GRB 200524A
GCN Circular 27797
Subject
GRB 200524A: Fermi-LAT detection
Date
2020-05-24T14:49:12Z (5 years ago)
From
Masanori Ohno at Hiroshima University <ohno@astro.hiroshima-u.ac.jp>
F. Fana Dirirsa (Univ. of Johannesburg), M. Axelsson (KTH & Stockholm
Univ.), M. Ohno (Hiroshima Univ.), F. Piron (CNRS/IN2P3/LUPM) and F. Longo
(University and INFN, Trieste) report on behalf of the Fermi-LAT
Collaboration:
On May 24, 2020, Fermi-LAT detected high-energy emission from
GRB 200524A, which was also detected by Fermi-GBM (trigger 611989445).
At the time of the trigger (T0 = 05:04:00.36 UT) Fermi-LAT was passing
through the SAA, and observations started at roughly
T0+110 seconds. The GRB is detected at high energy (>100 MeV) by Fermi-LAT
at a location of:
RA, Dec = 212.8, 61.0 (degrees, J2000) with an error radius of 0.2 deg (90%
containment, statistical error only).
This was ~25 deg from the LAT boresight when observations started
(T0+110s), and is ~3 deg from the GBM final ground position.
The photon flux above 100 MeV in the time interval 110-900 s after the GBM
trigger is 2.2e-06 +/- 0.8e-06 ph/cm2/s. The estimated photon index above
100 MeV is -1.7 +/ - 0.2. The highest-energy photon is a 9.2 GeV event
which is observed 748 seconds after the GBM trigger. After ~T0+900s, the
GRB location moved outside the LAT FoV.
A Swift ToO has been approved for this burst.
The Fermi-LAT point of contact for this burst is
Feraol Fana Dirirsa (fdirirsa@uj.ac.za ).
The Fermi-LAT is a pair conversion telescope designed to cover
the energy band from 20 MeV to greater than 300 GeV.
It is the product of an international collaboration between
NASA and DOE in the U.S. and many scientific institutions
across France, Italy, Japan and Sweden.
GCN Circular 27798
Subject
GRB 200524A: Swift ToO observations
Date
2020-05-24T15:15:41Z (5 years ago)
From
Phil Evans at U of Leicester <pae9@leicester.ac.uk>
P. A. Evans (U. Leicester) reports on behalf of the Swift team:
Swift has initiated a ToO observation of the Fermi/LAT GRB 200524A.
Automated analysis of the XRT data will be presented online at
https://www.swift.ac.uk/ToO_GRBs/00021001
Any uncatalogued X-ray sources detected in this analysis will be
reported on this website and via GCN COUNTERPART notices. These are
not necessarily related to the Fermi/LAT event. Any X-ray source
considered to be a probable afterglow candidate will be reported via a
GCN Circular after manual consideration.
Details of the XRT automated analysis methods are detailed in Evans et
al. (2007, A&A, 469, 379; 2009, MNRAS, 397, 1177 and 2014, ApJS, 210, 8).
This circular is an official product of the Swift-XRT team.
GCN Circular 27799
Subject
ZTF Discovery of ZTF20abbiixp: The Likely Optical Afterglow to GRB 200524A
Date
2020-05-24T18:47:58Z (5 years ago)
From
Anna Ho at Caltech <annayqho@gmail.com>
Anna Y. Q. Ho, Yuhan Yao (Caltech), Daniel A. Perley (LJMU) report on
behalf of the Zwicky Transient Facility collaboration:
The Zwicky Transient Facility (ZTF, Bellm et al. 2019, Graham et al. 2019)
discovered ZTF20abbiixp, a fast transient at
14h12m10.33s +60d54m19.0s (J2000)
213.043037 +60.905288 (J2000)
as part of the ZTF Uniform Depth Survey (Goldstein et al. in prep).
ZTF20abbiixp was first detected at r~17.4 mag on UT 2020-05-24T06:52:07 and
faded by 0.3 mag over the next 30 minutes, with a total of four
observations showing continuous fading. The last non-detection was 24 hours
prior (2020-05-23T06:43:03) with a limiting magnitude of r>20.4 mag. There
is no counterpart in ZTF reference images down to a limiting magnitude of
r>22.90.
We searched the GCN archive and determined that ZTF20abbiixp is in the
error circle of GRB 200524A, which was detected by Fermi-GBM and Fermi-LAT
(GCN 27797). The position of ZTF20abbiixp is 0.151 degrees offset from the
LAT position, within the 0.2 degree error radius (90% containment).
The time of GRB 200524A was 1.802 hours prior to the first detection of
ZTF20abbiixp. We conclude that ZTF20abbiixp is very likely to be the GRB
afterglow.
Follow-up observations are highly encouraged.
ZTF is a project led by PI S. R. Kulkarni at Caltech (see ATEL #11266), and
includes IPAC; WIS, Israel; OKC, Sweden; JSI/UMd, USA; UW,USA; DESY,
Germany; NRC, Taiwan; UW Milwaukee, USA and LANL USA. ZTF acknowledges the
generous support of the NSF under AST MSIP Grant No 1440341. Alert
distribution service provided by DIRAC@UW. Alert filtering is being
undertaken by the GROWTH marshal system, supported by NSF PIRE grant
1545949.
GCN Circular 27800
Subject
GRB 200524A: GROWTH-India confirmation of optical afterglow
Date
2020-05-24T19:58:19Z (5 years ago)
From
Harsh Kumar at Indian Inst of Tech,Bombay <harshkosli13@gmail.com>
H. Kumar, V. Bhalerao(IITB), G. C. Anupama, S. Barway, U. Stanzin (IIA)
report on behalf of the GROWTH-India collaboration:
We followed up GRB 200524A (F. F. Dirirsa et al., GCN 27797, A. Ho et al.,
GCN 27799) with 0.7m GROWTH-India telescope. We obtained 600-sec exposures
in SDSS g, r, i filters starting at UT 2020-05-24T10:41:57 (~5.6 hrs after
the burst). We detect a faint transient with magnitudes r = 20.56 +- 0.14
and i = 20.59 +- 0.28 (calibrated against PanSTARRs PS1 data release,
Flewelling
et al., 2018). The source position matches with the likely afterglow
candidate by A. Ho et al. (GCN 27799). The fading rate is approximately 3
magnitudes in four hours, consistent with the fading rate reported in the
ZTF GCN. We hereby, confirm ZTF20abbiixp as the afterglow of GRB 200524A.
We obtained the following photometric results:-
------------------------------------------------------------------
JD(Start) | T-T0(hrs) | Filter | Mag |
------------------------------------------------------------------
2458993.946 | 5.64 | g | > 21.01 (5-sigma)
2458993.954 | 5.83 | r | 20.56 +/- 0.14
2458993.962 | 6.02 | i | 20.59 +/- 0.28
------------------------------------------------------------------
Given the fast fading, we encourage the followup of the source. The
magnitudes are not corrected for galactic extinction.
