GRB 210722A
GCN Circular 31754
Subject
GRB 210722A: TAROT Reunion observatory optical light curve
Date
2022-03-13T22:11:59Z (4 years ago)
From
Alain Klotz at IRAP-CNRS-OMP <Alain.Klotz@free.fr>
A. Klotz (CNRS-OMP-IRAP),
M. Fortune, R. Augerai (Universite de la Renuion),
P. Thierry�� (AGORA),
L. Eymar, S. Antier, M. Boer, A. de Ugarte Postigo (CNRS-OCA-ARTEMIS),
We analyzed archive images of the SWIFT trigger 1061223 (GRB 210722A,
BAT detection by D'Avanzo et al. GCN Circ. 30475,
early optical ground observations by Zhu et al. GCN Circ. 30476,
redshift by Thoene et al. GCN Circ. 30487)
with the TAROT robotic telescope (D=18cm) located
at Les Makes Observatory, Reunion Island, France.
Images were acquired without any filter, camera FLI PL16803
and Takahashi Epsilon 180ED.
According the reference star NOMAD-1 0836-0016935 R=12.57
we give the photometry of the GRB optical transient:
t1(s) t2(s)�������� R�� dmag
��2170�� 2935 16.08�� 0.16
��2944�� 4067 16.24�� 0.12
��4074�� 4653 16.78�� 0.14
��4659�� 5238 16.60�� 0.14
��5244�� 6744 17.04�� 0.22
t1 and t2 are start and stop acquisition since the trigger.
Magnitudes are not corrected for Galactic dust extinction.
GCN Circular 30505
Subject
GRB 210722A: continued Assy optical observations
Date
2021-07-25T08:13:48Z (4 years ago)
From
Alexei Pozanenko at IKI, Moscow <apozanen@iki.rssi.ru>
V. Kim (FAI, Pulkovo Observatory), A. Pozanenko (IKI), N. Pankov (HSE,
IKI), M. Krugov (FAI), S. Belkin (IKI) report on behalf of GRB IKI FuN:
We continue observations of of the field of GRB 210722A (D'Avanzo et
al., GCN 30475; Page et al., GCN 30483; Barthelmy et al. GCN 30489;
Wood et al., GCN30490) with AZT-20 telescope of Assy-Turgen
observatory. We obtained several frames in r' - filter starting on
21-07-24 (UT) 21:34:39. We clearly detect the bright optical afterglow
(D'Avanzo et al., GCN 30475; Zhu et al., GCN 30476; Pankov et al., GCN
30478, 30488, 30494; Kumar et al., GCN 30481; Butler et al., GCN 30484;
Thoene et al., GCN 30487; Jelinek et al., GCN 30492; Fu et al., GCN 30504).
Preliminary photometry of the afterglow in the stacked image is following
Date UT start t-T0 Exp. Filter OT Err. UL(3sigma)
(mid, days) (s) (AB)
2021-07-24 20:56:07 n/d 42*60 r' 21.3 0.2 21.7
The photometry is based on the nearby PS1 stars.
The photometry is still compatible with the single power law of the
afterglow light curve.
GCN Circular 30504
Subject
GRB 210722A: Nanshan/NEXT further optical observations
Date
2021-07-25T07:56:29Z (4 years ago)
From
Dong Xu at NAOC/CAS <dxu@nao.cas.cn>
S.Y. Fu (NAOC), Z.P. Zhu (NAOC, HUST), X. Liu, D. Xu (NAOC), X. Gao
(Urumqi No.1 Senior High School), J.Z. Liu (XAO) report:
We continued to observe the field of GRB 210722A (D'Avanzo et al., GCN
30475) using the NEXT-0.6m telescope located at Nanshan, Xinjiang,
China. We obtained 15x200 s frames in the Sloan r-band, starting at
20:41:20 UT on 2021-07-24, i.e., 1.99 days after the burst.
