- GCN Circular #16763
J. R. Cummings (NASA/UMBC), D. N. Burrows (PSU),
P. A. Evans (U Leicester), N. Gehrels (NASA/GSFC), J. A. Kennea (PSU),
N. P. M. Kuin (UCL-MSSL), K. L. Page (U Leicester) and
D. M. Palmer (LANL) report on behalf of the Swift Team:
At 15:00:30 UT, BAT triggered on a possible GRB at
RA, dec = 238.036, +27.578 (J2000).
However, due to a TDRSS telemetry gap, no further
data is available at this time.
No XRT source was detected in 90 s of downlinked data taken approximately 1.5ks
after the trigger time. We are waiting for the full dataset to detect and localise
the XRT counterpart.
No UVOT data is available at this time.
The full data set will be available following the next ground pass.
Burst Advocate for this burst is J. R. Cummings (jayc AT milkyway.gsfc.nasa.gov).
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.)
- GCN Circular #16764
J. A. Kennea (PSU) and J. R. Cummings (NASA/UMBC) report on behalf of the
Swift/XRT Team:
Swift/XRT began observing the position of GRB 140903A at 15:01:29UT,
approximately 59 seconds after the BAT trigger (GCN #16763). In
preliminary data we find an uncatalogued fading source at the following
location: RA/Dec(J2000) = 238.01597, 27.603287, which is equivalent to:
RA(J2000) = 15h 52m 3.83s,
Dec(J2000) = 27d 36m 11.8s,
with an estimated uncertainty of 10 arc-seconds radius (90% confidence).
The light-curve appears to show rapid fading, consistent with this X-ray
source being a GRB afterglow. We will publish an improved position for
this burst when more data become available.
- GCN Circular #16765
J. R. Cummings (NASA/UMBC) reports on behalf of the Swift Team:
At 15:00:30 UT, BAT triggered on GRB 140903A. The onboard BAT localization
was at RA, dec = 238.036, +27.578, which is
RA (J2000) 15h 52m 08.6s
Dec (J2000) +27d 34' 41"
with an estimated 90% uncertainty radius of 3 arcmin.
The BAT lightcurve shows a single peak about 0.45 seconds long.
- GCN NOTICE
TITLE: GCN/SWIFT NOTICE
NOTICE_DATE: Wed 03 Sep 14 18:08:39 UT
NOTICE_TYPE: Swift-XRT Position
TRIGGER_NUM: 611599, Seg_Num: 0
GRB_RA: 238.0159d {+15h 52m 03.81s} (J2000),
238.1677d {+15h 52m 40.24s} (current),
237.4989d {+15h 50m 00.26s} (1950)
GRB_DEC: +27.6033d {+27d 36' 11.8"} (J2000),
+27.5601d {+27d 33' 36.4"} (current),
+27.7518d {+27d 45' 06.5"} (1950)
GRB_ERROR: 10.0 [arcsec radius, statistical plus systematic, 90% containment]
GRB_INTEN: 1.00e-10 [erg/cm2/sec]
GRB_SIGNIF: 5.00 [sigma]
IMG_START_DATE: 16903 TJD; 246 DOY; 14/09/03
IMG_START_TIME: 54089.00 SOD {15:01:29.00} UT, 29235.0 [sec] since BAT Trigger Time
TAM[0-3]: 327.61 237.19 261.35 242.66
AMPLIFIER: 2
WAVEFORM: 134
SUN_POSTN: 162.62d {+10h 50m 28s} +7.38d {+07d 22' 43"}
SUN_DIST: 73.81 [deg] Sun_angle= -5.0 [hr] (East of Sun)
MOON_POSTN: 267.50d {+17h 50m 00s} -18.55d {-18d 33' 15"}
MOON_DIST: 54.16 [deg]
MOON_ILLUM: 64 [%]
GAL_COORDS: 44.40, 50.12 [deg] galactic lon,lat of the burst
ECL_COORDS: 227.11, 46.39 [deg] ecliptic lon,lat of the burst
COMMENTS: SWIFT-XRT Coordinates.
