GRB 210527A
GCN Circular 30081
Subject
GRB 210527A: Swift detection of a burst
Date
2021-05-27T07:22:18Z (4 years ago)
From
Kim Page at U.of Leicester <klp5@leicester.ac.uk>
S. Laha (GSFC/UMBC/CRESST), P. A. Evans (U Leicester),
K. L. Page (U Leicester) and B. Sbarufatti (PSU) report on behalf of
the Neil Gehrels Swift Observatory Team:
At 07:07:48 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 210527A (trigger=1051453). Swift did not slew immediately
due to an observing constraint.
The BAT on-board calculated location is
RA, Dec 172.355, +31.618 which is
RA(J2000) = 11h 29m 25s
Dec(J2000) = +31d 37' 06"
with an uncertainty of 3 arcmin (radius, 90% containment, including
systematic uncertainty). As is normal for an image trigger, the BAT
light curve does not show any significant structure.
Due to an observing constraint, Swift will not slew until T0+49.6
minutes. There will be no XRT or UVOT data until this time.
Burst Advocate for this burst is S. Laha (sib.laha 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 30082
Subject
GRB 210527A: Swift-XRT observations
Date
2021-05-27T08:40:43Z (4 years ago)
From
Phil Evans at U of Leicester <pae9@leicester.ac.uk>
J.P. Osborne (U. Leicester), D.N. Burrows (PSU), J.A. Kennea (PSU), G.
Tagliaferri (INAF-OAB), S. Campana (INAF-OAB) and P.A. Evans (U.
Leicester) report on behalf of the Swift-XRT team:
The XRT began observing the field of GRB 210527A at 08:00:28.4 UT,
3159.5 seconds after the BAT trigger. Using promptly downlinked data we
find an uncatalogued X-ray source located at RA, Dec 172.32169,
31.62421 which is equivalent to:
RA(J2000) = 11h 29m 17.21s
Dec(J2000) = +31d 37' 27.2"
with an uncertainty of 3.9 arcseconds (radius, 90% containment). This
location is 104 arcseconds from the BAT onboard position, within the
BAT error circle. This position may be improved as more data are
received; the latest position is available at
https://www.swift.ac.uk/sper. We cannot determine whether the source
is fading at the present time.
A power-law fit to a spectrum formed from promptly downlinked event
data gives a column density consistent with the Galactic value of 1.85
x 10^20 cm^-2 (Willingale et al. 2013).
GCN Circular 30083
Subject
GRB 210527A: Enhanced Swift-XRT position
Date
2021-05-27T14:44:11Z (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 1707 s of XRT Photon Counting mode data and 4 UVOT
images for GRB 210527A, 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 = 172.32085, +31.62621 which is equivalent
to:
RA (J2000): 11h 29m 17.00s
Dec (J2000): +31d 37' 34.3"
with an uncertainty of 2.3 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 30084
Subject
GRB 210527A: RATIR Optical and NIR Observations
Date
2021-05-27T17:53:44Z (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 210527A (Laha, et al., GCN 30081) 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 2021/05 27.30 to 2021/05 27.32 UTC (0.01 to 0.56 hours
after the BAT trigger), obtaining a total of 0.19 hours exposure in the r
and i bands and 0.25 hours exposure in the Z, Y, J, and H bands.
We find no new sources within the refined XRT error region (Evans, et al.,
GCN 30083). In comparison with the SDSS DR9 and 2MASS catalogs, we obtain
the following upper limits (3-sigma):
r > 21.67
i > 21.70
Z > 21.54
Y > 21.32
J > 20.78
H > 20.42
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 30085
Subject
GRB 210527A: Swift-XRT refined Analysis
Date
2021-05-27T17:56:04Z (4 years ago)
From
Phil Evans at U of Leicester <pae9@leicester.ac.uk>
V. D'Elia (SSDC & INAF-OAR), A. D'Ai (INAF-IASFPA), J.A. Kennea (PSU),
A. Tohuvavohu (U. Toronto), B. Sbarufatti (PSU), P.A. Evans (U.
Leicester), J.P. Osborne (U. Leicester), K.L. Page (U. Leicester), A.