The previously reported optical afterglow (e.g., D'Avanzo et al., GCN
30475; Zhu et al., GCN 30476) is not detected in our stacked image, down
to a limiting magnitude of r~21.0, calibrated with the nearby PanSTARRS
field.
GCN Circular 30494
Subject
GRB 210722A: continued Assy optical observations
Date
2021-07-24T12:10:35Z (4 years ago)
From
Alexei Pozanenko at IKI, Moscow <apozanen@iki.rssi.ru>
N. Pankov (HSE, IKI), V. Kim (FAI, Pulkovo Observatory), A. Pozanenko
(IKI), M. Krugov (FAI), S. Belkin (IKI) report on behalf of GRB IKI FuN:
We continue observations of of the field of GRB 210722A (D'Avanzo et
al., GCN 30475; Page et al., GCN 30483; Barthelmy et al. GCN 30489;
Wood et al., GCN30490) with AZT-20 telescope of Assy-Turgen
observatory. We obtained several frames in r' - filter starting on
21-07-23 (UT) 21:34:39. We clearly detect the bright optical afterglow
(D'Avanzo et al., GCN 30475; Zhu et al., GCN 30476; Pankov et al., GCN
30478 & 30488; Kumar et al., GCN 30481; Butler et al., GCN 30484;
Thoene et al., GCN 30487; Jelinek et al., GCN 30492).
Preliminary photometry of the afterglow in the stacked image is following
Date UT start t-T0 Exp. Filter OT Err. UL(3sigma)
(mid, days) (s) (AB)
2021-07-23 21:34:39 1.03677 26*60 r' 20.37 0.07 22.5
The photometry is based on the nearby PS1 stars.
The light curve can still be approximated by a single power law with a
an index of -1.1.
GCN Circular 30492
Subject
GRB 210722A: D50 optical detection
Date
2021-07-24T08:40:09Z (4 years ago)
From
Martin Jelinek at Astro.Inst-AVCR,Ondrejov <martin.jelinek@asu.cas.cz>
M. Jelinek, J. Strobl, R. Hudec, C. Polasek (ASU CAS Ondrejov) report:
We observed the position of the bright GRB 210722A (D'Avanzo et al., GCN
30475; Page et a., GCN 30483; Barthelmy et al. GCN 30489; and Wood, GCN
30490) with the D50 telescope of the Astronomical Institute Ondrejov, near
Prague, Czech Republic. We performed a set of 35x 60s exposures in SDSS-i'
filter on July 24 from 1:20 to 2:01 UT.
The optical afterglow (Zhu et al., GCN 30476; Pankov et al., GCN 30478 &
30488; Kumar et al., GCN 30481; Butler et al., GCN 30484; and Thoene et
al., GCN 30487) is weakly detected in the overall combined image with the
exposure mean time 28.9h after trigger. The Atlas-calibrated magnitude of
the object is i' = 19.8 +/- 0.4.
GCN Circular 30490
Subject
GRB 210722A: Fermi GBM observation
Date
2021-07-23T21:29:26Z (4 years ago)
From
Joshua Wood at MSFC/Fermi-GBM <joshua.r.wood@nasa.gov>
J. Wood (NASA/MSFC)
reports on behalf of the Fermi GBM Team:
"At 20:54:40.87 UT on 22 July 2021, the Fermi Gamma-Ray Burst Monitor (GBM)
triggered and located GRB 210722A (trigger 648680085 / 210722871)
which was also detected by the Swift/BAT and Swift/XRT (P. D'Avanzo et al. 2021, GCN 30475).
The GBM on-ground location is consistent with the Swift position.
The GBM light curve consists of a single peak
with a duration (T90) of about 62 s (50-300 keV).
