GRB 210807C
GCN Circular 30609
Subject
GRB 210807C: Fermi GBM Final Real-time Localization
Date
2021-08-07T23:05:39Z (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 LONG GRB
At 22:55:24 UT on 7 Aug 2021, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 210807C (trigger 650069729.307352 / 210807955).
The on-ground calculated location, using the Fermi GBM trigger data, is RA = 147.6, Dec = -51.4 (J2000 degrees, equivalent to J2000 09h 50m, -51d 23'), with a statistical uncertainty of 1.7 degrees.
The angle from the Fermi LAT boresight is 60.0 degrees.
The skymap can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2021/bn210807955/quicklook/glg_skymap_all_bn210807955.png
The HEALPix FITS file, including the estimated localization systematic, can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2021/bn210807955/quicklook/glg_healpix_all_bn210807955.fit
The GBM light curve can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2021/bn210807955/quicklook/glg_lc_medres34_bn210807955.gif
GCN Circular 30610
Subject
GRB 210807C: Swift detection of a burst
Date
2021-08-07T23:14:05Z (4 years ago)
From
David Palmer at LANL <palmer@lanl.gov>
A. Y. Lien (GSFC/UMBC), C. Gronwall (PSU), J.D. Gropp (PSU),
N. J. Klingler (GSFC/UMBC/CRESSTII), K. L. Page (U Leicester) and
D. M. Palmer (LANL) report on behalf of the Neil Gehrels Swift
Observatory Team:
At 22:57:08 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 210807C (trigger=1064421). Swift slewed immediately to the burst.
The BAT on-board calculated location is
RA, Dec 143.551, -51.409 which is
RA(J2000) = 09h 34m 12s
Dec(J2000) = -51d 24' 31"
with an uncertainty of 3 arcmin (radius, 90% containment, including
systematic uncertainty). Although the lightcurve before T+8s is
not currently available due to a telemetry dropout, the later lightcurve
shows a complex structure extending at least to T+90s. The peak count
rate in the available lightcurve was ~800 counts/sec (15-350 keV),
at ~20 sec after the trigger.
The XRT began observing the field at 23:00:05.5 UT, 177.1 seconds after
the BAT trigger. Using promptly downlinked data we find a bright,
uncatalogued X-ray source located at RA, Dec 143.53455, -51.40237 which
is equivalent to:
RA(J2000) = 09h 34m 08.29s
Dec(J2000) = -51d 24' 08.5"
with an uncertainty of 7.1 arcseconds (radius, 90% containment). This
location is 43 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 does not constrain the column density.
The initial flux in the 2.5 s image was 2.31e-09 erg cm^-2 s^-1 (0.2-10
keV).
UVOT took a finding chart exposure of 250 seconds with the V filter starting
180 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 19.2 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 18.0 mag. No
correction has been made for the large, but uncertain, extinction expected.
Burst Advocate for this burst is A. Y. Lien (amy.y.lien AT nasa.gov).
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 30612
Subject
Fermi GRB 210807C: Global MASTER-Net observations report
Date
2021-08-08T03:30:32Z (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-OAFA robotic telescope (Global MASTER-Net: http://observ.pereplet.ru, Lipunov et al., 2010, Advances in Astronomy, vol. 2010, 30L) located in Argentina (OAFA observatory of San Juan National University) started inspect of the Fermi GRB 210807C ( Fermi GBM team, GCN 30609) errorbox 114 sec after notice time and 206 sec after trigger time at 2021-08-07 22:58:50 UT, with upper limit up to 18.6 mag. Observations started at twilight. The observations began at zenith distance = 64 deg. The sun altitude is -12.1 deg.
MASTER-SAAO robotic telescope located in South Africa (South African Astronomical Observatory) started inspect of the Fermi GRB 210807C errorbox 15419 sec after notice time and 15511 sec after trigger time at 2021-08-08 03:13:56 UT, with upper limit up to 17.5 mag. The observations began at zenith distance = 81 deg. The sun altitude is -27.5 deg.
The galactic latitude b = 2 deg., longitude l = 277 deg.
Real time updated cover map and OT discovered available here:
https://master.sai.msu.ru/site/master2/observ.php?id=1683879
We obtain a following upper limits.