The GROWTH India Telescope (GIT) is a 70-cm telescope with a 0.7 degree
field of view, set up by the Indian Institute of Astrophysics and the
Indian Institute of Technology Bombay with support from the Indo-US Science
and Technology Forum (IUSSTF) and the Science and Engineering Research
Board (SERB) of the Department of Science and Technology (DST), Government
of India (https://sites.google.com/view/growthindia/). It is located at the
Indian Astronomical Observatory (Hanle), operated by the Indian Institute
of Astrophysics (IIA).
[GCN OPS NOTE(24may20): Please see Circular 27804 for a correction to this Circular.]
GCN Circular 27801
Subject
Fermi GRB 200524A: Global MASTER-Net observations report
Date
2020-05-24T20:45:10Z (5 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),
H.Levato
(Instituto de Ciencias Astronomicas, de la Tierra y del Espacio ICATE),
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-IAC robotic telescope (Global MASTER-Net: http://observ.pereplet.ru, Lipunov et al., 2010, Advances in Astronomy, vol. 2010, 30L) located in Spain (IAC Teide Observatory) started inspect of the Fermi GRB 200524A ( F. Fana Dirirsa et al., GCN 27797) errorbox 74 sec after notice time and 111 sec after trigger time at 2020-05-24 05:05:51 UT, with upper limit up to 17.9 mag. Observations started at twilight. The observations began at zenith distance = 67 deg. The sun altitude is -13.1 deg.
MASTER-Tavrida robotic telescope located in Russia (Lomonosov MSU, SAI Crimea astronomical station) started inspect of the Fermi GRB 200524A errorbox 47446 sec after notice time and 47483 sec after trigger time at 2020-05-24 18:15:23 UT, with upper limit up to 18.9 mag. Observations started at twilight. The observations began at zenith distance = 22 deg. The sun altitude is -10.0 deg.
The galactic latitude b = 53 deg., longitude l = 110 deg.
Real time updated cover map and OT discovered available here:
https://master.sai.msu.ru/site/master2/observ.php?id=1364553
We obtain a following upper limits.
Tmid-T0 | Date Time | Site | Coord (J2000) |Filt.| Expt. | Limit| Comment
_________|_____________________|_____________________|____________________________________|_____|_______|_______|________
121 | 2020-05-24 05:05:51 | MASTER-IAC | (13h 54m 44.48s , +64d 23m 18.5s) | P| | 20 | 16.4 |
121 | 2020-05-24 05:05:51 | MASTER-IAC | (13h 52m 51.72s , +64d 28m 46.4s) | P- | 20 | 16.2 |
202 | 2020-05-24 05:07:06 | MASTER-IAC | (14h 05m 35.11s , +64d 25m 10.2s) | P| | 30 | 16.5 |
262 | 2020-05-24 05:07:06 | MASTER-IAC | (14h 05m 35.11s , +64d 25m 10.3s) | P| | 150 | 17.4 | Coadd
447 | 2020-05-24 05:07:06 | MASTER-IAC | (14h 05m 35.11s , +64d 25m 10.2s) | P| | 520 | 17.5 | Coadd
202 | 2020-05-24 05:07:06 | MASTER-IAC | (14h 03m 42.26s , +64d 30m 39.9s) | P- | 30 | 16.6 |
262 | 2020-05-24 05:07:06 | MASTER-IAC | (14h 03m 42.26s , +64d 30m 39.9s) | P- | 150 | 17.7 | Coadd
447 | 2020-05-24 05:07:06 | MASTER-IAC | (14h 03m 42.26s , +64d 30m 39.9s) | P- | 520 | 17.9 | Coadd
298 | 2020-05-24 05:08:33 | MASTER-IAC | (14h 05m 41.22s , +64d 25m 34.8s) | P| | 50 | 16.8 |
298 | 2020-05-24 05:08:33 | MASTER-IAC | (14h 03m 48.47s , +64d 31m 05.3s) | P- | 50 | 17.0 |
417 | 2020-05-24 05:10:22 | MASTER-IAC | (14h 05m 37.30s , +64d 26m 44.3s) | P| | 70 | 16.7 |
417 | 2020-05-24 05:10:22 | MASTER-IAC | (14h 03m 44.58s , +64d 32m 15.1s) | P- | 70 | 17.0 |
555 | 2020-05-24 05:12:30 | MASTER-IAC | (14h 05m 37.10s , +64d 25m 14.7s) | P| | 90 | 16.7 |
695 | 2020-05-24 05:12:30 | MASTER-IAC | (14h 05m 37.10s , +64d 25m 14.7s) | P| | 370 | 17.2 | Coadd
555 | 2020-05-24 05:12:30 | MASTER-IAC | (14h 03m 44.50s , +64d 30m 45.6s) | P- | 90 | 17.0 |
695 | 2020-05-24 05:12:30 | MASTER-IAC | (14h 03m 44.49s , +64d 30m 45.6s) | P- | 370 | 17.7 | Coadd
720 | 2020-05-24 05:15:00 | MASTER-IAC | (14h 05m 40.33s , +64d 26m 43.7s) | P| | 120 | 16.6 |
720 | 2020-05-24 05:15:00 | MASTER-IAC | (14h 03m 47.66s , +64d 32m 14.6s) | P- | 120 | 17.0 |
922 | 2020-05-24 05:18:02 | MASTER-IAC | (14h 05m 33.40s , +64d 26m 06.3s) | P| | 160 | 16.4 |
922 | 2020-05-24 05:18:02 | MASTER-IAC | (14h 03m 40.77s , +64d 31m 37.6s) | P- | 160 | 16.6 |
1151 | 2020-05-24 05:21:41 | MASTER-IAC | (14h 05m 33.93s , +64d 27m 05.4s) | P| | 180 | 15.8 |
1151 | 2020-05-24 05:21:41 | MASTER-IAC | (14h 03m 41.21s , +64d 32m 36.9s) | P- | 180 | 16.4 |
1331 | 2020-05-24 05:21:41 | MASTER-IAC | (14h 03m 41.17s , +64d 32m 36.9s) | P- | 540 | 16.5 | Coadd
1391 | 2020-05-24 05:25:41 | MASTER-IAC | (14h 05m 40.44s , +64d 26m 04.0s) | P| | 180 | 15.3 |
1391 | 2020-05-24 05:25:41 | MASTER-IAC | (14h 03m 47.80s , +64d 31m 35.5s) | P- | 180 | 15.8 |
1629 | 2020-05-24 05:29:39 | MASTER-IAC | (14h 03m 42.61s , +64d 30m 34.8s) | P- | 180 | 15.5 |
47513 | 2020-05-24 18:15:23 | MASTER-Tavrida | (14h 04m 04.92s , +62d 01m 07.4s) | C | 60 | 17.4 |
