Central Bureau for Astronomical Telegrams
IAUC 5709: 1993E; G272.2-3.2
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Circular No. 5709
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@CFA or GREEN@CFA (.SPAN, .BITNET or .HARVARD.EDU)
SUPERNOVA 1993E IN KUG 0940+495
C. Pollas, Observatoire de la Cote d'Azur, reports his discovery
of an apparent supernova (mag about 19) on a Tech Pan film taken
Jan. 27.08 UT with the 0.9-m Schmidt telescope. SN 1993E is located
at R.A. = 9h40m26s.26, Decl. = +49 31'41".7 (equinox 1950.0),
or 11" west and 7".8 north of the center of a galaxy known as KUG
0940+495 (Lyon-Meudon extragalactic database). SN 1993E is present
at the limiting magnitude of a V plate taken Jan. 17, but not present
on the POSS prints. A blue object (mag about 20) has end figures
25s.71, 40".6, and a nearby star (mag 15) has end figures
32s.06, 30'45".7. A. Maury, J. B. Emond, and Pollas found SN 1993E
at mag about 20 on Feb. 14.1 with the same telescope (+ unfiltered
CCD).
G272.2-3.2
J. Greiner and R. Egger, Max-Planck-Institut fur Extraterrestrische
Physik, Garching, communicate: "G272.2-3.2, a nearly-circular
supernova remnant (SNR) newly discovered in the ROSAT All-Sky
Survey, is centered at R.A. = 9h06m45s.7, Decl. = -52 07'03" (equinox
J2000.0). A thermal plasma model fit reveals a temperature of
about 1.6 x 10E7 K and an interstellar absorption of N(H) = 2 x
10E21 cmE-2 towards G272.2-3.2. This corresponds to about 20 percent
of the total galactic column density, suggesting a distance of
about 1.5 kpc. Accordingly, the SNR, which has an x-ray radius of
about 9', would be roughly 10E3 yr old. However, the spectral data
also allow a non-thermal origin of the x-ray emission. In particular,
G272.2-3.2 is centrally filled and contains an x-ray point
source at the geometrical center. Low statistics, however, prevent
any time-variability analysis. The x-ray emission surrounding the
central 9' region appears harder than the typical background,
indicating that the entire remnant may be larger in size and the
central nebula may be synchrotron driven. The pulsar PSR 0905-51
(spindown age 2 x 10E6 yr) is located near the northeastern rim of
G272.2-3.2, suggesting a physical relation between the two objects.
The 3-sigma upper limit for the x-ray emission from PSR 0905-51 is
1.6 x 10E-13 erg cmE-2 sE-1 in the hard band 0.9-2.4 keV and 2 x
10E-13 erg cmE-2 sE-1 in the soft band 0.1-0.4 keV. No radio
counterpart of G272.2-3.2 has been found in available radio maps,
possibly due to the vicinity of the Vela-SNR complex. On the ESO/SRC
R plate, there is a faint nebulosity near the center of G272.2-3.2
and another, more extended one about 6' west of the center."
1993 February 15 (5709) Daniel W. E. Green
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