GRB 200806A
GCN Circular 28234
Subject
GRB 200806A: CALET Gamma-Ray Burst Monitor detection
Date
2020-08-09T12:42:57Z (5 years ago)
From
Valentin Pal'shin at AGU <val@phys.aoyama.ac.jp>
Y. Shimizu (Kanagawa U),
A. Yoshida, T. Sakamoto, V. Pal'shin, S. Sugita (AGU),
Y. Kawakubo (LSU), K. Yamaoka (Nagoya U), S. Nakahira (RIKEN),
Y. Asaoka (ICRR), S. Torii, Y. Akaike, K. Kobayashi (Waseda U),
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 GRB 200806A (Swift detection: Ambrosi et al., GCN Circ. 28211,
Lien et al., GCN Circ. 28223; AstroSat CZTI detection: Gupta et al.,
GCN Circ. 28216; https://gcn.gsfc.nasa.gov/other/200806A.gcn3)
triggered the CALET Gamma-ray Burst Monitor (CGBM) at 15:28:52.289 UTC
on 6 August 2020. The burst signal was seen by all CGBM detectors.
No real-time CGBM GCN notice was distributed about this trigger because
the real-time communication from the ISS was off (loss of signal).
The burst light curve shows a multi-peaked structure which starts
at T-2.7 sec, peaks at T+20.0 sec and ends at T+40.9 sec.
The T90 and T50 durations measured by the SGM data are 33.4 +- 3.1 sec
and 14.5 +- 2.0 sec (40-1000 keV), respectively.
The ground processed light curve is available at
http://cgbm.calet.jp/cgbm_trigger/ground/1280762930/
The CALET data used in this analysis are provided by
the Waseda CALET Operation Center located at the Waseda University.
GCN Circular 28229
Subject
GRB 200806A: Nanshan/NEXT optical upper limit
Date
2020-08-08T06:35:51Z (5 years ago)
From
Dong Xu at NAOC/CAS <dxu@nao.cas.cn>
S.Y. Fu, Z.P. Zhu, 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 200806A (Ambrosiet al., GCN 28211) using
the NEXT-0.6m telescope located at Nanshan, Xinjiang, China. We obtained
8x100s frames in the Sloan r-band, starting at 19:42:36 UT on
2020-08-07, i.e., 28.22 hr after the burst.
No optical source is detected in our stacked image at the enhanced XRT
position (Beardmore et al., GCN 28214), down to a limiting magnitude of
r~20.2, calibrated with the nearby PanSTARRS field.
GCN Circular 28227
Subject
GRB 200806A: CAHA optical afterglow confirmation
Date
2020-08-07T22:19:18Z (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), C. C. Thoene, M. Blazek, J. F. Agui Fernandez (all
HETH/IAA-CSIC), and L. Montoya (CAHA) report:
We observed the afterglow position (Beardmore et al., GCN #28214;
Marshall et al., GCN #28222) of the bright Swift GRB 200806A (Ambrosi et
al., GCN #28211; Lien et al., GCN #28223) with CAFOS at the 2.2m
telescope at Calar Alto, Almeria, Spain, in the SDSS i' band. We
obtained 20 x 180 s exposures, centered at 0.49185 days after the GRB,
under good conditions but moonlight.
At the position of the potential UVOT afterglow (Marshall et al., GCN
#28222), we detect a faint source not visible in PanSTARRS archival
imaging, at position (J2000) RA = 03:31:43.76, Dec. = +37:04:43.90, with
an estimated error of 0".75.
Photometry is made complicated by an uneven background, but measured
against two nearby SDSS stars, we derive i' = 22.95 +/- 0.25 mag.
As this is significantly fainter than the UVOT detection, we consider
this to be the afterglow of GRB 200806A. We note foreground extinction
is rather high (E(B-V)=0.3564 mag according to the maps of Schlafly &
Finkbeiner 2011), and there is additional hydrogen column density along
the line-of-sight (Page et al., GCN #28221), implying this is likely a
dark GRB.
GCN Circular 28224
Subject
GRB 200806A: VIRT optical observations
Date
2020-08-07T18:21:00Z (5 years ago)
From
Priyadarshini Gokuldass at U. of the Virgin Islands <priyadass.94@gmail.com>
P. Gokuldass (UVI), R. Strausbaugh (UVI), D. Morris (UVI), N. Orange
(OrangeWave Innovative Science, LLC), A. Cucchiara (UVI/College of Marin)
report:
We observed the field of GRB200806A (Ambrosi et al, GCN 28211) with the
0.5m Virgin Island Robotic Telescope (VIRT) at the University of the Virgin
Islands' Etelman Observatory on 08-06-2020 starting at 06:22:50 UT (T+15
hrs). We performed a series of exposures in R filter with a total exposure
of 5810 s. The weather conditions were clear during the hours of
observation with an average airmass of 1.6.
