GRB 220521A
GCN Circular 32111
Subject
GRB 220521A: ATCA detection
Date
2022-05-24T21:37:04Z (4 years ago)
From
Tanmoy Laskar at U of Bath <tanmoylaskar@gmail.com>
T. Laskar (University of Bath), S. Bhandari (ASTRON/JIVE), K. D. Alexander
(Northwestern), E. Berger (Harvard), R. Chornock (UC Berkeley), D.
Coppejans (Northwestern), M. Drout (U. Toronto), H. van Eerten (University
of Bath), W. Fong (Northwestern), C. Guidorzi (U. Ferrara), R. Margutti (UC
Berkeley), C. G. Mundell (University of Bath), P. Schady (University of
Bath), and G. Schroeder (Northwestern) report:
"We observed GRB 220521A (Dichiara et al., GCN 32076) with the Australia
Telescope Compact Array (ATCA) at 39 GHz beginning on 2022 May 24 14:44 UT.
We detect a radio counterpart at a position consistent with the X-ray
position (Evans et al., GCN 32077), optical position (Malesani et al., GCN
32078), and mm-band position (Laskar et al., GCN 32110) with a preliminary
flux density of ~ 0.2 mJy at a mid-time of 2.4 days after the burst.
We thank the CSIRO staff for approving and scheduling these observations.
The Australia Telescope Compact Array is part of the Australia Telescope
National Facility which is funded by the Australian Government for
operation as a National Facility managed by CSIRO. We acknowledge the
Gomeroi people as the traditional owners of the Observatory site."
GCN Circular 32110
Subject
GRB 220521A: ALMA detection
Date
2022-05-24T21:30:44Z (4 years ago)
From
Tanmoy Laskar at U of Bath <tanmoylaskar@gmail.com>
T. Laskar (University of Bath), S. Bhandari (ASTRON/JIVE), K. D. Alexander
(Northwestern), R. Margutti (Berkeley), E. Berger (Harvard), W. Fong
(Northwestern), R. Chornock (Berkeley), C. G. Mundell (University of Bath),
and P. Schady (University of Bath) report on behalf of a larger
collaboration:
"We observed GRB 220521A (Dichiara et al., GCN 32076) with the Atacama
Large Millimeter/Submillimeter Array (ALMA) at 97.5 GHz beginning on 2022
May 23 05:30 UT (1.26 days after the burst).
Preliminary analysis reveals a millimeter source with flux density of ~ 0.3
mJy at position:
RA (J2000) = 18:20:55.12 (+/- 0.03")
Dec (J2000) = 10:22:20.52 (+/- 0.03")
consistent with the X-ray position (Evans et al., GCN 32077) and optical
position (Malesani et al., GCN 32078).
We thank the JAO staff, AoD, P2G, and the entire ALMA team for their help
with these observations."
GCN Circular 32107
Subject
GRB 220521A: BOOTES-2/TELMA and CAHA 2.2m telescope optical upper limit
Date
2022-05-24T15:14:20Z (4 years ago)
From
Youdong HU at IAA-CSIC <huyoudong072@hotmail.com>
Y.-D. Hu, E. Fernandez-Garcia, T.-R. Sun, A. J. Castro-Tirado, M.D. Caballero-Garcia, R. Sanchez-Ramirez, I. Perez-Garcia (IAA-CSIC), I. Vico, S. Cikota (CAHA), C. Perez del Pulgar, A. Castellon, M. A. Castro Tirado (Univ. de Malaga), R. Fernandez-Munoz (IHSM/UMA-CSIC) and M. Jelinek (ASU-CAS), on behalf of a larger collaboration, report:
Following the detection of GRB 220521A by Fermi (GBM team GCNC 32075) and Swift (Dichiara et al. GCNC 32076), the 0.6m BOOTES-2/TELMA robotic telescope in Algarrobo Costa (Malaga, Spain) automatically respond to this event and pointed to the Swift/XRT position (Evans et al. GCNC 32077) on May 21, 23:20:56 UT (35 s post trigger). Due to the cloudy weather, only useful frames were obtained starting at 23:39:23 UT (i.e. ~19 min after trigger). The afterglow detected by both XRT and NOT is not detected in our co-added image (60 x 23 s, clear filter), down to 18.4 mag.