COMMENTS: This Notice was ground-generated -- not flight-generated.
COMMENTS: TAM values are not valid.
- GCN Circular #16766
Derek B. Fox (PSU) and J. R. Cummings (NASA/UMBC) report:
"The BAT (Cummings, GCN 16765) and XRT (Kennea & Cummings, GCN 16764)
localizations of GRB 140903A (Cummings et al., GCN 16763) are located
within 2.5' (<0.2 Mpc projected) of the center of the galaxy cluster
NSC J155202+273349, as cataloged by the Northern Optical Cluster
Survey (Gal et al. 2003, AJ, 125, 2064). While the photometric
redshift for the cluster is provided as z=0.2955 in the catalog, four
of the five SDSS-resolved galaxies nearest the XRT position have
spectroscopic redshifts (SDSS and 2MASX surveys, as retrieved from the
NASA Extragalactic Database) within the range z=0.074 +/- 0.001. In
particular, the two nearest galaxies with known redshifts are SDSS
J155208.34+273631.8 at z=0.073 (1.05' distance) and 2MASX
J15520787+2735016 at z=0.075 (1.47' distance).
Given past associations (and proposed associations) of short bursts
with evolved galaxies and galaxy clusters at z<~0.3 we consider the
presence of this coincident galaxy cluster at z~0.074 suggestive."
This research has made use of the NASA/IPAC Extragalactic Database
(NED) which is operated by the Jet Propulsion Laboratory, California
Institute of Technology, under contract with the National Aeronautics
and Space Administration.
- GCN Circular #16767
M. De Pasquale, A. Maselli (IASF-Palermo), J. R. Cummings (NASA/UMBC)
reports on behalf of the Swift-XRT team:
We have analysed 2.9 ks of XRT data for GRB 140903A (Cummings et al.
GCN Circ. 16763), from 74 s to 7.3 ks after the BAT trigger. The data
are entirely in Photon Counting (PC) mode. Using 3407 s of PC mode data
and 7 UVOT images, we find an enhanced XRT position (using the XRT-UVOT
alignment and matching UVOT field sources to the USNO-B1 catalogue):
RA, Dec = 238.01361, +27.60259 which is equivalent to:
RA (J2000): 15h 52m 03.27s
Dec(J2000): +27d 36' 09.3"
with an uncertainty of 1.7 arcsec (radius, 90% confidence).
The light curve can be modelled with a power-law decay with a decay
index of alpha=0.21 (+/-0.08).
A spectrum formed from the PC mode data can be fitted with an absorbed
power-law with a photon spectral index of 1.71 (+0.21, -0.20). The
best-fitting absorption column is 1.2 (+0.7, -0.6) x 10^21 cm^-2, in
excess of the Galactic value of 3.3 x 10^20 cm^-2 (Willingale et al.
2013). The counts to observed (unabsorbed) 0.3-10 keV flux conversion
factor deduced from this spectrum is 4.0 x 10^-11 (4.7 x 10^-11) erg
cm^-2 count^-1.
A summary of the PC-mode spectrum is thus:
Total column: 1.2 (+0.7, -0.6) x 10^21 cm^-2
Galactic foreground: 3.3 x 10^20 cm^-2
Excess significance: 2.5 sigma
Photon index: 1.71 (+0.21, -0.20)
If the light curve continues to decay with a power-law decay index of
0.21, the count rate at T+24 hours will be 0.11 count s^-1,
corresponding to an observed (unabsorbed) 0.3-10 keV flux of 4.5 x
10^-12 (5.3 x 10^-12) erg cm^-2 s^-1.
The results of the XRT-team automatic analysis are available at
http://www.swift.ac.uk/xrt_products/00611599.
This circular is an official product of the Swift-XRT team.
