- GCN/BACODINE POSITION NOTICE
TITLE: GCN/HETE BURST POSITION NOTICE
NOTICE_DATE: Mon 24 Mar 03 03:12:48 UT
NOTICE_TYPE: HETE S/C_Alert
TRIGGER_NUM: 2641, Seq_Num: 1
GRB_DATE: 12722 TJD; 83 DOY; 03/03/24
GRB_TIME: 11562.80 SOD {03:12:42.80} UT
TRIGGER_SOURCE: Trigger on the 25-400 keV band.
GAMMA_RATE: 142 [cnts/s] on a 1.300 [sec] timescale
SC_LONG: 20 [deg East]
SUN_POSTN: 2.82d {+00h 11m 17s} +1.22d {+01d 13' 21"}
MOON_POSTN: 260.00d {+17h 20m 01s} -24.72d {-24d 43' 25"}
MOON_ILLUM: 61 [%]
COMMENTS: No s/c ACS pointing info available yet.
COMMENTS: Probable GRB.
- GCN/BACODINE POSITION NOTICE
TITLE: GCN/HETE BURST POSITION NOTICE
NOTICE_DATE: Mon 24 Mar 03 03:13:07 UT
NOTICE_TYPE: HETE S/C_Update
TRIGGER_NUM: 2641, Seq_Num: 2
GRB_DATE: 12722 TJD; 83 DOY; 03/03/24
GRB_TIME: 11562.80 SOD {03:12:42.80} UT
TRIGGER_SOURCE: Trigger on the 25-400 keV band.
GAMMA_RATE: 142 [cnts/s] on a 1.300 [sec] timescale
SC_-Z_RA: 177 [deg]
SC_-Z_DEC: 0 [deg]
SC_LONG: 20 [deg East]
WXM_CNTR_RA: 204.258d {+13h 37m 02s} (J2000),
204.300d {+13h 37m 12s} (current),
203.617d {+13h 34m 28s} (1950)
WXM_CNTR_DEC: -0.451d {-00d 27' 04"} (J2000),
-0.468d {-00d 28' 03"} (current),
-0.197d {-00d 11' 48"} (1950)
WXM_MAX_SIZE: 28.00 [arcmin] diameter
WXM_LOC_SN: 8 sig/noise (pt src in image)
WXM_IMAGE_SN: X= 6.2 Y= 5.2 [sig/noise]
WXM_LC_SN: X= 8.0 Y= 12.5 [sig/noise]
SUN_POSTN: 2.82d {+00h 11m 17s} +1.22d {+01d 13' 21"}
SUN_DIST: 158.51 [deg]
MOON_POSTN: 260.00d {+17h 20m 01s} -24.72d {-24d 43' 25"}
MOON_DIST: 58.99 [deg]
MOON_ILLUM: 61 [%]
GAL_COORDS: 326.46,60.32 [deg] galactic lon,lat of the burst
ECL_COORDS: 202.63,8.99 [deg] ecliptic lon,lat of the burst
COMMENTS: Probable GRB.
COMMENTS: WXM error box is circular; not rectangular.
- GCN/BACODINE POSITION NOTICE
TITLE: GCN/HETE BURST POSITION NOTICE
NOTICE_DATE: Mon 24 Mar 03 03:15:10 UT
NOTICE_TYPE: HETE S/C_Update
TRIGGER_NUM: 2641, Seq_Num: 3
GRB_DATE: 12722 TJD; 83 DOY; 03/03/24
GRB_TIME: 11562.80 SOD {03:12:42.80} UT
TRIGGER_SOURCE: Trigger on the 25-400 keV band.