Later on, we also triggered the 2.2m CAHA telescope (+ CAFOS) at the Calar Alto Observatory (Almeria, Spain). Images (Sloan i-band) were gathered since May. 23 01:36 UT (i.e. 1.1 day post trigger). On the co-added image (14 x 180 s), the afterglow is not detected down to i = 24.1 mag.
Those non-detections are consistent with the previous reports from NOT (Malesani et al. GCNC 32078, Fynbo et al. GCNC 32079), SAO (Goranskij et al. GCNC 32082), RATIR (Watson et al. GCNC 32087), Sintesz-Newton (Nazarov et al. GCNC 32088), LCO (Strausbaugh et al. GCNC 32091), REM (Ferro et al. GCNC 32096), MMT (Rastinejad et al. GCNC 32097), Gemini (Cucchiara et al. GCNC 32099), MITSuME (Sato et al. GCNC 32101) and ISON-Castelgrande (Belkin et al. GCNC 32103).
We thank the staff at IHSM/UMA-CSIC La Mayora and CAHA for their excellent support.
GCN Circular 32105
Subject
GRB 220521A: classification and detection by SPI-ACS/INTEGRAL
Date
2022-05-24T14:55:52Z (4 years ago)
From
Alexei Pozanenko at IKI, Moscow <apozanen@iki.rssi.ru>
P. Minaev (IKI), A. Pozanenko (IKI), G. Mozgunov (MIPT, IKI) report on
behalf of GRB IKI FuN:
We analyzed GRB 220521A till now detected by Swift and GBM/Fermi (Fermi
GBM Team, GCN 32075; Dichiara et al., GCN 32076; Poolakkil and Meegan,
GCN 32089) using publicly available data of GBM/Fermi and
SPI-ACS/INTEGRAL. Using GBM/Fermi data we estimated the duration of T_90
= 12.0 +/- 0.5 s in 7 - 100 keV energy band and performed spectral
analysis in the time interval of (-1, 12) s. The best fit is obtained
for CPL model with following parameters: E_p = 62 (-15, +68) keV, alpha
= -1.5 +/- 0.4. The fluence of F = (9.8 +/- 1.2)E-7 erg/cm**2 is
obtained in 10 - 1000 keV energy band. The parameters are close to those
reported in (Poolakkil and Meegan, GCN 32089).
Using redshift of z = 5.6 (Fynbo et al., GCN 32079; Cucchiara et al.,
GCN 32099) we obtain E_iso = (6.2 �� 0.8)E52 erg in 1-10000 keV energy
range. Using T_90,i - EH diagram [1,2] we classify the burst as type II
(long burst) for any possible redshift greater than z = 0.07. T_90,i -
EH diagram can be found in
http://grb.rssi.ru/GRB220521A/GRB220521A_EHD.png
The burst was also detected by SPI-ACS/INTEGRAL with total statistical
significance of 5.8 sigma. The angle to the SPI-ACS axis is 47 degrees.
Comparing fluences of long-duration GRBs registered by both SPI-ACS and
GBM/Fermi (Chelovekov et al., in preparation) we estimated the GRB
220521A fluence to be 1.1E-6 erg/cm**2 in the 10-1000 keV energy band
(the 95% confidence region 3.4E-7 ��� 4.1E-6 erg/cm**2, incl.
systematics). Light curves based on GBM/Fermi and SPI-ACS/INTEGRAL data
can be found in
http://grb.rssi.ru/GRB220521A/GRB220521A_light_curves.png
[1] - Minaev et al., MNRAS, 492, 1919, 2020
[2] - Minaev et al., Astronomy Letters, 46, 9, 573, 2020
GCN Circular 32103
Subject
GRB 220521A: ISON-Castelgrande observatory optical observations
Date
2022-05-24T13:31:23Z (4 years ago)
From
Alexei Pozanenko at IKI, Moscow <apozanen@iki.rssi.ru>
S. Belkin (IKI, HSE), A. Pozanenko (IKI), S. Schmalz (KIAM RAS), A.
Schmalz (KIAM RAS), N. Pankov (HSE), Filippo Graziani (GAUSS Srl),
Riccardo Di Roberto (GAUSS Srl) report on behalf of IKI GRB FuN:
We observed the GRB 220521A (Fermi GBM Team, GCN 32075; Dichiara et
al., GCN 32076; Poolakkil and Meegan, GCN 32089) with ORI-22 telescope
of ISON-Castelgrande observatory. Observation started on 2022-05-21 (UT)
23:25:00, i.e. 4.65 min after GRB trigger. The series consists of 60
images with an exposure of 60 s in a Clear filter.
