| Summary table |
|---|
| Variable |
Value |
Source |
| T0 |
22:40:50 UTC |
Swift |
| ra |
194.3685° |
Swift |
| decl |
28.3850° |
Swift |
| pos_error |
2.20e-04° |
Swift |
| T90 |
17.42 s |
Swift |
| T90_start |
22:40:50 UTC |
Swift |
| fluence |
3.40e-07 erg/cm² |
Swift |
| redshift |
4.7000 |
Swift |
| T100 |
17.42 s |
|
| GBM_located |
False |
|
| mjd |
56775.945023148146 |
Swift |
| IPN table |
|---|
| GRB_name |
GRB140428A |
| ra |
194.3417° |
| decl |
28.3500° |
| pos_error |
5.00e-02° |
| redshift |
4.7000 |
| Swift table |
|---|
| GRB_name |
GRB140428A |
| t_trigger |
22:40:50 UTC |
| ra |
194.3685° |
| decl |
28.3850° |
| pos_error |
2.20e-04° |
| T90 |
17.42 s |
| fluence |
3.40e-07 erg/cm² |
| redshift |
4.7000 |
| GCN 16177 table |
|---|
| GRB_name |
GRB140428A |
| GCN_number |
16177 |
| Detection_method |
Swift Other |
| ra |
194.3420° |
| decl |
28.3570° |
| Circular_text |
TITLE: GCN CIRCULAR
NUMBER: 16177
SUBJECT: GRB 140428A: Swift Detection of a Possible Burst
DATE: 14/04/28 23:34:36 GMT
FROM: Scott Barthelmy at NASA/GSFC
D. Kocevski (NASA/GSFC/ORAU), S. D. Barthelmy (GSFC),
A. Y. Lien (NASA/GSFC/ORAU), D. Malesani (DARK/NBI),
C. B. Markwardt (NASA/GSFC) and D. M. Palmer (LANL) report on behalf
of the Swift Team:
At 22:40:50 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 140428A (trigger=597519). Swift slewed immediately to the burst.
The BAT on-board calculated location is
RA, Dec 194.342, +28.357, which is
RA(J2000) = 12h 57m 22s
Dec(J2000) = +28d 21' 26"
with an uncertainty of 3 arcmin (radius, 90% containment, including
systematic uncertainty). Most of the expected realtime products were
not available for this trigger so we have limited information. We
know that the trigger duration is 4 seconds and the image significance
is 9 sigma during that exposure. A light curve is not yet available.
We note that the position reported in TDRSS light curve notices are
incorrect. The position reported above is correct.
Because of outage in the TDRSS telemetry downlink,
all but one BAT light curve notice and all of the XRT notices
are missing. Only a pair of UVOT SourceList and Image notices were
received on the ground.
However, based on the strong detection in BAT, we believe that this is
most likely a real GRB. We will issue a Circular when the full dataset
is downlinked.
Burst Advocate for this burst is D. Kocevski (dankocevski AT gmail.com).
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 16178 table |
|---|
| GRB_name |
GRB140428A |
| GCN_number |
16178 |
| Detection_method |
Swift-XRT Other |
| ra |
194.3685° |
| decl |
28.3849° |
| Circular_text |
TITLE: GCN CIRCULAR
NUMBER: 16178
SUBJECT: GRB 140428A: Swift-XRT detection of a source
DATE: 14/04/29 05:13:35 GMT
FROM: Kim Page at U.of Leicester
K.L. Page (U. Leicester), D. Malesani (DARK/NBI) and D. Kocevski
(NASA/GSFC/ORAU) report on behalf of the Swift-XRT team:
We have analysed the initial downlinked Swift-XRT data for the possible
GRB 140428A (GCN Circ. 16177) and find a fading X-ray source within the
BAT field of view.
Using 1124 s of XRT Photon Counting mode data and 3 UVOT images, we find
an astrometrically corrected X-ray position (using the XRT-UVOT alignment
and matching UVOT field sources to the USNO-B1 catalogue): RA, Dec =
194.36852, 28.38490 which is equivalent to:
RA (J2000): 12h 57m 28.45s
Dec (J2000): +28d 23′ 05.7′′
with an uncertainty of 1.7 arcsec (radius, 90% confidence).