Melandri (INAF-OAB) and report on behalf of the Swift-XRT team: report
on behalf of the Swift-XRT team:
We have analysed 7.1 ks of XRT data for GRB 210527A, from 3.2 ks to
27.7 ks after the BAT trigger. The data are entirely in Photon
Counting (PC) mode.
The light curve can be modelled with a power-law decay with a decay
index of alpha=0.90 (+0.23, -0.20).
A spectrum formed from the PC mode data can be fitted with an absorbed
power-law with a photon spectral index of 3.1 (+0.6, -0.5). The
best-fitting absorption column is 6.6 (+2.6, -2.1) x 10^21 cm^-2, in
excess of the Galactic value of 1.8 x 10^20 cm^-2 (Willingale et al.
2013). The counts to observed (unabsorbed) 0.3-10 keV flux conversion
factor deduced from this spectrum is 2.6 x 10^-11 (1.3 x 10^-10) erg
cm^-2 count^-1.
A summary of the PC-mode spectrum is thus:
Total column: 6.6 (+2.6, -2.1) x 10^21 cm^-2
Galactic foreground: 1.8 x 10^20 cm^-2
Excess significance: 5.0 sigma
Photon index: 3.1 (+0.6, -0.5)
If the light curve continues to decay with a power-law decay index of
0.90, the count rate at T+24 hours will be 4.0 x 10^-3 count s^-1,
corresponding to an observed (unabsorbed) 0.3-10 keV flux of 1.1 x
10^-13 (5.1 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/01051453.
This circular is an official product of the Swift-XRT team.
GCN Circular 30086
Subject
Swift GRB 210527A: Global MASTER-Net observations report
Date
2021-05-27T18:53:22Z (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-Kislovodsk robotic telescope (Global MASTER-Net: http://observ.pereplet.ru, Lipunov et al., 2010, Advances in Astronomy, vol. 2010, 30L) located in Russia (Lomonosov MSU, Kislovodsk Solar Station of Pulkovo observatory) was pointed to the Swift GRB 210527A ( S. Laha et al., GCN 30081) errorbox 41282 sec after notice time and 41473 sec after trigger time at 2021-05-27 18:39:02 UT, with upper limit up to 19.2 mag. The observations began at zenith distance = 30 deg. The sun altitude is -17.1 deg.
The galactic latitude b = 72 deg., longitude l = 195 deg.
Real time updated cover map and OT discovered available here:
https://master.sai.msu.ru/site/master2/observ.php?id=1622598
We obtain a following upper limits.
Tmid-T0 | Site |Filt.| Expt. | Limit| Comment
_________|_____________________|_____|_______|______|________
41564 | MASTER-Kislovodsk | C | 180 | 18.5 |
41564 | MASTER-Kislovodsk | C | 180 | 19.2 |
Filter C is a clear (unfiltred) band.
The observation and reduction will continue.
The message may be cited.
GCN Circular 30087
Subject
GRB 210527A: MITSuME Akeno optical upper limits
Date
2021-05-28T05:47:33Z (4 years ago)
From
Ryohei Hosokawa at Tokyo Institute of Technology <hosokawa@hp.phys.titech.ac.jp>
Y. Imai, R. Hosokawa, K. L. Murata, M. Niwano, N. Ito, H. Takamatsu,
S. Sato, M. Takaku, R. Noto, R. Yamaguchi, Y. Yatsu, and N. Kawai
(TokyoTech) report on behalf of the MITSuME collaboration:
We observed the field of GRB 210527A (S. Laha et al. GCN Circular
#30081, J.P. Osborne et al. GCN Circular #30082, P.A. Evans et al. GCN
Circular #30083, Nat Butler et al. GCN Circular #30084, V. D'Elia et
al. GCN Circular #30085, V. Lipunov et al. GCN Circular #30086) with
the optical three color (g', Rc, and Ic) CCD cameras attached to the
MITSuME 50 cm telescope Akeno.
The observation with a series of 60 sec exposures started at 2021-05-27
10:23:37 UT (3.3 hours after the triggers). We stacked the images with
good conditions. We did not detect any sources within the enhanced XRT
error region (P.A. Evans et al. GCN Circular #30083) in all three
bands. We obtained the 5-sigma limits of the stacked images as
follows.