The optical afterglow (Malesani et al., GCN 32078; Fynbo et al., GCN
32079; Goranskij et al., GCN 32082; Strausbaugh et al., GCN 32091;
Rastinejad et al., GCN 32097) is not detected in the initial part of the
series and is marginally detected in the stacked image of the second
part of the series.
Preliminary photometry of the stacked images is following
Date UT start t-T0 Filter Exp. OT err UL(3)
(mid, days) (s)
2022-05-21 23:25:00 0.012951 Clear 28*60 n/d n/d 20.5
2022-05-21 23:57:00 0.035868 Clear 30*60 20.3 0.4 20.2
The photometry is based on nearby USNO-B1.0 (R2) stars
RA DEC R2
18:21:04.76880 +10:21:04.7232 16.26
18:21:07.39800 +10:20:37.5000 16.73
GCN Circular 32101
Subject
GRB 220521A: MITSuME Akeno optical upper limits
Date
2022-05-24T09:32:51Z (4 years ago)
From
Naohiro Ito at Tokyo Tech <n.ito@hp.phys.titech.ac.jp>
S. Sato, M. Sasada, K. L. Murata, R. Hosokawa, Y. Imai, N. Ito, M. Niwano,
Y. Takamatsu, M. Tateda, T. Hattori, Y. Yatsu, and N. Kawai (Tokyo Tech)
report on behalf of the MITSuME collaboration:
We observed the field of GRB 220521A (The Fermi GBM team GCN Circular
#32075, Dichiara et al. GCN Circular #32076, Evans et al. GCN Circular
#32077, Malesani and Pursimo et al. GCN Circular #32078, Fynboet al. GCN
Circular #32079, Evans et al. GCN Circular #32081, Goranskij et al. GCN
Circular #32082, Kuin and Dichiara GCN Circular #32085, Tohuvavohu et al.
GCN Circular #32086, Watson et al. GCN Circular #32087, Nazarov et al. GCN
Circular #32088, Poolakkil and Meegan GCN Circular #32089, Lien et al. GCN
Circular #32090, Strausbaugh et al. GCN Circular #32091) 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 2022-05-22
11:56:05 UT (12.6 hours after the Fermi/GBM trigger). We stacked the images
with good conditions. We did not detect the optical afterglow (Malesani et
al. GCN Circular #32078, Goranskij et al. GCN Circular #32082, Strausbaugh
et al. GCN Circular #32091, Rastinejad et al. GCN Circular #32097,
Cucchiara et al. GCN Circular #32099). We obtained the 5-sigma limits of
the stacked images as follows.
T0+[hour] | MID-UT | T-EXP[sec] | 5-sigma limits
------------------------------------------------------------------------------------------------
16.6 | 2022-05-22 15:56:34 | 6780 | g' > 19.3, Rc > 19.1, Ic > 18.6
------------------------------------------------------------------------------------------------
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 32099
Subject
GRB 220521A: Gemini Observations
Date
2022-05-23T23:35:25Z (4 years ago)
From
Robert Strausbaugh at U. of the Virgin Islands <robert.strausbaugh@uvi.edu>
A. Cucchiara (College of Marin), R. Strausbaugh (U. of the Virgin Islands), J. Rastinejad, A. Nugent, W. Fong (Northwestern), D. B. Malesani (Radboud Univ. and DAWN/NBI) report on behalf of a larger collaboration:
On May 22.16 UT (T0+4.5 hr after the GRB) we observed the afterglow, of GRB 220521A (Fermi GBM team, GCN 32075; Dichiara et al., GCN 32076; Poolakkil & Meegan, GCN 32089; Strausbaugh et al., GCN 32091) with the Gemini-South telescope and the GMOS camera.
We performed a series of spectroscopic observations with the R400 grating centered at 7500 AA (2x600 s) and 8100 AA (2x600 s). Observations were obtained at an average airmass of 2.34. In our 300 s, z-band acquisition image we detected the GRB counterpart at the NOT optical afterglow location (Malesani et al., GCN 32078).
In our preliminary analysis we measured z (AB)=20.9 +/- 0.3, calibrated against 10 PS1 stars. No extinction correction has been applied.
Our visual inspection of the spectroscopic data confirms the redshift reported by Fynbo et al. (GCN 32079) as z=5.57 based on the detection of Lyman alpha, SiIV and Ni lines.
