GRB 070412
GCN Circular 6488
Subject
GRB 070412: TAROT Calern observatory optical observations
Date
2007-06-08T05:52:32Z (19 years ago)
From
Alain Klotz at CESR-CNRS <Alain.Klotz@free.fr>
Klotz, A. (CESR-OMP), Boer M. (OHP), Atteia J.L. (LATT-OMP) report:
We imaged the field of GRB 070412 detected by SWIFT
(trigger 275119) with the TAROT robotic telescope (D=25cm)
located at the Calern observatory, France.
Analysis of this burst is late due to a technichal
problem.
The observations started 676.6s after the GRB trigger
(4.4s after the notice). The elevation of the field decreased from
from 53 degrees above horizon and weather conditions
were very good.
The date of trigger : t0 = 2007-04-12T01:27:03.744
The first image is 90.0s exposure in tracking mode:
We do not detect any OT in the XRT location
(Romano et al. 2007 GCNC 6273)
with a limiting magnitude of:
t0+676.6s to t0+766.6s : R > 18.5
We co-added a series of exposures:
t0+676.6s to t0+1251.3s : R > 19.5
Magnitudes were estimated with the nearby USNO-B1 stars
and are not corrected for galactic dust extinction.
This message may be cited.
GCN Circular 6465
Subject
GRB 070412: Deep Keck imaging
Date
2007-05-28T00:31:03Z (19 years ago)
From
Daniel Perley at U.C. Berkeley <dperley@astro.berkeley.edu>
D. A. Perley, J. S. Bloom, R. J. Foley, and D. Kocevski (UC Berkeley)
report:
On the night of 2007-04-16 (UT) we performed imaging on the field of
GRB070412 (GCN 6273), the long burst located approximately 45" in
projection from a nearby early-type galaxy (GCN 6275), using Keck I
(/LRIS) under poor seeing conditions. We acquired a total of 113
minutes of usable exposure time in I-band and 132 minutes in V-band,
with a mid-exposure time of approximately 11:27 UT, 106 hours after the
BAT trigger.
Using the astrometrically-corrected XRT position [1] (RA=12:06:10.18,
dec=+40:08:35.3, uncertainty=2.2"), we observe a faint source at the
edge of the uncertainty region in I-band. This source is not detected
in V-band. Calibrating with respect to nearby stars from SDSS, we
calculate a magnitude of:
I = 24.6 +/- 0.3
The V-band limiting magnitude is V > 26.5.
We note that the same source is also apparent in LBT r' imaging from
Prieto et al. (GCN 6374) in both their epochs of observation (2.8 hours
and 8.2 days after the burst), suggesting the source is not transient,
in which case we place an I-band limiting magnitude of I > 25.0 on any
transient source in the XRT error circle. The red color is suggestive
of a high-redshift potential host galaxy. The LBT r' detection would
place a firm upper limit on the redshift to be z < 5.9.
Images of the field are located at:
http://lyra.berkeley.edu/~dperley/070412/070412keck.png
http://lyra.berkeley.edu/~dperley/070412/070412keckzoom.png
The low-redshift galaxy has been subtracted using a Sersic model fit in
the first image and a median filter in the second (zoom) image.
[1] http://astro.berkeley.edu/~nat/swift/xrt_pos.html
GCN Circular 6382
Subject
GRB070412: MAGIC telescope GeV observation
Date
2007-05-07T17:05:18Z (19 years ago)
From
Markus Garczarczyk at MPI/MAGIC <garcz@mppmu.mpg.de>
Galante N., Garczarczyk M., Gaug M., Scapin V., Bastieri D. and Longo F.
report for the MAGIC collaboration:
The MAGIC Imaging Atmospheric Cherenkov Telescope performed a follow-up
observation of the SWIFT-BAT burst GRB070412 (GCN circular 6273, Romano P.
et al.). We received the delayed GCN alert at T0+647s, The data taking
with MAGIC started at T0+701s, 27s after the alert income. We observed the
sky positon for 124min on April 12th and for further 178min on April 13th,
starting at T0+7.6x10^4s.
