GRB 200528A
GCN Circular 27883
Subject
Konus-Wind observation of GRB200528A
Date
2020-06-02T09:06:41Z (5 years ago)
From
Anastasia Tsvetkova at Ioffe Institute <tsvetkova@mail.ioffe.ru>
A. Tsvetkova, S. Golenetskii, R.Aptekar, D. Frederiks,
M. Ulanov, D. Svinkin, A. Lysenko, A. Ridnaia and T. Cline
on behalf of the Konus-Wind team, report:
The long-duration, soft-spectrum GRB200528A
(Swift detection: Ambrosi et al., GCN 27832;
Barthelmy et al., GCN 27839;
Fermi GBM Observation: Fletcher, von Kienlin & Meegan, GCN 27841;
CALET Gamma-Ray Burst Monitor detection: Pal'shin et al., GCN 27855)
triggered Konus-Wind at T0=37675.256 s UT (10:27:55.256).
The burst light curve shows a complex structure
which starts at ~T0-33.8 s, with a total duration of~60.0 s,
and comprises two double-peaked emission episodes.
The emission is seen up to ~1 MeV.
As observed by Konus-Wind, the burst
had a fluence of 2.12(-0.07,+0.07)x10^-5 erg/cm2,
and a 64-ms peak energy flux, measured from T0+1.696 s,
of 2.38(-0.35,+0.35)x10^-6 erg/cm2/s
(both in the 20 keV - 10 MeV energy range).
The time-integrated spectrum of the burst
(measured from T0 to T0+33.024 s)
is best fit in the 20 keV - 1 MeV range
by a power law with exponential cutoff model:
dN/dE ~ (E^alpha)*exp(-E*(2+alpha)/Ep)
with�� alpha = -1.41(-0.14,+0.14),
and Ep = 64(-5,+5) keV (chi2 = 50/60 dof).
Fitting by the GRB (Band) model yields the same alpha and Ep,
and an upper limit on the high energy photon index:
beta < -2.89 (chi2 = 49/59 dof).
The spectrum near the peak count rate
(measured from T0+0.256 to T0+8.448 s)
is best fit in the 20 keV - 1 MeV range
by the power law with exponential cutoff model
with�� alpha = -1.14(-0.15,+0.16),
and Ep = 75(-4,+5) keV (chi2 = 52/60 dof).
Fitting by the GRB (Band) model yields the same alpha and Ep,
and an upper limit on the high energy photon index:
beta < -3.03 (chi2 = 51/59 dof).
The Konus-Wind light curve of this GRB is available at
http://www.ioffe.ru/LEA/GRBs/GRB200528_T37675/
All the quoted errors are at the 90% confidence level.
All the quoted values are preliminary.
GCN Circular 27860
Subject
GRB 200528A: CAHA Upper Limit
Date
2020-05-29T22:44:01Z (5 years ago)
From
Alexander Kann at IAA-CSIC <kann@iaa.es>
D. A. Kann (HETH/IAA-CSIC), A. de Ugarte Postigo (HETH/IAA-CSIC,
DARK/NBI), M. Blazek, C. C. Thoene, J. F. Agui Fernandez (all
HETH/IAA-CSIC), and I. Hermelo (CAHA) report:
We observed the XRT error circle (Evans et al., GCN #27836) of the
bright GRB 200528A (Swift detection: Ambrosi et al., GCN #27832; Fermi
GBM detection: The Fermi GBM team, GCN #27831) with the 2.2m telescope
at CAHA (Almeria, Spain), equipped with the CAFOS detector. We obtained
21 x 180 s exposures in the Ic band under adverse observing conditions
(moonlight, bad seeing and transparency).
At the enhanced XRT position, we detect no source (but would have
preferred to). We derive a 3 sigma limiting magnitude of Ic > 23.5 mag
(Vega) at 0.440865 days after the GRB, calibrated against SDSS standard
stars transformed to the Ic band following Lupton (2005). This limit is
comparable to those achieved by NOT about an hour later (Malesani et
al., GCN #27842).