Combined with the results from MMT (Rastinejad et al., GCN 32097)we derive a decay index in z-band of alpha=1.57, consistent with the current X-ray behavior (Tohuvavohu et al., GCN 32086). Further analysis is in progress.
We thank the Gemini-S staff, particularly Javier Fuentes and Veronica Firpo, for conducting these observations.
GCN Circular 32097
Subject
GRB 220521A: MMT Afterglow Imaging
Date
2022-05-23T20:22:56Z (4 years ago)
From
Jillian Rastinejad at Northwestern Univ. <jillianrastinejad2024@u.northwestern.edu>
J. Rastinejad, W. Fong (Northwestern), D. B. Malesani (Radboud Univ. and DAWN/NBI), A. Cucchiara (College of Marin/UVI), and G. Schroeder (Northwestern) report:
''We observed the location of the Fermi and Swift GRB 220521A (Fermi GBM team, GCN 32075, Dichiara et al., GCN 32076; Poolakkil & Meegan, GCN 32089, Strausbaugh et al. GCN 32091) with the Binospec imager and spectrograph mounted on the MMT 6.5-meter telescope on Mount Hopkins, Arizona. We obtain 15x100 s imaging in the z-band at a mid-time of 2022 May 23.423 (1.45 days post-burst) at an average airmass of 1.08. We detect a source at the position of the afterglow reported by Malesani & Pursimo (GCN 32078). Calibrated to PS1, we measure z = 24.04 +/- 0.16 mag (AB system and not corrected for Galactic extinction in the direction of the burst).
We thank Ryan Howie and Ben Weiner at the MMT for the rapid scheduling and execution of these observations.''
GCN Circular 32096
Subject
GRB 220521A: REM optical/NIR upper limits
Date
2022-05-23T20:14:11Z (4 years ago)
From
Paolo D'Avanzo at INAF-OAB <pda.davanzo@gmail.com>
M. Ferro, R. Brivio, A. Melandri, P. D'Avanzo, S. Covino, D. Fugazza, (INAF-OAB) on behalf of the REM team, report:
We observed the field of GRB 220521A (Fermi/GBM team GCN Circ. 32075; Dichiara et al., GCN Circ. 32076) with
the REM 60cm robotic telescope located at the ESO premise of La Silla (Chile). The observations were carried in the
g, r, i, z, J, H and K bands, starting on 2022 May 22 at 02:24:40 UT (i.e. about 3.1 hours after the burst) and lasting for
about one hour.
The optical afterglow (Malesani et al., GCN Circ. 32078) is not detected. From preliminary photometry we derive the
following magnitude upper limits (3sigma c.l.):
g > 19.5
r > 19.1
i > 18.8
z > 17.4
(AB; calibrated against the Pan-STARRS catalogue) at a mid time of t-t0 ~ 3.5 hours;
J > 16.6
H > 16.2
K > 13.5
(Vega; calibrated against the 2MASS catalogue) at a mid time of t-t0 ~ 3.9 hours.
GCN Circular 32091
Subject
GRB 220521A: LCO Optical Detection
Date
2022-05-22T20:52:33Z (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 (College of Marin) report on behalf of a larger collaboration:
We observed GRB 220521A (Dicharia et al., GCN 32076; Fermi GBM Team, GCN 32075) with the LCO 1-m Sinistro instrument at the Teide Observatory, Tenerife site, on May 22, from 00:04 to 00:32 UT (corresponding to 0.73 to 1.20 hours from the GRB trigger time) with the Bessel R and I filters.
We performed a series of 3x300s exposures in R and I bands. We detect an optical counterpart at the NOT optical afterglow location (Malesani et al., 32078 GCN 32078) that is consistent with other optical detections (Malesani et al., GCN 32078; Fynbo et al., GCN 32079; Goranskij et al., GCN 32082). The following magnitudes are calculated using the USNO-B.1 catalog as reference:
R=21.57+/-0.23
I=18.61+/-0.63
These magnitudes are not corrected for galactic extinction.