No evidence for VHE gamma-ray emission above the analysis threshold of
90 GeV was found in both data sets. A preliminary analysis, for the
hypothesis of steady emission and assumption of a differential photon
spectral index of -2.5, yields the following 95% CL differential flux
upper limits (inc. 30% systematic error on the absolute flux level):
E(80-125 GeV) : 1.03 x 10^(-11) erg/cm^2/s
E(125-175 GeV) : 0.31 x 10^(-11) erg/cm^2/s
E(175-300 GeV) : 0.75 x 10^(-11) erg/cm^2/s
E(300-1000 GeV) : 0.77 x 10^(-11) erg/cm^2/s
The upper limits correspond to the time period between T0+701s and
T0+8181s.
We can also exclude emission of a constant flux during our observation in
any 100s time bin higher than:
E(80-200 GeV) : 2.2 x 10^(-9) erg/cm^2/s
E(200-1000 GeV) : 0.5 x 10^(-9) erg/cm^2/s
for the time period between T0+701s and T0+8181s, and:
E(80-200 GeV) : 2.5 x 10^(-9) erg/cm^2/s
E(200-1000 GeV) : 0.5 x 10^(-9) erg/cm^2/s
for the time period between T0+7.6x10^4 s and T0+8.7x10^4 s.
This message can be cited.
GCN Circular 6374
Subject
GRB 070412, deep LBT imaging
Date
2007-05-04T23:39:44Z (19 years ago)
From
Peter Garnavich at U of Notre Dame <pgarnavi@nd.edu>
J. Prieto (Ohio State), P. Garnavich (Notre Dame), J. Hill (LBTO/UAz),
X. Fan, J. Harris, J. Bechtold (U Ariz), X. Dai, P. Martini,
K. Z. Stanek (Ohio State), R. M. Wagner (LBTO/OSU),
J. Rhoads (Ariz State), E. Pian (INAF) report:
The Large Binocular Telescope (LBT) imaged the position of the GRB 070412
afterglow (Romano et al, GCN 6273; Romano et al. GCN 6282) with the
LBC-blue CCD camera (http//lbc.mporzio.astro.it) and 8.4-m SX mirror on
2007 April 12.18 (UT) and again on April 20.31 (UT). These are 2.8 hours
and 8.2 days after the burst respectively. On the first visit,
ten dithered, 200 second exposures were obtained
with the Sloan-r filter in 1.7" seeing while on the second visit, five
exposures were obtained in 1.0" seeing.
Image matching, PSF correction and subtraction of the two images shows
no variable sources within 30" of the corrected XRT position
(Romano et al. GCN 6282). We place a 3-sigma upper-limit on any
optical afterglow at R>25.2 around 2.8 hours post-burst.
No new source is detected in our second epoch image
(also see Rol et al. GCN 6353) and we place a similar detection
upper-limit as our April 12 image. If the burst is associated
with the bright elliptical galaxy near the XRT position (Ofek &
Berger GCN 6275), then we find any supernova or other GRB progenitor
would have an absolute magnitude fainter than -11 mag eight days
after the burst.
