GRB 150317A
GCN Circular 17592
Subject
GRB 150317A: Swift detection of a burst
Date
2015-03-17T05:17:11Z (10 years ago)
From
David Palmer at LANL <palmer@lanl.gov>
M. H. Siegel (PSU), S. D. Barthelmy (GSFC), M. M. Chester (PSU),
N. Gehrels (NASA/GSFC), H. A. Krimm (CRESST/GSFC/USRA),
A. Y. Lien (GSFC/UMBC), D. Malesani (DARK/NBI),
C. B. Markwardt (NASA/GSFC), F. E. Marshall (NASA/GSFC),
D. M. Palmer (LANL) and B. Sbarufatti (INAF-OAB/PSU) report on behalf
of the Swift Team:
At 04:22:42 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 150317A (trigger=635148). Swift slewed immediately to the burst.
The BAT on-board calculated location is
RA, Dec 138.935, +55.452, which is
RA(J2000) = 09h 15m 45s
Dec(J2000) = +55d 27' 08"
with an uncertainty of 3 arcmin (radius, 90% containment, including
systematic uncertainty). The BAT light curve shows three spikes
spaced about 10 seconds apart, with a total duration of about 35 sec.
The peak count rate was ~1700 counts/sec (15-350 keV), at ~0 sec
after the trigger.
The XRT began observing the field at 04:23:46.5 UT, 64.6 seconds after
the BAT trigger.
In a 25 s SPER image XRT detects 10 photons at
RA, DEC 138.9832, 55.4681 which is
RA(J2000) = 09h 15m 55.98s
Dec(J2000) = +55:28:05.23
with an uncertainty of 8.6 arcsec (radius, 90% containment). This position is 1.9
arcmin away from the BAT onboard position, within the BAT error circle.
We notice the presence of a bright star (R~11) at 11 arcseconds from the XRT
position. At this time we cannot exclude that emission from the star
may be affecting the XRT data.
UVOT took a finding chart exposure of 250 seconds with the U filter
starting 126 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 XRT error circle. The typical 3-sigma upper limit has been about 19.6 mag.
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 expected extinction corresponding to E(B-V) of
0.03.
Burst Advocate for this burst is M. H. Siegel (siegel AT swift.psu.edu).
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 17593
Subject
GRB 150317A: NOT optical observations
Date
2015-03-17T05:44:01Z (10 years ago)
From
Daniele Malesani at Dark Cosmology Centre, Niels Bohr Inst <malesani@dark-cosmology.dk>
D. Xu (DARK/NBI), D. Malesani (DARK/NBI), P. Blay (IAC, NOT), P.
Jakobsson (Univ. Iceland), report on behalf of a larger collaboration:
We observed the field of the Swift GRB 150317A (Siegel et al., GCN
17592) with the NOT equipped with the AlFOSC camera. A single 300-s
R-band exposure was secured, starting at 04:48 UT (25 min after the GRB).
No new sources are detected within the X-ray position reported by Siegel
et al. (GCN 17592), but we remark that in our image the bright glare
from the nearby R=11 USNO star 1454-0197654 covers part of the XRT error
circle. The limiting magnitude of our image is R ~ 21.5, but it is
considerably shallower in the regions contaminated by the star PSF.
It cannot be excluded at the present time that the X-ray source detected
by XRT is due to the USNO star. Visual inspection of the BAT error
circle also does not reveal any new object compared to archival DSS and
SDSS images, down to R = 21.5.
GCN Circular 17594
Subject
GRB 150317A: Enhanced Swift-XRT position
Date
2015-03-17T08:03:37Z (10 years ago)
From
Phil Evans at U of Leicester <pae9@leicester.ac.uk>
P.A. Evans and M.R. Goad (U. Leicester) report on behalf of the
Swift-XRT team:
Using 2091 s of XRT Photon Counting mode data and 2 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 = 138.98467, 55.46618 which is equivalent to:
RA (J2000): 09h 15m 56.32s
Dec (J2000): +55d 27' 58.2"
with an uncertainty of 2.2 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).
This circular is an official product of the Swift-XRT team.