47594 | 2020-05-24 18:16:44 | MASTER-Tavrida | (13h 50m 59.78s , +64d 00m 37.7s) | C | 60 | 17.6 |
47675 | 2020-05-24 18:18:05 | MASTER-Tavrida | (13h 29m 49.44s , +62d 00m 37.3s) | C | 60 | 17.6 |
47756 | 2020-05-24 18:19:25 | MASTER-Tavrida | (13h 44m 19.15s , +60d 01m 24.6s) | C | 60 | 17.8 |
47836 | 2020-05-24 18:20:46 | MASTER-Tavrida | (14h 03m 58.14s , +62d 02m 08.5s) | C | 60 | 17.8 |
48129 | 2020-05-24 18:25:38 | MASTER-Tavrida | (14h 18m 44.20s , +62d 08m 50.8s) | C | 60 | 18.1 |
48209 | 2020-05-24 18:26:59 | MASTER-Tavrida | (13h 48m 27.80s , +64d 10m 01.2s) | C | 60 | 18.3 |
48290 | 2020-05-24 18:28:19 | MASTER-Tavrida | (14h 06m 45.51s , +64d 11m 10.3s) | C | 60 | 18.2 |
48451 | 2020-05-24 18:31:01 | MASTER-Tavrida | (13h 44m 38.52s , +62d 11m 16.6s) | C | 60 | 18.4 |
48531 | 2020-05-24 18:32:21 | MASTER-Tavrida | (13h 42m 06.69s , +60d 10m 42.5s) | C | 60 | 18.5 |
48612 | 2020-05-24 18:33:41 | MASTER-Tavrida | (13h 58m 09.72s , +60d 11m 28.6s) | C | 60 | 18.8 |
48693 | 2020-05-24 18:35:03 | MASTER-Tavrida | (14h 18m 50.75s , +62d 10m 04.4s) | C | 60 | 18.6 |
48773 | 2020-05-24 18:36:23 | MASTER-Tavrida | (14h 06m 42.74s , +64d 09m 24.8s) | C | 60 | 18.7 |
48854 | 2020-05-24 18:37:44 | MASTER-Tavrida | (13h 44m 37.74s , +62d 10m 11.8s) | C | 60 | 18.9 |
48935 | 2020-05-24 18:39:04 | MASTER-Tavrida | (13h 58m 12.40s , +60d 11m 28.7s) | C | 60 | 18.8 |
Filter C is a clear (unfiltred) band.
The observation and reduction will continue.
The message may be cited.
GCN Circular 27802
Subject
GRB 200524A: CrAO observations of ZTF20abbiixp
Date
2020-05-24T20:53:20Z (5 years ago)
From
Alexei Pozanenko at IKI, Moscow <apozanen@iki.rssi.ru>
V. Rumyantsev (CrAO), A. Pozanenko (IKI), S. Belkin (IKI), E. Mazaeva
(IKI), A. Volnova (IKI) report on behalf of IKI-GRB-FuN:
We observed Fermi-LAT detected GRB 200524A (Dirirsa et al., GCN 27797)
with ZTSh 2.6m telescope of CrAO starting on 2020-05-24 (UT) 19:35:16.
We clearly detected the OT discovered by ZTF (Ho et al., GCN 27799); see
also Kumar et al. (GCN 27800). The R magnitude of the OT is 20.1 +/- 0.2
at the time of the first exposure. Observations and data reduction is
ongoing.
GCN Circular 27803
Subject
GRB 200524A: 3.6m DOT observations of the afterglow candidate ZTF20abbiixp
Date
2020-05-24T21:50:57Z (5 years ago)
From
Kuntal Misra at ARIES,India <kuntal@aries.res.in>
Pankaj Sanwal, Kuntal Misra, Ankur Ghosh, Dimple, Amit Kumar, Amar Aryan, Rahul Gupta, S. B. Pandey, Brijesh Kumar, T. S. Kumar and Amitesh Omar (ARIES) report on behalf of the GRB collaboration:
We observed the field of GRB 200524A (Fana Dirirsa et al., GCN 27797) with the 3.6m Devasthal Optical Telescope (DOT) located in Devasthal, India on 2020-05-24T19:18:00 (UT) using the recently commissioned ADFOSC instrument. We observed a sequence of 300 sec images in g, r and i bands. We clearly detect the optical transient discovered by ZTF (Ho et al., GCN 27799) and also reported by Kumar et al. (GCN 27800) and Rumyantsev et al. (GCN 27802). In the first r band image the afterglow has a r band magnitude of 21.1+/-0.03. Further processing of the data is in progress.
GCN Circular 27804
Subject
GRB 200524A: Correction to the GCN 27800
Date
2020-05-24T21:53:38Z (5 years ago)
From
Harsh Kumar at Indian Inst of Tech,Bombay <harshkosli13@gmail.com>
H. Kumar, V. Bhalerao(IITB), G. C. Anupama, S. Barway, U. Stanzin (IIA)
report on behalf of the GROWTH-India collaboration:
We mistakenly reported the wrong observation time in our previous GCN
27800. We deeply apologize for the confusion caused.
Here is the corrected GCN:-
-----------------------------------------------------------------
We followed up GRB 200524A (F. F. Dirirsa et al., GCN 27797, A. Ho et al.,
GCN 27799) with 0.7m GROWTH-India telescope. We obtained 600-sec exposures
in SDSS g, r, i filters starting at UT 2020-05-24T16:11:57 (~11.11 hrs
after the burst). We detect a faint transient with magnitudes r = 20.56 +/-
0.14 and i = 20.59 +/- 0.28 (calibrated against PanSTARRs PS1 data
release, Flewelling
et al., 2018). The source position matches with the likely afterglow
candidate by A. Ho et al. (GCN 27799). The fading rate is approximately 3
magnitudes in ~9.4 hours, consistent with the fading rate reported in the
ZTF GCN. We hereby, confirm ZTF20abbiixp as the afterglow of GRB 200524A.
We obtained the following photometric results:-
------------------------------------------------------------------
JD(Start) | T-T0(hrs) | Filter | Mag |
------------------------------------------------------------------
2458994.174 | 11.11 | g | > 21.01
2458994.183 | 11.33 | r | 20.56 +/- 0.14
2458994.191 | 11.52 | i | 20.59 +/- 0.28
------------------------------------------------------------------
Given the fast fading of the source, we encourage the followup of the
source. The magnitudes are not corrected for galactic extinction.
