has flared up again in the 1720-MHz
OH line. On May 30d07h UT a circularly-polarized line was detected
with the 100-m radio telescope. It consists of two oppositely
circularly-polarized line components each with an amplitude
of 2.0 +/- 0.2 Jy and a half-intensity width of 0.19 km/s. The left
and right circularly-polarized lines have radial velocities of 1.43
+/- 0.01 and 1.74 +/- 0.01 km/s, respectively. The 1720-MHz line was
reobserved on May 31, with no significant changes. Upper limits of
~ 0.5 Jy were obtained for the (unpolarized) flux density of the
other three 18-cm lines. Prior to the outburst, the most recent
1720-MHz observation of which we are aware was on 1978 June 7, when
the flux was less than 0.1 Jy (Andersson et al., Astron. Astrophys.,
in press). Using the astrograph of the Hoher List Observatory, F.
Gieseking found B = 12.6 for V1057 Cyg on May 31d00h, consistent
with the slow decrease in brightness since 1970 (see Herbig 1977,
Astrophys. J. 217, 693). It is of great interest that optical and
infrared observations be made to look for correlations with the
maser emission; observations of other molecular lines would also
be very worthwhile."
4U 1626-67
J. Middleditch, K. Mason and J. Nelson, University of California
at Berkeley; and N. White, Goddard Space Flight Center, report
the detection of pulsed optical emission from the 7-s pulsar
4U 1626-67 at both the fundamental frequency and the first harmonic.
Observations lasting up to six hours were made with 100-ms time
resolution at the 400-cm telescope at Cerro Tololo Interamerican
Observatory during April. The power in the fundamental was ~ 300
times the average power spectrum level, corresponding to a pulsed
fraction of 2-2.5 percent, consistent with previous observations.
The apparent period of the fundamental was 7.676 s. The relative
amplitude of the first harmonic was 0.29 +/- 0.03. The pulse appears
symmetric with a narrow minimum and a broad maximum. The longest
and most photometric time series, of duration ~ 6 hr, suggests a
large-amplitude (up to ~ 0.2 magnitude) flickering in the source on
a timescale as short as 1 min.
1979 June 4 (3364) Daniel W. E. Green
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