This position may be improved as more data are received. The latest
position can be viewed at http://www.swift.ac.uk/xrt_positions. Position
enhancement is described by Goad et al. (2007, A&A, 476, 1401) and Evans
et al. (2009, MNRAS, 397, 1177).
The light curve can be modelled with a power-law decay with a decay index
of alpha=0.92 (+0.11,-0.10).
We therefore confirm that Swift trigger number 597519 is, indeed, a real
GRB.
This circular is an official product of the Swift-XRT team.
|
| GCN 16179 table |
|---|
| GRB_name |
GRB140428A |
| GCN_number |
16179 |
| Detection_method |
Other |
| Circular_text |
TITLE: GCN CIRCULAR
NUMBER: 16179
SUBJECT: GRB 140428A: NOT observations
DATE: 14/04/29 05:39:59 GMT
FROM: Daniele Malesani at Dark Cosmology Centre, Niels Bohr Inst
D. Malesani (DARK/NBI), D. Xu (DARK/NBI), H. Dahle (Univ. Oslo), E. Soto
(CUA), report on behalf of the Nordic GRB collaboration:
We observed the field of GRB 140428A (Kocevski et al., GCN 16177) with
the NOT equipped with the ALFOSC imager. Observations started on 2014
Apr 29.223 UT (5.34 hr after the GRB) and consisted of 20 minutes in r
and 12 in z.
Within the X-ray error circle (Page et al., GCN 16178), we do not find
any object down to a depth r > 22.5 and z > 20.5 (all AB), calibrated to
the SDSS.
DM thanks Thomas Kruehler (ESO) for insightful discussion.
|
| GCN 16180 table |
|---|
| GRB_name |
GRB140428A |
| GCN_number |
16180 |
| Detection_method |
Optical |
| Circular_text |
TITLE: GCN CIRCULAR
NUMBER: 16180
SUBJECT: GRB 140428A: Keck detection of a red optical afterglow candidate
DATE: 14/04/29 07:23:15 GMT
FROM: Daniel Perley at Caltech
D. A. Perley (Caltech) reports:
I observed the position of GRB 140428A (Kocevski et al., GCN 16177; Page
et al., GCN 16178) using LRIS on the Keck I 10-meter telescope. A
single 150-second imaging exposure was acquired simultaneously in both g
and i filters. An faint source is well-detected inside the XRT error
circle in the i-band image at the following location (J2000):
RA = 12:57:28.392
dec = +28:23:06.28
However, the object is completely absent in g-band. Photometry relative
to SDSS gives magnitudes of:
g > 26.42
i = 23.55 +/- 0.07
at a time of 06:09:30 UT (2014-04-29), 7.478 hours after the GRB trigger.
If this corresponds to the afterglow of the GRB, the red color suggests
either a (moderately) high-redshift or dust-extinguished event. Further
observations are planned.
|
| GCN 16181 table |
|---|
| GRB_name |
GRB140428A |
| GCN_number |
16181 |
| Detection_method |
Other |
| Circular_text |
TITLE: GCN CIRCULAR
NUMBER: 16181
SUBJECT: GRB 140428A: Keck redshift estimate
DATE: 14/04/29 08:49:50 GMT
FROM: Daniel Perley at Caltech
D. A. Perley (Caltech) reports:
I re-observed the afterglow candidate of GRB 140428A in longslit mode
using LRIS on the Keck I 10m telescope. One 940-second exposure was
taken using the 400/8500 grating (red camera) and 600/4000 grism (blue
camera).
In a provisional reduction, the spectrum of the object shows a weak,
flat continuum between 7000 Angstroms and the red limit of the
wavelength range at approximately 10100 Angstroms. The flux sharply
drops to zero at 7000 angstroms, though there is faint flux detected in
some places slightly further to the blue. No trace is detected on the
blue camera.