The GROWTH India Telescope (GIT) is a 70-cm telescope with a 0.7 degree
field of view, set up by the Indian Institute of Astrophysics and the
Indian Institute of Technology Bombay with support from the Indo-US Science
and Technology Forum (IUSSTF) and the Science and Engineering Research
Board (SERB) of the Department of Science and Technology (DST), Government
of India (https://sites.google.com/view/growthindia/). It is located at the
Indian Astronomical Observatory (Hanle), operated by the Indian Institute
of Astrophysics (IIA).
GCN Circular 27805
Subject
GRB 200524A: Liverpool Telescope observations
Date
2020-05-24T22:28:15Z (5 years ago)
From
Daniel Perley at Liverpool JMU <d.a.perley@ljmu.ac.uk>
D. A. Perley (LJMU) and Anna Ho (Caltech) report:
We observed the location of ZTF20abbiixp/AT2020krl (Ho et al., GCN
27799), the presumed optical afterglow of GRB 200524A (Fana Dirirsa et
al., GCN 27797), with the 2m robotic Liverpool Telescope between UT
2020-05-24 21:39 and 21:53. We acquired 120s of exposure time in each
of the u, g, r, i, and z filters. Photometry is as follows (all times
relative to the LAT trigger as reported in GCN 27797):
t_mid(d) filter magnitude
-------- ------ ----------
0.6921 z 20.49 +/- 0.15
0.6941 i 20.86 +/- 0.09
0.6961 r 21.03 +/- 0.07
0.6981 g 21.32 +/- 0.06
0.7000 u 21.64 +/- 0.24
DisclaimerNone
GCN Circular 27806
Subject
GRB 200524A: 1.3m DFOT Optical Observation of ZTF20abbiixp
Date
2020-05-24T22:32:48Z (5 years ago)
From
Amit Kumar at ARIES, India <amitkundu515@gmail.com>
A. Kumar (ARIES), S. B. Pandey (ARIES), A. Ghosh (ARIES), Dimple (ARIES),
K. Misra (ARIES), R. Gupta (ARIES), K. Chand (ARIES) and A. Aryan (ARIES)
report:
We observed the optical afterglow of GRB 200524A (F. F. Dirirsa et al., GCN
27797, Evans et al., GCN 27798) with the 1.3m Devasthal Fast Optical
Telescope (DFOT) at Aryabhatta Research Institute of Observational Sciences
(ARIES), Nainital (India), from 2020-05-24T19:50:12 UTC (corresponding to
~14.770 hours after
the burst).
We observed 5 frames each of 300 seconds in Bessell I filter. In the
stacked image, we clearly detected the optical afterglow of GRB 200524A
(detected by Ho et al., GCN 27799, see also Kumar et al., GCN 27800,
Rumyantsev et al., GCN 27802 and Sanwal et al., GCN 27803).
The observed magnitude is as follows:
T_start-T0 (hours) Start Date (UTC) End Date (UTC) Filter
Magnitudes (mag)
---------------------------------------------------------------------------------------------------------------
14.770 2020-05-24T19:50:12 2020-05-24T20:32:37 I
20.33 +- 0.07
Photometry is done based on the USNO-B1.0 catalog. The quoted magnitude is
not corrected for Galactic extinction.
GCN Circular 27807
Subject
GRB 200524A: CAHA multicolor afterglow detection
Date
2020-05-24T23:38:09Z (5 years ago)
From
Alexander Kann at IAA-CSIC <kann@iaa.es>
A. de Ugarte Postigo (HETH/IAA-CSIC, DARK/NBI), D. A. Kann, M. Blazek,
C. Thoene, J. F. Agui Fernandez (all HETH/IAA-CSIC), R. Pedro Hedrosa,
and A. Guijarro (both CAHA) report:
We observed the field of GRB 200524A (Fermi-LAT detection: Dirirsa et
al. GCN #27797) with CAFOS, on the 2.2 m telescope, at Calar Alto
observatory (Almeria, Spain). Observations consisted of 3 x 500 s in
BVRc each, and 8 x 180 s in Ic-band.
The afterglow (Ho et al., GCN #27799, Kumar et al., GCN #27800,
Rumyantsev et al., GCN #27802, Sanwal et al., GCN #27803, Perley et al.,
GCN #27805, Kumar et al., GCN #27806) is well-detected in each image. In
an Rc image starting at 21:49:33 UT (mid-time 0.701188 days after the
Fermi GBM trigger), we measure Rc = 20.86 +/- 0.12 mag (Vega mags)
against five nearby SDSS stars transformed to the Rc band.
GCN Circular 27809
Subject
GRB 200524A: Fermi GBM detection
Date
2020-05-25T00:03:51Z (5 years ago)
From
Stephen Lesage at Fermi-GBM Team <sjl0014@uah.edu>
S. Pookalil (UAH), B. Mailyan (Institute for Basic Science, South Korea),
and R. Hamburg (UAH)
report on behalf of the Fermi GBM Team:
"At 05:04:00.36 UT on 24 May 2020, the Fermi Gamma-Ray Burst Monitor (GBM)
triggered and located GRB 200524A (trigger 611989445 / GBM200524211),
which was also detected by the Fermi/LAT (Dirirsa et al. 2020, GCN 27797)
The Fermi GBM Final Real-time Localization is consistent with the LAT
position.
Swift has initiated a ToO observation of this burst (GCN 27798).
The angle from the Fermi LAT boresight at the GBM trigger time is 23
degrees.
The GBM light curve shows a multi-peaked structure
with a duration (T90) of about 38 s (50-300 keV).
The time-averaged spectrum from T0-1.5 s to T0+25.1 s is
best fit by a Band function with Epeak = 192 +/- 16 keV,
alpha = -0.66 +/- 0.06, and beta = -1.77 +/- 0.03
The event fluence (10-1000 keV) in this time interval is
(2.08 +/- 0.03)E-05 erg/cm^2. The 1-sec peak photon flux measured
starting from T0+5.3 s in the 10-1000 keV band
is 13.3 +/- 0.3 ph/s/cm^2.
The spectral analysis results presented above are preliminary;
final results will be published in the GBM GRB Catalog:
https://heasarc.gsfc.nasa.gov/W3Browse/fermi/fermigbrst.html
For Fermi GBM data and info, please visit the official Fermi GBM Support
Page:
https://fermi.gsfc.nasa.gov/ssc/data/access/gbm/"
GCN Circular 27810
Subject
GRB 200524A: OAJ multicolor afterglow detection
Date
2020-05-25T00:52:33Z (5 years ago)
From
Alexander Kann at IAA-CSIC <kann@iaa.es>
M. Blazek, D. A. Kann (both HETH/IAA-CSIC), A. de Ugarte Postigo
(HETH/IAA-CSIC, DARK/NBI), C. Thoene, J. F. Agui Fernandez (both
HETH/IAA-CSIC), and N. Maicas (CEFCA) report:
We observed the field of GRB 200524A (Fermi-LAT detection: Dirirsa et
al. GCN #27797, Fermi GBM detection: Pookalil et al., GCN #27809) with
the T80 0.8m telescope at the Observatorio de Javalambre (Teruel,
Spain). Observations consisted of 3 x 300 s in g', 2 x 300 s in r', and
5 x 180 s in i' and z' each.
