GRB 130626A
GCN Circular 15004
Subject
GRB 130626A: Retraction of possible X-ray afterglow
Date
2013-07-12T13:59:31Z (13 years ago)
From
Kim Page at U.of Leicester <klp5@leicester.ac.uk>
K.L. Page (U. Leicester) and M. De Pasquale (UCL-MSSL) report on behalf of
the Swift-XRT team:
In GCN Circ. 14937, Page, Oates & De Pasquale reported the Swift detection
of a weak X-ray source within the BAT error circle of GRB 130626A.
Follow-up observations of this source, obtained between 5.8 x 10^5 and 1.3
x 10^6 s after the trigger, show it is still detected, at a level of (1.3
+/- 0.3) x 10^-3 count s^-1, compared to the initial detection of (2.0
+0.5/-0.4) x 10^-3 count s^-1 (errors at the 1-sigma confidence level).
Since the source has not faded significantly over this long time span, we
do not believe it to be the X-ray afterglow of GRB 130626A.
The 90% upper limit for any other source within the BAT error circle is 8
x 10^-4 count s^-1, corresponding to a flux of 3 x 10^-14 erg cm^-2 s^-1,
assuming a typical counts-to-observed-flux conversion factor of 4 x 10^-11
erg cm^-2 count^-1.
This circular is an official product of the Swift-XRT team.
GCN Circular 14944
Subject
GRB 130626A: KAIT Optical Observations
Date
2013-06-28T05:02:18Z (13 years ago)
From
Weikang Zheng at U.of Michigan <zwk@umich.edu>
WeiKang Zheng, Alexei V. Filippenko, Adam Morgan (UC Berkeley), and
S. B. Cenko (NASA/Goddard Space Flight Center) report on behalf of the
KAIT GRB team:
The 0.76-m Katzman Automatic Imaging Telescope (KAIT), located at
Lick Observatory, responded to the short-duration GRB 130626A
(De Pasquale et al., GCN 14931) starting at 10:52:40 UT, 97 s after
the burst. Observations were performed with an automatic sequence
in V, I, and clear filters (20 s exposure for each image). We detect
the DSS source mentioned by Butler et al. (GCN 14943) in the
corrected candidate XRT circle (Page et al., GCN 14937). We do not
detect any new source in the XRT error circle. The estimated limiting
magnitude in our first clear-band (close to R) image is about 18.7
(calibrated to USNO B1.0) at a midtime of 174 s after the burst.
GCN Circular 14943
Subject
GRB 130626A: RATIR Optical Observations
Date
2013-06-27T21:36:50Z (13 years ago)
From
Nat Butler at Az State U <natbutler@asu.edu>
Nat Butler (ASU), Alan M. Watson (UNAM), Alexander Kutyrev (GSFC), William
H. Lee (UNAM), Michael G. Richer (UNAM), Chris Klein (UCB), Ori Fox (UCB)
J. Xavier Prochaska (UCSC), Josh Bloom (UCB), Antonino Cucchiara (UCSC),
Eleonora Troja (GSFC), Owen Littlejohns (ASU), Enrico Ramirez-Ruiz (UCSC),
Jos� A. de Diego (UNAM), Leonid Georgiev (UNAM), Jes�s Gonz�lez (UNAM),
Carlos Rom�n-Z��iga (UNAM), Neil Gehrels (GSFC), and Harvey Moseley (GSFC)
report:
We observed the field of the short-duration GRB 130626A (De Pasquale, et
al., GCN 14931) with the Reionization and Transients Infrared Camera
(RATIR; www.ratir.org) on the 1.5m Harold Johnson Telescope at the
Observatorio Astron�mico Nacional on Sierra San Pedro M�rtir beginning 200
seconds after the BAT trigger, obtaining simultaneous 80 second exposures
in the r' and i' bands.
We note that there is DSS source at the center of the corrected candidate
Swift-XRT error circle (Page, et al., GCN 14937). In comparison with 2MASS
and the RATIR zero points, we measure for this source:
r' 18.69 +/- 0.07
i' 17.40 +/- 0.05
No uncatalogued sources are detected within the XRT error circle. We
derive the following 3-sigma limits:
r' > 20.8
i' > 20.5
These magnitudes are in the AB system and not corrected for Galactic
extinction in the direction of the GRB.
We thank the staff of the Observatorio Astron�mico Nacional in San
Pedro M�rtir.
GCN Circular 14942
Subject
GRB 130626A, Swift-BAT refined analysis
Date
2013-06-27T20:18:56Z (13 years ago)
From
Amy Lien at GSFC <amy.y.lien@nasa.gov>
T. Sakamoto (AGU), S. D. Barthelmy (GSFC), W. H. Baumgartner (GSFC/UMBC),
J. R. Cummings (GSFC/UMBC), M. De Pasquale (UCL-MSSL), E. E. Fenimore (LANL),
N. Gehrels (GSFC), H. A. Krimm (GSFC/USRA), A. Y. Lien (NASA/GSFC/ORAU),
C. B. Markwardt (GSFC), D. M. Palmer (LANL), G. Sato (ISAS),
M. Stamatikos (OSU), J. Tueller (GSFC), T. N. Ukwatta (MSU)
(i.e. the Swift-BAT team):
Using the data set from T-119 to T+243 sec from the recent telemetry downlink,
we report further analysis of BAT GRB 130626A (trigger #559075)
(De Pasquale, et al., GCN Circ. 14931). The BAT ground-calculated position is
RA, Dec = 273.128, -9.525 deg which is
RA(J2000) = 18h 12m 30.6s
Dec(J2000) = -09d 31' 29.9"
with an uncertainty of 1.8 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 100%.
