Central Bureau for Astronomical Telegrams

IAUC 6395: S/1995 S 5; GRO J1744-28

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                                                  Circular No. 6395
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)


S/1995 S 5
     B. Sicardy and F. Poulet, Paris Observatory; and J.-L. Beuzit
and P. Prado, European Southern Observatory, write:  "Further to
IAUC 6269, four images taken on 1995 Aug. 9 reveal the presence of
an unresolved object.  The observed separations, measured west of
the planet's center, are (typical accuracy 0".15):  1995 Aug.
9.24479 UT, 15".83; 9.24549, 15".99; 9.24618, 16".10; 9.24688,
16".14.  We identified this object as S/1995 S 5, detected by the
HST more than a day later (IAUC 6243; Nicholson et al. 1996,
Science 272, 509).  Combining the ESO data with the HST data, we
derive the mean motion, 581.7 +/- 2.1 deg/day; the longitude
measured from the ascending node of Saturn's equatorial plane on
the earth's equator (equinox J2000.0) at epoch 1995 Aug. 10.5 UT
(at Saturn), 130.7 deg; the estimated radius, 37 km; and the short-
K magnitude at mean opposition, 16.0.  The radius is estimated from
the object's integrated flux, assuming a spherical shape and the
albedo of Saturn X (Janus).  Assuming also a circular orbit, and
including the effects of Saturn's J2, J4, and J6, the mean motion
derived above yields a geometric orbital radius of 140 265 +/- 330
km, closer to the F-ring radius (140 209 +/- 4 km) than the
previously derived value derived from the HST data alone (139 682
+/- 370 km)."


GRO J1744-28
     C. Kouveliotou, Universities Space Research Association (USRA);
K. Deal, P. Woods, M. Briggs, University of Alabama in Huntsville
(UAH); B. A. Harmon, G. J. Fishman, Marshall Space Flight Center,
NASA; J. van Paradijs, UAH and University of Amsterdam; M. H.
Finger, USRA; and J. Kommers and W. H. G. Lewin, Massachusetts
Institute of Technology, report:  "BATSE is no longer detecting
bursts or persistent emission from the bursting pulsar GRO J1744-28.
A total of 3080 bursts were detected from this source (not
corrected for earth occultation or other deadtime effects) between
its onset on 1995 Dec. 2 until its cessation on 1996 May 3.  During
most of this 152-day interval, the burst rate was fairly constant
at an average of about 20 bursts/day, but after Apr. 27 the rate
declined rapidly.  The last detected event had a fluence of 1.2 x
10E-7 erg cmE-2.  The pulsing signal in the persistent emission was
last detected on Apr. 26; after this date, the pulsed flux was
below 7 x 10E-10 erg cmE-2 sE-1 (r.m.s., between 20 and 40 keV).
Between Apr. 30 and May 6, earth-occultation measurement yields a
3-sigma upper limit on the total flux above 20 keV of 2.7 x 10E-9
erg cmE-2 sE-1, or about 150 mCrab."

                      (C) Copyright 1996 CBAT
1996 May 9                     (6395)            Daniel W. E. Green

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