Central Bureau for Astronomical Telegrams
IAUC 6371: GRO J1744-28; C/1996 B2
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Circular No. 6371
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)
GRO J1744-28
J. Kommers and W. H. G. Lewin, Massachusetts Institute of
Technology; C. Kouveliotou and M. H. Finger, Universities Space
Research Association; G. J. Fishman, C. A. Wilson, and R. B. Wilson,
Marshall Space Flight Center; M. S. Briggs, University of Alabama
in Huntsville (UAH); and J. van Paradijs, University of Amsterdam
and UAH, report on the 2.1-Hz pulsations: "For a sample of 61
bursts from GRO J1744-28 observed by BATSE over a 3-month period
(Jan.-Mar.), the average value of the pulsed fraction within bursts
in the range 20-60 keV is 14 +/- 1 percent (rms variation). The
average value for the persistent emission observed by BATSE
(covering the period Jan. 10-16) is 16.8 +/- 0.3 percent (rms) in
the energy range 20-40 keV. By comparison, the pulse fraction in
the persistent emission observed by the PCA instrument (M. J. Stark,
private communication) onboard XTE on Feb. 19 is 8 percent (rms) in
the range 2-12.5 keV and 12 percent (rms) for E > 12.5 keV. No
background subtraction or correction for the PCA response was
performed. The pulse fraction in the upper energy range is
therefore an underestimate. Dotani et al. (ASCA) report a 'peak-
to-peak' pulsed fraction in the persistent emission of 10 percent
in the band 2-10 keV (IAUC 6337, and T. Dotani, private
communication). For comparison with the numbers given above, we
note that this converts to a pulse fraction of roughly 3.5 percent
(rms). [For an approximately sinusoidal pulse shape, as is the
case here, the peak-to-peak pulse fraction is 2(2)E0.5 times the
rms pulse fraction.] From the combined BATSE-XTE-ASCA
observations, it is very clear that there is a strong energy
dependence of the pulsed fraction from GRO J1744-28."
COMET C/1996 B2 (HYAKUTAKE)
S. Ganesh, A. Chitre, H. O. Vats, K. S. Baliyan, U. C. Joshi,
M. R. Deshpande, N. M. Vadher, and A. B. Shah, Physical Research
Laboratory (PRL), report: "Photopolarimetric observations of
comet C/1996 B2 were made with the PRL 1.2-m telescope (+ optical
polarimeter) at Gurushikhar, through IHW continuum filters (u, 365-
368 nm; b, 484.5-486.5 nm; r, 684-689 nm), with an aperture of 31"
centered on the nucleus. On Mar. 13.97 UT, the polarization
percentage (estimated error) and polarization angle for the filters
mentioned above were, respectively: 6.38 (0.50), 15 deg; 5.78
(0.22), 14 deg; 6.32 (0.29), 14 deg. On Mar. 18.88, the values
were, respectively: 5.04 (0.24), 3 deg; 5.30 (0.14), 6 deg; 6.00
(0.22), 6 deg."
(C) Copyright 1996 CBAT
1996 April 4 (6371) Daniel W. E. Green
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