Central Bureau for Astronomical Telegrams
IAUC 3616: PG 1550+191; GX 339-4; 1980i
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Circular No. 3616
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
PG 1550+191
H. Stockman, J. Liebert, S. Tapia, R. Green, R. Williams and
D. Ferguson, Steward Observatory, University of Arizona; and P.
Szkody, University of Washington, write: "We have discovered PG
1550+191 (R.A. = 15h50m33s.08, Decl. = +19o05'17".7, equinox 1950.0,
uncertainty +/- 0".5) to be an AM Her-type variable. Monitoring of the
linear and circular polarization yields an ephemeris for the peak
of linear polarization: HJD 2444763.7593 +/- 0.0007 + E (0.078863 +/-
0.000007). The maximum of linear polarization is generally weak
(~ 2-5 percent), while the circular polarization varies between 0
and -12 percent with a symmetric minimum at phase 0.50. Simultaneous
UBVR photometry shows mild flickering and smooth variations
which are roughly synchronous with the polarization. At minimum
(phase ~ 0.62), V = 15.8, U-B = -1.3, B-V = -0.05; at maximum
(phase ~ 0.16), V = 15.0, U-B = -1.0, B-V = +0.3. The emission
line spectrum shows strong He II, He I, H, C II and high excitation
lines. The peak radial velocities have K ~ 165 km/s (semiamplitude)
and positive zero crossing at magnetic phase 0.5. A
broad emission component is present with K ~ 360 km/s and positive
zero crossing near 0.3."
GX 339-4
M. Oda and the Hakucho Team, Institute of Space and Astronautical
Science, University of Tokyo, telex: "The Hakucho satellite
has been observing GX 339-4 (= 4U 1659-48) since June 5 (cf.
IAUC 3609). The source exhibited intermediate intensity (0.1-0.2
Crab at 1-10 keV) during June 5-22, with a moderate day-by-day intensity
variation. Beginning about June 24, GX 339-4 turned into
an unusually bright state (0.4-0.5 Crab at 1-10 keV). During a
scan of the data, no significant intensity variability has been
found on timescales of 0.1-500 s (upper limit 10-20 percent). A
more detailed analysis is in progress. Hakucho will have continued
observing this object until about July 20. We encourage optical
observers to monitor this source.
PERIODIC COMET BORRELLY (1980i)
Total visual magnitude estimates: Apr. 5.17 UT, 10.6 (D.
Machholz, San Jose, CA, 0.25-m reflector); May 4.07, 11.4 (J. E.
Bortle, Stormville, NY, 0.32-m reflector); 8.07, 11.4 (Bortle).
1981 July 22 (3616) Daniel W. E. Green
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