GRB 210919A
GCN Circular 30846
Subject
GRB 210919A: Swift detection of a short burst
Date
2021-09-19T00:54:18Z (4 years ago)
From
Scott Barthelmy at NASA/GSFC <scott@milkyway.gsfc.nasa.gov>
A. Tohuvavohu (U Toronto), S. D. Barthelmy (GSFC),
A. Y. Lien (U Tampa) and B. Sbarufatti (PSU) report on behalf of the
Neil Gehrels Swift Observatory Team:
At 00:28:33 UT, the Swift Burst Alert Telescope (BAT) triggered and
located a short GRB 210919A (trigger=1073893). Swift slewed immediately
to the burst. The BAT on-board calculated location is
RA, Dec 80.230, +1.274 which is
RA(J2000) = 05h 20m 55s
Dec(J2000) = +01d 16' 27"
with an uncertainty of 3 arcmin (radius, 90% containment, including
systematic uncertainty). The BAT light curve showed a single-peaked
structure with a duration of about 0.3 sec. The peak count rate
was ~3500 counts/sec (15-350 keV), at ~0 sec after the trigger.
The XRT began observing the field at 00:30:10.5 UT, 97.0 seconds after
the BAT trigger. Using promptly downlinked data we find an uncatalogued
X-ray source located at RA, Dec 80.25441, 1.31189 which is equivalent
to:
RA(J2000) = 05h 21m 01.06s
Dec(J2000) = +01d 18' 42.8"
with an uncertainty of 6.9 arcseconds (radius, 90% containment). This
location is 162 arcseconds from the BAT onboard position, within the
BAT error circle. This position may be improved as more data are
received; the latest position is available at
https://www.swift.ac.uk/sper. We cannot determine whether the source
is fading at the present time.
A power-law fit to a spectrum formed from promptly downlinked event
data gives a column density consistent with the Galactic value of 1.56
x 10^21 cm^-2 (Willingale et al. 2013).
UVOT took a finding chart exposure of 150 seconds with the White filter
starting 99 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 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 0.142.
Burst Advocate for this burst is A. Tohuvavohu (tohuvavohu AT astro.utoronto.ca).
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/)
GCN Circular 30847
Subject
Swift GRB 210919A: Global MASTER-Net observations report
Date
2021-09-19T01:48:24Z (4 years ago)
From
Vladimir Lipunov at Moscow State U/Krylov Obs <lipunov@xray.sai.msu.ru>
V. Lipunov, E. Gorbovskoy, V.Kornilov, N.Tyurina, P.Balanutsa, A.Kuznetsov, F.Balakin,
V.Vladimirov, D. Vlasenko, I.Gorbunov, D.Zimnukhov, V.Senik, T.Pogrosheva,
D.Kuvshinov, D. Cheryasov
(Lomonosov Moscow State University, SAI, Physics Department),
R. Podesta, C.Lopez, F. Podesta, C.Francile
(Observatorio Astronomico Felix Aguilar OAFA),
R. Rebolo, M. Serra
(The Instituto de Astrofisica de Canarias),
D. Buckley
(South African Astronomical Observatory),
O.A. Gres, N.M. Budnev, O.Ershova
(Irkutsk State University, API),
A. Tlatov, D. Dormidontov
(Kislovodsk Solar Station of the Pulkovo Observatory),
V. Yurkov, A. Gabovich, Yu. Sergienko
(Blagoveschensk Educational State University)
MASTER-SAAO robotic telescope (Global MASTER-Net: http://observ.pereplet.ru, Lipunov et al., 2010, Advances in Astronomy, vol. 2010, 30L) located in South Africa (South African Astronomical Observatory) was pointed to the Swift GRB 210919A ( A. Tohuvavohu et al., GCN 30846) errorbox 47 sec after trigger time at 2021-09-19 00:29:20 UT, with upper limit up to 18.6 mag. The observations began at zenith distance = 61 deg. The sun altitude is -49.0 deg.
MASTER-Kislovodsk robotic telescope located in Russia (Lomonosov MSU, Kislovodsk Solar Station of Pulkovo observatory) was pointed to the Swift GRB 210919A errorbox 363 sec after notice time and 790 sec after trigger time at 2021-09-19 00:41:44 UT, with upper limit up to 14.3 mag. The observations began at zenith distance = 50 deg. The sun altitude is -24.1 deg.
The galactic latitude b = -19 deg., longitude l = 201 deg.
Real time updated cover map and OT discovered available here:
https://master.sai.msu.ru/site/master2/observ.php?id=1725958
We obtain a following upper limits.