A comparison of the two images after unsharp masking to
reduce the elliptical galaxy light variations can be found at:
http://www.nd.edu/~pgarnavi/grb070412/grb070412_LBT.jpg
The LBT is an international collaboration among institutions in the
United States, Italy and Germany. The LBT Corporation partners are:
* The University of Arizona on behalf of the Arizona university system
* Istituto Nazionale di Astrofisica, Italy
* LBT Beteiligungsgesellschaft, Germany, representing the Max Planck
Society, the Astrophysical Institute Potsdam, and Heidelberg University
* The Ohio State University
* The Research Corporation, on behalf of The University of Notre Dame,
University of Minnesota and University of Virginia
This message may be cited
GCN Circular 6353
Subject
LT monitoring of GRB070412
Date
2007-04-27T11:54:45Z (19 years ago)
From
Evert Rol at U.Leicester <er45@star.le.ac.uk>
E. Rol, N. Tanvir (U. of Leicester), R. Smith (Liverpool JMU), report
for a larger collaboration:
We have observed the field of GRB070412 (Romano, GCN Circ. 6273) in r'
and i' bands with the 2m Liverpool Telescope at several epochs. At the
position of the X-ray afterglow (Romano, GCN Circ. 6282), we do not
detect any new sources. Our photometry is calibrated relative to the
SDSS (Adelman-McCarthy et al., 2007 ApJS in press), and our limiting
magnitudes at the observed epochs are as follows:
UT start days post T0 exptime filter lim. mag
(2007) (mid-epoch) (sec) (5-sigma)
04-12T03:13:03 0.077 600 r' 22.5
04-12T04:07:56 0.115 600 i' 21.9
04-12T04:31:59 0.132 600 r' 22.4
04-12T21:33:59 0.849 1800 r' 22.6
04-13T01:48:36 1.026 1350 i' 21.6
04-13T03:32:13 1.098 1800 r' 23.4
04-13T04:06:36 1.122 900 i' 20.7
04-15T01:11:04 3.000 1800 r' 23.7
04-15T01:50:38 3.012 1800 i' 23.2
04-25T21:34:13 13.85 1800 r' 22.3 *
04-25T22:08:19 13.87 1800 i' 22.2 *
* observations are affected by contamination from the nearby moon
Since the upper limits indicate no apparent supernova at the X-ray
position, the GRB position is either a chance coincidence with the
nearby bright galaxy (CGCG 215-024; see also Ofek, GCN Circ. 6275), or
belongs to the newly suggested class of long-duration GRBs that show
no associated supernovae (Fynbo et al. 2006, Nature 444, 1047; Della
Valle et al. 2006, Nature 444, 1050; Gal-Yam et al. 2006, Nature 444,
1053). For comparison, the expected magnitudes at 13.9 days for a
SN1998bw-like supernova at the redshift of the galaxy (z=0.0307), are
r' = 17.3 and i' = 17.6.
GCN Circular 6294
Subject
GRB070412: UKIRT-WFCAM JHK upper limits
Date
2007-04-12T21:46:49Z (20 years ago)
From
Evert Rol at U.Leicester <er45@star.le.ac.uk>
E. Rol, N. Tanvir (U. of Leicester), A. Levan (U. of Warwick), L. Fuhrman
(JAC), report for a larger collaboration:
We observed the field of GRB070412 between 4.3 and 5.4 hours after the GRB
trigger (Romano et al., GCNC 6273). At the position of the X-ray
afterglow (Romano et al., GCNC 6282), we detect no source. We place the
following 5-sigma limiting magnitudes at this position:
J 20.7
H 20.1
K 19.8
The magnitudes are calibrated with respect to the 2MASS catalogue.
GCN Circular 6293
Subject
GRB070412: Swift UVOT observations
Date
2007-04-12T18:03:03Z (20 years ago)
From
Patricia Schady at MSSL/Swift <ps@mssl.ucl.ac.uk>
P. Schady (MSSL/PSU) and P.Romano (Univ. Bicocca & INAF-OAB) report on
behalf of the Swift UVOT team:
Swift/UVOT observed the field of GRB 070412 starting 97.6s after the
BAT trigger. No new source is detected within the XRT refined position
(GCN 6282) or at the position reported by Jelinek et al. (GCN 6279) and
Berger et al. (GCN 6280) in any of the UVOT filters, in either single
or co-added exposures. The 3-sigma upper limits for the co-added
exposures in each filter are as follows:
Filter T_mid Exp. Mag 3-sig UL
(s) (s)
White 9252 936 20.55
V 17432 1769 20.52
B 5763 171 20.22
U 23567 1082 21.12
UVW1 23107 1284 20.52
UVM2 19141 1082 20.65
UVW2 14440 1195 20.94
where T_mid is the weighted mid time of the co-added images. The
reported upper limits are uncorrected for the estimated Galactic
reddening of E(B-V) = 0.02 mag.