- GCN Circular #16768
D. M. Palmer (LANL), S. D. Barthelmy (GSFC), W. H. Baumgartner (GSFC/UMBC),
J. R. Cummings, N. Gehrels (GSFC), H. A. Krimm (GSFC/USRA),
A. Y. Lien (GSFC/UMBC), C. B. Markwardt (GSFC), T. Sakamoto (AGU),
M. Stamatikos (OSU), J. Tueller (GSFC), T. N. Ukwatta (LANL)
(i.e. the Swift-BAT team):
Using the data set from T-61 to T+159 sec from the recent telemetry downlink,
we report further analysis of BAT GRB 140903A (trigger #611599)
(Cummings, et al., GCN Circ. 16763). The BAT ground-calculated position is
RA, Dec = 238.021, 27.608 deg which is
RA(J2000) = 15h 52m 05.0s
Dec(J2000) = +27d 36' 27.6"
with an uncertainty of 1.0 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 83%.
The mask-weighted light curve shows a single FRED peak. T90 (15-350 keV) is
0.30 +- 0.03 sec (estimated error including systematics).
The time-averaged spectrum from T-0.01 to T+0.35 sec is best fit by a simple
power-law model. The power law index of the time-averaged spectrum is
1.99 +- 0.12. The fluence in the 15-150 keV band is 1.4 +- 0.1 x 10^-07 erg/cm2.
The 1-sec peak photon flux measured from T-0.33 sec in the 15-150 keV band
is 2.5 +- 0.2 ph/cm2/sec. All the quoted errors are at the 90% confidence
level.
This burst was short but we note that it was not particularly hard.
The results of the batgrbproduct analysis are available at
http://gcn.gsfc.nasa.gov/notices_s/611599/BA/
- GCN Circular #16769
J. Capone (UMD), V. Toy (UMD), S.B. Cenko (NASA-GSFC), A. Cucchiara
(NASA-GSFC), E. Troja (NASA-GSFC), A. Kutyrev (NASA-GSFC), S. Veilleux
(UMD), and S. Gezari (UMD) report on behalf of a larger collaboration:
We observed the field of GRB140903A (Cummings et al., GCN 16763) with the
Large Monolithic Imager (LMI) on the 4.3m Discovery Channel Telescope (DCT)
at Happy Jack, AZ. We observed in r' for a total of 600 seconds beginning
at 2014-09-04 03:10 UTC (approximately 12 hours after the Swift trigger).
A source is clearly detected at the location of the x-ray afterglow (De
Pasquale et al, GCN 16767). Using nearby point sources from SDSS for
calibration, we measure a preliminary magnitude of r' = 20.2 +/- 0.3. This
value is not corrected for Galactic extinction in the direction of the GRB.
We also note the presence of a 9th magnitude star ~10 arcseconds from the
afterglow candidate.
We thank the staff of the Discovery Channel Telescope for assistance with
these observations.
- GCN Circular #16770
S. B. Cenko (NASA/GSFC) and D. A. Perley (Caltech) report on behalf of a larger collaboration:
We observed the field of the Swift short GRB 140903A (Cummings et al., GCN 16763) with the robotic Palomar 60 inch telescope. Observations were obtained in the g', r', and i' filters beginning at 3:13 UT on 4 September 2014 (12.2 hr after the Swift trigger time).
We detect a faint source at the northern edge of the revised XRT error circle (De Pasquale et al., GCN 16767), with (J2000.0) coordinates
RA: 15:52:03.28 Dec: +27:36:10.7
and an estimated uncertainty of ~ 0.5" in each coordinate. Visual comparison reveals that this is the same source identified by Capone et al. in the Discovery Channel Telescope imaging reported in GCN 16769.
Using nearby point sources from SDSS for calibration, we estimate a magnitude of r' = 20.0 for the source at this time. We caution, however, that the photometry is strongly affected by the presence of the nearby bright star. We estimate an uncertainty of ~ 0.5 mag, but accurate photometry will need to await a more thorough analysis.
Since our observations overlap with those reported by Capone et al., we cannot confirm any variability in this object. Inspection of the archival SDSS images does not reveal an obvious source at this location, but the images are strongly affected by the nearby bright star, and thus the depth may be insufficient for a meaningful comparison. We encourage additional follow-up to determine if this is indeed the optical afterglow of GRB 140903A.