GCN Circular 17595
Subject
GRB 150317A: RATIR Optical Afterglow Detection
Date
2015-03-17T14:41:50Z (10 years ago)
Edited On
2024-11-07T19:42:03Z (7 months ago)
From
Nat Butler at Az State U <natbutler@asu.edu>
Edited By
Vidushi Sharma at NASA GSFC/UMBC <vidushi.sharma@nasa.gov> on behalf of Leo P. Singer at NASA/GSFC <leo.p.singer@nasa.gov>
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
(ORAU/GSFC), Eleonora Troja (GSFC), Owen Littlejohns (ASU), Enrico
Ramirez-Ruiz (UCSC), José A. de Diego (UNAM), Leonid Georgiev (UNAM), Jesús
González (UNAM), Carlos Román-Zúñiga (UNAM), Neil Gehrels (GSFC), and
Harvey Moseley (GSFC) report:
We observed the field of GRB 150317A (Siegel, et al., GCN 17592) with the
Reionization and Transients Infrared Camera (RATIR; www.ratir.org) on the
1.5m Harold Johnson Telescope at the Observatorio Astronómico Nacional on
Sierra San Pedro Mártir from 2015/03 17.18 to 2015/03 17.43 UTC (3 minutes
to 5.9 hours after the BAT trigger), obtaining a total of 3 hours exposure
in the r, i, and z bands.
We find an uncatalogued source within the Swift-XRT error circle (Evans et
al., GCN 17594). In comparison with the SDSS DR9 and 2MASS, we obtain the
following detections and upper limit (3-sigma):
r 20.5 +/- 0.1
i 21.7 +/- 0.1
z > 20.8
These magnitudes are in the AB system and are not corrected for Galactic
extinction in the direction of the GRB. This photometry is preliminary and
can be expected to improve with a more detailed analysis due to the
proximity of a bright star (e.g., Xu, et al., GCN 17593).
We thank the staff of the Observatorio Astronómico Nacional in San Pedro
Mártir.
GCN Circular 17596
Subject
GRB 150317A: Swift-BAT refined analysis
Date
2015-03-17T20:52:03Z (10 years ago)
From
Hans Krimm at NASA-GSFC <hans.a.krimm@nasa.gov>
H. A. Krimm (GSFC/USRA), S. D. Barthelmy (GSFC), W. H. Baumgartner (GSFC/UMBC),
J. R. Cummings (GSFC/UMBC), N. Gehrels (GSFC), A. Y. Lien (GSFC/UMBC),
C. B. Markwardt (GSFC), D. M. Palmer (LANL), T. Sakamoto (AGU),
M. H. Siegel (PSU), M. Stamatikos (OSU), T. N. Ukwatta (LANL)
(i.e. the Swift-BAT team):
Using the data set from T-236 to T+963 sec from the recent telemetry downlink,
we report further analysis of BAT GRB 150317A (trigger #635148)
(Siegel, et al., GCN Circ. 17592). The BAT ground-calculated position is
RA, Dec = 138.995, 55.477 deg which is
RA(J2000) = 09h 15m 58.8s
Dec(J2000) = +55d 28' 38.7"
with an uncertainty of 1.7 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 78%.
The mask-weighted light curve shows three separate peaks, each of duration ~5
seconds, with maxima at T+0, T+12 and T+23 seconds. T90 (15-350 keV) is 23.29 +-
0.85 sec (estimated error including systematics).
The time-averaged spectrum from T-0.44 to T+24.00 sec is best fit by a simple
power-law model. The power law index of the time-averaged spectrum is
1.52 +- 0.16. The fluence in the 15-150 keV band is 6.5 +- 0.6 x 10^-7 erg/cm2.
The 1-sec peak photon flux measured from T-0.15 sec in the 15-150 keV band
is 1.2 +- 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/635148/BA/
GCN Circular 17597
Subject
GRB 150317A: Swift-XRT refined Analysis
Date
2015-03-17T21:12:25Z (10 years ago)
From
Boris Sbarufatti at INAF-OAB/IASFPA <boris.sbarufatti@brera.inaf.it>
A.P. Beardmore (U. Leicester), A. Amaral-Rogers (U. Leicester), M. de
Pasquale (INAF-IASFPA), A. Maselli (INAF-IASFPA), A. Melandri
(INAF-OAB), D.N. Burrows (PSU), J.A. Kennea (PSU), B. Sbarufatti
(INAF-OAB/PSU) and M. H. Siegel (PSU) report on behalf of the Swift-XRT
team:
We have analysed 15 ks of XRT data for GRB 150317A (Siegel et al. GCN
Circ. 17592), from 68 s to 42.4 ks after the BAT trigger. The data
comprise 19 s in Windowed Timing (WT) mode with the remainder in Photon
Counting (PC) mode. Using 5905 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 =
138.98467, +55.46573 which is equivalent to:
RA (J2000): 09h 15m 56.32s
Dec(J2000): +55d 27' 56.6"
with an uncertainty of 1.8 arcsec (radius, 90% confidence).