Tmid-T0 | Site |Filt.| Expt. | Limit| Comment
_________|_____________________|_____|_______|______|________
52 | MASTER-SAAO | P\ | 10 | 16.1 |
67 | MASTER-SAAO | P\ | 40 | 17.0 | Coadd
397 | MASTER-SAAO | P\ | 700 | 18.4 | Coadd
77 | MASTER-SAAO | P\ | 10 | 16.4 |
103 | MASTER-SAAO | P\ | 20 | 16.6 |
141 | MASTER-SAAO | P\ | 30 | 16.0 |
176 | MASTER-SAAO | P\ | 100 | 16.6 | Coadd
183 | MASTER-SAAO | P\ | 30 | 14.7 |
230 | MASTER-SAAO | P\ | 40 | 16.4 |
288 | MASTER-SAAO | P\ | 50 | 15.9 |
358 | MASTER-SAAO | P\ | 190 | 16.6 | Coadd
355 | MASTER-SAAO | P\ | 60 | 15.1 |
437 | MASTER-SAAO | P\ | 80 | 16.4 |
541 | MASTER-SAAO | P\ | 100 | 17.8 |
676 | MASTER-SAAO | P\ | 370 | 18.6 | Coadd
662 | MASTER-SAAO | P\ | 120 | 17.8 |
810 | MASTER-SAAO | P\ | 150 | 18.1 |
871 | MASTER-Kislovodsk | P| | 160 | 14.2 |
987 | MASTER-SAAO | P\ | 180 | 17.5 |
1167 | MASTER-SAAO | P\ | 540 | 17.9 | Coadd
1048 | MASTER-Kislovodsk | P- | 180 | 12.4 |
1048 | MASTER-Kislovodsk | P| | 180 | 14.1 |
1188 | MASTER-SAAO | P\ | 180 | 17.4 |
1249 | MASTER-Kislovodsk | P- | 180 | 12.9 |
1249 | MASTER-Kislovodsk | P| | 180 | 14.2 |
1387 | MASTER-SAAO | P\ | 180 | 17.4 |
1449 | MASTER-Kislovodsk | P- | 180 | 13.4 |
1449 | MASTER-Kislovodsk | P| | 180 | 14.3 |
1587 | MASTER-SAAO | P\ | 180 | 17.4 |
1650 | MASTER-Kislovodsk | P- | 180 | 13.6 |
The observation and reduction will continue.
The message may be cited.
GCN Circular 30848
Subject
GRB 210919A: BOOTES-2/TELMA optical upper limit
Date
2021-09-19T01:57:54Z (4 years ago)
From
Youdong HU at IAA-CSIC <huyoudong072@hotmail.com>
Y.-D. Hu, T.-R. Sun, E. Fernandez-Garcia, A. J. Castro-Tirado, M.D. Caballero-Garcia (IAA-CSIC), C. Perez del Pulgar, A. Castellon, I. Carrasco (Univ. de Malaga), R. Fernandez-Munoz (IHSM/UMA-CSIC) and M. Jelinek (ASU-CAS), on behalf of a larger collaboration, report:
The 60cm BOOTES-2/TELMA robotic telescope at IHSM La Mayora (UMA-CSIC) in Algarrobo Costa (Malaga, Spain) automatically responded to the Swift trigger of short GRB 210919A (Tohuvavohu et al. GCNC 30846). Images were taken starting at 00:32 UT on 19 Sep (~4 min after trigger) under high airmass conditions. In the co-added 10 x 10 s exposure image (clear filter), no optical afterglow is detected within the reported XRT/Swift source position (Tohuvavohu et al. GCNC 30846) down to 17.5 mag. This non-detection is consistent with reports from Tohuvavohu et al.(GCNC 30846) and Lipunov et al.(GCNC 30847).
We thank the staff at La Mayora for its excellent support.
GCN Circular 30849
Subject
GRB 210919A: LCO Optical Upper Limit
Date
2021-09-19T04:55:40Z (4 years ago)
From
Robert Strausbaugh at U. of the Virgin Islands <robert.strausbaugh@uvi.edu>
R. Strausbaugh (U. of the Virgin Islands), A. Cucchiara (U. of the Virgin Islands/College of Marin) report on behalf of a larger collaboration:
We observed Swift GRB 210919A (Tohuvavohu, et al., GCN 30846) with the LCO 1-m Sinistro instrument at the South African Astronomical Observatory site, on September 19, from 01:41 to 02:08 UT (corresponding to 1.22 to 1.67 hours from the GRB trigger time) with the Bessel R and I filters.
We performed a series of 4x200s exposures in R and 3x200s in I. In the large XRT detection region (Tohuvavohu, et al., GCN 30846) we find no obvious optical counterpart could be detected down to the following upper limits (consistent with previous reports (Tohuvavohu et al., GCNC 30846; Lipunov et al., GCNC 30847; Hu et al., GCN 30848)), calculated using the USNO-B.1 catalog as reference:
R>20.5
I>18.7
These magnitudes are not corrected for galactic extinction.
R.S. is funded by NSF AST grant #1831682
GCN Circular 30850
Subject
GRB 210919A: Enhanced Swift-XRT position
Date
2021-09-19T05:06:55Z (4 years ago)
From
Phil Evans at U of Leicester <pae9@leicester.ac.uk>
M.R. Goad, J.P. Osborne, A.P. Beardmore and P.A. Evans (U. Leicester)
report on behalf of the Swift-XRT team.
Using 453 s of XRT Photon Counting mode data and 1 UVOT
images for GRB 210919A, 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 = 80.25448, +1.31153 which is equivalent
to:
RA (J2000): 05h 21m 1.08s
Dec (J2000): +01d 18' 41.5"
with an uncertainty of 4.6 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 was automatically generated, and is an official product of the
Swift-XRT team.
GCN Circular 30851
Subject
GRB 210919A: AbAO optical upper limit
Date
2021-09-19T09:24:53Z (4 years ago)
From
Alexei Pozanenko at IKI, Moscow <apozanen@iki.rssi.ru>
N. Pankov (HSE, IKI), R. Ya. Inasaridze (AbAO), A. Pozanenko (IKI), S.
Belkin (IKI), D. Datashvili (AbAO), V. R. Ayvazian (AbAO), G. V.