R.S. is funded by NSF AST grant #1831682
GCN Circular 32090
Subject
GRB 220521A: Swift-BAT refined analysis
Date
2022-05-22T16:41:20Z (4 years ago)
From
Amy Lien at GSFC <amy.y.lien@nasa.gov>
A. Y. Lien (U Tampa), S. D. Barthelmy (GSFC),
S. Dichiara (PSU), H. A. Krimm (NSF),
S. Laha (GSFC/UMBC), 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-240 to T+962 sec from the recent telemetry
downlink, we report further analysis of BAT GRB 220521A (trigger #1107466)
(Dichiara et al., GCN Circ. 32076). The BAT ground-calculated position is
RA, Dec = 275.218, 10.372 deg which is
RA(J2000) = 18h 20m 52.3s
Dec(J2000) = +10d 22' 20.0"
with an uncertainty of 1.7 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 46%.
The mask-weighted light curve shows a multi-peaked structure that
starts at ~T0 and ends at ~T+16 s. The two main peaks occur at ~T+0.5 s
and ~T+10 s, respectively. T90 (15-350 keV) is 13.55 +- 2.69 sec (estimated
error including systematics).
The time-averaged spectrum from T-0.23 to T+16.17 sec is best fit by
a simple power-law model. The power law index of the time-averaged
spectrum is 1.97 +- 0.18. The fluence in the 15-150 keV band
is 8.1 +- 0.8 x 10^-7 erg/cm2. The 1-sec peak photon flux measured
from T-0.18 sec in the 15-150 keV band is 4.7 +- 0.4 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/1107466/BA/
GCN Circular 32089
Subject
GRB 220521A: Fermi GBM detection
Date
2022-05-22T15:25:46Z (4 years ago)
From
Suraj Poolakkil at UAH <sp0076@uah.edu>
S. Poolakkil (UAH) and C. Meegan (UAH)
report on behalf of the Fermi GBM Team:
"At 23:20:21.73 UT on 21 May 2022, the Fermi Gamma-Ray Burst Monitor (GBM)
triggered and located GRB 220521A (trigger 674868026 / 220521972)
which was also detected by the Swift/BAT (Dichiara et al. 2022, GCN 32076).
The Fermi GBM Final Real-time Localization (GCN 32075) is consistent with
the Swift/BAT position.
The angle from the Fermi LAT boresight at the GBM trigger time is 105
degrees.
The GBM light curve consists of multiple peaks followed
by some extended emission with a duration (T90) of about 14 s (50-300 keV).
The time-averaged spectrum from T0-1.024 s to T0+3.072 s
is best fit by a power law function with an exponential
high-energy cutoff. The power law index is -1.51 +/- 0.23 and
the cutoff energy, parameterized as Epeak, is 37 +/- 7 keV.
The event fluence (10-1000 keV) in this time interval is
(6.62 +/- 0.49)E-07 erg/cm^2. The 1-sec peak photon flux measured
starting from T0-0.32 s in the 10-1000 keV band
is 6.3 +/- 0.4 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 32088
Subject
GRB 220521A: Sintesz-Newton/CrAO optical upper limit
Date
2022-05-22T15:17:22Z (4 years ago)
From
Alexei Pozanenko at IKI, Moscow <apozanen@iki.rssi.ru>
S. Nazarov (CrAO), A. Pozanenko (IKI), S. Belkin (IKI, HSE), N. Pankov
(HSE) report on behalf of IKI GRB FuN:
We observed the GRB 220521A (Dichiara et al., GCN 32076; Fermi GBM
Team, GCN 32075) with Sintesz-Newton 350mm f/5 telescope of CrAO
observatory. Observation started on 2022-05-22 (UT) 01:05:40. The series
consists of images with an exposure of 60 s in a Clear filter.
The optical afterglow (Malesani et al., GCN 32078; Fynbo et al., GCN
32079; Goranskij et al., GCN 32082) is not detected in the stacked image.
Preliminary photometry of the stacked images is following
Date UT start t-T0 Filter Exp. OT err UL(3)
(mid, days) (s)
2022-05-22 01:05:40 0.07626 Clear 9*60 n/d n/d 18.2
The photometry is based on nearby USNO-B1.0 (R2) stars
RA DEC R2
18:21:04.76880 +10:21:04.7232 16.26
18:21:07.39800 +10:20:37.5000 16.73
GCN Circular 32087
Subject
GRB 220521A: RATIR Optical and NIR Observations
Date
2022-05-22T15:02:40Z (4 years ago)
From
Alan M Watson at UNAM <alan@astro.unam.mx>
Alan M. Watson (UNAM), Nat Butler (ASU), William H. Lee (UNAM), Alexander
Kutyrev (GSFC), Eleonora Troja (UTV), Michael G. Richer (UNAM), Ori Fox (STScI),
J. Xavier Prochaska (UCSC), Josh Bloom (UCB), Enrico Ramirez-Ruiz (UCSC), Jes��s
Gonz��lez (UNAM), Carlos Rom��n-Z����iga (UNAM), Harvey Moseley (GSFC), Rosa L.