The mask-weighted light curve shows a double short-peaked structure at T~ 0 sec.
The second peak is slightly weaker than the first peak, and starts immediately
at the end of the first peak. Each peak lasts ~ 0.08 sec.
T90 (15-350 keV) is 0.16 +- 0.03 sec (estimated error including systematics).
The time-averaged spectrum from T-0.0 to T+0.2 sec is best fit by a power law
with an exponential cutoff. This fit gives a photon index -0.53 +- 1.39,
and Epeak of 74.5 +- 25.6 keV (chi squared 54.40 for 56 d.o.f.). For this
model the total fluence in the 15-150 keV band is 5.2 +- 0.8 x 10^-08 erg/cm2
and the 1-sec peak flux measured from T-0.41 sec in the 15-150 keV band is
0.9 +- 0.2 ph/cm2/sec. A fit to a simple power law gives a photon index
of 1.30 +- 0.21 (chi squared 62.40 for 57 d.o.f.). All the quoted errors
are at the 90% confidence level.
The results of the batgrbproduct analysis are available at
http://gcn.gsfc.nasa.gov/notices_s/559075/BA/
GCN Circular 14937
Subject
GRB 130626A: Swift-XRT possible detection and UVOT upper limits
Date
2013-06-27T13:31:45Z (13 years ago)
From
Kim Page at U.of Leicester <klp5@leicester.ac.uk>
K.L. Page (U. Leicester), S.R. Oates (UCL-MSSL) and M. De Pasquale
(UCL-MSSL) report on behalf of the Swift-XRT and UVOT teams:
We have analysed 9.5 ks of Swift-XRT Photon Counting mode data collected
for GRB 130626A, starting 111 s after the trigger (De Pasquale et al., GCN
Circ. 14931). Of these data, only 10s were collected promptly following
the trigger before Swift had to slew away because of a pointing
constraint.
Within the onboard BAT error circle, there is a possible source detected,
with a count rate (averaged between 111 s and 34.7 ks after the trigger)
of (2.0 +0.5/-0.4) x 10^-3 count s^-1. The position of this source is RA,
Dec = 273.14043, -9.50093, which is equivalent to:
RA (J2000): 18h 12m 33.70s
Dec (J2000): -09d 30' 03.3"
with an uncertainty of 5.5 arcsec (radius, 90% confidence). It is not
possible to determine whether this candidate source is fading at present;
a follow-up observation will be performed at a later date.
We do note, however, that there are other possible sources detected at a
similar level in the XRT field of view, although outside the BAT error
circle.
The Swift-UVOT began settled observations of the field of GRB 130626A
67 s after the BAT trigger (De Pasquale et al., GCN Circ. 14931).
In the initial UVOT exposures, no optical afterglow is found within
the BAT error circle or consistent with the candidate XRT position.
Preliminary 3-sigma upper limits using the UVOT photometric system
(Breeveld et al. 2011, AIP Conf. Proc. 1358, 373) for the initial
exposures are:
Filter T_start(s) T_stop(s) Exp(s) Mag
white (FC) 67 124 57 >20.5
white 67 5608 597 >22.0
v 4384 5892 269 >19.8
b 3768 5403 393 >21.1
u 3563 5198 393 >20.7
w1 4794 4993 197 >20.1
The magnitudes in the table are not corrected for the heavy, but
uncertain, Galactic extinction due to the reddening of E(B-V) = 1.45 in
the direction of the burst (Schlegel et al. 1998).
This circular is an official product of the Swift-XRT and UVOT teams.
GCN Circular 14931
Subject
GRB 130626A: Swift detection of a short burst
Date
2013-06-26T11:08:40Z (13 years ago)
From
Scott Barthelmy at NASA/GSFC <scott@milkyway.gsfc.nasa.gov>
M. De Pasquale (UCL-MSSL), S. D. Barthelmy (GSFC),
D. N. Burrows (PSU), J. R. Cummings (NASA/UMBC), V. D'Elia (ASDC),
A. Y. Lien (NASA/GSFC/ORAU), C. B. Markwardt (NASA/GSFC),
F. E. Marshall (NASA/GSFC), S. R. Oates (UCL-MSSL) and
K. L. Page (U Leicester) report on behalf of the Swift Team:
At 10:51:03 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 130626A (trigger=559075). Swift slewed immediately to the burst.
The BAT on-board calculated location is
RA, Dec 273.130, -9.531 which is
RA(J2000) = 18h 12m 31s
Dec(J2000) = -09d 31' 50"
with an uncertainty of 3 arcmin (radius, 90% containment, including
systematic uncertainty). The BAT light curve shows a single spike
with a duration of about 0.2 sec. The peak count rate
was ~5000 counts/sec (15-350 keV), at ~0.0 sec after the trigger.
The XRT began observing the field at 10:52:02.1 UT, 58.6 seconds after
the BAT trigger, but centroided on a cosmic ray. Because of the short
on-target time, we do not have enough data to identify an afterglow.
UVOT took a finding chart exposure of 57 seconds with the White filter
starting 67 seconds after the BAT trigger. No credible afterglow candidate has
been found in the initial data products. The 2.7'x2.7' sub-image covers none of
the BAT error circle. The 8'x8' region for the list of sources
generated on-board covers 100% of the BAT error circle. No correction has
been made for the large, but uncertain extinction expected.
Burst Advocate for this burst is M. De Pasquale (m.depasquale AT ucl.ac.uk).
Please contact the BA by email if you require additional information
regarding Swift followup of this burst. In extremely urgent cases, after
trying the Burst Advocate, you can contact the Swift PI by phone (see
Swift TOO web site for information: http://www.swift.psu.edu/too.html.)