The afterglow (Ho et al., GCN #27799, Kumar et al., GCN #27800,
Rumyantsev et al., GCN #27802, Sanwal et al., GCN #27803, Perley et al.,
GCN #27805, Kumar et al., GCN #27806, de Ugarte Postigo et al., GCN
#27807) is well-detected in each image. In the stacked r' image centered
at 21:59:24 UT (mid-time 0.705135 days after the Fermi GBM trigger), we
measure r' = 21.08 +/- 0.04 mag (AB mags) against PanSTARRS stars in the
field.
GCN Circular 27811
Subject
GRB 200524A: Swift-XRT afterglow detection
Date
2020-05-25T04:14:56Z (5 years ago)
From
Kim Page at U.of Leicester <klp5@leicester.ac.uk>
M. Capalbi (INAF-IASFPA), M. Perri (ASDC), V. D'Elia (ASDC), A.
Tohuvavohu (U. Toronto), B. Sbarufatti (PSU), D.N. Burrows (PSU), J.P.
Osborne (U. Leicester), K.L. Page (U. Leicester) and P.A. Evans (U.
Leicester) report on behalf of the Swift-XRT team:
Swift-XRT has performed follow-up observations of the
Fermi/LAT-detected burst GRB 200524A (Fana Dirirsa et al. GCN Circ.
27797), collecting 5.0 ks of Photon Counting (PC) mode data between
T0+36.4 ks and T0+55.7 ks.
Four uncatalogued X-ray sources are detected, of which one ("Source 6")
is believed to be the afterglow. Using 1644 s of PC mode data and 1
UVOT image, we find an enhanced XRT position (using the XRT-UVOT
alignment and matching UVOT field sources to the USNO-B1 catalogue):
RA, Dec = 213.04474, +60.90538 which is equivalent to:
RA (J2000): 14h 12m 10.74s
Dec(J2000): +60d 54' 19.4"
with an uncertainty of 4.4 arcsec (radius, 90% confidence). This
position is 9.2 arcmin from the Fermi/LAT position, and 3 arcsec from
ZTF20abbiixp (Ho et al., GCN 27799).
The light curve can be modelled with a power-law decay with a decay
index of alpha=3.42 (+0.06, -2.83).
The results of the XRT-team automatic analysis are available at
http://www.swift.ac.uk/xrt_products/00021001.
The results of the full analysis of the XRT observations are available
at https://www.swift.ac.uk/ToO_GRBs/00021001.
This circular is an official product of the Swift-XRT team.
GCN Circular 27813
Subject
GRB 200524A: MITSuME Akeno optical observation
Date
2020-05-25T07:18:07Z (5 years ago)
From
Ogawa Futa at Tokyo Institute of Technology <ogawa@hp.phys.titech.ac.jp>
F. Ogawa, R. Hosokawa, R. Adachi, K. L. Murata, M. Niwano, N.
Nakamura, Y. Yatsu, and N. Kawai (TokyoTech) report on behalf of the
MITSuME collaboration:
We observed the field of GRB 200524A (Fermi-LAT detection: Dirirsa et
al., GCN #27797, Fermi-GBM detection: Pookalil et al., GCN #27809,
Swift-XRT afterglow detection: Capalbi et al. GCN #27811, and others)
with the optical three color (g', Rc, and Ic) CCD cameras attached to
the MITSuME 50 cm telescope of Akeno Observatory, Yamanashi, Japan.
The observation started on 13:07:01.89 UT. We detected a point source
clearly in g' and Rc band, and marginally in Ic band at the position
consistent with the afterglow reported previously (Ho et al., GCN
#27799, Kumar et al., GCN #27800, Rumyantsev et al., GCN #27802,
Sanwal et al., GCN #27803, Perley et al., GCN #27805, Kumar et al.,
GCN #27806, de Ugarte Postigo et al., GCN #27807, Blazek et al., GCN
#27810). We measured the magnitudes as follows.
T0+[hour] MID-UT T-EXP[sec] measured magnitudes
------------------------------------------------------------------------------------------------
8.03 13:10:54 420 g'=19.6+/-0.3, Rc=19.5+/-0.3, Ic=19.4+/-0.5
------------------------------------------------------------------------------------------------
T0+: Elapsed time after the burst
T-EXP: Total Exposure time
We used GSC2.3 catalog for flux calibration. The magnitudes are
expressed in the Vega system. The images were processed in real-time
through the MITSuME GPU reduction pipeline (Niwano et al. ,in prep;
https://github.com/MNiwano/Eclair)
GCN Circular 27814
Subject
GRB 200524A: KAIT Optical Observations
Date
2020-05-25T08:57:28Z (5 years ago)
From
Weikang Zheng at UC Berkeley <weikang@berkeley.edu>
WeiKang Zheng and Alexei V. Filippenko (UC Berkeley) report on
behalf of the KAIT GRB team:
The 0.76-m Katzman Automatic Imaging Telescope (KAIT), located at
Lick Observatory, observed the field of GRB 200524A (Fermi-LAT
detection: Dirirsa et al., GCN 27797; Fermi GBM detection: Pookalil
et al., GCN 27809), starting at ~1.08 days after the burst.
We obtained 24x60s images in the clear (roughly R) filter. We detect
the optical afterglow at the location of ZTF20abbiixp/AT2020krl
(Ho et al., GCN 27799) in our co-added image. We estimate the afterglow,
which was also reported by other groups (Kumar et al., GCN 27800;
Rumyantsev et al., GCN 27802; Sanwal et al., GCN 27803; Perley et al.,
GCN 27805; Kumar et al., GCN 27806; de Ugarte Postigo et al., GCN
27807; Blazek et al., GCN 27810; Ogawa et al., GCN 27813), to be
21.2 +/- 0.2 magnitude in clear filter, calibrated to PS1 catalog.
GCN Circular 27817
Subject
GRB 200524A: Further Liverpool Telescope observations
Date
2020-05-25T11:26:47Z (5 years ago)
From
Luca Izzo at DARK/NBI <luca.izzo@gmail.com>
L. Izzo (DARK/NBI) reports:
We observed the field of GRB 200524A (Fermi-LAT detection: Dirirsa et al. GCN #27797, Fermi GBM detection: Pookalil et al., GCN #27809) with the IO:O camera mounted on the 2-m Liverpool Telescope located in La Palma, Spain. Observations started on May 25th at 01:08:27 UT (0.837 days after the GRB trigger) and we obtained a series of 5x60s images in the gri filters.