Becerra (UNAM), Simone Dichiara (PSU), and Oc��lotl L��pez (UNAM) report:
We observed the field of GRB 220521A (Dichiara et al., GCN Circ. 32076) 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 2022/05 22.22 to 2022/05 22.47 UTC (6.04 to 12.03 hours after the BAT
trigger), obtaining a total of 2.98 hours exposure in the r and i bands and 1.23
hours exposure in the Z, Y, J, and H bands.
For a source within the enhanced (Evans et al., GCN Circ. 32081) Swift-XRT error
circle, in comparison with the USNO-B1 and 2MASS catalogs, we obtain the
following 3-sigma upper limits:
r > 23.07
i > 22.77
Z > 21.13
Y > 21.87
J > 21.75
H > 21.30
These magnitudes are in the AB system and are not corrected for Galactic
extinction in the direction of the GRB.
Our non-detection of the NOT afterglow (Malesani & Pursimo, GCN Circ. 32078) is
consistent with a temporal power-law index steeper than about -0.5.
We thank the staff of the Observatorio Astron��mico Nacional in San Pedro
M��rtir.
GCN Circular 32086
Subject
GRB 220521A: Swift-XRT refined Analysis
Date
2022-05-22T14:22:11Z (4 years ago)
From
Phil Evans at U of Leicester <pae9@leicester.ac.uk>
A. Tohuvavohu (U. Toronto), B. Sbarufatti (PSU), K.L. Page (U.
Leicester), A.P. Beardmore (U. Leicester), P.A. Evans (U. Leicester),
T. Sbarrato (INAF-OAB), P. D'Avanzo (INAF-OAB), M.G. Bernardini
(INAF-OAB), D.N. Burrows (PSU) and S. Dichiara report on behalf of the
Swift-XRT team:
We have analysed 8.4 ks of XRT data for GRB 220521A (Dichiara et al.
GCN Circ. 32076), from 104 s to 45.1 ks after the BAT trigger. The
data are entirely in Photon Counting (PC) mode. The enhanced XRT
position for this burst was given by Evans et al. (GCN Circ. 32077).
The late-time light curve (from T0+3.8 ks) can be modelled with a
power-law decay with a decay index of alpha=1.53 (+0.27, -0.23).
A spectrum formed from the PC mode data can be fitted with an absorbed
power-law with a photon spectral index of 1.90 (+0.26, -0.16). The
best-fitting absorption column is 1.94 (+0.96, -0.07) x 10^21 cm^-2,
consistent with the Galactic value of 1.9 x 10^21 cm^-2 (Willingale et
al. 2013). The counts to observed (unabsorbed) 0.3-10 keV flux
conversion factor deduced from this spectrum is 3.7 x 10^-11 (4.8 x
10^-11) erg cm^-2 count^-1.
A summary of the PC-mode spectrum is thus:
Total column: 1.94 (+0.96, -0.07) x 10^21 cm^-2
Galactic foreground: 1.9 x 10^21 cm^-2
Excess significance: <1.6 sigma
Photon index: 1.90 (+0.26, -0.16)
If the light curve continues to decay with a power-law decay index of
1.53, the count rate at T+24 hours will be 1.0 x 10^-3 count s^-1,
corresponding to an observed (unabsorbed) 0.3-10 keV flux of 3.7 x
10^-14 (4.9 x 10^-14) erg cm^-2 s^-1.
The results of the XRT-team automatic analysis are available at
http://www.swift.ac.uk/xrt_products/01107466.
This circular is an official product of the Swift-XRT team.
GCN Circular 32085
Subject
GRB 220521A: Swift/UVOT Upper Limits
Date
2022-05-22T13:57:22Z (4 years ago)
From
Paul Kuin at MSSL <npkuin@gmail.com>
N. P. M. Kuin (UCL-MSSL) and S. Dichiara (PSU)
report on behalf of the Swift/UVOT team:
The Swift/UVOT began settled observations of the field of GRB 220521A
100 s after the BAT trigger (Dichiara et al., GCN Circ. 32076).No optical
afterglow consistent with the XRT position (Evans et al. GCN Circ. 32081)
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 100 250 147 >20.8
u_FC 312 548 232 >19.2
white 100 4178 344 >21.5
v 4389 4589 197 >19.5
b 3773 3973 197 >20.4
u 312 5050 278 >19.4
w1 4798 4998 197 >20.2
m2 4593 4793 197 >19.7
w2 4184 4383 197 >19.7
The magnitudes in the table are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 0.185 in the direction of the burst
(Schlegel et al. 1998).