Kapanadze (AbAO) report on behalf of GRB IKI FuN:
We observed the field of Swift short GRB 210919A (Tohuvavohu et al. GCN
30846) with AS-32 telescope of Abastumani observatory (AbAO) in
R-filter starting on Sep., 19 (UT) 00:48:33. We do not detect any object
in the enhanced XRT position (Goad et al. GCN 30850). This is consistent
with optical observations (Tohuvavohu et al. GCN 30846; Lipunov et al.,
GCN 30847; Hu et al. GCN 30848; Strausbaugh et al. GCN 30849).
Preliminary photometry of the field is following
Date UT start t-T0 Filter Exp. OT Err. UL(3sigma)
(mid, days) (s)
2021-09-19 00:48:33 0.03194 R 52*60 n/d n/d 22.1
The photometry is based on the nearby SDSS stars:
SDSS-DR12 R(Lupton)
5:21:01.5917 +1:18:14.862 17.82
5:20:58.8314 +1:18:59.733 18.36
GCN Circular 30852
Subject
GRB 210919A: NOT upper limits
Date
2021-09-19T12:24:18Z (4 years ago)
From
Daniel Perley at Liverpool JMU <d.a.perley@ljmu.ac.uk>
D. A. Perley (LJMU), Z. P. Zhu (NAOC, HUST), D. Xu, S.Y. Fu (NAOC), D.
B. Malesani (DTU Space), and A. Avramova-Boncheva (NOT) report:
We observed the field of GRB210919A (Tohuvavohu et al. GCN 30846) using
the Nordic Optical Telescope (NOT) equipped with the ALFOSC camera. We
obtained 3x300s frames in the Sloan r-band filter and 5x240s in the
i-band filter. Observations were carried out on 2021-09-19 between
03:29 and 04:08 UT.
No source is detected inside the enhanced XRT error circle (Goad et al.,
GCN 30850), to 3-sigma limits of: r>23.4 mag (at t=3.15 hours
post-trigger) and i>23.9 (at t=3.47 hours post-trigger).
DisclaimerNone
GCN Circular 30854
Subject
GRB 210919A: Swift-XRT refined Analysis
Date
2021-09-19T15:57:30Z (4 years ago)
From
Phil Evans at U of Leicester <pae9@leicester.ac.uk>
M. Perri (SSDC & INAF-OAR), V. D'Elia (SSDC & INAF-OAR), A. D'Ai
(INAF-IASFPA), J. D. Gropp (PSU), J.A. Kennea (PSU), P.A. Evans (U.
Leicester), J.P. Osborne (U. Leicester), K.L. Page (U. Leicester) and
A. Tohuvavohu report on behalf of the Swift-XRT team:
We have analysed 1.5 ks of XRT data for GRB 210919A (Tohuvavohu et al.
GCN Circ. 30846), from 105 s to 1.6 ks after the BAT trigger. The data
are entirely in Photon Counting (PC) mode. The enhanced XRT position
for this burst was given by Goad et al. (GCN Circ. 30850). We cannot
determine at the present time whether the source is fading.
The results of the XRT-team automatic analysis are available at
http://www.swift.ac.uk/xrt_products/01073893.
This circular is an official product of the Swift-XRT team.
GCN Circular 30855
Subject
GRB 210919A: MITSuME Akeno optical upper limits
Date
2021-09-20T00:36:51Z (4 years ago)
From
Yutaka Takamatsu at Tokyotech <takamatsu@hp.phys.titech.ac.jp>
Y. Takamatsu, R. Hosokawa, K. L. Murata, N. Ito, Y. Imai, M. Niwano,
R. Noto, S. Sato, M. Takaku, R. Yamaguchi, Y. Yatsu, and N. Kawai
(TokyoTech) report on behalf of the MITSuME collaboration:
We observed the field of GRB 210919A (A. Tohuvavohu et al. GCN
Circular #30846, V. Lipunov et al. GCN Circular #30847, Y.-D. Hu et
al. GCN Circular #30848, R. Strausbaugh et al. GCN Circular #30849,
M.R. Goad et al. GCN Circular #30850, N. Pankov et al. GCN Circular
#30851, D. A. Perley et al. GCN Circular #30852, M. Perri et al. GCN
Circular #30854) with the optical three color (g', Rc, and Ic) CCD
cameras attached to the MITSuME 50 cm telescope Akeno. The observation
with a series of 60 sec exposures started at 2021-09-19 15:22:32 UT
(14.9 hours after Swift trigger). We stacked the images with good
conditions. We did not detect any uncatalogued sources within the XRT
error region (M.R. Goad et al. GCN Circular #30850). We obtained the
5-sigma limits of the stacked images as follows.
T0+[hour] MID-UT T-EXP[sec] 5-sigma limits
------------------------------------------------------------------------------------------------
17.3 2021-09-19 17:48:08.43 11160 g'>19.2, Rc>20.5, Ic>19.6
------------------------------------------------------------------------------------------------
T0+ : Elapsed time after the burst
T-EXP: Total Exposure time
We used PS1 catalog for flux calibration.
The magnitudes are expressed in the AB system.
The images were processed in real-time through the MITSuME GPU
reduction pipeline (Niwano et al. 2021, PASJ, Vol.73, Issue 1, Pages
4-24; https://github.com/MNiwano/Eclaire).
GCN Circular 30856
Subject
GRB 210919A: LOAO and LSGT optical upper limits
Date
2021-09-20T08:00:38Z (4 years ago)
From
Sophia Kim at Seoul National U. <sophiak@astro.snu.ac.kr>
GRB 210919A: LOAO and LSGT optical upper limits
Sophia Kim (Seoul National University, SNU), Myungshin Im (SNU); Jeff Cooke
(Swinburne University of Technology), Gu Lim (SNU); report on behalf of
IMSNG & GECKO Collaboration
We carried out follow-up observations of GRB210919A (A. Tohuvanohu et al.