The time-averaged spectrum from T0-1.5 s to T0+62 s is
well fit by a power law function with an exponential
high-energy cutoff. The power law index is -1.1 +/- 0.1 and
the cutoff energy, parameterized as Epeak, is 160 +/- 30 keV
The event fluence (10-1000 keV) in this time interval is
(5.8 +/- 0.6)E-06 erg/cm^2. The 1-sec peak photon flux measured
starting from T0+2.3 s in the 10-1000 keV band
is 4.0 +/- 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 30489
Subject
GRB 210722A: Swift-BAT refined analysis
Date
2021-07-23T20:37:20Z (4 years ago)
From
Amy Lien at GSFC <amy.y.lien@nasa.gov>
S. D. Barthelmy (GSFC), P. D'Avanzo (INAF-OAB)
H. A. Krimm (NSF), S. Laha (GSFC/UMBC),
A. Y. Lien (GSFC/UMBC), C. B. Markwardt (GSFC),
D. M. Palmer (LANL), T. Sakamoto (AGU),
M. Stamatikos (OSU), T. N. Ukwatta (LANL)
(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 210722A (trigger #1061223)
(D'Avanzo et al., GCN Circ. 30475). The BAT ground-calculated position is
RA, Dec = 27.031, -6.347 deg which is
RA(J2000) = 01h 48m 07.4s
Dec(J2000) = -06d 20' 49.9"
with an uncertainty of 1.2 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 43%.
The mask-weighted light curve shows a single-peaked structure that
starts at ~T-5 s, peaks at ~T0, and ends at ~T+30 s, with
some weak tail emission that lasts until ~T+60 s. T90 (15-350 keV)
is 50.20 +- 10.54 sec (estimated error including systematics).
The time-averaged spectrum from T-4.40 to T+59.59 sec is best fit by
a simple power-law model. The power law index of the time-averaged
spectrum is 1.62 +- 0.14. The fluence in the 15-150 keV band
is 2.5 +- 0.2 x 10^-06 erg/cm2. The 1-sec peak photon flux measured
from T+1.00 sec in the 15-150 keV band is 2.2 +- 0.5 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/1061223/BA/
GCN Circular 30488
Subject
GRB 210722A: Kitab optical observations, light curve
Date
2021-07-23T17:59:25Z (4 years ago)
From
Alexei Pozanenko at IKI, Moscow <apozanen@iki.rssi.ru>
N. Pankov (IKI, HSE), A. Zhornichenko (KIAM), A. Pozanenko (IKI), V.
Agletdinov (KIAM), M. Krugov (FAI), V. Kim (FAI), S. Belkin (IKI), Sh.
Ehgamberdiev (UBAI) report on behalf of IKI-GRB-FuN:
We observed the field of GRB 210722A (D'Avanzo et al., GCN 30475) with
Kitab-ISON RC-36 telescope in Clear filter. Observation started on
July, 22 (UT) 21:31:44 and ended on July, 22 (UT) 23:20:06. We clearly
detect the bright optical afterglow (D'Avanzo et al., GCN 30475; Zhu et
al., GCN 30476; Pankov et al., GCN 30478; Lipunov et al., GCN 30480;
Kumar et al., GCN 30481; Siegel et al., GCN 30421; Butler et al., GCN
30484).
Preliminary photometry of the first and latest combined images are following
Date, UT start, t-T0, Exp., Filter, OT, Err, UL(3 sigma)
(mid, days)
2021-07-22 21:31:44 0.02572 5*60 CR 16.00 0.15 18.4
2021-07-22 23:13:54 0.09667 7*60 CR 17.33 0.12 19.0
The photometry is based on nearby USNO-B1.0 stars, R2 magnitude.
USNO-B1.0_id R2
USNO_B10-0836-00016699
USNO_B10-0836-00016715
We approximate the light curve by single PL model with power law index
of -1.1 which is corroborating with PL index reported by Kumar et al.