GCN Circular 32082
Subject
GRB 220521A: SAO RAS optical observations
Date
2022-05-22T09:06:22Z (4 years ago)
From
Moskvitin Alexander at SAO RAS <mosk@sao.ru>
Goranskij V. P. (SAI, Moscow University) and Moskvitin A. S. (Special
Astrophysical Observatory of RAS) report on behalf of a larger
collaboration:
We observed the field of the GRB 220521A (Dichiara et al., GCN 32076;
Evans, GCN 32077) with the SAO RAS 1-m telescope Zeiss-1000
+ CCD-photometer. The observations started 16.6 minutes
after the trigger. We obtained 200 sec. exposures in V, Rc, Ic filters.
The OT (Malesani & Pursimo, GCN 32078; Fynbo et al., GCN 32079)
is clearly detected in Ic and Rc bands (with the brightness of
I = 17.82 +/- 0.04; R = 20.3 +/- 0.2) and not detected in V band
down to the limiting magnitude of V_lim ~ 21.4 (T_mid-T0 = 22.8 min).
Preliminary photometry is based on nearby stars of PS1 catalogue,
gri --> V, R, I by Lupton 2005 transformations.
GCN Circular 32081
Subject
GRB 220521A: Enhanced Swift-XRT position
Date
2022-05-22T07:37:30Z (4 years ago)
From
Phil Evans at U of Leicester <pae9@leicester.ac.uk>
P.A. Evans, M.R. Goad, J.P. Osborne and A.P. Beardmore (U. Leicester)
report on behalf of the Swift-XRT team.
Using 441 s of XRT Photon Counting mode data and 1 UVOT
images for GRB 220521A, 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 = 275.22990, +10.37175 which is equivalent
to:
RA (J2000): 18h 20m 55.18s
Dec (J2000): +10d 22' 18.3"
with an uncertainty of 2.1 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 32079
Subject
GRB 220521A: NOT spectroscopic redshift
Date
2022-05-22T02:04:13Z (4 years ago)
From
Daniele B Malesani at Radboud U <d.malesani@astro.ru.nl>
J. P. U. Fynbo (DAWN/NBI), Z. Zhu (NAO/CAS, HUST), D. Xu (NAOC/CAS), D.
B. Malesani (Radboud Univ. and DAWN/NBI), T. Pursimo (NOT), K.
Matilainen (NOT), report on behalf of a larger collaboration:
Spectroscopy of the optical counterpart of GRB 220521A (Dichiara et al.,
GCN 32076; Malesani & Pursimo, GCN 32078) was secured using the Nordic
Optical Telescope (NOT) equipped with the ALFOSC spectrograph. Grism #4
was used, covering the wavelength range 3650-9500 AA. Our first spectrum
(1200 s exposure time) started on May 22.004 UT (0.76 hr after the GRB).
Preliminary analysis of the data, using archival calibration files,
reveals a bright continuum in the red part, with a clear break around
8150 AA, which we interpret as due to Lyman alpha. We also identify the
Lyman limit, the Lyman forest, and several metal absorption features
(among which Si II 1260, O I 1302, Si II 1304, C II 1334, Si IV
1393,1402), which allow to determine z = 5.6.
The precision of the redshift can be improved after utilizing updated
calibration files.
GCN Circular 32078
Subject
GRB 220521A: NOT optical afterglow detection
Date
2022-05-22T00:09:27Z (4 years ago)
From
Daniele B Malesani at Radboud U <d.malesani@astro.ru.nl>
D. B. Malesani (Radboud Univ. and DAWN/NBI) and T. Pursimo (NOT) report
on behalf of more people:
We observed the field of GRB 220521A (Dichiara et al., GCN 32076) with
the Nordic Optical Telescope (NOT) equipped with the ALFOSC imager. In a
300-s exposure beginning on 2022 May 21.983 UT (0.248 hr after the GRB),
we detect a new object consistent with the UVOT-enhanced X-ray position
(Evans, GCN 32077), at J2000 coordinates:
RA = 18:20:55.13
Dec = +10:22:20.5
Calibration is against the Gaia catalog, with an expected uncertainty <
0.3".