GCNC #30846) with the 1-m telescope at Mt. Lemon Optical Astronomy
Observatory (LOAO) in US Arizona. Observations began on September 19 at
10:42:02 UT , ~10.23 hours after the GRB trigger. We took 19 X 180s
exposures in Johnson R-band.
We also observed the same field with the 0.43-meter (17 inch) Lee Sang Gak
Telescope (LSGT) located at the Siding Spring Observatory (SSO) in
Australia. Imaging began on the same day at 16:12:53 UT, ~15.73 hours after
the GRB trigger. The observations were performed in a Sloan r-, i- and
z-band sequences with 11 X 300s exposures in each band.
No GRB optical counterpart was found in the LOAO and LSGT data within the
XRT error area (M. R. Goad et al. GCNC #30850). This result is consistent
with the optical observational results by other teams (V. Lipunov et al.
GCNC #30847, Y.-D. Hu et al. GCNC #30848, R. Strausbaugh et al. GCNC
#30849, M.R. Goad et al. GCNC #30850, N. Pankov et al. GCNC #30851, D. A.
Perley et al. GCNC #30852, M. Perri et al. GCNC #30854 and Y.Takamatsu et
al. GCNC #30855).
The following is our observation results.
We calibrated flux with the PS1 catalog and used AB magnitude system. (The
magnitudes are not corrected for extinction.)
#--------------------------------------------------------------------------------------------------------------
OBS/TEL DATE-OBS(UT) FILTER EXPT UL(3��)[ABmag] UL(5��)[ABmag]
LOAO/1-m 2021-09-19T10:42:02 R 3420s >21.716 >21.162
SSO/LSGT 2021-09-19T16:12:53 r 3300s >20.160 >19.605
SSO/LSGT 2021-09-19T16:18:17 i 3300s >19.107 >18.553
SSO/LSGT 2021-09-19T16:23:53 z 3300s >18.674 >18.119
--------------------------------------------------------------------
[GCN OPS NOTE(20sep2021): Per author's request, the signiture block
that is automatically added to the bottom has been removed.]
GCN Circular 30857
Subject
GRB 210919A: Swift/UVOT Upper Limits
Date
2021-09-21T02:35:14Z (4 years ago)
From
Mike Siegel at PSU/Swift MOC <mhs18@psu.edu>
M. H. Siegel (PSU) and A. Tohuvavohu (U. Toronto)
report on behalf of the Swift/UVOT team:
The Swift/UVOT began settled observations of the field of GRB 210919A
100 s after the BAT trigger (Tohuvavohu et al., GCN Circ. 30846).
No optical afterglow consistent with the XRT position
(Goad et al. GCN Circ. 30850) 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 first
finding chart (FC) exposure and subsequent exposures are:
Filter T_start(s) T_stop(s) Exp(s) Mag
white_FC 100 249 147 >20.8
u_FC 312 561 246 >19.9
white 100 1193 343 >21.4
v 643 1244 70 >18.7
b 568 1342 63 >19.3
u 312 1318 304 >19.8
w1 693 1293 58 >19.7
m2 1248 1268 19 >19.0
w2 618 1044 39 >19.4
The magnitudes in the table are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 0.141 in the direction of the burst
(Schlegel et al. 1998).
GCN Circular 30858
Subject
GRB210919A: Keck NIRC2 Kp band upper limits
Date
2021-09-21T06:58:23Z (4 years ago)
From
Jielai Zhang at Swinburne U. of Tech. <jielaizhangscience@gmail.com>
GRB210919A: Keck NIRC2 Kp band upper limits
Jielai Zhang (Swinburne University of Technology, Swinburne), Jeff Cooke
(Swinburne), Gabriela Canalizo (University of California Riverside), Sara
Marlene Doan (George Mason University), Shobita Satyapal (George Mason
University), Thomas Bohn (University of California Riverside), Jeffrey
Mckaig (George Mason University)
We carried out follow-up observations of GRB210919A (A. Tohuvanohu et al.
GCNC #30846) with Keck II, using the NIRC2 instrument with the wide camera.
Observations began on September 19 at 13:48:32.649 UT , ~13.3 hours after
the GRB trigger. We took 6 X 107s exposures using the Kp filter. No GRB IR
counterpart was found in the NIRC2 data within the XRT error area (M. R.
Goad et al. GCNC #30850).
No GRB IR counterpart was found in the NIRC2 data within the XRT error area
(M. R. Goad et al. GCNC #30850) to an upper limit of Kp > 21.5 mag (AB,
with no Galactic extinction correction).
GCN Circular 30859
Subject
GRB 210919a: Lowell Discovery Telescope upper limits
Date
2021-09-21T15:25:55Z (4 years ago)
From
Amy Gottlieb at UMD <Agottlieb7@gmail.com>
[GCN OPS REPORT(21 Sep 2021): Per submittor's request, this Circular
was removed because it was serverly covered with formating directives.
It will be resubmitted when a cleaner version is made.]
GCN Circular 30860
Subject
GRB 210919A: Lowell Discovery Telescope upper limits (correction to GCN 30859)
Date
2021-09-21T19:15:27Z (4 years ago)
From
Amy Gottlieb at UMD <Agottlieb7@gmail.com>
This is the corrected version of GCN 30859 submitted as plain text
instead of html.