Tmid-T0 | Date Time | Site | Coord (J2000) |Filt.| Expt. | Limit| Comment
_________|_____________________|_____________________|____________________________________|_____|_______|_______|________
222 | 2021-08-07 22:58:50 | MASTER-OAFA | (09h 51m 36.60s , -48d 08m 16.7s) | C | 30 | 16.4 |
285 | 2021-08-07 22:59:59 | MASTER-OAFA | (09h 32m 30.94s , -50d 38m 28.4s) | C | 20 | 16.6 |
320 | 2021-08-07 22:59:59 | MASTER-OAFA | (09h 32m 30.95s , -50d 38m 28.4s) | C | 90 | 17.3 | Coadd
615 | 2021-08-07 22:59:59 | MASTER-OAFA | (09h 32m 30.93s , -50d 38m 28.5s) | C | 680 | 18.3 | Coadd
330 | 2021-08-07 23:00:39 | MASTER-OAFA | (09h 32m 26.75s , -50d 36m 58.8s) | C | 30 | 16.8 |
384 | 2021-08-07 23:01:28 | MASTER-OAFA | (09h 32m 26.54s , -50d 38m 17.9s) | C | 40 | 17.0 |
449 | 2021-08-07 23:02:28 | MASTER-OAFA | (09h 32m 28.68s , -50d 37m 04.2s) | C | 50 | 17.1 |
524 | 2021-08-07 23:02:28 | MASTER-OAFA | (09h 32m 28.68s , -50d 37m 04.3s) | C | 200 | 17.8 | Coadd
528 | 2021-08-07 23:03:37 | MASTER-OAFA | (09h 32m 22.55s , -50d 37m 43.5s) | C | 70 | 17.3 |
622 | 2021-08-07 23:05:06 | MASTER-OAFA | (09h 32m 22.46s , -50d 36m 42.4s) | C | 80 | 17.5 |
732 | 2021-08-07 23:06:46 | MASTER-OAFA | (09h 32m 28.12s , -50d 37m 41.4s) | C | 100 | 17.7 |
877 | 2021-08-07 23:06:46 | MASTER-OAFA | (09h 32m 28.14s , -50d 37m 41.5s) | C | 390 | 18.3 | Coadd
866 | 2021-08-07 23:08:45 | MASTER-OAFA | (09h 32m 22.16s , -50d 38m 40.7s) | C | 130 | 17.9 |
1030 | 2021-08-07 23:11:14 | MASTER-OAFA | (09h 32m 29.66s , -50d 38m 09.7s) | C | 160 | 18.0 |
1220 | 2021-08-07 23:14:14 | MASTER-OAFA | (09h 32m 25.67s , -50d 37m 04.8s) | C | 180 | 18.2 |
1400 | 2021-08-07 23:14:14 | MASTER-OAFA | (09h 32m 25.67s , -50d 37m 04.8s) | C | 540 | 18.6 | Coadd
1420 | 2021-08-07 23:17:34 | MASTER-OAFA | (09h 32m 25.60s , -50d 38m 34.9s) | C | 180 | 18.2 |
1619 | 2021-08-07 23:20:53 | MASTER-OAFA | (09h 32m 28.21s , -50d 36m 47.5s) | C | 180 | 18.3 |
1819 | 2021-08-07 23:24:13 | MASTER-OAFA | (09h 32m 22.92s , -50d 37m 36.2s) | C | 180 | 18.2 |
1999 | 2021-08-07 23:24:13 | MASTER-OAFA | (09h 32m 22.92s , -50d 37m 36.2s) | C | 540 | 18.6 | Coadd
2019 | 2021-08-07 23:27:32 | MASTER-OAFA | (09h 32m 22.25s , -50d 36m 35.5s) | C | 180 | 18.3 |
2218 | 2021-08-07 23:30:52 | MASTER-OAFA | (09h 32m 28.88s , -50d 37m 34.8s) | C | 180 | 18.3 |
2417 | 2021-08-07 23:34:11 | MASTER-OAFA | (09h 32m 22.28s , -50d 38m 34.3s) | C | 180 | 18.2 |
2597 | 2021-08-07 23:34:11 | MASTER-OAFA | (09h 32m 22.29s , -50d 38m 34.3s) | C | 540 | 18.6 | Coadd
2617 | 2021-08-07 23:37:31 | MASTER-OAFA | (09h 32m 29.11s , -50d 38m 18.2s) | C | 180 | 18.2 |
2816 | 2021-08-07 23:40:50 | MASTER-OAFA | (09h 32m 25.11s , -50d 36m 58.5s) | C | 180 | 18.3 |
3016 | 2021-08-07 23:44:09 | MASTER-OAFA | (09h 32m 25.02s , -50d 38m 21.0s) | C | 180 | 18.3 |
3196 | 2021-08-07 23:44:09 | MASTER-OAFA | (09h 32m 25.02s , -50d 38m 21.0s) | C | 540 | 18.5 | Coadd
3215 | 2021-08-07 23:47:29 | MASTER-OAFA | (09h 32m 28.03s , -50d 36m 52.9s) | C | 180 | 18.2 |