GCN Circular 27855
Subject
GRB 200528A: CALET Gamma-Ray Burst Monitor detection
Date
2020-05-29T12:29:14Z (5 years ago)
From
Valentin Pal'shin at AGU <val@phys.aoyama.ac.jp>
V. Pal'shin, A. Yoshida, T. Sakamoto, S. Sugita (AGU),
Y. Kawakubo (LSU), K. Yamaoka (Nagoya U), S. Nakahira (RIKEN),
Y. Asaoka, S. Torii (Waseda U), Y. Shimizu, T. Tamura (Kanagawa U),
N. Cannady (GSFC/UMBC), M. L. Cherry (LSU),
S. Ricciarini (U of Florence), P. S. Marrocchesi (U of Siena),
and the CALET collaboration:
The long soft GRB 200528A (Swift detection: Ambrosi et al.,
GCN Circ. 27832, Barthelmy et al., GCN Circ. 27839;
Fermi GBM observation: Fletcher and Meegan, GCN Circ. 27841;
https://gcn.gsfc.nasa.gov/other/200528A.gcn3)
triggered the CALET Gamma-ray Burst Monitor (CGBM) at 10:27:27.087 UTC
on 28 May 2020. The burst signal was seen by all CGBM detectors.
Because of a problem in one of the ground alert processing script,
the GCN notice was not distributed automatically for this event.
The burst light curve shows a multi-peaked structure which starts at
T-4.5 sec, peaks at T+30.8 sec and ends at T+35.1 sec. The T90 and T50
durations measured by the SGM data are 36.6 +- 3.2 sec and 27.9 +- 4.0 sec
(40-1000 keV), respectively.
The ground processed light curve is available at
http://cgbm.calet.jp/cgbm_trigger/ground/1274696855/
The CALET data used in this analysis are provided by
the Waseda CALET Operation Center located at the Waseda University.
GCN Circular 27852
Subject
GRB 200528A: Swift-XRT refined Analysis
Date
2020-05-29T10:39:04Z (5 years ago)
From
Phil Evans at U of Leicester <pae9@leicester.ac.uk>
M. Perri (ASDC), V. D'Elia (ASDC), A. D'Ai (INAF-IASFPA), B. Sbarufatti
(PSU), D.N. Burrows (PSU), J. D. Gropp (PSU), J.P. Osborne (U.
Leicester), K.L. Page (U. Leicester), A.P. Beardmore (U. Leicester) and
E. Ambrosi report on behalf of the Swift-XRT team:
We have analysed 5.7 ks of XRT data for GRB 200528A (Ambrosi et al. GCN
Circ. 27832), from 73 s to 50.9 ks after the BAT trigger. The data
comprise 226 s in Windowed Timing (WT) mode with the remainder in
Photon Counting (PC) mode. The enhanced XRT position for this burst was
given by Evans et al. (GCN Circ. 27836).
The late-time light curve (from T0+5.1 ks) can be modelled with a
power-law decay with a decay index of alpha=0.97 (+/-0.07).
A spectrum formed from the WT mode data can be fitted with an absorbed
power-law with a photon spectral index of 2.30 (+/-0.05). The
best-fitting absorption column is 3.63 (+0.19, -0.18) x 10^21 cm^-2,
in excess of the Galactic value of 1.2 x 10^20 cm^-2 (Willingale et al.
2013). The PC mode spectrum has a photon index of 2.24 (+0.16, -0.15)
and a best-fitting absorption column of 3.8 (+0.7, -0.6) x 10^21 cm^-2.
The counts to observed (unabsorbed) 0.3-10 keV flux conversion factor
deduced from this spectrum is 3.4 x 10^-11 (6.1 x 10^-11) erg cm^-2
count^-1.
A summary of the PC-mode spectrum is thus:
Total column: 3.8 (+0.7, -0.6) x 10^21 cm^-2
Galactic foreground: 1.2 x 10^20 cm^-2
Excess significance: 9.8 sigma
Photon index: 2.24 (+0.16, -0.15)
If the light curve continues to decay with a power-law decay index of
0.97, the count rate at T+24 hours will be 0.041 count s^-1,
corresponding to an observed (unabsorbed) 0.3-10 keV flux of 1.4 x
10^-12 (2.5 x 10^-12) erg cm^-2 s^-1.
