Central Bureau for Astronomical Telegrams
IAUC 6432: GRS 1915+105; 2S 1417-624; CAL 83
The following International Astronomical Union Circular may be linked-to from your own Web pages, but must not otherwise be redistributed (see these notes on the conditions under which circulars are made available on our WWW site).
Read IAUC 6433
.dvi or
.ps format.
Circular No. 6432
Central Bureau for Astronomical Telegrams
INTERNATIONAL ASTRONOMICAL UNION
Postal Address: Central Bureau for Astronomical Telegrams
Smithsonian Astrophysical Observatory, Cambridge, MA 02138, U.S.A.
IAUSUBS@CFA.HARVARD.EDU or FAX 617-495-7231 (subscriptions)
BMARSDEN@CFA.HARVARD.EDU or DGREEN@CFA.HARVARD.EDU (science)
Phone 617-495-7244/7440/7444 (for emergency use only)
GRS 1915+105
E. Gerard, Observatoire de Paris-Meudon, reports that a new
radio outburst was detected from this hard x-ray transient in
Aquila with the Nancay Radio Telescope on July 9. The observed
radio fluxes were: July 8.009 UT, < 26 mJy at 1414 MHz and < 40 mJy
at 3310 MHz; July 9.009, < 30 mJy at 1414 MHz and 83 mJy at 3310
MHz; July 9.995, 140 mJy at 1414 MHz and 94 mJy at 3310 MHz.
Multi-wavelength observations are encouraged.
2S 1417-624
M. H. Finger and M. Scott, Universities Space Research
Association; T. A. Prince and B. Vaughan, California Institute of
Technology; and R. B. Wilson, Marshall Space Flight Center, NASA,
report for the Compton Observatory BATSE team: "Renewed activity
from the x-ray-transient pulsar 2S 1417-624 is being observed.
Hard x-ray pulses were first detected on June 30, with the pulsed
flux rising to 17 +/- 3 mCrab (20-50 keV) by July 8. A barycentric
frequency of 0.05694816(25) Hz on July 4.5 UT and barycentric
frequency rate of 3.35(14) x 10E-11 Hz/s were obtained from a fit
of frequency measurements from July 1-8. The source had been
undetected by BATSE since a series of six outbursts were observed,
beginning on 1994 Aug. 26 (IAUC 6075) and ending 1995 July 8."
CAL 83
P. Kahabka, University of Amsterdam, reports: "During
ROSAT/HRI observation on Apr. 28.162-28.222 UT, the supersoft
source numbered 83 by Long et al. (1981, ApJ 248, 925; = 1E
0543.8-6823) was not detected. On Apr. 7, the ROSAT/HRI detected
this source at a rate of 0.2 count/s. The x-ray off-state on Apr.
28 implies a reduction in x-ray flux by a factor of > 43 in 21 days.
High- and low-intensity states of CAL 83 are also seen in the
ultraviolet. CAL 83 may be similar to the recurrent LMC transient
RX J0513.9-6951, which shows optical dips with a recurrence period
of about 100-200 days during which x-ray outbursts occur. The
disappearance of the source in x-rays is understood to be due to a
shift of the temperature to lower values, rendering the source
undetectable in x-rays. The length of x-ray on- and off-states may
be different in RX J0513.9-6951 and CAL 83, due to different white-
dwarf masses and mass-accretion rates."
(C) Copyright 1996 CBAT
1996 July 10 (6432) Daniel W. E. Green
Read IAUC 6433
.dvi or
.ps format.
Our Web policy. Index to the CBAT/MPC/ICQ pages.
