Central Bureau for Astronomical Telegrams
IAUC 3626: V1333 Aql = 4U 1908+00; V1343 Aql = SS 433
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Read IAUC 3627
Circular No. 3626
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
V1333 AQUILAE = 4U 1908+00
J. V. Paradijs, University of Amsterdam; H. Pedersen, European
Southern Observatory; and W. H. G. Lewin, Massachusetts Institute
of Technology, report that the recurrent transient x-ray burst
source 4U 1908+00 = Aql X-1 is in outburst and burst-active. The
source was last reported to be in outburst in 1980 May (IAUC 3478),
when x-ray bursts were detected with Hakucho (IAUC 3481). The
approximate magnitude (350-650 nm) of the optical counterpart V1333
Aql was 16.2 on 1981 Aug. 1.25 UT and 16.6 on Aug. 2.25. In a
total of six hours of observing with the 1.5-m Danish telescope at
La Silla one optical burst from this source was detected (but no
simultaneous x-ray observations were made). The optical burst
lasted ~ 15 s. At the burst maximum the signal was about 20 percent
higher than the pre-burst level. This is the first time that
an optical burst has been observed from this object. Optical observers
are urged to continue observations of this object while it
is in outburst.
M. Oda and the Hakucho Team report that Hakucho was maneuvered
to observe this object on Aug. 4. The x-ray flux was ~ 0.7 Crab
(3-10 keV) on Aug. 4 and nearly the same level on Aug. 5. Hakucho
will continue observation of Aql X-1 until the end of August, or
the fading away of the object, whichever is the earlier.
V1343 AQUILAE = SS 433
B. Margon and S. Anderson, University of Washington; and S.
Grandi and R. Downes, University of California at Los Angeles, report
that spectroscopic observations of SS 433 on 320 nights during
the past three years confirm the previous suggestion (IAUC 3547)
that the 164-day period is decreasing. Use of the published ephemeris
for the moving spectral lines (Margon et al. 1980, AP.J. 241,
306) can now cause phase errors of up to 20 days. The assumption
of a constant rate of period change yields the value P = (-9 +/- 1) x
10**-3. Doppler shifts can be predicted by using the parameter values
(notation as in the cited paper) v = 0.259 c, i = 19o.87, e =
78o.91, alpha = 0.3412, and P0 = 168.7 days at T0 = JD 2443550.8.
Independent evidence (e.g., the linear extent of the x-ray jets and
historical photometry of the 164-day period) indicates strongly that
this large rate of period change must be transient and cannot be
monotonic.
1981 August 13 (3626) Brian G. Marsden
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