The results of the XRT-team automatic analysis are available at
http://www.swift.ac.uk/xrt_products/00974827.
This circular is an official product of the Swift-XRT team.
GCN Circular 27849
Subject
GRB 200528A: Assy optical upper limit
Date
2020-05-29T08:09:05Z (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 200528A (Fermi GBM Team GCN 27831; Ambrosi et al.,
GCN 27832) with AZT-20 1.5 m telescope of Assy-Turgen observatory
starting on May., 28 (UT) 16:16:12.
We do not detect any sources in the Swift-XRT extended position (Evans
et al., GCN 27836).
Preliminary photometry of the field is following.
Date UT start t-T0 Filter Exp. OT Err. UL (3sigma)
(mid, days) (s)
2020-05-28 16:16:12 0.26777 r(AB) 54*60 n/d n/d 22.4
The photometry is based on the nearby stars of SDSS catalog
SDSS-DR12_id r
J114613.33+581329.5 19.455
J114632.90+581307.2 19.190
J114549.81+581044.3 19.004
J114600.53+580839.6 16.985
GCN Circular 27842
Subject
GRB 200528A: NOT optical upper limits
Date
2020-05-29T00:02:50Z (5 years ago)
From
Daniele B Malesani at DTU Space <malesani@space.dtu.dk>
D. B. Malesani (DTU Space), J. P. U. Fynbo (DAWN/NBI), L. Izzo
(DARK/NBI), D. Xu (NAOC/CAS), T. Pursimo (NOT), report on behalf of a
larger collaboration:
We observed the field of GRB 200528A (Ambrosi et al., GCN 27832) using
the Nordic Optical Telescope (NOT) equipped with the ALFOSC camera.
Observations were carried out under variable, thin clouds. After
stacking the good images in each filter, no afterglow is visible in
either band within the XRT position (Evans et al., GCN 27836). At mean
epochs May 28.926 and 28.927 UT (11.78 and 11.80 hr after the GRB,
respectively), we derive limiting magnitudes r > 23.5 and z > 22 AB
(calibrated against nearby stars in the Pan-STARRS catalog).
We note that the galaxy visible in the archival surveys and noted by de
Ugarte Postigo & Kann (GCN 27833) is about 10.6 arcsec away of the
UVOT-enhanced XRT position (1.5" error; Evans et al., GCN 27836), and is
thus likely unrelated to the GRB.
GCN Circular 27841
Subject
GRB 200528A: Fermi GBM Observation
Date
2020-05-28T23:28:45Z (5 years ago)
From
Cori Fletcher at USRA <cfletcher@usra.edu>
C. Fletcher (USRA), A. von Kienlin and C. Meegan (UAH)
report on behalf of the Fermi GBM Team:
"At 10:27:24.35 UT on 28 May 2020, the Fermi Gamma-Ray Burst Monitor (GBM)
triggered and located GRB 200528A (trigger 612354449 / 200528436)
which was also detected by the Swift/BAT (Ambrosi et al. 2020, GCN 27832)
The Fermi GBM Final Real-time Localization (GCN 27831) is consistent with the Swift position.
The angle from the Fermi LAT boresight at the GBM trigger time is 16 degrees.
The GBM light curve shows multiple peaks
with a duration (T90) of about 56 s (50-300 keV).
The time-averaged spectrum from T0+2.05 s to T0+59.4 s is
best fit by a power law function with an exponential
high-energy cutoff. The power law index is -1.39 +/- 0.02 and
the cutoff energy, parameterized as Epeak, is 55.5 +/- 0.8 keV.
The event fluence (10-1000 keV) in this time interval is
(2.54 +/- 0.02)E-05 erg/cm^2. The 1-sec peak photon flux measured
starting from T0+33.3 s in the 10-1000 keV band
is 27.2 +/- 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 27840
Subject
GRB 200528A: Swift/UVOT Upper Limits
Date
2020-05-28T22:25:58Z (5 years ago)
From
Frank Marshall at Swift/UVOT <marshall@milkyway.gsfc.nasa.gov>
F. E. Marshall (NASA/GSFC) and E. Ambrosi (INAF-IASFPA)
report on behalf of the Swift/UVOT team:
The Swift/UVOT began settled observations of the field of GRB 200528A
81 s after the BAT trigger (Ambrosi et al., GCN Circ. 27832).