GAMMA_RATE: 142 [cnts/s] on a 1.300 [sec] timescale
SC_-Z_RA: 177 [deg]
SC_-Z_DEC: 0 [deg]
SC_LONG: 20 [deg East]
WXM_CNTR_RA: 204.258d {+13h 37m 02s} (J2000),
204.300d {+13h 37m 12s} (current),
203.617d {+13h 34m 28s} (1950)
WXM_CNTR_DEC: -0.451d {-00d 27' 04"} (J2000),
-0.468d {-00d 28' 03"} (current),
-0.197d {-00d 11' 48"} (1950)
WXM_MAX_SIZE: 28.00 [arcmin] diameter
WXM_LOC_SN: 8 sig/noise (pt src in image)
WXM_IMAGE_SN: X= 6.2 Y= 5.2 [sig/noise]
WXM_LC_SN: X= 8.0 Y= 12.5 [sig/noise]
SUN_POSTN: 2.82d {+00h 11m 17s} +1.22d {+01d 13' 21"}
SUN_DIST: 158.51 [deg]
MOON_POSTN: 260.00d {+17h 20m 01s} -24.72d {-24d 43' 25"}
MOON_DIST: 58.99 [deg]
MOON_ILLUM: 61 [%]
GAL_COORDS: 326.46,60.32 [deg] galactic lon,lat of the burst
ECL_COORDS: 202.63,8.99 [deg] ecliptic lon,lat of the burst
COMMENTS: Probable GRB.
COMMENTS: WXM error box is circular; not rectangular.
- GCN/BACODINE POSITION NOTICE
TITLE: GCN/HETE BURST POSITION NOTICE
NOTICE_DATE: Mon 24 Mar 03 03:16:09 UT
NOTICE_TYPE: HETE S/C_Last
TRIGGER_NUM: 2641, Seq_Num: 4
GRB_DATE: 12722 TJD; 83 DOY; 03/03/24
GRB_TIME: 11562.80 SOD {03:12:42.80} UT
TRIGGER_SOURCE: Trigger on the 25-400 keV band.
GAMMA_RATE: 142 [cnts/s] on a 1.300 [sec] timescale
SC_-Z_RA: 177 [deg]
SC_-Z_DEC: 0 [deg]
SC_LONG: 20 [deg East]
WXM_CNTR_RA: 204.258d {+13h 37m 02s} (J2000),
204.300d {+13h 37m 12s} (current),
203.617d {+13h 34m 28s} (1950)
WXM_CNTR_DEC: -0.451d {-00d 27' 04"} (J2000),
-0.468d {-00d 28' 03"} (current),
-0.197d {-00d 11' 48"} (1950)
WXM_MAX_SIZE: 28.00 [arcmin] diameter
WXM_LOC_SN: 8 sig/noise (pt src in image)
WXM_IMAGE_SN: X= 6.2 Y= 5.2 [sig/noise]
WXM_LC_SN: X= 8.0 Y= 12.5 [sig/noise]
SUN_POSTN: 2.82d {+00h 11m 17s} +1.22d {+01d 13' 21"}
SUN_DIST: 158.51 [deg]
MOON_POSTN: 260.00d {+17h 20m 01s} -24.72d {-24d 43' 25"}
MOON_DIST: 58.99 [deg]
MOON_ILLUM: 61 [%]
GAL_COORDS: 326.46,60.32 [deg] galactic lon,lat of the burst
ECL_COORDS: 202.63,8.99 [deg] ecliptic lon,lat of the burst
COMMENTS: Probable GRB.
COMMENTS: WXM error box is circular; not rectangular.
- GCN/BACODINE POSITION NOTICE
TITLE: GCN/HETE BURST POSITION NOTICE
NOTICE_DATE: Mon 24 Mar 03 04:23:48 UT
NOTICE_TYPE: HETE Ground Analysis
TRIGGER_NUM: 2641, Seq_Num: 5
GRB_DATE: 12722 TJD; 83 DOY; 03/03/24
GRB_TIME: 11562.80 SOD {03:12:42.80} UT
TRIGGER_SOURCE: Trigger on the 25-400 keV band.