If the drop at 7000 Angstroms is interpreted as a DLA and the onset of
the Lyman-alpha forest, this would indicate a redshift for this object
of approximately z=4.7.
|
| GCN 16182 table |
|---|
| GRB_name |
GRB140428A |
| GCN_number |
16182 |
| Detection_method |
Optical |
| Circular_text |
TITLE: GCN CIRCULAR
NUMBER: 16182
SUBJECT: GRB 140428A: 1.5m OSN I-band detection
DATE: 14/04/29 11:34:51 GMT
FROM: Javier Gorosabel at IAA-CSIC
F.J. Aceituno (OSN/IAA-CSIC), A.J. Castro-Tirado (IAA-CSIC/UMA), R.
Sanchez-Ramirez (IAA-CSIC), J. Gorosabel (IAA-CSIC/UPV-EHU), report on
behalf of a larger collaboration:
We observed the field of GRB 140428A (Kocevski et al., GCN 16177; Page
et al., GCN 16178) with the 1.5m OSN telescope at Observatorio de Sierra
Nevada. Three 300s images were acquired in the I-band starting on Apr 29,
00:09:39 UT (i.e. ~1.5 hours burst). A preliminary reduction clearly shows
the optical afterglow reported by Perley (GCNC 16180) with a Vega
magnitude of I~20.8. This magnitude must be taken with caution given the
likely presence of the Lyman-alpha break in the I-band filter pass-band.
|
| GCN 16186 table |
|---|
| GRB_name |
GRB140428A |
| GCN_number |
16186 |
| Detection_method |
Swift-BAT Det |
| ra |
194.3650° |
| decl |
28.3310° |
| Circular_text |
TITLE: GCN CIRCULAR
NUMBER: 16186
SUBJECT: GRB 140428A: Swift-BAT refined analysis
DATE: 14/04/29 19:57:28 GMT
FROM: Amy Lien at GSFC
H. A. Krimm (GSFC/USRA), S. D. Barthelmy (GSFC), W. H. Baumgartner (GSFC/UMBC),
J. R. Cummings (GSFC/UMBC), N. Gehrels (GSFC), D. Kocevski (NASA/GSFC/ORAU)
A. Y. Lien (NASA/UMBC), C. B. Markwardt (GSFC), D. M. Palmer (LANL),
T. Sakamoto (AGU), M. Stamatikos (OSU), J. Tueller (GSFC),
T. N. Ukwatta (MSU) (i.e. the Swift-BAT team):
Using the data set from T-240 to T+602 sec from the recent telemetry downlink,
we report further analysis of BAT GRB 140428A (trigger #597519)
(Kocevski et al., GCN Circ. 16177). The BAT ground-calculated position is
RA, Dec = 194.365, 28.331 deg which is
RA(J2000) = 12h 57m 27.5s
Dec(J2000) = +28d 19' 53.4"
with an uncertainty of 2.2 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 70%.
The mask-weighted light curve shows a multi-peaked structure starts
at ~T-14 s and ends at ~T+6 s. The structure contains two main peaks
at ~T-4 s and ~T+2 s. T90 (15-350 keV) is 17.42 +- 5.90 sec (estimated
error including systematics).
The time-averaged spectrum from T-14.19 to T+5.82 sec is best fit by a simple
power-law model. The power law index of the time-averaged spectrum is
1.54 +- 0.26. The fluence in the 15-150 keV band is 3.4 +- 0.6 x 10^-7 erg/cm2.
The 1-sec peak photon flux measured from T+1.30 sec in the 15-150 keV band
is 0.6 +- 0.2 ph/cm2/sec. 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/597519/BA/
|
| GCN 16187 table |
|---|
| GRB_name |
GRB140428A |
| GCN_number |
16187 |
| Detection_method |
Swift-UVOT Other |
| Circular_text |
TITLE: GCN CIRCULAR
NUMBER: 16187
SUBJECT: GRB 140428A: Swift/UVOT Upper Limits
DATE: 14/04/29 21:13:07 GMT
FROM: Frank Marshall at GSFC
F. E. Marshall (NASA/GSFC) and D. Kocevski (NASA/GSFC/ORAU)
report on behalf of the Swift/UVOT team:
The Swift/UVOT began settled observations of the field of GRB 140428A
104 s after the BAT trigger (Kocevski et al., GCN Circ. 16177).