T0+[hour] MID-UT T-EXP[sec] 5-sigma limits
------------------------------------------------------------------------------------------------
3.3 2021-05-27 15:28 1980 g'>18.0, Rc>18.6, Ic>18.1
------------------------------------------------------------------------------------------------
T0+ : Elapsed time after the burst
T-EXP: Total Exposure time
We used the 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 30088
Subject
GRB 210527A: GIT optical upper limit
Date
2021-05-28T07:33:04Z (4 years ago)
From
Harsh Kumar at Indian Inst of Tech,Bombay <harshkosli13@gmail.com>
H. Kumar(IITB), U. Stanzin (IAO), G. C. Anupama(IIA), V. Bhalerao(IITB), S.
Barway(IIA) report on behalf of the GIT team:
We observed GRB 210527A detected by Swift-BAT (S. Laha et al., GCN #30081)
with the 0.7m GROWTH-India Telescope (GIT). We obtained 10 exposures, each
of 300 sec, in the r' filter starting at ~467 mins after the trigger. We
did not detect any new source in our stacked image within a 3 arcmin circle
around R.A. = 11h 29m 25s Dec(J2000) = +31d 37' 06" (GCN #30081). The
obtained upper limit follows as:
-------------------------------------------------------------------------
JD (mid) | T_mid-T0(hrs) | Exposure(sec) | Filter | Lim_mag (5-sigma) |
-------------------------------------------------------------------------
2459362.1416 | ~8.27 | 3000 (stacked) | r' | > 21.98 |
-------------------------------------------------------------------------
Our upper limit is consistent with Nat Butler et al., GCN #30084; V.
Lipunov et al., GCN #30086; Y. Imai et al., GCN #30087. The magnitude is
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 30089
Subject
GRB 210527A: Swift/UVOT Observations
Date
2021-05-28T12:22:26Z (4 years ago)
From
Mike Siegel at PSU/Swift MOC <mhs18@psu.edu>
M. H. Siegel (PSU) and S. L. Laha (GSFC/UMBC/CRESST)
report on behalf of the Swift/UVOT team:
The Swift/UVOT began settled observations of the field of GRB 210527A
3164 s after the BAT trigger (Laha et al., GCN Circ. 30081).
No optical afterglow consistent with the XRT position
(Evans et al., GCN Circ. 30083) 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 3164 3313 147 >20.2
white 3164 3932 344 >21.2
v 4143 4343 197 >19.4
b 3528 3727 197 >20.4
u 3322 4895 331 >20.4
w1 4553 4753 197 >20.2
m2 4348 4548 197 >20.0
w2 3938 4138 197 >20.5
The magnitudes in the table are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 0.023 in the direction of the burst
(Schlegel et al. 1998).
GCN Circular 30092
Subject
GRB 210527A: Swift-BAT refined analysis
Date
2021-05-28T22:26:49Z (4 years ago)
From
Sibasish Laha at GSFC <sibasish.laha@nasa.gov>
M. Stamatikos (OSU), S. D. Barthelmy (GSFC),
J. R. Cummings (CPI), H. A. Krimm (NSF),
S. Laha (GSFC/UMBC), A. Y. Lien (GSFC/UMBC),
C. B. Markwardt (GSFC), D. M. Palmer (LANL),
T. Sakamoto (AGU), 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 210527A (trigger #1051453)
(Laha et al., GCN Circ. 30081). The BAT ground-calculated position is
RA, Dec = 172.346, 31.627 deg which is
RA(J2000) = 11h 29m 23.0s
Dec(J2000) = +31d 37' 37.0"
with an uncertainty of 1.8 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 90%.
The BAT light curve showed a complex structure with a duration of about ~70 sec.
T90 (15-350 keV) is 63.21 +- 11.15 sec (estimated error including systematics).
The time-averaged spectrum from T-17.07 to T+62.45 sec is best fit by a simple
power-law model. The power law index of the time-averaged spectrum is
2.33 +- 0.26. The fluence in the 15-150 keV band is 6.5 +- 1.0 x 10^-07 erg/cm2.
The 1-sec peak photon flux measured from T+17.86 sec in the 15-150 keV band
is 0.4 +- 0.1 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/1051453/BA/