GAMMA_RATE: 142 [cnts/s] on a 1.300 [sec] timescale
SC_-Z_RA: 177 [deg]
SC_-Z_DEC: 0 [deg]
SC_LONG: 20 [deg East]
WXM_CNTR_RA: 204.295d {+13h 37m 11s} (J2000),
204.336d {+13h 37m 21s} (current),
203.654d {+13h 34m 37s} (1950)
WXM_CNTR_DEC: -0.323d {-00d 19' 22"} (J2000),
-0.339d {-00d 20' 21"} (current),
-0.069d {-00d 04' 06"} (1950)
WXM_MAX_SIZE: 14.00 [arcmin] diameter
WXM_LOC_SN: 16 sig/noise (pt src in image)
WXM_IMAGE_SN: X= 6.2 Y= 5.2 [sig/noise]
WXM_LC_SN: X= 8.0 Y= 12.5 [sig/noise]
SUN_POSTN: 2.82d {+00h 11m 17s} +1.22d {+01d 13' 21"}
SUN_DIST: 158.47 [deg]
MOON_POSTN: 260.00d {+17h 20m 01s} -24.72d {-24d 43' 25"}
MOON_DIST: 59.02 [deg]
MOON_ILLUM: 61 [%]
GAL_COORDS: 326.62,60.43 [deg] galactic lon,lat of the burst
ECL_COORDS: 202.62,9.12 [deg] ecliptic lon,lat of the burst
COMMENTS: Definite GRB.
COMMENTS: WXM error box is circular; not rectangular.
COMMENTS: Burst_Validity flag is true.
COMMENTS: WXM data refined since S/C_Last Notice.
- red DSS finding chart of the HETE error circle (
ps-file)
Error radius = 7 arcmin, North up, East to the left.
- GCN notice #1945
S. Guzyi, A. J. Castro-Tirado (IAA-CSIC, Granada),
N. Cardiel, S. Pedraz (CAHA, Calar Alto),
S. Huferath, G. Worseck (AIP, Potsdam),
J. Greiner (MPE, Garching),
S. Klose (TLS, Tautenburg),
A. de Ugarte (IAA-CSIC),
J. Gorosabel (IAA-CSIC/STScI)
report:
Following the HETE-2 ground-based analysis position
for GRB 030324 (trigger 2641), we have gotten a 300-s
R-band image with the 2.2-m CAHA telescope (+CAFOS,
16' diameter FOV) at the German-Spanish Calar Alto
Observatory in Southern Spain. The frame covers 90% of
the HETE-2 14' diameter error box (missing a 2' ring
at the border towards the NW of it) and it was taken
starting at 04:41:43 UT (i.e.about 1.5 hr after the
onset of the event). No obvious counterpart is found
down to R = 20, when comparing with the DSS-2 (R-band).
Further near-IR and deeper optical observations would
be potentially interesting.
This message can be quoted.
- GCN notice #1947
W. Li, S. Jha, R. Chornock, and A. V. Filippenko (UC Berkeley), report
that unfiltered images of a 12 arcmin x 12 arcmin region centered at the
position of GRB 030324 (HETE Trigger #2641; 13h37m11s -00d19'22" J2000),
covering roughly 90% of the HETE WXC error circle, were taken with the
Katzman Automatic Imaging Telescope (KAIT) at 06:18 UT (about 3 hours
after the burst) and show no obvious new source compared with the DSS II
(red) to a limiting magnitude of 19.5 mag, consistent with the results of
Guzyi et al. (GCN 1945).
This message may be cited.
- GCN notice #1950
A. Henden (USRA/USNO) reports on behalf of the USNO GRB team:
We have acquired BVRcIc all-sky photometry for
a 20x20 arcmin field centered at the coordinates
for the HETE burst GRB030324 (HETE trigger 2641)
with the USNOFS 1.0-m telescope on one very marginal
photometric night. Stars brighter than V=13.5 are saturated and
should be used with care. We have placed the photometric data
on our anonymous ftp site:
ftp://ftp.nofs.navy.mil/pub/outgoing/aah/grb/grb030324.dat
The astrometry in this file is based on linear plate solutions
with respect to UCAC2. The external errors are less than 100mas.
There were approaching clouds from a weak frontal system
that do not appear to have reached this field until well
after the observations, but until further calibration
is performed, a systematic error is possible. Based purely
on the standard star observations, the estimated external
photometric error is 0.03mag.