No optical afterglow consistent with the optical position
(Perley, GCN_Circ. 16180) is detected in the initial UVOT exposures.
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 104 254 147 >21.2
v 5454 5653 197 >20.3
b 4838 5039 197 >21.4
u 264 271 7 >19.5
uw1 5864 6030 197 >20.5
The magnitudes in the table are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 0.009 in the direction of the burst
(Schlegel et al. 1998).
|
| GCN 16191 table |
|---|
| GRB_name |
GRB140428A |
| GCN_number |
16191 |
| Detection_method |
GROND |
| ra |
194.3683° |
| decl |
28.3851° |
| redshift |
4.8000 |
| Circular_text |
TITLE: GCN CIRCULAR
NUMBER: 16191
SUBJECT: GRB 140428A: GROND observations
DATE: 14/04/30 22:02:44 GMT
FROM: Karla Varela at MPE
F. Knust, K. Varela, J. Greiner (MPE Garching), and D. A. Kann
(TLS Tautenburg) report on behalf of the GROND team:
We observed the field of GRB 140428A (Swift trigger 597519; Kocevski et
al., GCN #16177) simultaneously in g'r'i'z'JHK with GROND (Greiner et al.
2008, PASP 120, 405) mounted at the 2.2 m MPG telescope at La Silla
Observatory (Chile).
Observations started at 00:43 UT on 2014-04-29, 2 hours after the GRB
trigger. They were performed at an average seeing of 1.4" and at an
average airmass of 1.9.
We found a single point source within the 1.7" Swift-XRT error circle
reported by Page et al. (GCN #16178) at
RA (J2000) = 12h 57m 28.39s
DEC (J2000) = +28d 23' 06.4"
with an uncertainty of 0.5" in each coordinate.
This source is consistent with the one reported by Perley (GCN #16180).
Based on the first 1133 s of total exposures in g'r'i'z' and 1920 s in
JHK, we estimate preliminary magnitudes (all in AB system) of
g' > 24.4 mag,
r' = 23.6 +/- 0.2 mag,
i' = 21.7 +/- 0.1 mag,
z' = 21.5 +/- 0.1 mag,
J > 19.7 mag,
H > 20.6 mag, and
K > 19.1mag.
From our data, fading can not be established. We note that our r'-band
magnitude is similar to that reported by Perley (GCN #16180) at a mid-time
of 7.5 hrs after the GRB.
The spectral energy distribution is best-fit by a straight power-law and
a sharp cut-off below
the i'-band which cannot be modelled with extinction alone. If this is the
GRB afterglow, the cut-off corresponds to a photometric redshift of z =
4.8 +-0.3, consistent with the Keck spectroscopy
as reported by Perley (GCN #16181).
Given magnitudes are calibrated against SDSS (griz) as well as 2MASS
(JHK) field stars and are not corrected for the expected Galactic
foreground extinction corresponding to a reddening of E_(B-V) = 0.01 mag
in the direction of the burst (Schlegel et al. 1998).
|
| GCN 16252 table |
|---|
| GRB_name |
GRB140428A |
| GCN_number |
16252 |
| Detection_method |
GROND |
| Circular_text |
TITLE: GCN CIRCULAR
NUMBER: 16252
SUBJECT: GRB 140428A: GROND afterglow confirmation
DATE: 14/05/12 21:05:18 GMT
FROM: Karla Varela at MPE
K. Varela, C. Delvaux, and J. Greiner (all MPE Garching) report on behalf of
the GROND team:
We re-observed the field of GRB 140428A (Swift trigger 597519; Kocevski et
al.,
GCN #16177) simultaneously in g'r'i'z'JHK with GROND (Greiner et al. 2008,
PASP 120, 405) mounted at the 2.2 m MPG telescope at La Silla Observatory
(Chile).
A second epoch obtained on May 6th at 02:01 UT, about 7 days after the
trigger,
shows that the source reported by Knust et al. (GCN # 16191) has clearly
faded.
We find z' > 23.3, suggesting that the source has faded by at least 1.9 mag,
and confirming that this was the afterglow of GRB 140428A.
|