The afterglow (Ho et al., GCN #27799, Kumar et al., GCN #27800, Rumyantsev et al., GCN #27802, Sanwal et al., GCN #27803, Perley et al., GCN #27805, Kumar et al., GCN #27806, de Ugarte Postigo et al., GCN #27807, Blazek et al., GCN #27810, Ogawa et al., GCN #27813, Zheng et al., GCN #27814) is detected in all the stacked images. We measure a preliminary AB magnitude for the afterglow of g = 21.67 +- 0.35 mag (t_mid = 0.839 d), r = 21.37 +- 0.20 mag (t_mid = 0.844 d), i = 21.34 +- 0.25 mag(t_mid = 0.849 d) calibrated against Pan-STARRS catalogue stars.
GCN Circular 27818
Subject
GRB 200524A: AstroSat CZTI detection
Date
2020-05-25T14:44:59Z (5 years ago)
From
Soumya Gupta at IUCAA/ASTROSAT <soumya@iucaa>
S. Gupta, V. Sharma and D. Bhattacharya (IUCAA), V. Bhalerao (IIT-B), A. R. Rao (IUCAA/TIFR) and S. Vadawale (PRL) report on behalf of the AstroSat CZTI collaboration:
Analysis of AstroSat CZTI data showed the detection of a long GRB 200524A, which was also detected by Fermi-LAT (Dirirsa F. et al., GCN #27797), Swift (Evans P.et al., GCN # 27798), ZTF (Ho A. et al., GCN # 27799), GROWTH-India (Kumar H. et al., GCN # 27800), Global MASTER-Net (Lipunov V. et al., GCN # 27801), CrAO (Rumyantsev V. et al., GCN # 27802), 3.6m DOT (Sanwal P. et al., GCN # 27803), Liverpool (Perley D. et al., GCN # 27805), CAHA (Postigo A. et al., GCN # 27807), Fermi GBM (Pookalil S. et al., GCN # 27809), OAJ (Blazek M. et al., GCN # 27810) and Swift-XRT (Capalbi M. et al., GCN # 27811).
The source was clearly detected in the 40-200 keV energy range. The light curve showed multiple peaks of emission with the strongest peak at 2020-05-24 05:04:05.494 UT. The measured peak count rate associated with the burst is 303 +/- 22 cts/s above the background in the combined data of four quadrants, with a total of 2111 +/- 37 cts. The local mean background count rate was 537 +/- 1 cts/s. Using cumulative rates, we measure a T90 of 15.38 +/- 0.27 s.
It was also clearly detected in the CsI anticoincidence (Veto) detector in the 100-500 keV energy range. The light curve showed multiple peaks of emission with the strongest peak at 2020-05-24 05:04:04.236 UT. The measured peak count rate is 430 +/- 40 cts/s above the background in the combined Veto data of four quadrants, with a total of 2951 +/- 79 cts. The local mean background count rate was 1623 +/- 3 cts/s. We measure a T90 of 16.89 +/- 0.67 s from the cumulative Veto light curve.
CZTI GRB detections are reported regularly on the payload site at http://astrosat.iucaa.in/czti/?q=grb. CZTI is built by a TIFR-led consortium of institutes across India, including VSSC, ISAC, IUCAA, SAC and PRL. The Indian Space Research Organisation funded, managed and facilitated the project.
GCN Circular 27820
Subject
GRB 200524A: Kitab observatory afterglow observations
Date
2020-05-25T15:37:06Z (5 years ago)
From
Alexei Pozanenko at IKI, Moscow <apozanen@iki.rssi.ru>
S. Belkin (IKI), A. Novichonok (Petrozavodsk State University, KIAM), A.
Pozanenko (IKI), E. Mazaeva (IKI), A. Volnova (IKI), I. Molotov
(KIAM), Sh. Ehgamberdiev (UBAI) report on behalf of IKI-GRB-FuN:
We observed Fermi-LAT detected localization area of GRB 200524A (Dirirsa
et al., GCN 27797; see also Pookalil et al., GCN 27809; Capalbi et al.,
GCN 27811; Gupta et al., GCN 27818) with Kitab-ISON RC-36 telescope
starting on 2020-05-24 (UT) 19:07:41. In a stacked image in Clear filter
(CR) we marginally detected optical afterglow discovered by ZTF (Ho et
al., GCN 27799) and confirmed by several observations (Kumar et al. GCN
27800; (Kumar et al., GCN 27800; Rumyantsev et al., GCN 27802; Sanwal et
al., GCN 27803; Perley et al., GCN 27805; Kumar et al., GCN 27806; de
Ugarte Postigo et al., GCN 27807; Blazek et al., GCN 27810; Ogawa et
al., GCN 27813; Izzo, GCN 27817). Preliminary photometry is following
Date, UT start, t-T0, Exp., Filter, OT, Err., UL
(mid, days)
2020-05-24 19:07:41 0.60673 60*60 CR 20.48 0.25 21.0
The photometry is based on nearby USNO-B1.0 stars
USNO-B1.0_id R2
1508-0206198 15.78
1509-0204466 16.48
1509-0204434 16.53
GCN Circular 27821
Subject
GRB 200524A: CrAO optical observations
Date
2020-05-25T16:02:51Z (5 years ago)
From
Alexei Pozanenko at IKI, Moscow <apozanen@iki.rssi.ru>
S. Belkin (IKI), A. Pozanenko (IKI), V. Rumyantsev (CrAO), A. Volnova
(IKI), E. Mazaeva (IKI) report on behalf of larger GRB follow-up
collaboration:
We observed Fermi-LAT GRB 200524A (Dirirsa et al., GCN 27797; see also
Pookalil et al., GCN 27809; Capalbi et al., GCN 27811; Gupta et al.,
GCN 27818) with ZTSH 2.6m telescope of CrAO observatory starting on
2020-05-24 (UT) 19:35:16 (Rumyantsev et al., GCN 27802). Optical
afterglow discovered by ZTF (Ho et al., GCN 27799) and confirmed by
several observations (Kumar et al., GCN 27800; Rumyantsev et al., GCN
27802; Sanwal et al., GCN 27803; Perley et al., GCN 27805; Kumar et al.,
GCN 27806; de Ugarte Postigo et al., GCN 27807; Blazek et al., GCN
27810; Ogawa et al., GCN 27813; Izzo, GCN 27817). Preliminary photometry
of the afterglow is following
Date, UT start, t-T0, Exp., Filter, OT, Err., UL
(mid, days)
2020-05-24 19:35:16 0.60644 240 R 20.43 0.05 22.6
2020-05-24 19:39:28 0.60935 240 R 20.48 0.05 22.7
2020-05-24 19:43:39 0.61226 240 R 20.52 0.05 22.7
2020-05-24 19:47:52 0.61519 240 R 20.55 0.05 22.6
2020-05-24 19:52:03 0.61809 240 R 20.60 0.08 22.5
2020-05-24 19:56:15 0.62101 240 R 20.59 0.09 22.5
2020-05-24 20:00:27 0.62392 240 R 20.60 0.09 22.3
The photometry is based on nearby USNO-B1.0 stars
USNO-B1.0_id R2
1508-0206198 15.78
1509-0204466 16.48
1509-0204434 16.53
GCN Circular 27824
Subject
GRB 200524A: optical upper limits from further MITSuME Akeno observation
Date
2020-05-26T07:22:56Z (5 years ago)