(GCN 30481). The light curve of our observations in Assy (Pankov et
al., GCN 30478) and Kitab observatory can be found at
http://grb.rssi.ru/GRB210722A/GRB210722A_LC.jpeg
GCN Circular 30487
Subject
GRB 210722A: Redshift from OSIRIS/GTC
Date
2021-07-23T17:50:29Z (4 years ago)
From
C. C. Thoene at HETH/IAA-CSIC <christina.thoene@gmail.com>
C. C. Thoene (HETH/IAA-CSIC), A. de Ugarte Postigo (HETH/IAA-CSIC,
DARK/NBI), D. A. Kann, M. Blazek, J. F. Agui Fernandez (all
HETH/IAA-CSIC), J. P. U Fynbo (DAWN/NBI), L. Izzo (DARK/NBI), N. R. Tanvir
(U. Leicester) and N. Castro (GTC) report:
We obtained spectroscopy of the afterglow of GRB 210722A (D���Avanzo et al.
GCN #30475, Page et al. GCN #30483, Zhu et al. GCN #30476) with OSIRIS
mounted on the 10.4 m GTC telescope at the Roque de los Muchachos
observatory (La Palma, Spain). Observations started at 05:02:09 UT with a
mid-time of 05:17:30 UT (8.38 hr after the burst) and consisted of 2x900s
spectra taken with grism R1000B, which covers the spectral range between
3700 and 7800 AA. We also obtained an acquisition image of 60s in r'-band
at 04:58:25 UT. Observing conditions were rather bad with a seeing of 1.7
arcsec and taken during morning twilight.
We detect several weak absorption lines, consistent with the MgII doublet,
FeII 2344, 2374, 2383, 2587 and 2600 at a common redshift of z=1.145. The
lines are in the weakest 1.7% of the average GRB absorption line strength
(de Ugarte Postigo et al. 2012, A&A 548, 11). The detection of the
afterglow in all UVOT filters (Siegel et al. GCN #30482) is consistent with
this redshift.
The acquisition image shows the afterglow to be r��� = 18.92 +/- 0.03
compared to 7 SDSS field stars.
GCN Circular 30484
Subject
GRB 210722A: RATIR Optical Observations
Date
2021-07-23T14:49:14Z (4 years ago)
From
Nat Butler at Az State U <natbutler@asu.edu>
Nat Butler (ASU), Alan M. Watson (UNAM), Alexander Kutyrev (GSFC), William
H. Lee (UNAM), Michael G. Richer (UNAM), Ori Fox (STScI), J. Xavier
Prochaska (UCSC), Josh Bloom (UCB), Antonino Cucchiara (UVI), Eleonora
Troja (GSFC), Owen Littlejohns (ASU), Enrico Ramirez-Ruiz (UCSC), Jes��s
Gonz��lez (UNAM), Carlos Rom��n-Z����iga (UNAM), Harvey Moseley (GSFC), John
Capone (UMD), V. Zach Golkhou (U. Wash.), and Vicki Toy (UMD) report:
We observed the field of GRB 210722A (D'Avanzo, et al., GCN 30475) with the
Reionization and Transients Infrared Camera (RATIR) on the 1.5m Harold
Johnson Telescope at the Observatorio Astron��mico Nacional on Sierra San
Pedro M��rtir from 2021/07 23.40 to 2021/07 23.48 UTC (12.43 to 14.36 hours
after the BAT trigger), obtaining a total of 1.22 hours exposure in the r
and i bands.
In comparison with the SDSS DR9 and 2MASS catalogs, we obtain the following
detections of the optical afterglow:
r = 19.41 +/- 0.05
i = 19.35 +/- 0.04
These magnitudes are in the AB system and are not corrected for Galactic
extinction in the direction of the GRB.
We thank the staff of the Observatorio Astron��mico Nacional in San Pedro
M��rtir.
GCN Circular 30483
Subject
GRB 210722A: Swift-XRT refined Analysis
Date
2021-07-23T14:27:18Z (4 years ago)
From
Phil Evans at U of Leicester <pae9@leicester.ac.uk>
K.L. Page (U. Leicester), A.P. Beardmore (U. Leicester), P.A. Evans (U.
