Central Bureau for Astronomical Telegrams
IAUC 3475: BL Lac; SS 433; 4U 2129+47; U Gem
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Read IAUC 3476
Circular No. 3475
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
BL LACERTAE
M. F. Aller, H. D. Aller and P. E. Hodge, University of Michigan
Radio Astronomy Observatory, report a major outburst in progress
in BL Lac at 14.5 and 8.0 GHz. The flux density at 14.5 GHz
on May 6 was 10.4 +/- 0.3 Jy, up from 5.7 +/- 0.2 Jy on Apr. 17, and
the 8.0-GHz flux density on May 4 was 6.9 +/- 0.1 Jy. This is the
highest level observed at centimeter wavelengths in BL Lac since
mid-1974 and follows a period of increase in flux density from a
minimum below 2 Jy in 1979 Aug.
SS 433
G. H. Newsom and G. W. Collins, II, Department of Astronomy,
Ohio State University, write: "The amplitude of the 6-day periodicity
in SS 433, reported on IAUC 3459, is about 5 percent of the
dominant 165-day variation. Hence the search by Margon et al.
(IAUC 3469), sensitive to a 6-day amplitude of twice this amount,
should not have detected this periodicity. The periods we reported
on IAUC 3459 are statistica1ly significant (p < 0.01 for each set
of moving lines). We repeated Margon's sampling technique for
detecting artifact periods in the data base available to us, and we
do find large amplitudes for some periods, but none is statistically
significant for either set of lines (p < 0.04). Hence the presence
of the period in these data is not an artifact of the nonuniform
spacing of the observations."
4U 2129+47
J. McClintock, Massachusetts Institute of Technology, communicates
that 4U 2129+47 (cf. Thorstensen et al. 1979, A .J. 233, L57)
will be observed using the Einstein X-Ray Observatory during the
interval June 13.2-13.5 UT. Persons interested in making coordinated
optical observations should contact him (telephone 617-253-7528)
or J. Kriss (617-253-7457) for further information.
U GEMINORUM
J. Mattei communicates the following AAVSO observations of the
latest outburst: May 6.07 UT, mv = 13.4 (E. Mayer, Barberton, OH);
7.07, 10.4 (Mayer); 7.20, 9.6 (C. Spratt, Victoria, BC); 8.08, 9.4
(P. Goodwin, Shreveport, LA); 9.08, 8.9 (Mayer).
1980 May 12 (3475) Brian G. Marsden
Read IAUC 3476
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