We find no new source within the enhanced XRT position error circle
(Beardmore et al., GCN 28214) and report the following 3-sigma upper limit:
T_mid ||Exposure ||Filter ||Limit
T+16 hrs ||5810s ||R ||19.6
The limit is estimated from comparison to nearby USNO B1 stars and is not
corrected for Galactic extinction. The VIRT is still in the commissioning
phase.
This work is supported by NASA-MUREP-MIRO grant NNX15AP95A, NSF EiR AST
Award 1901296, and NSF HBCU-UP AST Award 1831682. This message can be cited.
GCN Circular 28223
Subject
GRB 200806A: Swift-BAT refined analysis
Date
2020-08-07T18:10:15Z (5 years ago)
From
Hans Krimm at NSF/NASA-GSFC <hkrimm@nsf.gov>
A. Y. Lien (GSFC/UMBC), E. Ambrosi (INAF-IASFPA), S. D. Barthelmy (GSFC),
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-60 to T+243 sec from the recent telemetry downlink,
we report further analysis of BAT GRB 200806A (trigger #987016)
(Ambrosi, et al., GCN Circ. 28211). The BAT ground-calculated position is
RA, Dec = 52.933, 37.076 deg which is
RA(J2000) = 03h 31m 43.9s
Dec(J2000) = +37d 04' 33.5"
with an uncertainty of 1.0 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 57%.
The mask-weighted light curve shows a multi-peaked structure, with a sharp
rise close to T+0 sec. The emission peaked at T+22 sec and declined to
background by T+50 sec. T90 (15-350 keV) is 38.8 +- 1.1 sec (estimated error
including systematics).
The time-averaged spectrum from T-0.13 to T+61.22 sec is best fit by a power law
with an exponential cutoff. This fit gives a photon index 0.72 +- 0.12,
and Epeak of 148.1 +- 18.6 keV (chi squared 40.06 for 56 d.o.f.). For this
model the total fluence in the 15-150 keV band is 1.6 +- 0.02 x 10^-5 erg/cm2
and the 1-sec peak flux measured from T+22.24 sec in the 15-150 keV band is
14.1 +- 0.4 ph/cm2/sec. A fit to a simple power law gives a photon index
of 1.27 +- 0.03 (chi squared 111.98 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/987016/BA/
GCN Circular 28222
Subject
GRB 200806A: Swift/UVOT Possible Detection
Date
2020-08-07T17:37:59Z (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 200806A
86 s after the BAT trigger (Ambrosi et al., GCN Circ. 28211).
A source consistent with the enhanced XRT position
(Beardmore et al. GCN Circ. 28214)
is marginally detected in the initial UVOT exposures.
The preliminary detection and 3-sigma upper limits 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 86 236 147 20.26 +/- 0.28
v 629 821 39 >17.9
b 555 747 39 >19.3
u 300 722 265 >19.5
w1 678 870 39 >18.8
m2 653 845 39 >19.4
w2 604 1052 58 >19.0
The magnitudes in the table are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 0.42 in the direction of the burst
(Schlegel et al. 1998).
GCN Circular 28221
Subject
GRB 200806A: Swift-XRT refined Analysis
Date
2020-08-07T15:57:06Z (5 years ago)
From
Phil Evans at U of Leicester <pae9@leicester.ac.uk>
K.L. Page (U. Leicester), M. Capalbi (INAF-IASFPA), M. Perri (ASDC), V.
D'Elia (ASDC), J. D. Gropp (PSU), J.A. Kennea (PSU), A. Tohuvavohu (U.
Toronto), A.P. Beardmore (U. Leicester), P.A. Evans (U. Leicester) and
E. Ambrosi report on behalf of the Swift-XRT team:
We have analysed 5.9 ks of XRT data for GRB 200806A (Ambrosi et al. GCN
Circ. 28211), from 84 s to 22.1 ks after the BAT trigger. The data
comprise 372 s in Windowed Timing (WT) mode with the remainder in
Photon Counting (PC) mode. The enhanced XRT position for this burst was
given by Beardmore et al. (GCN Circ. 28214).
The light curve can be modelled with a power-law decay with a decay
index of alpha=1.01 (+/-0.04).
A spectrum formed from the WT mode data can be fitted with an absorbed
power-law with a photon spectral index of 1.58 (+/-0.07). The
best-fitting absorption column is 3.6 (+/-0.4) x 10^21 cm^-2, in
excess of the Galactic value of 2.6 x 10^21 cm^-2 (Willingale et al.
2013). The PC mode spectrum has a photon index of 1.85 (+/-0.14) and a
best-fitting absorption column of 4.8 (+0.9, -0.8) x 10^21 cm^-2. The
counts to observed (unabsorbed) 0.3-10 keV flux conversion factor
deduced from this spectrum is 4.4 x 10^-11 (6.6 x 10^-11) erg cm^-2
count^-1.