No optical afterglow consistent with the enhanced XRT position
(Evans et al. GCN Circ. 27836) 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 81 231 147 >21.1
u 293 305 12 >18.7
v 5743 5942 197 >18.8
b 5127 5327 169 >20.7
uvw2 5538 5738 197 >21.0
The magnitudes in the table are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 0.01 in the direction of the burst
(Schlegel et al. 1998).
GCN Circular 27839
Subject
GRB 200528A: Swift-BAT refined analysis
Date
2020-05-28T21:45:22Z (5 years ago)
From
Hans Krimm at NSF/NASA-GSFC <hkrimm@nsf.gov>
S. D. Barthelmy (GSFC), E. Ambrosi (INAF-IASFPA), 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-61 to T+242 sec from the recent telemetry downlink,
we report further analysis of BAT GRB 200528A (trigger #974827)
(Ambrosi, et al., GCN Circ. 27832). The BAT ground-calculated position is
RA, Dec = 176.637, 58.185 deg which is
RA(J2000) = 11h 46m 32.8s
Dec(J2000) = +58d 11' 07.3"
with an uncertainty of 1.0 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 62%.
The mask-weighted light curve shows a multi-peaked structure rising just before T0,
peaking around T+35 sec and decaying to background by T+120 sec.
T90 (15-350 keV) is 58.7 +- 1.4 sec (estimated error including systematics).
The time-averaged spectrum from T-1.02 to T+112.88 sec is best fit by a power law
with an exponential cutoff. This fit gives a photon index 1.62 +- 0.14,
and Epeak of 40.1 +- 5.5 keV (chi squared 25.28 for 56 d.o.f.). For this
model the total fluence in the 15-150 keV band is 1.8 +- 0.0 x 10^-5 erg/cm2
and the 1-sec peak flux measured from T+33.82 sec in the 15-150 keV band is
17.5 +- 0.5 ph/cm2/sec. A fit to a simple power law gives a photon index
of 2.14 +- 0.03 (chi squared 69.65 for 57 d.o.f.). 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/974827/BA/
GCN Circular 27838
Subject
GRB 200528A: 1.3m DFOT Optical Upper Limits
Date
2020-05-28T17:52:58Z (5 years ago)
From
Amit Kumar at ARIES, India <amitkundu515@gmail.com>
A. Kumar (ARIES), S. B. Pandey (ARIES), R. Gupta (ARIES), K. Misra (ARIES),
A. Aryan (ARIES), A. Ghosh (ARIES), and Dimple (ARIES) report:
We carried out observation of Fermi GBM detected GRB 200528A (GCN 27831,
Ambrosi et al., GCN 27832) with the 1.3m Devasthal Fast Optical Telescope
(DFOT) at Devasthal observatory of Aryabhatta Research Institute of
observational sciencES (ARIES), India.
The observation was started on 2020-05-28T15:37:05 UTC. We observed a
series of 4 x 300s exposures using the Bessell I filter covering Swift XRT
enhanced position (Evans et al., 27836).
We do not detect any new optical source within the Swift XRT enhanced error
circle in individual as well as in the stacked image (Adachi et al., GCN
27834, Lipunov et al., GCN 27835 and Zhu et al., GCN 27837).
We obtained the 3-sigma upper limit as follows:
T_start-T0(hrs) Start Date (UTC) End Date (UTC) Filter Limit (mag)
-----------------------------------------------------------------------------------------------
5.161 2020-05-28T15:37:05 2020-05-28T15:58:42 I 20.2 +- 0.2
Photometry is done based on the USNO-B1.0 catalog. This magnitude is not
corrected for Galactic extinction in the direction of the GRB.
GCN Circular 27837
Subject
GRB 200528A: Nanshan/NEXT optical upper limit
Date
2020-05-28T16:59:24Z (5 years ago)
From
Dong Xu at NAOC/CAS <dxu@nao.cas.cn>
Z.P. Zhu, S.Y. Fu, X. Liu, D. Xu (NAOC), X. Gao (Urumqi No.1 Senior High
School), X. Zhang, J.Z. Liu (XAO) report:
We observed the field of GRB 2005528A (Ambrosi et al., GCN 27832) using
the NEXT-0.6m telescope located at Nanshan, Xinjiang, China. We obtained
5x120s frames in the Sloan r-band, starting at 15:55:41 UT on
2020-05-28, i.e., 5.47 hr after the burst.