3415 | 2021-08-07 23:50:49 | MASTER-OAFA | (09h 32m 21.71s , -50d 37m 32.1s) | C | 180 | 18.2 |
3614 | 2021-08-07 23:54:08 | MASTER-OAFA | (09h 32m 21.47s , -50d 36m 31.4s) | C | 180 | 18.1 |
3794 | 2021-08-07 23:54:08 | MASTER-OAFA | (09h 32m 21.47s , -50d 36m 31.5s) | C | 540 | 18.5 | Coadd
3814 | 2021-08-07 23:57:27 | MASTER-OAFA | (09h 32m 27.57s , -50d 37m 32.7s) | C | 180 | 17.9 |
4013 | 2021-08-08 00:00:47 | MASTER-OAFA | (09h 32m 20.35s , -50d 38m 40.0s) | C | 180 | 18.1 |
4212 | 2021-08-08 00:04:06 | MASTER-OAFA | (09h 32m 27.14s , -50d 38m 22.6s) | C | 180 | 18.1 |
4392 | 2021-08-08 00:04:06 | MASTER-OAFA | (09h 32m 27.14s , -50d 38m 22.6s) | C | 540 | 18.5 | Coadd
4412 | 2021-08-08 00:07:26 | MASTER-OAFA | (09h 32m 23.81s , -50d 36m 49.8s) | C | 180 | 18.1 |
4612 | 2021-08-08 00:10:46 | MASTER-OAFA | (09h 32m 23.52s , -50d 38m 37.4s) | C | 180 | 18.1 |
4811 | 2021-08-08 00:14:05 | MASTER-OAFA | (09h 32m 25.80s , -50d 36m 50.7s) | C | 180 | 18.1 |
5330 | 2021-08-08 00:22:44 | MASTER-OAFA | (09h 32m 23.46s , -50d 36m 07.4s) | C | 180 | 17.6 |
5847 | 2021-08-08 00:31:20 | MASTER-OAFA | (09h 32m 22.91s , -50d 38m 05.8s) | C | 180 | 17.5 |
6366 | 2021-08-08 00:40:00 | MASTER-OAFA | (09h 32m 21.93s , -50d 36m 57.0s) | C | 180 | 17.2 |
6884 | 2021-08-08 00:48:38 | MASTER-OAFA | (09h 32m 25.05s , -50d 36m 50.2s) | C | 180 | 17.2 |
7402 | 2021-08-08 00:57:16 | MASTER-OAFA | (09h 32m 16.96s , -50d 36m 40.0s) | C | 180 | 16.9 |
7921 | 2021-08-08 01:05:55 | MASTER-OAFA | (09h 32m 16.80s , -50d 38m 40.1s) | C | 180 | 16.7 |
8437 | 2021-08-08 01:14:31 | MASTER-OAFA | (09h 32m 17.73s , -50d 36m 54.2s) | C | 180 | 16.6 |
8956 | 2021-08-08 01:23:10 | MASTER-OAFA | (09h 32m 20.07s , -50d 36m 39.2s) | C | 180 | 16.1 |
9475 | 2021-08-08 01:31:49 | MASTER-OAFA | (09h 32m 10.94s , -50d 36m 17.5s) | C | 180 | 14.0 |
15602 | 2021-08-08 03:13:56 | MASTER-SAAO | (09h 34m 22.59s , -51d 21m 56.9s) | C | 180 | 17.5 |
Filter C is a clear (unfiltred) band.
The observation and reduction will continue.
The message may be cited.
GCN Circular 30615
Subject
GRB 210807C: Enhanced Swift-XRT position
Date
2021-08-08T07:13:18Z (4 years ago)
From
Phil Evans at U of Leicester <pae9@leicester.ac.uk>
M.R. Goad, J.P. Osborne, A.P. Beardmore and P.A. Evans (U. Leicester)
report on behalf of the Swift-XRT team.
Using 722 s of XRT Photon Counting mode data and 1 UVOT
images for GRB 210807C, 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 = 143.53386, -51.40105 which is equivalent
to:
RA (J2000): 09h 34m 8.13s
Dec (J2000): -51d 24' 03.8"
with an uncertainty of 2.0 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 30619
Subject
GRB 210807C: Swift/UVOT Upper Limits
Date
2021-08-08T21:44:40Z (4 years ago)
From
Sam LaPorte at PSU <sjl5346@psu.edu>
GRB 210807C: Swift/UVOT Upper Limits
S. J. LaPorte (PSU) and A. Y. Lien (GSFC/UMBC)
report on behalf of the Swift/UVOT team:
The Swift/UVOT began settled observations of the field of GRB 210807C
180 s after the BAT trigger (Lien et al., GCN Circ. 30610).