A.Gottlieb (UMD, NASA-GSFC), S.Dichiara (UMD, NASA-GSFC), S.B. Cenko
(NASA-GSFC), E. Troja (UMD, NASA-GSFC), J.M. Durbak (UMD), A. Kutyrev
(UMD, NASA-GSFC), S. Veilleux (UMD), report on behalf of a larger
collaboration:
We observed the field of the short GRB 210919A (Tohuvavohu et al.,
GCN Circ. 30846) using the Large Monolithic Imager (LMI) on the 4.3m
Lowell Discovery Telescope (LDT) at Happy Jack, AZ. Observations
started on September 21, 11:27:43 UT (2.46 days after the Swift
trigger) taking 5 exposures of 200 s each with SDSS r filter.
Observations were taken at an airmass of about 1.27 and seeing of
about 1.5". We do not find any source inside the enhanced
XRT position (Goad et al., GCN Circ. 30850) down to a 3-sigma
limiting magnitude of r>23.6 AB mag.
Magnitudes are calibrated against the SDSS catalog and not
corrected for Galactic extinction.
We thank the staff of the Lowell Discovery Telescope for assistance
with these observations.
GCN Circular 30863
Subject
GRB 210919A: Swift-BAT refined analysis
Date
2021-09-22T22:04:47Z (4 years ago)
From
Sibasish Laha at GSFC <sibasish.laha@nasa.gov>
S. D. Barthelmy (GSFC), H. A. Krimm (NSF),
S. Laha (GSFC/UMBC), A. Y. Lien (U Tempa),
C. B. Markwardt (GSFC), D. M. Palmer (LANL),
T. Parsotan (GSFC/UMBC), T. Sakamoto (AGU),
M. Stamatikos (OSU) (i.e. the Swift-BAT team):
Using the data set from T-239 to T+963 sec from the recent telemetry downlink,
we report further analysis of BAT GRB 210919A (trigger #1073893)
(Tohuvavohu et al., GCN Circ. 30846). The BAT ground-calculated position is
RA, Dec = 80.242, 1.286 deg which is
RA(J2000) = 05h 20m 58.1s
Dec(J2000) = +01d 17' 08.8"
with an uncertainty of 2.0 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 50%.
The BAT light curve showed a short pulse of a duration ~ 1 sec.
T90 (15-350 keV) is 0.16 +- 0.03 sec (estimated error including systematics).
The time-averaged spectrum from T+0.05 to T+0.24 sec is best fit by a simple
power-law model. The power law index of the time-averaged spectrum is
1.58 +- 0.27. The fluence in the 15-150 keV band is 8.8 +- 1.7 x 10^-08 erg/cm2.
The 1-sec peak photon flux measured from T-0.35 sec in the 15-150 keV band
is 1.5 +- 0.3 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/1073893/BA/
GCN Circular 30868
Subject
GRB 210919A: DECam Upper Limits
Date
2021-09-23T14:09:18Z (4 years ago)
From
Justin Pierel at STScI <jpierel@stsci.edu>
J. Pierel (STScI), J. Cooke (Swinburne U.), A. Rest (STScI), R. Foley (UCSC), and R. Ridden-Harper (U. Canterbury) report:
We observed the field of GRB210919A (Tohuvavohu et al. GCN 30846) using the Dark Energy Camera (DECam) instrument on the 4m Victor M. Blanco Telescope at CTIO. We obtained 5x250s exposures in the i and z-band from 08:20-09:05 UTC on 2021-09-21.
No source is detected inside the enhanced Swfit-XRT uncertainty radius (Goad et al., GCN 30850), to 3-sigma limits of: i>24.1 mag and z>23.6 mag.
GCN Circular 30879
Subject
GRB 210919A: Chandra rapid ToO upper limit
Date
2021-09-25T01:27:01Z (4 years ago)
From
Takanori Sakamoto at AGU <tsakamoto@phys.aoyama.ac.jp>
T. Sakamoto (AGU), E. Troja (NASA/GSFC/ORAU), J. Norris (BSU),
S. D. Barthelmy (GSFC), J. L. Racusin (GSFC), N. Kawai (Tokyo Tech),
A. Fruchter (STScI), M. Im (SNU), B. Cenko (GSFC)
A Chandra ToO observation of a short GRB 200919A (Tohuvavohu et al., GCN Circ. 30846)
started on February 21 02:54 UT (~2.1 days after the GRB trigger) for a total of 19.8 ksec.
We do not detect an X-ray afterglow at the location of the enhanced XRT position
(Goad et al., GCN Circ. 30850). The calculated 3-sigma upper limit is 3.4 x 10^-4 c/s
in the 0.3-8 keV band using aprates of the CIAO software package. Assuming N_H of
1.5 x 10^21 cm^-2 and photon index of 2, we estimated an 3-sigma unabsorbed flux
upper limit of 6.9 x 10^-15 erg/cm2/s in the 0.3-8 keV band.
We would like to thank Patrick Slane, Harvey Tananbaum, Andrea Prestwich,
and the Chandra operation team for rapidly approving and making this observation.
GCN Circular 30883
Subject
GRB 210919A CAHA 2.2m Observations: Afterglow/Host Galaxy Candidate
Date
2021-09-26T22:58:23Z (4 years ago)
From
Alexander Kann at IAA-CSIC <kann@iaa.es>
D. A. Kann (HETH/IAA-CSIC), A. Rossi (INAF-OAS), A. de Ugarte Postigo
(HETH/IAA-CSIC, DARK/NBI), C. Thoene, M. Blazek, J. F. Agui Fernandez
(all HETH/IAA-CSIC), and P. Minguez (CAHA) report:
We obtained observations of the enhance XRT position (Goad et al., GCN
30850) of the Swift short GRB 210919A (Tohuvavohu et al., GCN #30846)
with CAFOS mounted on the 2.2m telescope at CAHA, Almeria, Spain. We
obtained 30 x 90 s images in the i' band, starting at 03:38 UT on
September 19, under good observing conditions.