GCN Circular 6290
Subject
GRB 070412, Swift-BAT refined analysis
Date
2007-04-12T13:39:26Z (20 years ago)
From
Hans Krimm at NASA-GSFC <krimm@milkyway.gsfc.nasa.gov>
T. Sakamoto (GSFC/ORAU), L. Barbier (GSFC), S. D. Barthelmy (GSFC),
J. Cummings (GSFC/UMBC), E. Fenimore (LANL), N. Gehrels (GSFC),
H. Krimm (GSFC/USRA), C. Markwardt (GSFC/UMD), D. Palmer (LANL),
A. Parsons (GSFC), P. Romano (Univ. Bicocca & INAF-OAB),
G. Sato (GSFC/ISAS), M. Stamatikos (GSFC/ORAU), J. Tueller (GSFC)
on behalf of the Swift-BAT team:
Using the data set from T-239.3 to T+962.8 sec from the recent telemetry
downlink, we report further analysis of BAT GRB 070412
(trigger #275119) (Romano, et al., GCN Circ. 6273). The BAT
ground-calculated position is RA, Dec = 181.525, 40.133 deg which is
RA(J2000) = 12h 06m 6.1s
Dec(J2000) = 40d 07' 57.0"
with an uncertainty of 1.5 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 98%.
The mask-weighted light curve shows a double-peaked structure
with the first peak from approximately T-4 sec to T+10 sec and
a second 2-sec long peak at T+30 sec. T90 (15-350 keV) is
34 +- 2 sec (estimated error including systematics). The spacecraft
slewed away from the burst location at T+122 sec, although the burst
remained in the partially coded field of view until T+716 sec,
when the spacecraft slewed away again.
The time-averaged spectrum from T-4.1 to T+31.2 is best fit by
a simple power-law model. The power law index of the time-averaged
spectrum is 1.45 +- 0.20. The fluence in the 15-150 keV band is
4.8 +- 0.7 x 10^-7 erg/cm2. The 1-sec peak photon flux measured
from T+5.32 sec in the 15-150 keV band is 0.7 +- 0.1 ph/cm2/sec.
All the quoted errors are at the 90% confidence level.
GCN Circular 6289
Subject
GRB 070412 Liverpool Telescope optical limit
Date
2007-04-12T13:17:35Z (20 years ago)
From
Andreja Gomboc at LT,ARI,Liverpool JMU <ag@astro.livjm.ac.uk>
A. Gomboc (Univ. of Ljubljana, Slovenia), A. Melandri, R.J. Smith, C.
Guidorzi, M. Burgdorf, C.G. Mundell, I.A. Steele, D. Carter, A.
Monfardini, C.J. Mottram, S. Kobayashi, D. Bersier (Liverpool JMU) report:
The 2-m Liverpool Telescope started observing the field of GRB 070412
(Romano et al. GCN 6273) at 14.1 min after the trigger time.
At the revised XRT position (Romano et al. GCN 6282 and GCN 6287) we do
not detect any new object in stacked images down to:
Filter t_mid (min from GRB) Tot_Exp (s) Lim
------------------------------------------------------------------
r' 35.8 720 22.0
i' 41.4 720 21.3
------------------------------------------------------------------
Magnitudes were calibrated vs the USNOB1 catalogue.
GCN Circular 6287
Subject
GRB 070412: Swift-XRT refined analysis
Date
2007-04-12T12:50:16Z (20 years ago)
From
Pat Romano at OAB-Swift <patrizia.romano@brera.inaf.it>
P. Romano (Univ. Bicocca & INAF-OAB), A. Moretti (INAF-OAB),
C. Guidorzi (Univ. Bicocca & INAF-OAB) report on behalf of the Swift Team:
We have analysed the first 4 orbits of XRT data from GRB 070412
(trigger=275119; Romano et al., GCN Circ. 6273), which include
40s in WT and 2.4ks in PC mode.
The refined XRT position is RA,Dec=181.5426 +40.1438:
RA(J2000) =12h 06m 10.2s
Dec(J2000) =+40d 08' 37.8"
with an uncertainty of 4 arcsec (90% containment, see GCN Circ. 6282).