From
Ryohei Hosokawa at Tokyo Institute of Technology <hosokawa@hp.phys.titech.ac.jp>
R. Hosokawa, N. Nakamura, K. L. Murata, R. Adachi, M. Niwano, F.
Ogawa, Y. Yatsu, and N. Kawai (TokyoTech) report on behalf of the
MITSuME collaboration:
We performed further observation of the field of GRB 200524A
(Fermi-LAT detection: Dirirsa et al., GCN #27797, Fermi-GBM detection:
Pookalil et al., GCN #27809, Swift-XRT afterglow detection: Capalbi et
al. GCN #27811, and others) with the optical three color (g', Rc, and
Ic) CCD cameras attached to the MITSuME 50 cm telescope of Akeno
Observatory, Yamanashi, Japan.
The observation started on 2020-05-25 11:27:25.65 UT. We did not
detect the optical afterglow (Ho et al., GCN #27799, Kumar et al., GCN
#27800, Rumyantsev et al., GCN #27802, Sanwal et al., GCN #27803,
Perley et al., GCN #27805, Kumar et al., GCN #27806, de Ugarte Postigo
et al., GCN #27807, Blazek et al., GCN #27810, Ogawa et al., GCN
#27813, Zheng et al., GCN #27814, Izzo et al., GCN #27817, Belkin et
al., GCN #27820, Belkin et al., GCN #27821) in the stacked images. We
obtained the 5-sigma limits as follows.
T0+[hour] MID-UT T-EXP[sec] 5-sigma limits
------------------------------------------------------------------------------------------------
30.5 2020-05-25 11:34:26 660 g'>18.7, Rc>18.7, Ic>18.0
------------------------------------------------------------------------------------------------
T0+: Elapsed time after the burst
T-EXP: Total Exposure time
We used the GSC2.3 catalog for flux calibration. The magnitudes are
expressed in the Vega system. The images were processed in real-time
through the MITSuME GPU reduction pipeline (Niwano et al. ,in prep;
https://github.com/MNiwano/Eclair)
GCN Circular 27825
Subject
GRB200524A: UVOT detection
Date
2020-05-26T13:49:24Z (5 years ago)
From
Paul Kuin at MSSL <npkuin@gmail.com>
N.P.M. Kuin (MSSL/UCL) and K.L. Page (U. Leicester) report on
behalf of the Swift UVOT team
Swift UVOT did a further follow up of the Fermi-LAT detected GRB200524A
(Dirirsa et al. GCN Circ. 27797). We detect the afterglow discovered
by Ho et al. (GCN Circ. 27799), ZTF20abbiixp, in the UVOT white filter
in 5.4ks exposure taken between To+1.15d and To+1.57d, with
white = 22.06 +/- 0.12 magnitudes (on the UVOT photometric system,
Breeveld et al. 2011, AIP Conf. Proc. 1358, 373 ). The source
does not vary significantly during these observations.
No correction has been made for the Galactic reddening E(B-V)=0.02
(Schlafy et al., ApJ 737, 10, 2011)
GCN Circular 27830
Subject
GRB 200524A: Assy optical observations
Date
2020-05-27T15:13:26Z (5 years ago)
From
Alexei Pozanenko at IKI, Moscow <apozanen@iki.rssi.ru>
S. Belkin (IKI), V. Kim (AFIF, Pulkovo Observatory), A. Pozanenko (IKI),
M. Krugov (AFIF), E. Mazaeva (IKI), A. Volnova (IKI) report on
behalf of larger GRB IKI FuN collaboration:
We observed Fermi-LAT GRB 200524A (Dirirsa et al., GCN 27797; see also
Pookalil et al., GCN 27809; Capalbi et al., GCN 27811; Gupta et al.,
GCN 27818) with AZT-20 1.5 m telescope of Assy-Turgen observatory
starting on May. 26 (UT) 15:34:49 in r'-filter. Optical afterglow
discovered by ZTF (Ho et al., GCN 27799) and observed by several
observations (Kumar et al., GCN 27800; Rumyantsev et al., GCN 27802;
Sanwal et al., GCN 27803; Perley et al., GCN 27805; Kumar et al., GCN
27806; de Ugarte Postigo et al., GCN 27807; Blazek et al., GCN 27810;
Ogawa et al., GCN 27813; Izzo, GCN 27817; Belkin et al., GCN 27820; Kuin
et al., GCN 27825). Preliminary photometry of the afterglow is following
Photometry of the field is following.
Date UT start t-T0 Filter Exp. OT Err. UL (3sigma)
(mid, days) (s)
2020-05-26 15:34:49 2.4721 r'(AB) 98*60 22.57 0.10 24.4
The photometry is based on the nearby stars of PS1 catalog.
PanSTARRS-PS1_id r
181072130294808209 20.4066
181072130171186332 20.9877
181082129951473104 20.1196
GCN Circular 27850
Subject
GRB 200524A: Assy continued optical observations
Date
2020-05-29T08:45:32Z (5 years ago)
From
Alexei Pozanenko at IKI, Moscow <apozanen@iki.rssi.ru>
S. Belkin (IKI), V. Kim (AFIF, Pulkovo Observatory), A. Pozanenko (IKI),
M. Krugov (AFIF), E. Mazaeva (IKI), A. Volnova (IKI) report on
behalf of larger GRB IKI FuN collaboration:
We observed GRB 200524A (Dirirsa et al., GCN 27797; Pookalil et al.,
GCN 27809; Capalbi et al., GCN 27811; Gupta et al., GCN 27818) with
AZT-20 1.5 m telescope of Assy-Turgen observatory starting on May. 27
(UT) 17:29:53 in r'-filter. Optical afterglow discovered by ZTF (Ho et
al., GCN 27799) and observed by several observations (Kumar et al., GCN
27800; Rumyantsev et al., GCN 27802; Sanwal et al., GCN 27803; Perley et
al., GCN 27805; Kumar et al., GCN 27806; de Ugarte Postigo et al., GCN
27807; Blazek et al., GCN 27810; Ogawa et al., GCN 27813; Izzo, GCN
27817; Belkin et al., GCN 27820; Kuin et al., GCN 27825).
