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IAUC 5311: 1991ak; 3C 279; PSR 0833-45; FG Ser

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IAUC number 

                                                  Circular No. 5311
Central Bureau for Astronomical Telegrams
INTERNATIONAL ASTRONOMICAL UNION
Postal Address: Central Bureau for Astronomical Telegrams
Smithsonian Astrophysical Observatory, Cambridge, MA 02138, U.S.A.
Telephone 617-495-7244/7440/7444 (for emergency use only)
TWX 710-320-6842 ASTROGRAM CAM     EASYLINK 62794505
MARSDEN or GREEN@CFA.BITNET    MARSDEN or GREEN@CFAPS2.SPAN


SUPERNOVA 1991ak IN NGC 5378
   A. V. Filippenko, T. Matheson, and J. C. Shields, University of
California at Berkeley, report that a CCD spectrum (range 390-710 nm,
resolution 1 nm) obtained on July 20 UT with the Shane 3-m reflector
at Lick Observatory shows that SN 1991ak is of type Ia, probably
about 2 months past maximum brightness.


3C 279
     The GRO/EGRET Team (D. L. Bertsch, C. E. Fichtel, R. C. Hartman,
S. D. Hunter, D. A. Kniffen, P. Kwok, J. R. Mattox, P. Sreekumar,
and D. J. Thompson, Goddard Space Flight Center, NASA; G. Kanbach,
H. A. Mayer-Hasselwander, K. Pinkau, H. Rothermel, M. Sommer, and C.
V. Montigny, Max-Planck-Institut fur Extraterrestrische Physik; Y.
C. Lin, P. F. Michelson, and P. L. Nolan, Stanford University; and
E. Schneid, Grumman Aerospace) communicates: "During the period June
15-28, we detected an intense localized source of 100-MeV gamma
radiation positionally coincident (within a 5' error circle) with the
variable quasar 3C 279.  At its present intensity, this source would
have been visible to the SAS-2 or COS-B high energy telescope; neither
reported a detection during 1972-73 and 1975-82, respectively."


PSR 0833-45
     C. Flanagan, Hartebeesthoek Radio Astronomy Observatory, telexes:
"PSR 0833-45 (the Vela pulsar) underwent a spin-up of magnitude
dP/P = +(2.715 +/- 2) x 10E-6 on July 20.382 UT (+/- 1 day).  This
is the ninth 'giant glitch' observed in Vela in 21 years.  The
relative change in period derivative was +(0.60 +/- 0.06), the largest
observed in any pulsar.  Ninety percent of the change in derivative
recovered within one day of the jump.  Observations commenced 7 min
after the assumed glitch epoch."


FG SERPENTIS
     This symbiotic variable may be undergoing an eclipse; visual
magnitude estimates (cf. IAUC 5061):  1990 Oct. 10.76 UT, 11.0 (E.
Schweitzer, Strasbourg, France); Nov. 7.0, 11.4 (J. E. Bortle,
Stormville, NY); 1991 Apr. 12.16, 11.5 (P. Schmeer, Bischmisheim,
Germany); June 19.06, 11.5 (Schmeer); July 21.94, 12.4 (Schmeer).


1991 July 22                   (5311)             Daniel W. E. Green

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