The 0.3-10 keV X-ray light curve can be fit with a simple power-law
with a decay slope of 0.98+/-0.05, although the initial descent could
be due to a flare or the tail of the prompt emission (slope of ~-3.5).
The X-ray spectrum from the XRT/WT data (40s starting from T+67.8) can be fit by an
absorbed power-law with a photon index
of 2.2+/-0.5 and column density of (1.8-0.9+1.1)E21 cm**-2, higher than the Galactic
column density in the direction of the source
(1.95E20 cm**-2). The unabsorbed (absorbed) 0.3-10 keV flux for this spectrum is
3.3E-10 (2.2E-10) erg/cm**2/s.
The XRT/PC data (2.4ks starting from T+3386) can be fit by an absorbed power-law with a
photon index of 2.3-0.5+0.6 and column density of (2.5-1.2+1.4)E21 cm**-2, consistently
with the WT data.
The unabsorbed (absorbed) 0.3-10 keV flux for this
spectrum is 6.1E-12 (3.3E-12) erg/cm**2/s.
Assuming the X-ray emission continues to decline at the same rate, we predict a 0.3-10
keV XRT count rate of 5.6E-3 count/s at T+24hr, which corresponds to an observed 0.3-10
keV flux of 2.8E-13 erg/cm**2/s.
This circular is an official product of the Swift XRT Team.
GCN Circular 6285
Subject
GRB 070412: further reanalysis of NOT images
Date
2007-04-12T10:57:47Z (20 years ago)
From
Daniele Malesani at Niels Bohr Inst,Dark Cosmology Center <malesani@astro.ku.dk>
Daniele Malesani (DARK/NBI) and Helena Uthas (NOT) report:
Following the revision of XRT error circle position (Romano et al., GCN
6282) of GRB 070412 (Romano et al., GCN 6723), we further inspected our
NOT R- and I-band images (Malesani & Uthas, GCNs 6276, 6281).
No objects are detected down to the same limits presented in GCN 6281.
GCN Circular 6284
Subject
GRB 070412: Optical observations at Crni Vrh
Date
2007-04-12T09:40:32Z (20 years ago)
From
Herman Mikuz at OCV <herman.mikuz@fmf.uni-lj.si>
H. Mikuz, J. Skvarc and B. Dintinjana on behalf of PIKA observing program at
Crni Vrh Observatory:
We observed a 42'x42' field centered on Swift position at ra=12:06:01
dec=+40:06:03 (J2000), using 60 cm Cichocki robotic telescope at Crni Vrh
Observatory, Slovenia. There is no obvious source down to R magnitude
20.7 +/-0.1 inside the error box 3x3 arc minutes on 90 s R filter
exposure, starting at 2007 Apr. 12 01:39:03 UT (46 seconds after reception
of the alert) and 5 subsequent images of the same duration. Magnitudes
were calibrated against the USNO-B1 catalogue. In particular we also do
not observe any source to this limiting magnitude at the coordinates
reported by NOT (Malesani and Uthars, GCN 6276) or Jelinek et al. (GCN
6279).
GCN Circular 6282
Subject
GRB 070412: Swift-XRT refined position
Date
2007-04-12T09:21:24Z (20 years ago)
From
Pat Romano at OAB-Swift <patrizia.romano@brera.inaf.it>
P. Romano, C. Guidorzi (Univ. Bicocca & INAF-OAB),
A. Moretti (INAF-OAB), P.A.Evans (LU)
report on behalf of the Swift Team:
We have analysed the first 4 orbits of XRT data from GRB 070412
(Romano et al., GCN Circ. 6273).
A 2.4ks photon counting mode image provides a refined XRT position RA,Dec=181.5426
+40.1438 :
RA(J2000) =12h 06m 10.22s
Dec(J2000) =+40d 08' 37.8"
with an uncertainty of 4 arcsec (90% containment). This is 10.5 arcsec away from the
initial XRT position quoted in GCN Circ. 6273 (Romano et al.). Based on these new
coordinates, the position of the NOT candidate (Malesani et al., GCN Circ.6276), the
IAC80 optical candidate (M. Jelinek et al., GCN Circ. 6279), as well as the position of
the i-band candidate afterglow (Berger et al., GCN Circ 6280), are all outside our
error circle.