In the stacked image, we detect a faint source within the enhanced XRT
error circle at:
RA (J2000) = 05:21:01.098
Dec. (J2000) = +01:18:43.15
with an error of 0".5.
Compared to three nearby comparison stars from the PanSTARRS catalog, we
measure:
i' = 24.14 +/- 0.30 mag (AB) @ 0.1525 days after the GRB.
We suggest this source to be either the afterglow or the host galaxy of
GRB 210919A.
Other teams have reported upper limits so far:
CR > 18.6 @ 0.007824 d (deepest, Lipunov et al., GCN #30847)
CR > 17.5 @ 0.002975 d (Hu et al., GCN #30848)
Rc > 20.5, Ic > 18.7 @ 0.05083 - 0.06958 d (Strausbaugh et al., GCN
#30849)
Rc > 22.1 @ 0.03194 d (Pankov et al., GCN #30851)
r' > 23.4 @ 0.13125 d, i' > 23.9 @ 0.14458 d (Perley et al., GCN #30852)
Rc > 20.5 @ 0.7208 d (Takamatsu et al., GCN #30855)
Rc > 21.716 @ 0.426 d (AB); r' > 20.16 @ 0.6558 d; i' > 19.107 @ 0.6595
d (Kim et al., GCN #30856)
white > 20.8 @ 0.001826 d (Siegel et al., GCN #30857)
Kp > 21.5 @ 0.5542 d (AB) (Zhang et al., GCN #30858)
r' > 23.6 @ 2.4635 d (Gottlieb et al., GCN #30860)
i' > 24.1, z' > 23.6 @ 2.343 d (Pierel et al., GCN #30868)
None of these limits are as deep as our image, with the NOT imaging
(Perley et al., GCN #30852) slightly earlier and the late DeCam imaging
(Pierel et al., GCN #30868) coming closest. This leaves it unclear as to
whether the source is fading, we can therefore not discern whether it is
an afterglow candidate or a host-galaxy candidate.
Deeper imaging is needed, if the source is undetected to deeper limits,
it is very likely the afterglow. If it is the host, it should be
detected at higher significance.
GCN Circular 30884
Subject
GRB 210919A OSN 1.5m Source Confirmation
Date
2021-09-26T23:01:27Z (4 years ago)
From
Alexander Kann at IAA-CSIC <kann@iaa.es>
D. A. Kann (HETH/IAA-CSIC), A. Rossi (INAF-OAS), A. de Ugarte Postigo
(HETH/IAA-CSIC, DARK/NBI), C. Thoene, M. Blazek, J. F. Agui Fernandez
(all HETH/IAA-CSIC), and F. Aceituno (IAA) report:
We obtained observations of the enhance XRT position (Goad et al., GCN
30850) of the Swift short GRB 210919A (Tohuvavohu et al., GCN #30846)
with the 1.5m telescope of OSN, Granada, Spain. We obtained 35 x 120 s
images in the Rc band, starting at 03:28:22 UT on September 19, under
good observing conditions. We obtained a second epoch, with 41 x 120 s
images, the following night, starting at 2:59:51 UT on September 20.
The source detected by Kann et al. (GCN #30883) is very faintly detected
in the first epoch.
Using the same comparison stars from the PanSTARRS catalog as used by
Kann et al. (GCN #30883) (transformed to Rc via the Lupton equations,
then transformed back to AB magnitudes), we measure:
Rc = 24.47 +/- 0.53 mag @ 0.14944 d after trigger (AB mag).
The source is undetected in the second epoch, but it is shallower, with
Rc > 23.6 mag (AB) @ 1.13649 d after the GRB. We note this detection is
also fainter than the upper limits listed in Kann et al. (GCN #30883).
GCN Circular 30888
Subject
GRB 210919A: iTelescope T-11 upper limits
Date
2021-09-27T09:23:47Z (4 years ago)
From
Takanori Sakamoto at AGU <tsakamoto@phys.aoyama.ac.jp>
K. Hasuda, T. Sakamoto (AGU)
We observed the field of GRB 210919A detected by Swift
(Tohuvavohu et al., GCN Circ. 30846) with the iTelescope.Net
(http://www.itelescope.net) T11 (Planewave 20" CDK) telescope
located at the New Mexico Skies Observatory (NM, USA).
59 images of 60 sec exposures were taken in the R filter
starting from September 21 on 10:04:47 (UT) about 2.4 days after
the trigger and stopped on 11:26:12 (UT). We further obtained
60 images of 60 sec exposures in the R filter starting from
September 22 on 10:01:34.4 (UT) and stopped on 11:27:50 (UT).
We do not detect the optical afterglow both in the individual
images and the stacked image at the XRT position
(Goad et al., GCN Circ. 30850). The estimated five sigma
upper limits of the combined image of the first observation
(total exposure of 3540 sec) and the second observation (total
exposure of 3600 sec) are 17.8 and 19.1 using the USNO-B1 catalog.