No optical source is detected in our stacked image at the enhanced XRT
position (Evans et al., GCN 27836), down to a limiting magnitude of
r~20.1, calibrated with nearby SDSS field.
GCN Circular 27836
Subject
GRB 200528A: Enhanced Swift-XRT position
Date
2020-05-28T14:43:12Z (5 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 910 s of XRT Photon Counting mode data and 3 UVOT
images for GRB 200528A, 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 = 176.63744, +58.19257 which is equivalent
to:
RA (J2000): 11h 46m 32.99s
Dec (J2000): +58d 11' 33.3"
with an uncertainty of 1.8 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 27835
Subject
Swift GRB 200528A: Global MASTER-Net observations report
Date
2020-05-28T13:24:40Z (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-Amur robotic telescope (Global MASTER-Net: http://observ.pereplet.ru, Lipunov et al., 2010, Advances in Astronomy, vol. 2010, 30L) located in Russia (Blagoveshchensk State Pedagogical University) was pointed to the Swift GRB 200528A ( E. Ambrosi et al., GCN 27832) errorbox 9786 sec after notice time and 9804 sec after trigger time at 2020-05-28 13:10:47 UT, with upper limit up to 16.7 mag. Observations started at twilight. The observations began at zenith distance = 22 deg. The sun altitude is -12.3 deg.
The galactic latitude b = 57 deg., longitude l = 138 deg.
Real time updated cover map and OT discovered available here:
https://master.sai.msu.ru/site/master2/observ.php?id=1368165
We obtain a following upper limits.
Tmid-T0 | Site |Filt.| Expt. | Limit| Comment
_________|_____________________|_____|_______|______|________
9894 | MASTER-Amur | C | 180 | 16.7 |
Filter C is a clear (unfiltred) band.
The observation and reduction will continue.
The message may be cited.
GCN Circular 27834
Subject
GRB 200528A: MITSuME Akeno optical upper limits
Date
2020-05-28T13:14:26Z (5 years ago)
From
Adachi Ryo at Tokyo Institute of Tech <adachi@hp.phys.titech.ac.jp>
R. Adachi, R. Hosokawa, K. L. Murata, M. Niwano, F. Ogawa, N.
Nakamura, Y. Yatsu, and N. Kawai (Tokyo Tech) report on behalf of the
MITSuME collaboration:
We observed the field of GRB 200528A (Fermi GBM team, GCN #27831;
Ambrosi et al., GCN #27832) with the optical three color (g', Rc, and
Ic) CCD cameras attached to the MITSuME 50 cm telescopes of Akeno
Observatory in Japan.
The observation started on 10:28:31.87 UT. The first 40 images were
heavily affected by twilight and bad weather at Akeno Observatory. We
checked single images and combined images. We did not find any new
point sources within the Swift/XRT error circle (Ambrosi et al., GCN
#27832) in all three bands. Also, we did not detect the potential host
galaxy (de Ugarte Postigo et al., GCN #27833) due to shallow upper
limits of our observation. We obtained the 5-sigma limits as follows.
T0+[min] MID-UT T-EXP[sec] 5-sigma limits
------------------------------------------------------------------------------------------------
36.7 11:28:34 1020 g'>18.9, Rc>18.3, Ic>17.4
------------------------------------------------------------------------------------------------
T0+ : Elapsed time after the burst
T-EXP: Total Exposure time
We used the UCAC4 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., submitted;
https://github.com/MNiwano/Eclair).