This circular is an official product of the Swift XRT Team.
GCN Circular 6281
Subject
GRB 070412: further NOT observations
Date
2007-04-12T09:01:56Z (20 years ago)
From
Daniele Malesani at Niels Bohr Inst,Dark Cosmology Center <malesani@astro.ku.dk>
Daniele Malesani (DARK/NBI) and Helene Uthas (NOT) report on behalf of a
larger collaboration:
We observed again the field of GRB 070412 (Romano et al., GCN 6273) with
the NOT. Observations were carried out at two epochs, ~0.9 and ~3.5 hr
after the GRB. R- and I-band images were secured at each epoch.
Inside the XRT error circle, we do not detect the sources reported by
Jelinek et al. (GCN 6279) and Berger (GCN 6280). The 3-sigma limiting
magnitudes are:
t-t0 I limit R limit
--------------------------
0.9 hr 22.9 24.0
3.5 hr 23.1 24.2
These numbers were computed assuming R = 17.38 and I = 17.17 for the USNO
star at RA = 12:06:02.17, Dec = +40:09:01.4. We note that the magnitude
reported by Berger (GCN 6280) is fainter than our limits. Our early
measurement implies a decay shallower than ~t^-0.7.
The object reported by Malesani & Uthas (GCN 6276) is detected only in the
first R-band image, thus leaving open the possibility that this source was
fading. However, we caution about the low significance of this detection.
GCN Circular 6280
Subject
GRB 070412: Gemini/GMOS afterglow candidate
Date
2007-04-12T07:23:34Z (20 years ago)
From
Edo Berger at Carnegie Obs <eberger@ociw.edu>
E. Begrer (Carnegie) reports on behalf of a larger collaboration:
"We observed the XRT error circle of GRB 070412 (GCN 6273) with GMOS on
the Gemini-north telescope for a total of 360 sec in i-band starting on
2007 Apr 12.229 UT (4 hr after the burst). Within the XRT error circle we
find a single faint object with i=23.9+/-0.2 mag (using the zeropoint on
the GMOS website) located at:
RA = 12:06:10.585
DEC = +40:08:24.83 (J2000)
with an uncertainty of about 0.2". This position is 3.2" away from the
center of the XRT error circle (GCN 6273) and 2.1" away from the I-band
source discussed in GCN 6279. The non-detection of an object at this
position in the R-band to a limit of 24 mag at t=1 hr (GCN 6276) indicates
that this object (if it is the afterglow) is red, with R-I ~ 1.6 mag for a
fading rate of t^-1."
GCN Circular 6279
Subject
GRB 070412: IAC80 optical afterglow candidate
Date
2007-04-12T04:58:25Z (20 years ago)
From
Martin Jelinek at Inst.Astrophys.Andalucia,Granada <mates@iaa.es>
M. Jelinek (IAA-CSIC, Granada). J. A. Caballero (MPIA
Heidelberg), A. de la Nuez (IAC La Laguna) and A. J.
Castro-Tirado (IAA-CSIC), on behalf of larger colaboration.
report:
"We have observed the field of GRB070412 (Romano et al. GCNC
6273) with the IAC80 telescope at Observatorio del Teide in I
filter, starting at 03:02 UT, i.e. 1.6 h after the trigger.
Inspection of a 30 minute combined image shows a faint
(4-sigma) source at
12:06:10.416,+40:08:24.12 +-0.5" (J2000)
with the I-band brightness 21.5+-0.5. The object is not
consistent with the candidate of Malesani et al. (GCN 6276).
The identification map is at
http://www.iaa.es/~mates/grb070412id.jpg.
Further observations are needed to confirm the transient
nature of this object.