- GCN Circular #16771
T. Sakamoto (AGU), J. Norris (BSU), S. D. Barthelmy (GSFC),
N. Gehrels (GSFC) report:
We report the spectral lag analysis for GRB 140903A (GCN Circ. 16764 & 16765)
based on the BAT data. Using 4-ms binned light curve, the spectral lag for
the 50-100 keV to 100-350 keV bands is 16 +- 7 ms, and 21 +- 7 ms for the 15-25 keV
to 50-100 keV bands. There is no evidence for extended emission. Those lag values
are consistent with the short end of the long-burst lag distribution. Although the
lag analysis suggests GRB 140903A is consistent with a long GRB population, a further
observation is needed to understand the nature of this burst.
- GCN Circular #16772
A. A. Breeveld (UCL-MSSL) and J. R. Cummings (NASA/UMBC)
report on behalf of the Swift/UVOT team:
The Swift/UVOT began settled observations of the field of GRB 140903A 76
s after the BAT trigger (Cummings et al., GCN Circ. 16763).
No optical afterglow consistent with the XRT position (De Pasquale et
al. GCN Circ. 16767) or optical position given by Cenko et al. (GCN
Circ. 16770), is detected in the initial UVOT exposures. The analysis is
complicated by the wings of the bright star mentioned by Capone et al.
(GCN Circ. 16767), and thus the upper limits should be treated with caution.
Preliminary 3-sigma upper limits using the UVOT photometric system
(Breeveld et al. 2011, AIP Conf. Proc. 1358, 373) for the first finding
chart (FC) exposure and subsequent exposures are:
Filter T_start(s) T_stop(s) Exp(s) Mag
white_FC 77 227 147 >20.01
u_FC 289 539 246 >17.4
white 77 17449 944 >21.0
v 618 29425 1322 >18.9
b 544 17228 1376 >20.0
u 289 23404 1138 >18.2
w1 1097 22967 1121 >18.4
m2 643 6613 255 >18.8
w2 5562 28728 1918 >18.6
The magnitudes in the table are not corrected for the Galactic
extinction due to the reddening of E(B-V) = 0.03 in the direction of the
burst (Schlegel et al. 1998).
- GCN Circular #16774
A. Cucchiara (NASA-GSFC), S.B. Cenko (NASA-GSFC),
D. A. Perley (Caltech), J. Capone (UMD), and V. Toy (UMD)
report on behalf of a larger collaboration:
On September 4.20 UT we observe the candidate afterglow of the short GRB
140903A (Cummings et al. GCN 16763, Kennea et al. GCN 16764, Capone et al.
GCN 16769) with the Gemini-North telescope equipped with the GMOS camera.
A set of 2x600s exposures were obtained in spectroscopic mode: our spectra
covered the wavelength range 4000-8100 Angstroms at a resolution of R~1200.
We clearly identify a strong absorption doublet feature at the observed wavelength
7954, 7965 Angstrom and a weak emission line at 6570 Angstrom.
We tentatively interpret these features as NaID in absorption and H-beta line
in emission at the common redshift of z=0.351.
No other clear features are visible neither in emission nor in absorption,
therefore we suggest this to be the redshift of the host galaxy of GRB 140903A.
We thank the Gemini staff, in particular Jess Ball, for their prompt
assistance with these observations.
- GCN Circular #16776
A.S. Fruchter reports:
The field of GRB 140903A was observed on numerous occasions in multiple filters by the Pan STARRS survey. An object is visible at the location reported by Cenko et al. (GCN 16770) in the r, i, z and y filter stacks. The proximity of the object to a bright star makes accurate photometry extremely difficult. However, in the i and z bands, where the object is most clearly visible against the scattered light from the nearby star, I estimate magnitudes of 20.0 +/- 0.2 in both filters. This agrees well with that reported by Cenko et al in the r band., suggesting that this source is stable.