Leicester), M.G. Bernardini (INAF-OAB), E. Ambrosi (INAF-IASFPA) , M.
Capalbi (INAF-IASFPA), J. D. Gropp (PSU), J.A. Kennea (PSU), A.
Tohuvavohu (U. Toronto) and P. D'Avanzo report on behalf of the
Swift-XRT team:
We have analysed 6.3 ks of XRT data for GRB 210722A (D'Avanzo et al.
GCN Circ. 30475), from 91 s to 47.1 ks after the BAT trigger. The data
comprise 294 s in Windowed Timing (WT) mode with the remainder in
Photon Counting (PC) mode. Using 3301 s of PC mode data and 8 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 =
27.03023, -6.34758 which is equivalent to:
RA (J2000): 01h 48m 07.26s
Dec(J2000): -06d 20' 51.3"
with an uncertainty of 2.0 arcsec (radius, 90% confidence).
The late-time light curve (from T0+4.5 ks) can be modelled with a
power-law decay with a decay index of alpha=1.31 (+0.10, -0.09).
A spectrum formed from the WT mode data can be fitted with an absorbed
power-law with a photon spectral index of 2.20 (+/-0.05). The
best-fitting absorption column is 4.2 (+1.0, -0.9) x 10^20 cm^-2, in
excess of the Galactic value of 2.2 x 10^20 cm^-2 (Willingale et al.
2013). The PC mode spectrum has a photon index of 1.84 (+0.11, -0.10)
and a best-fitting absorption column of 3.5 (+2.4, -1.2) x 10^20 cm^-2.
The counts to observed (unabsorbed) 0.3-10 keV flux conversion factor
deduced from this spectrum is 3.5 x 10^-11 (3.8 x 10^-11) erg cm^-2
count^-1.
A summary of the PC-mode spectrum is thus:
Total column: 3.5 (+2.4, -1.2) x 10^20 cm^-2
Galactic foreground: 2.2 x 10^20 cm^-2
Excess significance: <1.6 sigma
Photon index: 1.84 (+0.11, -0.10)
If the light curve continues to decay with a power-law decay index of
1.31, the count rate at T+24 hours will be 0.013 count s^-1,
corresponding to an observed (unabsorbed) 0.3-10 keV flux of 4.4 x
10^-13 (4.8 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/01061223.
This circular is an official product of the Swift-XRT team.
GCN Circular 30482
Subject
GRB 210722A: Swift/UVOT Detection
Date
2021-07-23T13:46:11Z (4 years ago)
From
Mike Siegel at PSU/Swift MOC <mhs18@psu.edu>
M. H. Siegel (PSU) and P. D'Avanzo (INAF-OAB)
report on behalf of the Swift/UVOT team:
The Swift/UVOT began settled observations of the field of GRB 210722A
94 s after the BAT trigger (D'Avanzo et al., GCN Circ. 30475).
A source consistent with the XRT position is detected in the initial UVOT exposures.
The preliminary UVOT position is:
RA (J2000) = 01:48:07.28 = 27.03033 (deg.)
Dec (J2000) = -06:20:49.7 = -6.34713 (deg.)
with an estimated uncertainty of 0.42 arc sec. (radius, 90% confidence).
Preliminary detections using the UVOT photometric system
(Breeveld et al. 2011, AIP Conf. Proc. 1358, 373) for the early exposures are:
Filter T_start(s) T_stop(s) Exp(s) Mag
white 94 244 147 14.31 +/- 0.02
v 637 656 19 14.52 +/- 0.06
b 563 583 20 14.65 +/- 0.04
u 308 557 246 13.68 +/- 0.02
w1 686 705 20 14.08 +/- 0.06
w2 4908 4971 62 17.08 +/- 0.14
The magnitudes in the table are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 0.027 in the direction of the burst
(Schlegel et al. 1998).