Preliminary photometry of the afterglow is following
Date UT start t-T0 Filter Exp. OT Err. UL (3sigma)
(mid, days) (s)
2020-05-27 17:29:53 3.55617 r'(AB) 110*60 22.80 0.17 24.4
The photometry is based on the nearby stars of PS1 catalog.
GCN Circular 27851
Subject
GRB 200524A: SAO RAS optical observations
Date
2020-05-29T09:29:23Z (5 years ago)
From
Alexei Pozanenko at IKI, Moscow <apozanen@iki.rssi.ru>
S. Belkin (IKI), A. Moskvitin (SAO RAS), A. Pozanenko (IKI), E. Mazaeva
(IKI), A. Volnova (IKI) report on behalf of larger GRB IKI FuN
collaboration:
We observed GRB 200524A (Dirirsa et al., GCN 27797; Pookalil et al.,
GCN 27809; Capalbi et al., GCN 27811; Gupta et al., GCN 27818) with
Zeiss-1.0 m telescope of SAO RAS observatory in Rc-filter. Optical
afterglow discovered by ZTF (Ho et al., GCN 27799) and observed by
several observations (Kumar et al., GCN 27800; Rumyantsev et al., GCN
27802; Sanwal et al., GCN 27803; Perley et al., GCN 27805; Kumar et al.,
GCN 27806; de Ugarte Postigo et al., GCN 27807; Blazek et al., GCN
27810; Ogawa et al., GCN 27813; Izzo, GCN 27817; Belkin et al., GCN
27820; Kuin et al., GCN 27825).
Preliminary photometry is following
Date UT start t-T0 Filter Exp. OT Err. UL (3sigma)
(mid, days) (s)
2020-05-27 21:48:28 3.71143 Rc 2400 22.54 0.20 23.6
2020-05-28 22:17:40 4.73171 Rc 2400 n/d n/d 22.6
The photometry is based on the nearby stars of SDSS DR12 catalog and
Lupton' transformation gri -> R.
GCN Circular 27867
Subject
Konus-Wind observation of GRB 200524A
Date
2020-05-30T14:10:03Z (5 years ago)
From
Dmitry Svinkin at Ioffe Institute <svinkin@mail.ioffe.ru>
D. Svinkin, S. Golenetskii, R. Aptekar, D. Frederiks,
M. Ulanov, A. Tsvetkova, A. Lysenko, A. Ridnaia, and T. Cline
on behalf of the Konus-Wind team, report:
The long-duration GRB 200524A
(Fermi-LAT detection: Fana Dirirsa et al., GCN Circ. 27797;
Fermi-GBM detection: Pookalil et al., GCN Circ. 27809;
AstroSat-CZTI detection: Gupta et al., GCN Circ. 27818)
triggered Konus-Wind at T0=18243.246 s UT (05:04:03.246).
The burst light curve shows a multipeaked structure
which starts at ~T0-4.8 s, peaks at ~T0-3.3 s,
and to background level at ~T0+84 s.
The total burst duration is ~89 s.
The emission is seen up to ~10 MeV.
The Konus-Wind light curve of this GRB is available at
http://www.ioffe.ru/LEA/GRBs/GRB200524_T18243/
As observed by Konus-Wind, the burst
had a fluence of 3.48(-0.62,+0.74)x10^-5 erg/cm2,
and a 64-ms peak flux, measured from T0+3.280 s,
of 6.33(-1.64,+1.75)x10^-6 erg/cm2/s
(both in the 20 keV - 10 MeV energy range).
The time-averaged spectrum of the burst
(measured from T0 to T0+40.704 s)
is best fit in the 20 keV - 10 MeV range
by the GRB (Band) model with the following parameters:
the low-energy photon index alpha = -0.75(-0.18,+0.25),
the high energy photon index beta = -2.13(-0.31,+0.20),
the peak energy Ep = 215(-46,+48) keV
(chi2 = 105/97 dof).
The spectrum near the maximum count rate
(measured from T0+0.256 to T0+7.936 s)
is best fit in the 20 keV - 10 MeV range
by the GRB (Band) model with the following parameters:
the low-energy photon index alpha = -0.55(-0.18,+0.26),
the high energy photon index beta = -2.14(-0.21,+0.16),
the peak energy Ep = 203(-36,+36) keV
(chi2 = 130/97 dof).
All the quoted errors are at the 90% confidence level.
All the quoted values are preliminary.
GCN Circular 29673
Subject
GRB 200524A: Redshift from Gemini-North
Date
2021-03-19T18:16:33Z (4 years ago)
From
Yuhan Yao at Caltech <yyao@astro.caltech.edu>
Yuhan Yao (Caltech), Adam Miller (Northwestern), Anna Ho (UCB), Daniel Perley (LJMU)
We observed ZTF20abbiixp/AT2020kym (Ho et al., GCN #27799), the afterglow of the long-duration GRB 200524A (Pookalil et al., GCN #27809; Fana Dirirsa et al., GCN #27797; Gupta et al., GCN #27818; Svinkin et al., GCN #27867), with GMOS-N under our ToO program GN-2020A-Q-117 (PI: Miller). The observation, conducted in the Nod-and-Shuffle mode with a 1 arcsec slit, started at 2020-05-25 07:39:14.9 UT, corresponding to 26.6 hours after the Fermi-GBM trigger (Pookalil et al., GCN #27809). A power-law fit to the afterglow light curve (Ho et al., GCN #27799; Kumar et al., GCN #27800, #27804; Perley & Ho, GCN #27805) suggests that ZTF20abbiixp was at r=21.5 and g=21.8 at the time of Gemini observation.
We obtained 3 x 550 s spectroscopic exposures with the B600 grating and 3 x 550 s exposures with the R400 grating, providing coverage over the range 3620-9600 AA. No flux calibration was performed. The spectrum was reduced using the IRAF package for GMOS. A trace was detected redwards of 4900 AA. Bluewards of 4900 AA, the source was not significantly detected, probably because of the faintness of the object, the intrinsic red color of the afterglow (g-r ~ 0.3 mag) and low sensitivity at the blue end.
We clearly identified absorption lines of Mg II 2796 and Mg II 2803 at the redshift of z = 1.256 in the three individual exposures. Absorption from Mg I 2852 is marginally detected in the combined spectrum at consistent redshift. We therefore identify z=1.256 as the most probable redshift for the GRB, although in practice this is only a lower limit. The lack of a DLA or Lyman break places an upper limit of z < 3.