GCN Circular 30934
Subject
GRB 210919A: LDT optical observations and candidate host galaxies
Date
2021-10-12T23:14:30Z (4 years ago)
From
Brendan O'Connor at UMD <oconnorb@umd.edu>
B. O'Connor (UMD, GWU),E. Hammerstein (UMD),S.B. Cenko (UMD,
NASA-GSFC),E. Troja (UMD, NASA-GSFC),A.Gottlieb (UMD,
NASA-GSFC),S.Dichiara (PSU),A. Kutyrev (UMD,NASA-GSFC),
S. Veilleux (UMD)
We observed the field of GRB 210919A (Tohuvavohu et al., GCN 30846)
using the Large Monolithic Imager (LMI) on the 4.3m Lowell Discovery
Telescope (LDT) at Happy Jack, AZ. Observations started on October 11,
2021 at 11:39:44 UT (~3 weeks after the GRB trigger), and were carried
out in r-band for 5x300 s exposures. The observations were performed at
airmass 1.2 with seeing 0.8".
At the position of the optical source reported by Kann et al.
(GCNs 30883 and 30884) we do not detect any source down to a
3-sigma upper limit of r>25.1 AB mag. However, within the XRT
enhanced position (Goad et al., GCN 30850), we detect a source
with magnitude r~24.0+/-0.1 AB mag at position
RA, DEC = 05:21:00.87,+01:18:42.68 +/- 0.5",
which is 3.4" offset from the Kann et al. source (GCNs 30883 and 30884).
The source appears marginally extended although it cannot be
confidently associated with GRB 210919A due to the high probability
of chance coincidence of Pcc=0.45 (Bloom et al. 2002). We also note
the presence of a bright galaxy (also seen in SDSS)
with r~20.47+/-0.05 mag at an offset of ~13" from the XRT localization.
This galaxy has a photometric redshift z~0.27+/-0.12, and probability
of chance coincidence is Pcc=0.15.
Magnitudes are calibrated against the SDSS catalog and are not corrected
for Galactic extinction.
We thank the staff of the Lowell Discovery Telescope for assistance
with these observations.
GCN Circular 30983
Subject
GRB 210919A: FORS2/VLT observations
Date
2021-10-25T00:51:58Z (4 years ago)
From
Alexander Kann at IAA-CSIC <kann@iaa.es>
D. A. Kann (HETH/IAA-CSIC), D. B. Malesani (Radboud U. Nijmegen), V.
D'Elia (ASI/SSDC, INAF/OAR), A. de Ugarte Postigo (HETH,DARK/NBI), A.
Rossi (INAF-OAS) and C. C. Thoene (HETH/IAA-CSIC) report on behalf of
the Stargate consortium:
We observed the field of the short GRB 210919A (Tohuvavohu et al., GCN
#30846) at late times with FORS2 mounted on the ESO VLT at Cerro Paranal
Observatory, Chile. We obtained 6 x 90 s exposure each in V, Rc, and Ic,
and 12 x 68 s in z_special, under excellent conditions (seeing 0".9 to
0".65 from V to z), on October 2.28 UT, 2021, at a midtime of 13.26 days
after the GRB.
Our results are in agreement with the LDT/LMI observations obtained by
O'Connor et al. (GCN #30934). At the position of the potential afterglow
(Kann et al., GCN #30883, #30884), we do not detect any source.
Calibrating against three nearby stars from the Pan-STARRS catalog
(converted to Johnson-Cousins filters for V, Rc, Ic, following the
Lupton transformations, then converted back to AB magnitudes), we derive
an upper limit of Ic > 25.8 mag, with the V, Rc observations reaching a
comparable depth and the z observation being shallower.
The nearby source reported by O'Connor et al. (GCN #30934) is detected
in all filters, and we find that it is marginally extended. We measure,
again in AB magnitudes, Ic = 23.83 +/- 0.06 mag in an aperture
corresponding to the stellar PSF, it being somewhat brighter using a
larger aperture. Therefore, this object is a host galaxy candidate for
GRB 210919A, in agreement with O'Connor et al. (GCN #30934).
At the eastern edge of the XRT error circle (Goad et al., GCN #30850),
we find a further, fainter source at RA = 5:21:01.35, Dec. = +1:18:41.9
(J2000) with an error of 0".5. For this source, we measure Ic = 25.01
+/- 0.19 mag. As the source is faint, we can't make any definite
statements about its extension. It is also a host galaxy candidate,
although its chance association probability is quite large.
GCN Circular 31453
Subject
GRB 210919A: LBT spectroscopic redshift of the host galaxy candidates
Date
2022-01-15T17:52:12Z (4 years ago)
From
Andrea Rossi at INAF <andrea.rossi@inaf.it>
A. Rossi, F. Cusano, E. Palazzi, L. Amati (INAF-OAS Bologna), D. B.
Malesani (Radboud U. Nijmegen and DAWN/NBI), S. Savaglio (UNICAL), on
behalf of the CIBO collaboration, and D. A. Kann (HETH/IAA-CSIC) report:
We report the results of spectroscopic observations of two galaxies
close to the position of the GRB (O'Connor et al. GCN #30934, Kann et
al., GCN #30983) of the short GRB 210919A (Tohuvavohu et al., GCN
#30846), obtained with the Multi-Object Double Spectrographs (MODS)
instrument mounted on the 2x8.4-m LBT telescope (Mt. Graham, AZ, USA).
Spectra were obtained at a mid-time of 12:35 UT on 2021-10-16, ~27.5
days after the burst trigger, for a total on-source time of 5400 s,
covering the wavelength range 3200-10000 AA.