If an OT is discovered, this calibration will be extended
with additional nights. We will not be performing U-band
calibration unless requested. As always, you should check
the dates on the .dat file prior to final publication to get
the latest photometry.
- GCN notice #1954
T. Donaghy, M. Suzuki, Y. Shirasaki, C. Graziani, M. Matsuoka, T.
Tamagawa, K. Torii, T. Sakamoto, A. Yoshida, E. Fenimore, M. Galassi,
T. Tavenner, Y. Nakagawa, D. Takahashi, R. Satoh, and Y. Urata, on
behalf of the HETE WXM Team;
G. Ricker, J-L Atteia, N. Kawai, D. Lamb, and S. Woosley on behalf of
the HETE Science Team;
R. Vanderspek, J. Doty, J. Villasenor, G. Crew, G. Monnelly, N.
Butler, T. Cline, J.G. Jernigan, A. Levine, F. Martel, E. Morgan, G.
Prigozhin, G. Azzibrouck, J. Braga, R. Manchanda, and G. Pizzichini,
on behalf of the HETE Operations and HETE Optical-SXC Teams;
M. Boer, J-F Olive, J-P Dezalay, C. Barraud and K. Hurley on behalf
of the HETE FREGATE Team;
write:
At 03:12:42.80 UTC (11562.80 s UT) on 24 Mar 2003, the HETE FREGATE
and WXM instruments detected event H2461, a long GRB.
The WXM flight localization was correct and was reported in a GCN
Notice at 03:13:07 UTC, 25 sec after the beginning of the burst
Ground analysis of the WXM WXM data for the burst produced a refined
location, which was reported in a GCN Notice at 04:23:48 UT, 71 minutes
after the burst. The WXM localization SNR was 16. The WXM location
can be expressed as a 90% confidence circle that is 7 arcminutes in
radius and is centered at
WXM: RA = +13h 37m 11s, Dec = -00d 19' 22" (J2000).
The SXC turns off at orbit dawn; this happened 10 sec before the
beginning of the burst, and therefore there will be no SXC localization
for this burst.
The burst duration t_90 in the 30-400 keV band was ~ 8.7 s. The
fluence of the burst was 1.6 x 10-6 ergs cm-2 and the peak flux over 5
s was ~1.4 x 10-7 ergs cm-2 s-1 (i.e., ~ 5 x Crab flux) in the same
energy band.
A light curve and skymap for GRB030324 is provided at the following URL:
http://space.mit.edu/HETE/Bursts/GRB030324
- GCN notice #1955
T. Donaghy, M. Suzuki, Y. Shirasaki, C. Graziani, M. Matsuoka, T.
Tamagawa, K. Torii, T. Sakamoto, A. Yoshida, E. Fenimore, M. Galassi,
T. Tavenner, Y. Nakagawa, D. Takahashi, R. Satoh, and Y. Urata, on
behalf of the HETE WXM Team;
G. Ricker, J-L Atteia, N. Kawai, D. Lamb, and S. Woosley on behalf of
the HETE Science Team;
R. Vanderspek, J. Doty, J. Villasenor, G. Crew, G. Monnelly, N.
Butler, T. Cline, J.G. Jernigan, A. Levine, F. Martel, E. Morgan, G.
Prigozhin, G. Azzibrouck, J. Braga, R. Manchanda, and G. Pizzichini,
on behalf of the HETE Operations and HETE Optical-SXC Teams;
M. Boer, J-F Olive, J-P Dezalay, C. Barraud and K. Hurley on behalf
of the HETE FREGATE Team;
write:
The title of GCN Circular 1954 is incorrect; it should read:
"GRB030324 (=H2641): A Long GRB Localized in Real Time by the HETE WXM."
- GCN notice #1958
E. S. Rykoff and D. A. Smith on behalf of the ROTSE collaboration report:
We have observed the full error box of GRB 030324 (HETE trigger 2641) using
the ROTSE-3B 0.45 meter telescope at McDonald Observatory, Texas, starting
March 24, 4:27 UT (1.24 hours after the burst). Sixty one-minute unfiltered
exposures were taken, with limiting magnitudes between 18.1 and 18.5 calibrated
against USNO A2.0 R-band. We co-added the frames in sets of 20 to achieve
limiting magnitudes of ~ 19.6.