Photometry against nearby Pan-STARRS calibrators yields r = 21.06 +-
0.03 AB. Given the consistency with the X-ray position and the lack of
detection in the Pan-STARRS archival images, we conclude that this
source is the optical afterglow of GRB 220521A.
GCN Circular 32077
Subject
GRB 220521A: Prompt enhanced Swift-XRT position
Date
2022-05-21T23:44:42Z (4 years ago)
From
Phil Evans at U of Leicester <pae9@leicester.ac.uk>
P.A. Evans (U. Leicester) reports on behalf of the Swift-XRT team:
Using promptly downlinked XRT event data for GRB 220521A, we find an
enhanced XRT position of the afterglow: RA, Dec: 275.22978, 10.37221
which is equivalent to:
RA (J2000) = 18 20 55.15
Dec (J2000) = +10 22 19.9
with an uncertainty of 1.9 arcseconds (radius, 90% confidence).
Analysis of the promptly available data is online at
http://www.swift.ac.uk/sper/1107466.
Position enhancement is is described by Goad et al. (2007, A&A, 476,
1401) and Evans et al. (2009, MNRAS, 397, 1177).
This circular is an official product of the Swift-XRT team.
GCN Circular 32076
Subject
GRB 220521A: Swift detection of a burst
Date
2022-05-21T23:31:51Z (4 years ago)
From
David Palmer at LANL <palmer@lanl.gov>
S. Dichiara (PSU), J.D. Gropp (PSU), D. M. Palmer (LANL) and
B. Sbarufatti (PSU) report on behalf of the Neil Gehrels Swift
Observatory Team:
At 23:20:21 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 220521A (trigger=1107466). Swift slewed immediately to the burst.
The BAT on-board calculated location is
RA, Dec 275.197, +10.384 which is
RA(J2000) = 18h 20m 47s
Dec(J2000) = +10d 23' 03"
with an uncertainty of 3 arcmin (radius, 90% containment, including
systematic uncertainty). The BAT light curve showed a double-peaked
structure with a duration of about 15 sec. The peak count rate
was ~4000 counts/sec (15-350 keV), at ~0 sec after the trigger.
The XRT began observing the field at 23:21:57.7 UT, 96.3 seconds after
the BAT trigger. Using promptly downlinked data we find an uncatalogued
X-ray source located at RA, Dec 275.22891, 10.37262 which is equivalent
to:
RA(J2000) = 18h 20m 54.94s
Dec(J2000) = +10d 22' 21.4"
with an uncertainty of 3.7 arcseconds (radius, 90% containment). This
location is 120 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.
A power-law fit to a spectrum formed from promptly downlinked event
data gives a column density consistent with the Galactic value of 1.87
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. Results from the 2.7'x2.7' sub-image
are not available at this time. 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 0.185.
Burst Advocate for this burst is S. Dichiara (simonedichiara55 AT gmail.com).
Please contact the BA by email if you require additional information
regarding Swift followup of this burst. In extremely urgent cases, after
trying the Burst Advocate, you can contact the Swift PI by phone (see
Swift TOO web site for information: http://www.swift.psu.edu/)
GCN Circular 32075
Subject
GRB 220521A: Fermi GBM Final Real-time Localization
Date
2022-05-21T23:30:48Z (4 years ago)
From
Fermi GBM Team at MSFC/Fermi-GBM <do_not_reply@GIOC.nsstc.nasa.gov>
The Fermi GBM team reports the detection of a likely SHORT GRB
At 23:20:21 UT on 21 May 2022, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 220521A (trigger 674868026.727134 / 220521972).
The on-ground calculated location, using the Fermi GBM trigger data, is RA = 292.6, Dec = 3.9 (J2000 degrees, equivalent to J2000 19h 30m, 3d 53'), with a statistical uncertainty of 13.6 degrees.
The angle from the Fermi LAT boresight is 88.0 degrees.
The skymap can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2022/bn220521972/quicklook/glg_skymap_all_bn220521972.png
The HEALPix FITS file, including the estimated localization systematic, can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2022/bn220521972/quicklook/glg_healpix_all_bn220521972.fit
The GBM light curve can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2022/bn220521972/quicklook/glg_lc_medres34_bn220521972.gif