The MODS slit inclination was adjusted to cover the positions of the two
objects singled out by O'Connor et al. (GCN #30934), with offsets of
~3.4 and 13" with respect to the candidate afterglow by Kann et al.
(GCNs #30883 and #30884) respectively, and of the faint source at the
eastern edge of the XRT error circle detected in the ESO-VLT/FORS2
images (Kann et al., GCN #30983). This latter source was not detected in
the MODS data. The spectra of the other two galaxies show several well
detected emission lines which we interpret as [OII] 3727AA, H-beta,
[OIII] 4959,5007AA and H-alpha at a common redshift for both sources of
z=0.2411. The clear detection of these emission lines, and especially
H-beta, indicates that these are two star forming galaxies.
At this redshift, the projected distances to the two galaxies at ~3.4"
and ~13" from the afterglow corresponds to ~13 and ~50 kpc. The distance
between the two galaxies corresponds to 63 kpc, similar to the distance
between the Milky Way and the SMC. There is at least another galaxy (RA,
DEC = 05:21:04.01, +01:18:49.23) within 0.5 arcmin with similar
photometric redshifts (SDSS DR16), suggesting that the two galaxies are
probably not isolated, but part of a larger group.
If GRB 210919A was at z = 0.2411, using standard cosmology (Planck 2016)
and the analysis of the BAT spectra (Barthelmy et al., GCN #30863 and
http://gcn.gsfc.nasa.gov/notices_s/1073893/BA), we find that it would be
consistent with the population of short GRBs in the Ep,i - Eiso plane.
We acknowledge the excellent support from the LBTO and LBT-INAF staff,
particularly D. Thompson, S. Allanson, and S. Paiano, in obtaining these
observations.
GCN Circular 31566
Subject
GRB 210919A: SPI-ACS/INTEGRAL observation and evaluation of Ep
Date
2022-02-10T18:14:13Z (3 years ago)
From
Alexei Pozanenko at IKI, Moscow <apozanen@iki.rssi.ru>
P. Minaev (IKI), A. Pozanenko (IKI) report on behalf of GRB IKI FuN:
We investigated SPI-ACS/INTEGRAL data of GRB 210919A detected by Swift
(Tohuvavohu et al. GCN 30846). GRB 210919A was not triggered by IBAS at
INTEGRAL observatory. We find the burst in SPI-ACS/INTEGRAL data with a
significance of 5 sigma and duration of 0.15 s. The total count fluence
of the burst is 900 �� 185 counts, which corresponds to the fluence of
2.4e-7 erg/cm^2 in 10-1000 keV energy band (the 95% confidence region is
7.2e-8 -- 8.4e-7 erg/cm^2, incl. systematics). We do not find both
precursor and extended emission components for the burst. Light curve of
GRB 210919A can be found in
http://grb.rssi.ru/GRB210919A/GRB210919A_SPI-ACS_light_curve.png
Using spectral data of BAT/Swift (Barthelmy et al. GCN 30863) and
possible redshift of z = 0.2411 (Rossi et al. GCN 31453) we estimated
Eiso = (1.3 �� 0.3)e49 erg in 15-150 keV energy band. Although spectral
parameter Ep was not constrained yet, we can estimate Ep using T90,i -
EH diagram [1] by constructing a trajectory depending on the Ep,i
parameter, where Ep,i is Ep in a rest frame. The most probable value is
found to be Ep,i = 90 keV with 95% confidence region of (14 ��� 640) keV
which is converted into observable Ep = 73 (11 -- 516) keV. Since GRB
210919A was detected by SPI-ACS with a nominal lower threshold of >80
keV, Ep can be further limited to the energy range of 80 - 516 keV.
The T90,i - EH diagram can be found in
http://grb.rssi.ru/GRB210919A/GRB210919A_EHD.png
[1] - Minaev et al., MNRAS, 492, 1919, 2020
GCN Circular 31567
Subject
GRB 210919A: Maidanak optical observations
Date
2022-02-10T18:18:46Z (3 years ago)
From
Alexei Pozanenko at IKI, Moscow <apozanen@iki.rssi.ru>
N. Pankov (HSE, IKI), A. Pozanenko (IKI), S. Belkin (IKI, HSE), O.
Burhonov (UBAI), Sh. Ehgamberdiev (UBAI) report on behalf of GRB IKI FuN:
We observed the filed of GRB 210919A detected by Swift (Tohuvavohu et
al. GCN 30846) with AZT-22 1.5m telescope of Maidanak observatory on
Sep. 19, and 20, 2021. Within enhanced Swift-XRT position (Goad et al.
GNC 30850) we do not detect the potential afterglow (Kann et al. GCN
30883, 30884) in both epochs. In the deep observation on 2021-09-19 with
a mean seeing of 1" we marginally detected the host galaxy candidate
reported by O'Connor et al. (GCN 30934) and Kann et al. (GCN 30983) at
the redshift of z=0.2411 (Rossi et al. GCN 31453). Using aperture
photometry we found R = 24.05 +/- 0.35 of the host galaxy candidate. We
do not detect the source at the eastern edge of the XRT error circle
reported by Kann et al. (GCN 30983).
Preliminary photometry of the field in following
Date UT start t-T0 Filter Exp. OT Err. UL(3sigma)
(mid, days) (s)
2021-09-19 22:27:50 0.94950 R 32*180 n/d n/d 24.2
2021-09-20 23:04:55 1.95651 R 14*180 n/d n/d 22.9
The photometry is based on the nearby SDSS-DR12 stars, R magnitude
calculated by Lupton' transformations.