GRB 011019

GRB011019: A Faint, X-ray Rich GRB localized by HETE

G. Ricker, D. Lamb, and S. Woosley on behalf of the HETE Science Team;

N. Butler, R. Vanderspek, G. Crew, J. Doty, G. Monnelly, J. Villasenor,
T. Cline, J.G. Jernigan, A. Levine, F. Martel, E. Morgan, G.
Prigozhin, J. Braga, R. Manchanda, and G. Pizzichini, on behalf of
the HETE Operations and HETE Optical-SXC Teams;

N. Kawai, M. Matsuoka, Y. Shirasaki, T. Tamagawa, K. Torii, T. Sakamoto,
A. Yoshida, E. Fenimore, M. Galassi, T. Tavenner, T. Donaghy, and
C. Graziani, on behalf of the HETE WXM Team;

J-L Atteia, M. Boer, J-F Olive, J-P Dezalay, and K. Hurley on behalf
of the HETE FREGATE Team;

write:

The HETE Fregate and WXM instruments detected and localized a faint 
burst at 31370 SOD {08:42:50} UT on 19 October. The burst was an 
untriggered event, and appears to be an X-ray rich GRB with a 
duration of ~30 seconds.

In the Fregate 8-40 keV band, the statistical significance was 8.2 
sigma. A total of 998 counts were detected during that interval, 
corresponding to a fluence  of ~1.8 x 10-7 ergs cm-2 . The peak flux 
was ~3.4 x 10-8 ergs cm-2 s-1  (ie ~1 x Crab flux). In the WXM 2-10 
keV band, the statistical significance was 8.4 sigma.

Based on the WXM data, the best fit location for GRB011019 is:

R.A.(2000) = 00h42m50s.23, Dec.(2000) = -12o26'58"

The 1-sigma (68.3%) uncertainty radius for this localization is 21 
arcminutes (7.5' statistical error combined in quadrature with 19.8' 
systematic error).  The 2-sigma (95.5%) uncertainty radius is 35 
arcminutes.

Although the HETE spacecraft was approaching the nighttime part of 
its orbit, and HETE's field of view was clear of the earth, the 
sunlit part of the earth was close to the star camera field of view. 
The star cameras could not track stars because of the scattered 
light. Thus the spacecraft attitude was estimated using data from the 
fine sun sensor and magnetometers rather than the star cameras. For 
this condition, the errors in the attitude solution are larger than 
if the star cameras are used.  As a result, the estimated error in 
the attitude solution is unusually large.

A. Henden (USRA/USNO) reports on behalf of the USNO GRB team:

We have acquired single V-band images with the NOFS 1.0m
telescope from 011020 0537-0703 UT, forming a mosaic that
covers the central 32x32arcmin of the HETE error box (GCN 1109
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 ).
Our images go somewhat fainter than the DPOSS limit.

We find no new source down to the DPOSS limit within
our field.  There is one bright asteroid about 9arcmin NW of
the field center, near a pair of bright stars, moving towards the east.

There is a small mistake in GCN 1110
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 .  The asteroid
is moving to the *west* at about 0.5arcsec/minute.

P.A. Price, B.P. Schmidt, T.S. Axelrod (RSAA, ANU) and D.W. Fox (Caltech)
report:

"We have observed the centre 40 arcmin square region of the error box
of GRB 011019 (GCN #1109
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 ) with the robotic 50-inch telescope at Mount
Stromlo Observatory, commencing at 2001 Oct 20.39 UT.  Our combined
3x300 sec images in MACHO R band have a limiting magnitude of
approximately R ~ 19.5 mag.  Neither automated or manual comparison
of the images with the Digital Sky Survey reveal the presence of an
optical transient.  Further observations are planned."

This message may be cited.

Carl Akerlof, Timothy McKay, Eli Rykoff, and Donald Smith
        on behalf of the ROTSE collaboration

The ROTSE-III 0.45-m telescope located at Los Alamos National
Laboratory responded to the announcement of GRB011019 (GCN 1109
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 ) at
2:20 UT, 20-Oct-2001, 17.6 hours after the burst was detected by
HETE-2. Twenty 60-second exposures were obtained followed by
additional images at 05:49 UT on 20-Oct-2001 and at 02:16 UT on
21-Oct-2001. With a threshold detection level of m_R ~ 19, no fading
transients were discovered within the 35' two sigma error circle.
Two asteroids within the error box were identified by their
proper motion.

This message may be cited.

D. W. Fox (Caltech) and P. A. Price (MSO/ANU), with S. Pravdo,
E. Helin, K. Lawrence, and M. Hicks of the NEAT/Palomar team, report
on behalf of the Caltech-NRAO-CARA GRB collaboration:

"We have observed the 35 arcmin-radius error circle of GRB011019 with
the 48-inch NEAT automated telescope on Mt. Palomar.  In 1.13-degree
by 1.13-degree images taken on 21 October 05:00 UT and 05:31 UT we
cover almost the full error circle to limiting magnitudes deeper than
the Digitized Sky Survey (DSS).  Visual comparison of the images with
the DSS reveals a single asteroid but no other obvious new objects, to
a limiting magnitude of roughly R~19.5."

This message may be cited.

Y. Komiyama, on behalf of the SuprimeCam Team:

G. Kosugi, N. Kobayashi, Y. Mizumoto, M. Iye, R.Ogasawara
T. Takata, K. Sekiguchi, T. Yamada, J. Watanabe, and T. Totani,
             on behalf of the Subaru GRB Team:

We have obtained several R-band images with the Subaru 8.2m
telescope atop Mauna Kea on 2001 October 20 beginning at 10:14
(25.5 hours after the burst), 10:19, 12:21, and 12:26 UT to
search fading objects.  The observing instrument was Suprime-Cam
and the central 34 x 50 arcmin of the HETE error box (GCN 1109
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 )
was covered by two consecutive pointings with the exposure
time of 180 seconds each.  Due to the heavy cirrus coverage
the limitting magnitude was R = 22.5 (+/- 0.2 mag of photometric
measurement error at the magnitude) for the first exposures and
R = 25.0 (+/- 0.2) for the second exposures.

We find no new object down to the DSS-2 limit within our field
and no fading object with the variability grater than 3 sigma
threshould of the photometric error in 2 hours.

S. Bondar (Kosmoten), A. Pozanenko (IKI), V. Rumyantsev (CrAO), G. Beskin
(SAO)

We have observed  the 35 arcmin-radius error circle of GRB 011019 (GCN 1109
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 )
with 600mm automated telescope (TT600) of Kosmoten observatory. Two images
were taken in at 22:00 UT on 19-Oct-2001 (13.3 hours after burst trigger)
and 00:01 UT on 20-Oct-2001. Limiting magnitude of first image was
approximately R ~ 15.5. Visual comparison with DSS reveals no optical
transients in both images.