A summary of the PC-mode spectrum is thus:
Total column: 4.8 (+0.9, -0.8) x 10^21 cm^-2
Galactic foreground: 2.6 x 10^21 cm^-2
Excess significance: 4.5 sigma
Photon index: 1.85 (+/-0.14)
If the light curve continues to decay with a power-law decay index of
1.01, the count rate at T+24 hours will be 0.023 count s^-1,
corresponding to an observed (unabsorbed) 0.3-10 keV flux of 9.9 x
10^-13 (1.5 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/00987016.
This circular is an official product of the Swift-XRT team.
GCN Circular 28218
Subject
GRB 200806A: AbAO optical upper limit
Date
2020-08-07T12:55:16Z (5 years ago)
From
Alexei Pozanenko at IKI, Moscow <apozanen@iki.rssi.ru>
S. Belkin (IKI), A. Pozanenko (IKI), R.Ya. Inasaridze (AbAO), N. Pankov
(HSE), K. Kamyshnikov (HSE), V.R. Ayvazian (AbAO), G.V. Kapanadze
(AbAO), E. Mazaeva (IKI), A. Volnova (IKI), I. Molotov (KIAM) report
on behalf of GRB IKI FuN:
We observed the field of Swift GRB 200806A (Ambrosi et al., GCN 28211)
also registered by AstroSat CZTI (Gupta et al., GCN 28216) with AS-32
(0.7m) telescope of Abastumani Observatory starting on 2020-08-06 (UT)
23:42:53. We do not detect any object within the enhanced XRT position
error circle (Beardmore et al., GCN 28214). Preliminary photometry of
the field is following.
Date UT start t-T0 Filter Exp. OT Err. UL
(mid, days) (s)
2020-08-06 23:42:53 0.36498 R 63*60 n/d n/d 21.0
The photometry is based on nearby USNO-B1.0 stars
USNO-B1.0_id R2
1270-0058216 15.48
1270-0058260 14.22
1270-0058260 14.98
1271-0065622 15.31
GCN Circular 28216
Subject
GRB 200806A: AstroSat CZTI detection
Date
2020-08-07T07:50:04Z (5 years ago)
From
Soumya Gupta at IUCAA/ASTROSAT <soumya@iucaa>
S. Gupta, V. Sharma, A. Vibhute and D. Bhattacharya (IUCAA), V. Bhalerao (IIT-B), A. R. Rao (IUCAA/TIFR) and S. Vadawale (PRL) report on behalf of the AstroSat CZTI collaboration:
Analysis of AstroSat CZTI data showed the detection of a long GRB 200806A, which was also detected by Swift (Ambrosi E. et al., GCN #28211), Global MASTER-Net (Lipunov V. et al., GCN #28212) and Swift-XRT (Beardmore A. et al., GCN #28214).
The source was clearly detected in the 40-200 keV energy range. The light curve showed multiple peaks of emission with the strongest peak at 2020-08-06 15:29:11.500 UT. The measured peak count rate associated with the burst is 665 +/- 33 cts/s above the background in the combined data of four quadrants, with a total of 5023 +/- 36 cts. The local mean background count rate was 402 +/- 1 cts/s. Using cumulative rates, we measure a T90 of 33.93 +/- 0.05 s. In the preliminary analysis, we find that 636 Compton events are associated with this event.
It was also clearly detected in the CsI anticoincidence (Veto) detector in the 100-500 keV energy range. The light curve showed multiple peaks of emission with the strongest peak at 2020-08-06 15:29:10.000 UT. The measured peak count rate is 987 +/- 50 cts/s above the background in the combined Veto data of four quadrants, with a total of 6708 +/- 67 cts. The local mean background count rate was 1506 +/- 1 cts/s. We measure a T90 of 33.68 +/- 0.13 s from the cumulative Veto light curve.
CZTI GRB detections are reported regularly on the payload site at http://astrosat.iucaa.in/czti/?q=grb. CZTI is built by a TIFR-led consortium of institutes across India, including VSSC, ISAC, IUCAA, SAC and PRL. The Indian Space Research Organisation funded, managed and facilitated the project.
GCN Circular 28215
Subject
GRB 200806A: MITSuME Akeno optical upper limits
Date
2020-08-07T05:56:59Z (5 years ago)
From
Katsuhiro L. Murata at Nagoya U <murata@u.phys.nagoya-u.ac.jp>
K. L. Murata, R. Adachi, R. Hosokawa, M. Niwano, F. Ogawa, N. Nakamura, N.
Ito, S. Ogata, H. Takamatsu, H. Hara, Y. Yatsu, and N. Kawai (TokyoTech)
report on behalf of the MITSuME collaboration:
We observed the field of GRB 200806A (Ambrosi et al., GCN 28211; Beardmore
et al., GCN 28214) with the optical three color (g', Rc, and Ic) CCD
cameras attached to the MITSuME 50 cm telescope of Akeno Observatory,
Yamanashi, Japan.