- GCN Circular #16777
W. Fong (U. Arizona) reports:
"We observed the position of the short-duration GRB 140903A (Cummings et
al., GCN 16763; GCN 16765) with the Karl G. Jansky Very Large Array (VLA)
beginning on 2014 Sept 4.040 UT (9.70 hr post-burst) at a mean frequency of
6 GHz. In 1 hour of observations, we detect a ~0.11 mJy radio source at the
position:
RA(J2000) = 15:52:03.21
Dec(J2000) = +27:36:10.7
with an uncertainty of 0.3" in each coordinate. This position is coincident
with the reported optical source (Capone et al., GCN 16769; Cenko et al.,
GCN 16770; Cucchiara et al., 16774; Fruchter, GCN 16776).
Further observations are planned. We thank the VLA staff for quickly
executing these observations."
- GCN Circular #16778
M. Serino (RIKEN), T. Sakamoto (AGU), N. Kawai (Tokyo Tech),
S. Ueno, H. Tomida, S. Nakahira, M. Kimura, M. Ishikawa, Y. E. Nakagawa (JAXA),
T. Mihara, M. Sugizaki, M. Morii, J. Sugimoto, T. Takagi, A. Yoshikawa, M. Matsuoka (RIKEN),
T. Yoshii, Y. Tachibana (Tokyo Tech),
A. Yoshida, Y. Kawakubo, H. Ohtsuki (AGU),
H. Tsunemi, D. Uchida (Osaka U.),
H. Negoro, M. Nakajima, K. Fukushima, T. Onodera, K. Suzuki, T. Namba, M. Fujita, F. Honda (Nihon U.),
Y. Ueda, M. Shidatsu, T. Kawamuro, T. Hori (Kyoto U.),
Y. Tsuboi, A. Kawagoe (Chuo U.),
M. Yamauchi, Y. Morooka, D. Itoh (Miyazaki U.),
K. Yamaoka (Nagoya U.)
report on behalf of the MAXI team:
The MAXI/GSC scanned the field of GRB 140903A
triggered by Swift BAT (Cumming et al. GCN Circ. 16763)
at 15:00:42 (12 sec after the trigger) UT on 2014-09-03.
The durations of the scan was 44 sec.
No obvious source was detected by MAXI/GSC at the location of BAT.
The 3 sigma upper limit of the scan derived by the MAXI/GSC data is
8.4 x 10^-10 erg/cm2/s (4-10 keV).
This upper limit is roughly consistent with the power-law
interpolation of the BAT prompt emission flux (T ~ 0-0.3 s) and
the first XRT point (t ~ 100 s), assuming that the BAT spectrum
(power-law with photon index 1.99, Palmer et al. GCN Circ. 16768)
extends down to soft X-ray emission with no spectral break.
It suggests that no strong soft extended emission was associated
with this GRB (Sakamoto et al. GCN Circ. 16771).
- GCN Circular #16779
A. Pozanenko (IKI), A. Volnova (IKI), N. Polyakov (ISON), E. Romas (ISON), I. Molotov (KIAM), report on behalf of larger collaboration:
We observed the field of GRB 140903A (Cummings et al., GCN 16763) with Santel-400AN telescope of ISON-Kislovodsk observatory starting on Sep. 03 (UT) 18:54:36. In the enhanced XRT position (De Pasquale et al., GCN 16767) we do not detect the object (Capone et al., GCN 16769; Cenko et al., GCN 16770; Fruchter, GCN 16776). A preliminary upper limit after subtraction of the nearby bright star is 16m. A formal upper limit of a point-like source in the image away of the bright nearby star is following
Date UT start t-T0 Filter Exp. UL(3 sigma)
(mid, days) (s)
2014-09-03 18:22:05 0.14057 None 100 18.6
The photometry is based on SDSS stars
SDSS J155213.13+273321.7 R_Lupton 15.392 ± 0.013
SDSS J155218.31+273433.5 R_Lupton 14.792 ± 0.013
SDSS J155155,39+273948,9 R_Lupton 15.421 ± 0.013
- GCN Circular #16781
S. Dichiara, C. Guidorzi (U. Ferrara), J. Japelj (U. Ljubljana)
on behalf of a large collaboration report:
The 2-m telescope Faulkes Telescope North in Hawaii began observing
Swift GRB 140903A (Cummings et al. GCN Circ 16763) on September 04
at 06:35:20 UT, i.e. ~15.6 hours after the BAT trigger, with
the r' and i' filters.
