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IAUC 6432: GRS 1915+105; 2S 1417-624; CAL 83

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IAUC number

                                                  Circular No. 6432
Central Bureau for Astronomical Telegrams
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)
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

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