GCN Circular 6276
Subject
GRB 070412: NOT observations
Date
2007-04-12T02:55:03Z (20 years ago)
From
Daniele Malesani at Niels Bohr Inst,Dark Cosmology Center <malesani@astro.ku.dk>
D. Malesani (DARK/NBI) and H. Uthars (NOT) report:
We observed the field of GRB 070412 (Romano et al., GCN 6273) using the
NOT + ALFOSC in the R and i bands. Inside the XRT error circle, we detect
a source at the detection limit (R = 24 +- 0.3) at the following
coordinates:
alpha = 12:06:10.83
delta = 40:08:27.8
The source is only detected in the (deeper) R-band frame. No other source
is deteted inside the XRT error circle fown to R~24.1. The observation was
carried out 56 min after the trigger.
Given the large size of the error box (5.6"), we cannot assess whether
this source is associated to the GRB. We note however the lack of bright
objects inside the XRT circle.
Further observations are underway.
GCN Circular 6275
Subject
GRB 070412: Nearby bright galaxy
Date
2007-04-12T02:30:59Z (20 years ago)
From
Edo Berger at Carnegie Obs <eberger@ociw.edu>
E. O. Ofek (Caltech) and E. Berger (Carnegie) reports on behalf of a larger
collaboration:
The XRT error circle of GRB 070412 (Romano et al. 2007; GCN 6273),
coincides with the outskirts of a nearby (z=0.037) bright (r=13.6) galaxy
(CGCG 215-024).
The XRT position is 46.5" from the galaxy center (34 kpc projected).
The SDSS coordinates of the galaxy are:
RA = 12:06:07.818
DEC= +40:09:02.68 (J2000)
GCN Circular 6273
Subject
GRB 070412: Swift detection of a burst
Date
2007-04-12T01:58:32Z (20 years ago)
From
David Palmer at LANL <palmer@lanl.gov>
P. Romano (Univ. Bicocca & INAF-OAB), S. D. Barthelmy (GSFC),
D. N. Burrows (PSU), J. R. Cummings (NASA/UMBC),
N. Gehrels (NASA/GSFC), S. T. Holland (CRESST/GSFC/USRA),
H. A. Krimm (GSFC/USRA), A. Moretti (INAF-OAB), C. Pagani (PSU),
D. M. Palmer (LANL), T. Sakamoto (NASA/ORAU),
M. Stamatikos (NASA/ORAU) and D. E. Vanden Berk (PSU) report on
behalf of the Swift Team:
At 01:27:03 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 070412 (trigger=275119). Swift slewed immediately to the burst.
The BAT on-board calculated location is
RA, Dec 181.505, +40.101 which is
RA(J2000) = 12h 06m 01s
Dec(J2000) = +40d 06' 03"
with an uncertainty of 3 arcmin (radius, 90% containment, including
systematic uncertainty). The BAT light curve showed a double-peaked
structure with peaks at approximately 5 and 30 seconds and a total
duration of about 40 sec. The peak count rate
was ~2400 counts/sec (15-350 keV), at ~5 sec after the trigger.
The XRT began observing the field at 01:28:04 UT, 61 seconds after the
BAT trigger. Analysis of XRT downlinked data found an X-ray source
located at RA, Dec 181.54, +40.141 which is
RA(J2000) = 12h 06m 10.5s
Dec(J2000) = 40d 08' 27.8"
with an uncertainty of 5.6 arcseconds (radius, 90% containment).
This location is 181 arcseconds from the BAT on-board position,
outside the BAT error circle. The initial flux in the 2.5s image
was 7.0e-10 erg/cm2/s (0.2-10 keV).
UVOT took a finding chart exposure of 54 seconds with the White (160-650 nm)
filter starting 70 seconds after the BAT trigger. No afterglow candidate has
been found in the initial data products. Image catalog data are not available
at this time. The 8'x8' region for the list of sources generated on-board
covers 100% of the XRT error circle. The list of sources is typically complete
to about 18 mag. No correction has been made for the extinction of E(B-V)=0.02.
The TDRSS transmissions were delayed by 11 minutes due to the trigger
occuring during a Malindi downlink.