The light curve can be modelled with a power-law decay with a decay
index of alpha=0.90 (+0.06, -0.05).
A spectrum formed from the PC mode data can be fitted with an absorbed
power-law with a photon spectral index of 2.3 (+/-0.3). The
best-fitting absorption column is 2.9 (+0.6, -0.5) x 10^22 cm^-2, in
excess of the Galactic value of 3.0 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 5.9 x 10^-11 (2.0 x 10^-10) erg
cm^-2 count^-1.
A summary of the PC-mode spectrum is thus:
Total column: 2.9 (+0.6, -0.5) x 10^22 cm^-2
Galactic foreground: 3.0 x 10^20 cm^-2
Excess significance: 9.2 sigma
Photon index: 2.3 (+/-0.3)
If the light curve continues to decay with a power-law decay index of
0.90, the count rate at T+24 hours will be 2.7 x 10^-3 count s^-1,
corresponding to an observed (unabsorbed) 0.3-10 keV flux of 1.6 x
10^-13 (5.3 x 10^-13) erg cm^-2 s^-1.
The results of the XRT-team automatic analysis are available at
http://www.swift.ac.uk/xrt_products/00635148.
This circular is an official product of the Swift-XRT team.
GCN Circular 17598
Subject
GRB 150317A: Swift/UVOT Upper Limits
Date
2015-03-18T03:49:56Z (10 years ago)
From
Margaret Chester at PSU <chester@swift.psu.edu>
M. M. Chester (PSU) and M. H. Siegel (PSU)
report on behalf of the Swift/UVOT team:
The Swift/UVOT began settled observations of the field of GRB 150317A
126 s after the BAT trigger (Siegel et al., GCN Circ. 17592).
Due to the location of the counterpart (Evans and Goad GCN Circ. 17594,
Butler et al. GCN Circ. 17595) in the wings of the nearby bright star
(V~11.2), we cannot report a certain detection. We therefore provide
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, as follows:
Filter T_start(s) T_stop(s) Exp(s) Mag
u_FC 126 376 246 >19.6
v 432 6158 334 >19.2
b 381 6978 571 >20.4
u 126 6773 739 >20.2
w1 481 6568 335 >19.6
m2 457 6363 255 >19.4
w2 407 7037 384 >20.0
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 17650
Subject
GRB 150317A: likely host galaxy detection
Date
2015-03-28T03:20:50Z (10 years ago)
From
Daniele Malesani at Dark Cosmology Centre, Niels Bohr Inst <malesani@dark-cosmology.dk>
Daniele Malesani (DARK/NBI), Nial R. Tanvir (Univ. Leicester), Zach Cano
(Univ. Iceland), Pall Jakobsson (Univ. Iceland), and Tapio Pursimo (NOT)
report on behalf of a larger collaboration:
We observed the field of GRB 150317A (Siegel et al., GCN 17592) using
the Nordic Optical Telescope (NOT) located in La Palma. The mean time of
the observation was March 23.95 UT, 6.77 days after the GRB. A 30 min
exposure was collected using the SDSS i filter.
Inside the XRT error circle (Evans & Goad, GCN 17594), we detect a
single source with i = 22.75 +- 0.25 AB (calibrated against nearby SDSS
stars). The large error is mostly due to the bright, variable background
from a nearby star. At the same position, an object with a consistent
magnitude is also marginally visible in the archival SDSS data. Assuming
that this object is coincident with the one detected by RATIR (Butler et
al., GCN 17595), we thus suggest that this is the host galaxy of GRB
150317A. Its coordinates are (J2000):
RA = 09:15:56.31
Dec = +55:27:58.0
with an uncertainty of 0.5". Such a bright galaxy may allow spectroscopy
from an 8-m class telescope.