Central Bureau for Astronomical Telegrams

Central Bureau for Astronomical Telegrams -- Image credits

IAUC 3611: SNe; 4U 1916-05; 1980u

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 3610  SEARCH Read IAUC 3612
IAUC number

                                                  Circular No. 3611
Central Bureau for Astronomical Telegrams
Postal Address: Central Bureau for Astronomical Telegrams
Smithsonian Astrophysical Observatory, Cambridge, MA 02138, U.S.A.
TWX 710-320-6842 ASTROGRAM CAM     Telephone 617-864-5758

     R. Kirshner, Department of Astronomy, University of Michigan,
reports the following observations made at McGraw-Hill and at Kitt
Peak National Observatory on June 9: 1) the supernova in NGC 5597
(cf. IAUC 3609), at mpg = 18 and past maximum light, is a type-Il
supernova; 2) the NGC 4874 object (cf. IAUC 3610) is a type-I supernova;
3) the Gonzalez supernova in an anonymous galaxy (cf. IAUC
3610) is type I and past maximum at mpg = 16.

     P. Osmer, Cerro Tololo Interamerican Observatory, telexes the
following photometric values for the Gonzalez supernova in an anonymous
galaxy, obtained by A. U. Landolt with the 1.5-m telescope on
June 9.049 UT: V = 14.98, B-V = +0.41, U-V = +0.24.

4U 1916-05
     F. M. Walter, University of California at Berkeley; and N. E.
White and J. Swank, Goddard Space Flight Center, write: "We have independently
discovered periodic absorption dips in the steady x-ray
flux from the burst source 4U 1916-05 in two observations made with
the Einstein Observatorv.  OSO-8 and HEAO-1 A2 data confirm the result
and yield a preliminary period of 50 +/- 0.5 min; the data cannot
yet be used to predict a ephemeris.  The dips are of varying
duration and depth, and cannot be due to eclipses by a companion;
they are also observed to disappear and reappear on a timescale of
a few days.  The dips are probably due to photoelectric absorption
by a bulge in the accretion disk, where the gas stream intercepts
the disk with the rapid variations due to turbulent fluctuations in
the height of the bulge, and the slower trends may be attributable
either to long-term changes in the bulge height or to precession of
a tilted accretion disk.  This is the first direct evidence to confirm
the binary nature of x-ray burst sources.  We urge further efforts
to identify an optical counterpart."

     Total visual magnitude estimates: Apr. 1.14 UT, 8.4 (J. Bortle,
Stormville, NY, 20 x 80 binoculars); 7.19, 9.3 (C. E. Spratt, Victoria,
BC, 0.25-m reflector); 23.12, 9.5 (C. S. Morris, Harvard, MA,
0.25-m reflector); May 5.24, 10.5 (Spratt); 8.22, 10.9 (Spratt);
June 1.11, 11.0 (Bortle, 0.32-m reflector); 3.09, 10.4 (Morris).

1981 June 12                   (3611)              Daniel W. E. Green

Read IAUC 3610  SEARCH Read IAUC 3612

Our Web policy. Index to the CBAT/MPC/ICQ pages.

Valid HTML 4.01!