Central Bureau for Astronomical Telegrams
IAUC 7682: 2001do; SGR 1806-20
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Circular No. 7682
Central Bureau for Astronomical Telegrams
INTERNATIONAL ASTRONOMICAL UNION
Mailstop 18, Smithsonian Astrophysical Observatory, Cambridge, MA 02138, U.S.A.
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SUPERNOVA 2001do IN UGC 11459
M. Modjaz and W. D. Li, University of California at Berkeley,
report the discovery by LOTOSS (cf. IAUC 7514) of an apparent
supernova in unfiltered Katzman Automatic Imaging Telescope CCD
frames taken on Aug. 14.2 (mag about 16.2) and 15.2 UT (mag about
16.1). The new object is located at R.A. = 19h37m23s.02, Decl. =
+40o42'24".3 (equinox 2000.0), which is 5".2 east and 3".7 north of
the nucleus of UGC 11459. A KAIT image taken on Aug. 10.2 showed
nothing at this position (limiting mag about 19.0).
SGR 1806-20
S. S. Eikenberry, M. Garske, D. Hu, M. A. Jackson, S. G.
Patel, D. J. Barry, M. Colonno, and J. R. Houck, Cornell
University, report the discovery of possible infrared counterparts
to the soft gamma-ray repeater SGR 1806-20: "Using archival Chandra
observations, we find the x-ray counterpart to be located at R.A. =
18h08m39s.32, Decl. = -20o24'39".8 (equinox 2000.0; uncertainty +/-
0".5 in each coordinate) -- in good agreement with the recently
announced localization of Kaplan et al. (http://xxx.lanl.gov/abs/
astro-ph/?0108195) based on longer Chandra observations. We took
near-infrared J, H, and K images of this field with the Cerro
Tololo 4-m telescope (+ OSIRIS infrared camera) on July 6 UT under
nonphotometric conditions, and photometrically calibrated them with
more shallow observations of the field and an infrared standard
star taken at the Hartung-Boothroyd Observatory 0.65-m telescope.
Using eight USNO-A2.0 stars in the field for astrometric reference,
we find an rms of 0".5 in the infrared astrometric solution,
allowing us to locate the Chandra source to about 1".0 accuracy,
including systematic uncertainties in the Chandra astrometry. We
find three possible counterparts within this error circle with K
(2.2-micron) magnitudes of 16.2, 16.7, and about 18, and with
position end figures of 39s.30, 40".5; 39s.35, 38".5; and 39s.32,
39".5, respectively. The two brightest objects are near the edges
of the error circle, while the faintest is near the center. The
brightest has color J-K = +2.6, making it likely to be a foreground
object. Neither of the other objects is detectable in the J band,
down to a 3-sigma limit of J > 21.0, and thus having color limits
consistent with the massive star cluster near SGR 1806-20 (J-K
about +5.0). At the proposed distance and reddening towards SGR
1806-20 and the star cluster, the two fainter candidates have
absolute K magnitudes of -2.3 and about -1, respectively. Further
observations to search for variability are needed to determine
which, if either, of these candidates is the infrared counterpart
to SGR 1806-20."
(C) Copyright 2001 CBAT
2001 August 15 (7682) Daniel W. E. Green
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