Of the sources detected within the 7' error radius from the position reported
in GCN 1954 (Donaghy, et. al.), most could be associated
with stars in the USNO catalog. None of the others was found to vary over the
hour of observations. Visual comparison between DSS-2 (R-band) and
several ROTSE images reveal no counterpart candidates. We have also compared
the first co-added frame to a co-added follow-up sequence taken the following
night (23 hours after the burst). Visual inspection reveals each ROTSE-III
source visible on March 24 is still visible on March 25.
- GCN notice #1959
P.A. Price and R. McNaught (RSAA, ANU) report:
We have observed the error box of GRB 030324 (HETE trigger #2641; Donaghy
et al., GCN 1954) with the 40-inch telescope at Siding Spring Observatory.
Observations consisted of 6x300 sec integrations in R-band at each of
three epochs and cover the entire error-circle. Approximate limiting
magnitudes at each epoch are:
Epoch (UT) R_lim
Mar 24.523 21.4 mag
Mar 24.727 21.0 mag
Mar 25.674 21.4 mag
We do not identify any afterglow candidates upon image subtraction between
each of the epochs or upon comparison of the first epoch with the DSS 2.
This message may be cited.
- GCN notice #1961
A. Klotz, J.L. Atteia, M. Boer communicate:
The TAROT robotic observatory reacted within seconds
to the HETE trigger H 2641 = GRB 030324.
The images started at 3h13m10.75s UT,
3 seconds after the GCN notice and 27.95s after the trigger.
The first 30s image, taken between 27.95s and 57.95s
after the trigger shows no OT with a limiting R magnitude of about 14.8.
Seven images were co-added, taken between 27.95s and 252.2s after the GRB.
The co-added image shows no OT with a limiting R magnitude about 15.2.
The limiting magnitude of TAROT images are lower than usual
because the hour angle motion of the telescope was
inopportunely stopped during images.
This acquisition mode allows to record time resolved
flickering in case were OT is very bright,
but it was not the case for this GRB.
- GCN notice #1963
A. Piccioni, C. Bartolini, S. Bernabei, A. Guarnieri, I. Bruni (Bologna
University and Bologna Astronomical Observatory) and G. Pizzichini
(IASF-CNR, Sezione di Bologna) report:
We have observed the error box of GRB030324 (GCN 1954, HETE trigger 2641)
in the nights of March 24 and 25 with the 152 cm Loiano telescope of
Bologna University.
We have obtained the following two images:
mid exp. filter exposure time approx.
UT (seconds) limiting mag
Mar 24.9837 R 1800 21.9
Mar 25.9852 R 1800 21.4
We find no OT candidate in our first frame with respect to DSSII.
By the comparison of the two frames we do not detect any object fading
more than the internal error of the measurements.
Our images can be retrieved in format jpeg by sftp using
hostname: ermione.bo.astro.it
username: publicGRB
password: GRB_bo
This message may be cited.
- GCN notice #1964
V.Rumyantsev (CrAO) and A.Pozanenko (IKI) report:
We have observed the full error box of GRB 030324 (HETE Trigger #2641,
Seq_Num: 5) in CrAO with AT-64 telescope. 10 unfiltered images were
obtained in March, 24 between (UT) 20:20 and 20:56.
No afterglow candidate was found in comparison with DSS2. Using
photometry by A. Henden (GCN 1950) R-band we estimate the limiting
magnitudes of combined images (S/N=3) as following
Start time (UT) telescope exposure limiting mag.
March 24 20:20 AT-64 10x180 s 20.0
This message can be cited.
- GCN notice #1972
G. Masi (University of Rome "Tor Vergata" and European Southern Observatory,
Chile), B. L. Jensen, J. Hjorth (Copenhagen University) and R. Michelsen
(Astronomical Observatory, Copenhagen) report:
We imaged the field around the GRB030324 event (trigger 2641) on March 24,
05:10 UT, with the 1.54-m Danish Telescope (La Silla) + DFOSC CCD, covering
a field of 13x13 square arcmins. Adding three 180s R-band images, we do not
see any obvious OT candidate down to the limit of the DSS-2 (R-band).