GCN Circular 27833
Subject
GRB 200528A: Potential host galaxy in PanSTARRS, SDSS and WISE
Date
2020-05-28T11:19:38Z (5 years ago)
From
Alexander Kann at IAA-CSIC <kann@iaa.es>
A. de Ugarte Postigo (HETH/IAA-CSIC, DARK/NBI), and D. A. Kann
(HETH/IAA-CSIC) report:
Within the XRT error circle of GRB 200528A (Fermi GBM team, GCN #27831;
Ambrosi et al., GCN #27832), a bright, extended object is detected, at
position (J2000, from SDSS):
RA = 176.64297
Dec. = 58.19313
It is found to have (from SDSS):
u' = 22.28 +/-0.42 mag;
g' = 21.46 +/- 0.075 mag;
r' = 20.45 +/- 0.047 mag;
i' = 20.13 +/- 0.052 mag;
z' = 19.88 +/- 0.147 mag.
It is also detected in PanSTARRS and WISE with W1 = 16.7 +/- 0.1 mag.
The photometric redshift in SDSS is given as z = 0.380 +/- 0.0792.
We suggest this galaxy to be the host galaxy of GRB 200528A. The early
non-detection in UVOT indicates this might be an optically dark GRB, as
the X-ray light curve is very bright early on. The X-ray column density
is unknown so far (Ambrosi et al., GCN #27832) but likely to be high.
Confirmation or rejection awaits a refined XRT position once data are
obtainable in PC mode.
GCN Circular 27832
Subject
GRB 200528A: Swift detection of a burst
Date
2020-05-28T10:39:36Z (5 years ago)
From
Kim Page at U.of Leicester <klp5@leicester.ac.uk>
E. Ambrosi (INAF-IASFPA), V. D'Elia (SSDC), P. A. Evans (U Leicester),
J.D. Gropp (PSU), N. J. Klingler (PSU), H. A. Krimm (NSF),
F. E. Marshall (NASA/GSFC) and K. L. Page (U Leicester) report on
behalf of the Neil Gehrels Swift Observatory Team:
At 10:27:23 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 200528A (trigger=974827). Swift slewed immediately to the burst.
The BAT on-board calculated location is
RA, Dec 176.637, +58.147 which is
RA(J2000) = 11h 46m 33s
Dec(J2000) = +58d 08' 50"
with an uncertainty of 3 arcmin (radius, 90% containment, including
systematic uncertainty). The BAT light curve showed a multi-peaked
structure with a duration of about 60 sec. The peak count rate
was ~19000 counts/sec (15-350 keV), at ~33 sec after the trigger.
The XRT began observing the field at 10:28:33.9 UT, 70.2 seconds after
the BAT trigger. XRT found a bright, uncatalogued X-ray source located
at RA, Dec 176.6438, 58.1921 which is equivalent to:
RA(J2000) = 11h 46m 34.51s
Dec(J2000) = +58d 11' 31.6"
with an uncertainty of 5.2 arcseconds (radius, 90% containment). This
location is 162 arcseconds from the BAT onboard position, within the
BAT error circle. No event data are yet available to determine the
column density using X-ray spectroscopy.
The initial flux in the 0.1 s image was 4.08e-08 erg cm^-2 s^-1 (0.2-10
keV).
UVOT took a finding chart exposure of 150 seconds with the White filter
starting 80 seconds after the BAT trigger. No credible afterglow candidate has
been found in the initial data products. The 2.7'x2.7' sub-image covers 100% of
the XRT error circle. The typical 3-sigma upper limit has been about 19.6 mag.
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
0.01.
Burst Advocate for this burst is E. Ambrosi (elena.ambrosi 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/)
GCN Circular 27831
Subject
GRB 200528A: Fermi GBM Final Real-time Localization
Date
2020-05-28T10:37:56Z (5 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 LONG GRB
At 10:27:24 UT on 28 May 2020, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 200528A (trigger 612354449.346938 / 200528436).
The on-ground calculated location, using the Fermi GBM trigger data, is RA = 169.2, Dec = 60.2 (J2000 degrees, equivalent to J2000 11h 16m, 60d 12'), with a statistical uncertainty of 1.0 degrees.
The angle from the Fermi LAT boresight is 19.0 degrees.
The skymap can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2020/bn200528436/quicklook/glg_skymap_all_bn200528436.png
The HEALPix FITS file, including the estimated localization systematic, can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2020/bn200528436/quicklook/glg_healpix_all_bn200528436.fit
The GBM light curve can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2020/bn200528436/quicklook/glg_lc_medres34_bn200528436.gif