GCN Circular 30481
Subject
GRB 210722A: GIT optical detection and preliminary analysis
Date
2021-07-23T13:44:05Z (4 years ago)
From
Harsh Kumar at Indian Inst of Tech,Bombay <harshkosli13@gmail.com>
H. Kumar(IITB), S. Joharle (Fergusson College), J. Stanzin (IAO), V.
Bhalerao(IITB), G. C. Anupama(IIA), S. Barway(IIA) report on behalf of the GIT
team:
We observed GRB 210722A detected by Swift Burst Alert Telescope (P.
D'Avanzo et al., GCN #30475) and optical afterglow detected by P. D'Avanzo
et al., GCN #30475; Z.P. Zhu et al., GCN #30476; N. Pankov et al., GCN
#30477; with 0.7m GROWTH-India Telescope (GIT). We obtained multiple
exposures in the g', r' filters. The image depth was shallower than usual
due to weather conditions. We clearly detected the afterglow in our images
at R.A.= 1:48:07.29, DEC.= -6:20:49.85, which agrees with the swift UVOT
position (GCN #30475). The photometric results follow as:
------------------------------------------------------------------------
T_start - T0 (days) | Exposure (sec) | Filter | Magnitude (AB)| Notes |
------------------------------------------------------------------------
0.014938 | 100 | g' | 15.95 +/- 0.23 | Low significance detection
0.012057 | 100 | r' | 15.11 +/- 0.08 |
0.032546 | 4x100 | r' | 16.34 +/- 0.08 | Stacked image
0.050742 | 100 | r' | 16.81 +/- 0.19 |
0.053035 | 100 | r' | 16.88 +/- 0.07 |
------------------------------------------------------------------------
Based on our observations, we found that the GRB is decaying with a
power-law index of 1.14 +/- 0.03 in r' band. Our observations are in
agreement with magnitudes reported by Z.P. Zhu et al., GCN #30476, and N.
Pankov et al., GCN #30477. The magnitudes are calibrated against PanSTARRS
(Flewelling et al., 2018) and 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 30480
Subject
Swift GRB 210722A: Global MASTER-Net observations report
Date
2021-07-23T00:11:36Z (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-Tavrida robotic telescope (Global MASTER-Net: http://observ.pereplet.ru, Lipunov et al., 2010, Advances in Astronomy, vol. 2010, 30L) located in Russia (Lomonosov MSU, SAI Crimea astronomical station) was pointed to the Swift GRB 210722A ( P. D'Avanzo et al., GCN 30475) errorbox 11033 sec after notice time and 11204 sec after trigger time at 2021-07-23 00:01:26 UT, with upper limit up to 17.6 mag. The observations began at zenith distance = 68 deg. The sun altitude is -19.1 deg.
The galactic latitude b = -65 deg., longitude l = 159 deg.
Real time updated cover map and OT discovered available here:
https://master.sai.msu.ru/site/master2/observ.php?id=1667717
We obtain a following upper limits.
Tmid-T0 | Site |Filt.| Expt. | Limit| Comment
_________|_____________________|_____|_______|______|________
11294 | MASTER-Tavrida | C | 180 | 17.6 |
Filter C is a clear (unfiltred) band.
The observation and reduction will continue.
The message may be cited.
GCN Circular 30478
Subject
GRB 210722A: Assy optical detection
Date
2021-07-22T22:49:40Z (4 years ago)
From
Alexei Pozanenko at IKI, Moscow <apozanen@iki.rssi.ru>
N. Pankov (HSE, IKI), M. Krugov (FAI), A. Pozanenko (IKI), V. Kim (FAI,
Pulkovo Observatory), S. Belkin (IKI) report on behalf of GRB IKI FuN:
We observed the field of GRB 210722A (D'Avanzo et al., GCN 30475) with
AZT-20 telescope of Assy-Turgen observatory starting on 2021-07-22 (UT)
21:42:07. We obtained 30 frames in r' - filter before a twilight.
