GRB 021023

K. Hurley and T. Cline, on behalf of the Ulysses, Konus, MO, and HETE
GRB teams,

E. Mazets and S. Golenetskii, on behalf of the Konus-Wind GRB team,

I. Mitrofanov, D. Anfimov, A. Kozyrev, M. Litvak and A. Sanin, on
behalf of the HEND/Odyssey GRB team,

W. Boynton, C. Fellows, K. Harshman, C. Shinohara and R. Starr, on
behalf of the GRS/Odyssey GRB team, and

G. Ricker, J-L Atteia, N. Kawai, D. Lamb, S. Woosley, J. Doty, R.
Vanderspek, J. Villasenor, G. Crew, G. Monnelly, N. Butler, J.G.
Jernigan, A. Levine, F. Martel, E. Morgan, G. Prigozhin, J. Braga, R.
Manchanda, G. Pizzichini, Y. Shirasaki, C. Graziani, M. Matsuoka, T.
Tamagawa, K. Torii, T. Sakamoto, A. Yoshida, E. Fenimore, M. Galassi,
T. Tavenner, T. Donaghy, M. Boer, J-F Olive, and J-P Dezalay, on behalf
of the HETE GRB team, report:

Ulysses, Mars Odyssey-HEND, HETE-FREGATE, and Konus-Wind observed this
GRB at 10425 seconds.  As observed by Ulysses, it had a duration of
approximately  15 seconds, a 25-100 keV fluence of approximately
4.1E-6 erg/cm2, and a peak flux of approximately  6.8E-07 erg/cm2 s
over 0.50 seconds.

We have triangulated it to a preliminary, 3 sigma error box whose
approximate area is 55 sq. arcmin. and whose coordinates are:

    RA(2000)                              DEC(2000)
 ERROR BOX CENTER:  7 h 24 m 55.03 s      -16 o 16 '  51.55 " 
 ERROR BOX CORNER 1: 7 h 24 m 19.40 s     -16 o 09 '  44.82 " 
 ERROR BOX CORNER 2: 7 h 25 m 01.41 s     -16 o 21 '  18.28 " 
 ERROR BOX CORNER 3: 7 h 24 m 48.66 s     -16 o 12 '  24.84 " 
 ERROR BOX CORNER 4: 7 h 25 m 30.74 s     -16 o 23 '  58.17 " 

This error box may be improved.

GRB 021023: Curious K-band Source(s) Just Outside of IPN Localization

J. S. Bloom and E. Falco (Harvard-Smithsonian Center for Astrophysics)
report:

"On 2002 Oct 25.5, we imaged the entire IPN error box of GRB 021023
(Hurley et al.; GCN #1653
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 ) at J and Ks-bands with the FLWO 1.2m
equipped with STELIRCam. A comparison between the mosaiced Ks-band
image and the 2MASS K-band QUICKLOOK image* reveals a bright new
source (OBJ1) at (J2000) 07:24:39.49,-16:10:56.8 (+/- 0.1"). A second
source (OBJ2), which appears to be just north of a faint counterpart
in the 2MASS image, is located at 07:24:39.09,-16:11:02.62.  OBJ1/OBJ2
was detected in each image in two separate pointing positions,
consisting of ~10-20 dithered frames of 30 sec. Therefore, OBJ1/OBJ2
is clearly not an array defect nor a cosmic ray hit. See:

      http://www-cfa.harvard.edu/~jbloom/grb021023.ps.gz

Curiously, there is no indication of OBJ1/OBJ2 in the simultaneous
J-band images, which might suggest a high redshift source or heavily
dust extincted source. However, given the proximity (66") of this
OBJ1/OBJ2 to FW CMa (=HD58483; V=5.33mag, type B2.5IVe), the sources
themselves may be a ghosting artifact. Two points weaken this
possibility: 1) earlier standard star images of HD 22686 showed no
indication of ghosting at similar separations in Ks and 2) though the
optical path in the blue-channel (J-band) diverges from the
red-channel, FW CMa is significantly brighter in J-band and no ghosts
are detected in the J-band image.

We encourage IR follow-up to help determine the nature of OBJ1/OBJ2."

*Summed, mosaiced 2MASS images in J,H,K were constructed using the
QUICKLOOK images from the 2MASS All-sky Data Release (see
http://irsa.ipac.caltech.edu/applications/2MASS/Visualizer/). These
images can be obtained by request (jbloom@tdc.harvard.edu).

We thank K. Stanek.

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GRB 021023: Infrared Imaging

J. S. Bloom and E. Falco (Harvard-Smithsonian Center for Astrophysics)
report:

"In analysis further to GCN #1657
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  (Bloom and Falco), we report that no new
sources were detected as compared to 2MASS in the entire IPN error box
given in GCN #1653
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  (Hurley et al.). The limiting magnitudes for any new
sources in the error box at t_burst + 2.4 days are approximately J= 16.0
mag and K= 15.6 mag."

   Stacked J and K data from 2MASS and STELIRCam are available at:
        http://www-cfa.harvard.edu/~jbloom/GRB021023

This message may be cited.