This message can be cited
- GCN notice #2032
K. Luhman, T. Megeath, T. Spahr, K.Z. Stanek (CfA), S. Holland
P. Garnavich (Notre Dame)
We observed the error circle of GRB 030324 (GCN 1954) with
the Fred L. Whipple 1.2-m telescope and R filter on three
epochs:
Date Time t (days) R_lim
Mar. 24 06:25 0.134 22.4
Mar. 24 10:37 0.309 22.5
Mar. 26 07:52 2.194 22.7
where R_lim is the 3-sigma limiting magnitude. Visual
comparison and subtraction of the the epochs reveals no new,
strongly variable sources down to the corresponding limits.
A star present on the digitized sky survey at
13:37:19.23 -00:16:21 (2000) is seen to vary between 19.2
and 18.8 in the R-band.
Deep R-band images centered on the error circle, but covering
only the inner 7.4' diameter field were obtained with the
Magellan 6.5-m Clay telescope and LDSS2 imaging/spectrograph:
Date Time t (days) R_lim
Mar. 24 08:14 0.210 23.1
Mar. 25 05:35 1.100 23.3
and subtraction of these images does not reveal any
new, variable sources.
This message may be cited.
- GCN notice #2037
J. Moran, A. Henden, D. Lamb, D. York, M. Nysewander, J. Barentine, J.
Dembicky, C. Graziani, E. Sheldon, R. Soule, M. Bayliss, H. Cheng, C. Cook,
M. Lopez-Morales, D. Reichart, R. McMillan, B. Ketsebeck, C. Blacker, and
A. Reese report on behalf of the USNO, ARC, and UNC GRB teams of the FUN
GRB collaboration:
We observed the 14 arcminute diameter error circle of GRB 030324 (Donaghy
et al., GCN 1954, 1955) in BVRci*IcH beginning 2.1 hours after the burst.
Using the field calibration of Henden (GCN 1860) and 2MASS, we report the
following limiting magnitudes:
Start Start Time Mean Time Filter Integration Limiting Telescope
Date Since GRB Since GRB Time (sec) Magnitude
(hours) (hours) x Pointings (3 sigma)
Mar 24.222 2.12 2.12 Ic 300 x 1 20.2 1.0-m USNO
Mar 24.227 2.24 2.24 Rc 300 x 1 21.1 1.0-m USNO
Mar 24.232 2.36 2.96 B 3000 x 1 23.0 1.0-m USNO
Mar 24.240 2.55 3.15 V 1200 x 1 22.4 1.0-m USNO
Mar 24.259 3.00 3.30 H 600 x 4 19.0 1.55-m USNO
Mar 24.332 4.76 5.90 Rc 1478 x 4 19.2 0.6-m MO(1)
Mar 24.345 5.06 5.06 B 600 x 1 22.0 1.0-m USNO
Mar 24.349 5.16 6.22 i* 1200 x 4 23.8 - 3.5-m ARC
+ 2400 x 1 24.3(2)
Mar 24.353 5.26 6.49 V 2400 x 1 22.7 1.0-m USNO
Mar 24.358 5.37 6.64 Rc 2400 x 1 22.3 1.0-m USNO
Mar 24.362 5.48 6.60 Ic 2400 x 1 21.6 1.0-m USNO
Mar 24.364 5.52 5.94 H 900 x 4 19.3 1.55-m USNO
Mar 24.389 6.11 6.71 Ic 4200 x 1 16.7(3) 0.2-m PST(4)
Mar 26.477 56.22 56.74 Ic 3600 x 1 21.9(5) 1.0-m USNO
(1) Morehead Observatory telescope
(2) Mosaic pattern results in a limiting magnitude that is 23.8 on the
sides and 24.3 in the center
(3) 5-sigma limiting magnitude
(4) Pisgah Survey Telescope at the Pisgah Astronomical Research Institute
(PARI)
(5) Central 11.3' x 11.3'
Using the image subtraction routine ISIS2 (Alard 2000), we find no
transient sources between any of our same-filter images to limiting
magnitudes of B = 22.0, V = 22.4, Rc = 21.1, Ic = 20.2, and H = 19.0
between 2.1 and 3.3 hours after the burst. Furthermore, we find no
transient sources between our ARC images and SDSS images of this field
taken in March 1999 to a limiting magnitude of i* = 22.2 at 6.2 hours after
the burst.