We detect the optical source reported by Capone et al. (GCN 16769),
Cenko et al. (GCN 16770), Fruchter (GCN 16776) within an estimated
magnitude of r'=20.4 +- 0.5.
Given the measured values and relatively large uncertainties,
nothing can be inferred on the possible fading.
- GCN Circular #16783
D. Xu (DARK/NBI), S. Geier (NOT), D. Malesani, J. P. U. Fynbo
(DARK/NBI), J. Harmanen (NOT), A. J. Levan (U. Warwick), P. Jakobsson
(U. Iceland) report on behalf of a large collaboration:
We observed the field of the short GRB 140903A (Cummings et al., GCN
16763) using the 2.5m Nordic Optical Telescope (NOT) equipped with
StanCam and NOTCam. We observed for a total of 20 and 30 min in the R-
and H- bands, respectively. The middle times of the observations are
29.898 hr and 30.315 hr after the BAT trigger, respectively.
The previously reported object (Capone et al., GCN 16769; Cenko et
al., GCN 16770; Fruchter, GCN 16776; Dichiara et al., GCN 16781) is
clearly detected in our R- and H-band stacked images. We found
R=20.1+/-0.5 mag calibrated with nearby SDSS stars and H=16.1+/-0.3
mag calibrated with the nearby 2MASS stars.
Note that a fuzzy source is present at the same position in the SDSS
field, especially in z-band. Together with the pre- and post-burst
observations, the optical brightness of the object either varies
slowly or remains constant (see also Fruchter, GCN 16776), which
implies that what we're observing in optical is basically the host
galaxy of the burst.
- GCN Circular #16784
A.J. Levan (U. Warwick), S.B. Cenko, A. Cucchiara (NASA-GSFC), D.A. Perley (Caltech) report for a larger collaboration:
"We observed the location of the short GRB 140903A (Cummings et al. GCN 16763, 16765) with Gemini-N beginning at 5 Sep 2014, 05:16 UT. At this epoch we obtained observations in iJ and K utilising GMOS-N and NIRI. The source reported by Capone et al. (GCN 16769) and Cenko et al. (GCN 1677) is well detected in all bands.
A comparison between these images and the acquisition images taken on 4 Sept 2014 (Cucchiaria et al. GCN 16774) is indicative of a fading by 0.12 +/- 0.04 mag. An image subtraction shows a residual consistent with this fading, although both photometry and image subtraction are complicated by the presence of the nearby bright star.
This decay is very slow in comparison to most GRB afterglows and implies a significant contribution from the underlying host galaxy, consistent with its pre-trigger detection (Fruchter GCN 16776, Xu et al. GCN 16783). We note that the source remains largely point like in our observation, and the centroid of the subtraction residual is offset only ~0.1" from the centre of the combined host+afterglow source."
- GCN Circular #16785
S. B. Cenko (NASA-GSFC), J. Capone, V. Toy (UMD), A. Cucchiara, E. Troja, A. Kutyrev (NASA-GSFC), S. Veilleux, and S. Gezari (UMD) report on behalf of a larger collaboration:
We obtained additional r'-band imaging of the candidate optical afterglow (Capone et al., GCN 16769) of the Swift short burst GRB 140903A (Cummings et al., GCN 16763) with the Discovery Channel Telescope, beginning at 2:55 UT on 6 September 2014 (2.5 d after the Swift trigger). Performing digital image subtraction using our most recent epoch as a template, we detect significant fading in this source, confirming the results of Levan et al. (GCN 16784). Assuming no afterglow contamination in our latest epoch, we measure an afterglow brightness of r' = 21.7 at the time of our first DCT images (~ 12 hr after the Swift trigger). This suggests the early emission was heavily contaminated by the host galaxy, consistent with the results of Fruchter et al. (GCN 16776) and Xu et al. (16783). A figure showing our subtraction image can be found at:
http://asd.gsfc.nasa.gov/Brad.Cenko/grb140903A_dct.pdf
The detection of optical variability, together with a coincident radio detection (Fong, GCN 16777), confirm the host association of z = 0.351 for GRB 140903A (Cucchiara et al., 16774). We encourage additional follow-up (e.g., super/kilonova searches) to help clarify the nature of the progenitor system of this event.