We clearly detect the bright optical afterglow (D'Avanzo et al., GCN
30475; Zhu et al., GCN 30476) in coordinates of 01:48:07.27
-06:20:50.00 with accuracy of 0.1 arcsec in both coordinates. The
coordinates are coincides with UVOT coordinates (D'Avanzo et al., GCN 30475)
Preliminary photometry of the optical afterglow in the first image of 60
s exposure is following
Date UT start t-T0 Exp. Filter OT Err. UL(3sigma)
(mid, days) (s) (AB)
2021-07-22 21:42:07 0.03293 1*60 r' 16.20 0.03 21.1
The photometry is based on the nearby PS1 stars.
GCN Circular 30476
Subject
GRB 210722A: Nanshan/NEXT optical afterglow observations
Date
2021-07-22T21:58:22Z (4 years ago)
From
Dong Xu at NAOC/CAS <dxu@nao.cas.cn>
Z.P. Zhu (NAOC, HUST), S.Y. Fu, D. Xu, X. Liu (NAOC), X. Gao (Urumqi
No.1 Senior High School), J.Z. Liu (XAO) report:
We observed the field of GRB 210722A (D'Avanzo et al., GCN 30475) using
the NEXT-0.6m telescope located at Nanshan, Xinjiang, China. We obtained
a series of 40 s, 60 s, 90 s frames in the Sloan r-band, starting at
20:56:45 UT on 2021-07-22, i.e., 123 s after the BAT trigger, among
which part of the frames are useless due to the cloudy weather.
An uncatalogued optical transient is detected at the Swift/UVOT position
(D'Avanzo et al., GCN 30475) with varying brightness, and thus confirms
it as the optical afterglow of the burst. Preliminary analysis of the
beginning photometry is as follows:
Tmid-T0(sec) Mag MagErr
143 14.33 0.01
361 13.94 0.01
452 14.01 0.01
All magnitudes are calibrated with the nearby PS1 field.
GCN Circular 30475
Subject
GRB 210722A: Swift detection of a burst with a bright optical counterpart
Date
2021-07-22T21:13:43Z (4 years ago)
From
David Palmer at LANL <palmer@lanl.gov>
P. D'Avanzo (INAF-OAB), A. Y. Lien (GSFC/UMBC),
F. E. Marshall (NASA/GSFC), A. Melandri (INAF-OAB), M. J. Moss (GWU),
D. M. Palmer (LANL) and A. Tohuvavohu (U Toronto) report on behalf of
the Neil Gehrels Swift Observatory Team:
At 20:54:42 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 210722A (trigger=1061223). Swift slewed immediately to the burst.
The BAT on-board calculated location is
RA, Dec 27.023, -6.354 which is
RA(J2000) = 01h 48m 06s
Dec(J2000) = -06d 21' 14"
with an uncertainty of 3 arcmin (radius, 90% containment, including
systematic uncertainty). The BAT light curve showed a complex
structure with a duration of about 30 sec. The peak count rate
was ~1500 counts/sec (15-350 keV), at ~0 sec after the trigger.
Using promptly downlinked XRT data we find an uncatalogued X-ray source located
at RA, Dec 27.028, -6.345 which is equivalent to:
RA(J2000) = +01h 48m 06.84
Dec(J2000) = -06d 20' 42.7"
with an uncertainty of 5.0 arcseconds (radius, 90% containment).
UVOT took a finding chart exposure of 150 seconds with the White filter
starting 94 seconds after the BAT trigger. There is a candidate afterglow in
the rapidly available 2.7'x2.7' sub-image at
RA(J2000) = 01:48:07.27 = 27.03028
DEC(J2000) = -06:20:49.8 = -6.34718
with a 90%-confidence error radius of about 0.74 arc sec. This position is 9.6
arc sec. from the center of the XRT error circle. The estimated magnitude is
14.37 with a 1-sigma error of about 0.14. No correction has been made for the
expected extinction corresponding to E(B-V) of 0.027.
Burst Advocate for this burst is P. D'Avanzo (paolo.davanzo AT inaf.it).
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/)