To these limiting magnitudes, GRB 030324 appears to be a dark burst, not
only at optical wavelengths, but interestingly also at NIR wavelengths.
Alard, C. 2000, A&AS, 114, 363
- GCN notice #2139
D. Q. Lamb, M. Nysewander, D. Reichart, D. G. York, J. Barentine, R.
McMillan, J. Dembicky, and B. Ketzeback report on behalf of the ARC
and UNC GRB teams of the FUN GRB collaboration:
We observed the 14 arcminute diameter HETE-2 WXM localization error
circle for GRB030324 (Donaghy et al., GCN 1954, 1955) in i* on the
night of March 24 UT, beginning 6.22 hours after the burst (Moran, GCN
2037). We also observed the WXM localization error circle in i* on the
night of April 5 UT, approximately 12 days after the burst. On both
nights, we took two 1200-second exposures centered at the origin of the
WXM error circle and a mosaic of four overlapping 1200-second exposures
covering the entire WXM error circle. The limiting magnitude of the
first observation thus ranged from i* = 24.3 (3 sigma) at the center of
the WXM error circle to i* = 23.8 (3 sigma) at the edge of the mosaic.
Similarly, the limiting magnitude of the second observation ranged from
i* = 24.0 (3 sigma) at the center of the WXM error circle to 23.5 (3
sigma) at the edge of the mosaic.
Subtraction of the two images, using the image subtraction routine
ISIS2 (Alard 2000), reveals a single candidate optical afterglow at
RA = +13h 37m 04.418s, Dec = -00d 15' 33.56" (J2000).
The candidate optical afterglow is i* = 23.4 +/- 0.2 (S/N = 4.3) in the
first epoch image, using the calibration of Henden (GCN 1860), whereas
no object is detected at the same location down to a limiting magnitude
of i* = 23.9 (2 sigma) in the second epoch image. The first and second
epoch images, with the location of the candidate optical afterglow
circled, can be found at
http://astro.uchicago.edu/candidate_optical_afterglow.jpg,
and a sky map showing the HETE-2 WXM localization error circle and the
location of the candidate optical afterglow can be found at
http://astro.uchicago.edu/wxm_loc_and_candidate.gif.
We cannot rule out that the candidate is a variable star. However, a
typical cataclysmic variable or an RR Lyrae variable would have to be
~ 0.5 Mpc away and a typical Cepheid variable would have to be ~2 Mpc
away to be as faint as i* = 23.4. In either case, the object can not
be associated with the Milky Way galaxy, making the likelihood very
small that the object that we have detected is a variable star.
If this object is indeed the optical afterglow of GRB030324, it would
be the faintest optical afterglow ever detected.
Alard, C. 2000, A&AS, 114, 363
- GCN notice #2140
D. Q. Lamb, M. Nysewander, D. Reichart, D. G. York, J. Barentine, R.
McMillan, J. Dembicky, and B. Ketzeback report on behalf of the ARC
and UNC GRB teams of the FUN GRB collaboration:
The coordinates we report for the candidate optical afterglow are in
the FK5 system and are uncertain to +/- 0.6 arcseconds.
The URLs at which the first and second epoch images and the sky map
can be found should read,
http://astro.uchicago.edu/home/web/lamb/candidate_optical_afterglow.jpg
and
http://astro.uchicago.edu/home/web/lamb/wxm_loc_and_candidate.gif.