No optical afterglow consistent with the XRT position
(Lien et al. GCN Circ. 30610)
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 initial exposures
are:
Filter T_start(s) T_stop(s) Exp(s) Mag
v 180 852 596 >19.4
The magnitudes in the table are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 3.076 in the direction of the burst
(Schlegel et al. 1998).
GCN Circular 30620
Subject
GRB 210807C: Fermi GBM detection
Date
2021-08-08T22:58:37Z (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 22:55:24.31 UT on 7 July 2021, the Fermi Gamma-Ray Burst Monitor (GBM)
triggered and located GRB 210807C (trigger 650069729 / 210807955)
which was also detected by the Swift/BAT (Lien et al. 2021, GCN 30610).
The GBM on-ground location is consistent with the Swift position.
The angle from the Fermi LAT boresight at the GBM trigger time is 61
degrees.
The GBM light curve consists of multiple peaks followed by some
extended emission with a duration (T90) of about 125 s (50-300 keV).
The time-averaged spectrum from T0 s to T0+94.2 s
is best fit by a Band function, with Epeak = 170 +/- 28 keV,
alpha = -1.08 +/- 0.06 and beta = -1.61 +/- 0.01.
The event fluence (10-1000 keV) in this time interval is
(56.43 +/- 0.54)E-06 erg/cm^2. The 1-sec peak photon flux measured
starting from T0+8.64 s in the 10-1000 keV band
is 7.2 +/- 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 30621
Subject
GRB 210807C: Swift-XRT refined Analysis
Date
2021-08-09T06:57:14Z (4 years ago)
From
Phil Evans at U of Leicester <pae9@leicester.ac.uk>
P.A. Evans (U. Leicester) and A. Y. Lien (GSFC/UMBC) reports on behalf
of the Swift-XRT team:
We have analysed 5.8 ks of XRT data for GRB 210807C (Lien et al. GCN
Circ. 30610), from 183 s to 56.8 ks after the BAT trigger. The data
comprise 203 s in Windowed Timing (WT) mode with the remainder in
Photon Counting (PC) mode. The enhanced XRT position for this burst was
given by Goad et al. (GCN Circ. 30615).
The light curve can be modelled with a power-law decay with a decay
index of alpha=3.11 (+2.96, -0.22), followed by a break at T0+420.7
(+18.1, -165.2) s to a decay of 1.32 (+0.09, -0.07).
A spectrum formed from the WT mode data can be fitted with an absorbed
power-law with a photon spectral index of 2.28 (+0.15, -0.14). The
best-fitting absorption column is 4.9 (+/-0.4) x 10^22 cm^-2, in
excess of the Galactic value of 8.5 x 10^21 cm^-2 (Willingale et al.
2013). The PC mode spectrum has a photon index of 2.5 (+/-0.6) and a
best-fitting absorption column of 6.0 (+1.8, -1.5) x 10^22 cm^-2. The
counts to observed (unabsorbed) 0.3-10 keV flux conversion factor
deduced from this spectrum is 7.6 x 10^-11 (4.1 x 10^-10) erg cm^-2
count^-1.
A summary of the PC-mode spectrum is thus:
Total column: 6.0 (+1.8, -1.5) x 10^22 cm^-2
Galactic foreground: 8.5 x 10^21 cm^-2
Excess significance: 5.5 sigma
Photon index: 2.5 (+/-0.6)
The results of the XRT-team automatic analysis are available at
http://www.swift.ac.uk/xrt_products/01064421.
This circular is an official product of the Swift-XRT team.
GCN Circular 30625
Subject
GRB 210807C: Swift-BAT refined analysis
Date
2021-08-10T21:58:19Z (4 years ago)
From
Sibasish Laha at GSFC <sibasish.laha@nasa.gov>
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),
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 210807C (trigger #1064421)
(Lien et al., GCN Circ. 30610). The BAT ground-calculated position is
RA, Dec = 143.540, -51.409 deg which is
RA(J2000) = 09h 34m 09.7s
Dec(J2000) = -51d 24' 32.8"
with an uncertainty of 1.0 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 20%.
The BAT light curve showed a complex structure with a duration of about ~100 sec.
T90 (15-350 keV) is 89.97 +- 6.26 sec (estimated error including systematics).
The time-averaged spectrum from T-31.36 to T+78.57 sec is best fit by a simple
power-law model. The power law index of the time-averaged spectrum is
1.65 +- 0.06. The fluence in the 15-150 keV band is 1.2 +- 0.0 x 10^-05 erg/cm2.
The 1-sec peak photon flux measured from T-24.22 sec in the 15-150 keV band
is 4.0 +- 0.7 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/1064421/BA/