- GCN Circular #16813
T. Sakamoto (AGU), E. Troja (GSFC/UMCP), N. Gehrels (GSFC),
J. Norris (BSU), S. D. Barthelmy (GSFC), J. L. Racusin (GSFC),
N. Kawai (Tokyo Tech), A. Fruchter (STScI)
A Chandra ToO observation of a short GRB 140903A (Cummings et al., GCN Circ. 16763;
Cummings et al., GCN Circ. 16765) started on September 6 08:54 UT (~2.7 days after the
GRB trigger) for a total of 19.8 ksec. The X-ray afterglow was clearly detected at
a position (RA, Dec) = (238.013519, +27.60303) which is equivalent to:
RA (J2000) = 15 52 03.24
Dec (J2000) = +27 36 10.9
The 1-sigma statistical error is 0.05 and 0.04 arcsec on RA and Dec respectively.
The systematic error of the Chandra aspect solution is 0.3 arcsec (radius, 68%
containment; i.e, http://cxc.harvard.edu/cal/ASPECT/celmon/) which dominates
the localization uncertainty.
The Chandra location is consistent with the enhanced XRT position (De Pasquale et al.,
GCN Circ. 16767) and the reported NIR, optical and radio afterglow/host candidate
(Capone et al., GCN Circ. 16769; Cenko et al., GCN Circ. 16785; Cenko et al.,
GCN Circ. 16770; Fruchter et al., GCN Circ. 16776; Fong, GCN Circ. 16777;
Dichiara et al., GCN Circ. 16781; Xu et al. GCN Circ. 16783; Levan et al. GCN Circ. 16784).
Our Chandra detection confirms the association of the reported NIR, optical and radio
candidate to GRB 140903A. Further Chandra observations are planned.
We would like to thank the Chandra operation team for rapidly approving and making
this observation.
- GCN Circular #16815
A. J. Nayana (NCRA-TIFR) and Poonam Chandra (NCRA-TIFR) report:
We carried out the Giant Metrewave Radio Telescope (GMRT) observations of
GRB 1400903A (Cummings et al. GCN 16763) in the 1390 MHz band on 2014
September 11.05 UT. We detect a 3.1-sigma source at the GRB position
(Cenko et al.
16770) with a flux density of 102+/-33 uJy. This is most likely the
radio afterglow of
GRB 140903A. We are carrying out further observations to confirm this
detection.
We thank GMRT staff for making these observations possible.
- 1605.03573 from 13 May 16
E. Troja et al.: An achromatic break in the afterglow of the short GRB 140903A: evidence for a narrow jet
We report the results of our observing campaign on GRB140903A, a nearby (z=0.351) short duration (T90~0.3 s) gamma-ray burst discovered by
Swift. We monitored the X-ray afterglow with Chandra up to 21 days after the burst, and detected a steeper decay of the X-ray flux after
approximately 1 day. Continued monitoring at optical and radio wavelengths showed a similar decay in flux at nearly the same time, and we
interpret it as evidence of a narrowly collimated jet. By using the standard fireball model to describe the afterglow evolution, we derive a
jet opening angle of 5 deg and a collimation-corrected total energy release of 2E50 erg. We further discuss the nature of the GRB progenitor
system. Three main lines disfavor a massive star progenitor: the properties of the prompt gamma-ray emission, the age and low star-formation
rate of the host galaxy, and the lack of a bright supernova. We conclude that this event was likely originated by a compact binary merger.
- Redshift z= 0.3529 +- 0.0002 from host galaxy emission (Halpha, [OIII])
W.-F. Fong et al. 2022, ApJ 940, 56
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