The observation with a series of 60 sec exposures started on 2020-08���06
15:30:34 UT. The first 15 images were heavily affected by the presence of
the moon. We stacked the images excluding the 15 images and did not find
any new point sources within the enhanced Swift/XRT error circle (Beardmore
et al., GCN 28214) of the stacked images. We obtained the 5-sigma limits as
follows.
T0+[min] MID-UT T-EXP[sec] 5-sigma limits
------------------------------------------------------------------------------------------------
19 2020-08-06T15:57:10 960 g'>16.7, Rc>16.7, Ic>16.9
------------------------------------------------------------------------------------------------
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., submitted;
https://github.com/MNiwano/Eclaire)
GCN Circular 28214
Subject
GRB 200806A: Enhanced Swift-XRT position
Date
2020-08-07T02:48:55Z (5 years ago)
From
Phil Evans at U of Leicester <pae9@leicester.ac.uk>
A.P. Beardmore, P.A. Evans, M.R. Goad and J.P. Osborne (U. Leicester)
report on behalf of the Swift-XRT team.
Using 619 s of XRT Photon Counting mode data and 1 UVOT
images for GRB 200806A, 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 = 52.93214, +37.07876 which is equivalent
to:
RA (J2000): 03h 31m 43.71s
Dec (J2000): +37d 04' 43.5"
with an uncertainty of 1.7 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 28212
Subject
Swift GRB 200806A: Global MASTER-Net observations report
Date
2020-08-06T21:40:17Z (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-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 200806A ( E. Ambrosi et al., GCN 28211) errorbox 17964 sec after notice time and 17986 sec after trigger time at 2020-08-06 20:28:36 UT, with upper limit up to 17.5 mag. The observations began at zenith distance = 80 deg. The sun altitude is -26.8 deg.
The galactic latitude b = -15 deg., longitude l = 156 deg.
Real time updated cover map and OT discovered available here:
https://master.sai.msu.ru/site/master2/observ.php?id=1414905
We obtain a following upper limits.
Tmid-T0 | Site |Filt.| Expt. | Limit| Comment
_________|_____________________|_____|_______|______|________
18076 | MASTER-Tavrida | C | 180 | 16.8 |
21887 | MASTER-Tavrida | C | 180 | 17.5 |
Filter C is a clear (unfiltred) band.
The observation and reduction will continue.
The message may be cited.
GCN Circular 28211
Subject
GRB 200806A: Swift detection of a burst
Date
2020-08-06T15:57:43Z (5 years ago)
From
David Palmer at LANL <palmer@lanl.gov>
E. Ambrosi (INAF-IASFPA), D. N. Burrows (PSU), V. D'Elia (SSDC),
J.D. Gropp (PSU), H. A. Krimm (NSF), N. P. M. Kuin (UCL-MSSL),
A. Y. Lien (GSFC/UMBC), F. E. Marshall (NASA/GSFC), M. J. Moss (GWU),
K. L. Page (U Leicester), D. M. Palmer (LANL), M. H. Siegel (PSU) and
A. Tohuvavohu (U Toronto) report on behalf of the Neil Gehrels Swift
Observatory Team:
At 15:28:49 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 200806A (trigger=987016). Swift slewed immediately to the burst.
The BAT on-board calculated location is
RA, Dec 52.905, +37.082 which is
RA(J2000) = 03h 31m 37s
Dec(J2000) = +37d 04' 55"
with an uncertainty of 3 arcmin (radius, 90% containment, including
systematic uncertainty). The BAT light curve showed a pulse
that starts at ~T0 and lasts beyond the currently available data,
which ends at ~T+8 s. The peak count rate was ~4800 counts/sec (15-350 keV),
at ~0 sec after the trigger.
The XRT began observing the field at 15:30:07.6 UT, 77.7 seconds after
the BAT trigger. Using promptly downlinked data we find a bright,
fading, uncatalogued X-ray source located at RA, Dec 52.93173, 37.07845
which is equivalent to:
RA(J2000) = 03h 31m 43.62s
Dec(J2000) = +37d 04' 42.4"
with an uncertainty of 3.5 arcseconds (radius, 90% containment). This
location is 77 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 2.56
x 10^21 cm^-2 (Willingale et al. 2013).
The initial flux in the 2.5 s image was 2.59e-09 erg cm^-2 s^-1 (0.2-10
keV).
UVOT took a finding chart exposure of 150 seconds with the White filter
starting 86 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
0.42.
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/)