- GCN notice #2177
E. Berger (Caltech) and D. A. Frail (NRAO) report on behalf of a larger
collaboration:
"We observed the error circle of GRB 030324 (GCN 1954) with the VLA on
2003, April 19.10 UT at 8.46 GHz. With the exception of a source at
(J2000) RA=13:36:59.3, DEC=-00:17:25.1 which is visible in a FIRST survey
image (http://sundog.stsci.edu/top.html), there are no sources within the
error circle down to a 3-sigma limit of 0.18 mJy. In particular, we do
not detect a radio source at the position of the putative optical
afterglow suggested by Lamb et al. (GCN 2139) down to the same limit."
This message may be cited.
- GCN notice #2239
D. Q. Lamb, M. Nysewander, D. Reichart, D. G. York, R. McMillan, J.
Barentine, J. Dembicky, and B. Ketzeback report on behalf of the ARC
and UNC GRB teams of the FUN GRB collaboration:
Using a larger sample of standard stars from Henden (GCN 1950), we
measure the magnitude of the candidate optical afterglow (Lamb et al.
GCNs 2139, 2140) of GRB030324 (Donaghy et al., GCN 1954, 1955) on the
night of March 24 UT to be i* = 23.48 +/- 0.21 (S/N = 4.3).
On May 3 UT, we obtained a further five 600-second i* images of the
field of the candidate optical afterglow. We find no object at the
location of the candidate optical afterglow down to the limiting
magnitude of the stacked image, which is i* = 25.1 (2 sigma). We also
find no object at the location of the candidate optical afterglow down
to the limiting magnitude of the stacked image constructed by combining
the 1200-second i* image obtained on April 5 UT (Lamb et al. GCNs 2139,
2140) and the five 600-second i* images obtained on May 3 UT, which is
i* = 25.3 (2 sigma).
This further rules out the possibility that the star-like object we
detected on the night of March 24 UT is a variable star and places a
limit on the brightness of the host galaxy of GRB030324 of i* > 25.3
(2 sigma), if the object is the optical afterglow of GRB030324.
- GCN notice #2601
M. C. Nysewander, P. A. Price, D. E. Reichart, and D. Q. Lamb report on
behalf of the Follow-Up Network for Gamma-Ray Bursts (FUN GRB)
Collaboration:
On April 15, 2004, we observed the location of the candidate afterglow
(Lamb et al., GCNs 2139, 2140, 2239) of GRB 030324 (Donaghy et al., GCNs
1954, 1955) with the LRIS instrument on the Keck I telescope in
simultaneous imaging mode in G and R filters. We obtained stacked images
of 2130 sec in G and 1805 sec in R (cut short due to instrument error)
under conditions of moderate humidity and seeing.
Using the standard transformation equations of Smith et al. (2002) and the
field calibration of Henden (GCN 1950), we calibrated the stacked images
using the six unsaturated stars in our field. A source is present at the
location of the candidate afterglow in both stacked images, with magnitudes
g' = 25.29 +/- 0.09 mag and R = 25.16 +/- 0.24 mag.
First, we rule out the possibility of a variable star. Fitting a blackbody
+ Galactic extinction curve model to these data, we find that log T > 3.75
at the 3 sigma level. This rules out flare stars (UV Cet variables), which
are cooler than log T = 3.5.
The fitted temperature is consistent with RR Lyraes and shorter period
Cepheids, but these classes of variables stars are also ruled out, for two
reasons:
1. RR Lyraes and Cepheids vary by less than 1.3 mag. However, Lamb et al.
(GCN 2239) measured a fading from i* = 23.48 +/- 0.21 mag to i* > 25.4 mag
(2 sigma upper limit; GCN 2239).
2. To be this faint, an RR Lyrae would have to be >0.5 Mpc away and a
Cepheid would have to be >3.5 Mpc away, placing either well outside of the
Galaxy.
Consequently, we conclude that we have detected the host galaxy of GRB
030324. Detection of the galaxy in the G band implies that its redshift is
<2.7. The spectral flux distribution of the galaxy is flat, which makes
this a relatively blue galaxy, even for a GRB host galaxy.
Images and the spectral flux distribution are available at
www.physics.unc.edu/~mnysewan/grb030324.html
Smith et al. 2002, ApJ, 123, 2121
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