GRB 201006A
GCN Circular 28598
Subject
GRB 201006A: Chandra upper limit on the X-ray afterglow
Date
2020-10-11T17:30:25Z (5 years ago)
From
Alicia Rouco Escorial at CIERA <alicia.rouco.escorial@northwestern.edu>
A. Rouco Escorial, W. Fong, G. Schroeder, K. Paterson, C. D. Kilpatrick, A. Nugent, J. Rastinejad, R. Margutti, K. D. Alexander (Northwestern), T. Laskar (Bath), and E. Berger (Harvard) report:
�We initiated observations with the Chandra X-ray Observatory of the short-duration GRB 201006A (Barthelmy et al., GCN 28560; Tohuvavohu, GCN 28563; Hamburg et al., GCN 28564; Lien et al., GCN 28567) starting on 2020 October 09 20:57:42 UT, with a median observation time of 3.98 days post-trigger. We obtained one ACIS-S observation under the Proposal 21400447 (ObsID 22401; PI: Fong), with an effective exposure time of 24.7 ks.
We do not detect an X-ray source within the enhanced Swift-XRT position (90% confidence; Evans et al., GCN 28562). Centered on the XRT position, we obtain a 3-sigma limit of <3.6e-4 cts/s in the 0.5-8 keV energy range (following Gehrels 1986). Applying the best-fit PC-mode XRT spectral parameters (Gamma=2.1, total NH=1.3e22 cm^-2; Evans et al., GCN 28568), we calculate a 3-sigma unabsorbed flux limit of FX<1.15e-14 erg/s/cm^2 in the 0.3-10 keV energy range.
The XRT afterglow, starting at ~153.3 s post-burst, can be modeled with a power law decline (where FX~t^alpha) with a decay index of alpha=-0.99(+0.14,-0.13) consistent with the results of Evans et al. (GCN 28568). Our Chandra upper limit is marginally consistent with the expected flux at dt~3.98 days drawn by this model.
We thank the Chandra Director, Patrick Slane, and staff for the rapid planning and scheduling of these observations.�
GCN Circular 28573
Subject
GRB 201006A: GROWTH-India Telescope optical upper limit
Date
2020-10-07T18:48:47Z (5 years ago)
From
Harsh Kumar at Indian Inst of Tech,Bombay <harshkosli13@gmail.com>
H. Kumar (IITB), J. Stanzin (IAO), V. Bhalerao(IITB), G. C. Anupama(IIA),
S. Barway(IIA), report on behalf of the GROWTH-India collaboration:
We observed GRB 201006A reported by Swift-BAT (J.D. Gropp et al., GCN
28560; also see: S.Mereghetti et al., GCN 28561; M.R. Goad et al., GCN
28562; Aaron Tohuvavohu GCN 28563; R. Hamburg and C. Meegan, GCN 28564; F.
E. Marshall and J. D. Gropp GCN 28565; S. D. Barthelmy et al., GCN 28567;
J. D. Gropp et al., GCN 28568; N. Ito et al., 28571, S.Dichiara et al., GCN
28572) with 0.7m GROWTH-India Telescope (GIT). The field was observed in
the SDSS r��� filter starting at 2020-10-06T18:32:40.4 UT i.e. ~17.25 hrs
after the event detection by Swift-BAT. We obtained 20 exposures of 300 sec
each. The field was close to the moon (~43 deg) during observations. We did
not find any source in the stacked image within the uncertainty region of
2.1 arcsec around the Swift-XRT position of RA(J2000): 04h 07m 34.25s,
Dec(J2000): +65d 09' 52.6" (GCN 28562). We obtained an upper limit of r >
20.09 mag, calibrated against PanSTARRs PS1 data release (Flewelling et
al., 2018).
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 28572
Subject
GRB 201006A: Lowell Discovery Telescope upper limits
Date
2020-10-07T14:35:50Z (5 years ago)
From
Simone Dichiara at UMCP/NASA/GSFC <dichiara@umd.edu>
S.Dichiara (UMD, NASA-GSFC), S.B. Cenko (NASA-GSFC), E. Troja (UMD,
NASA-GSFC), P. Gatkine (UMD), J.M. Durbak (UMD), A. Kutyrev (UMD,
NASA-GSFC), S. Veilleux (UMD), report on behalf of a larger
collaboration:
We observed the field of the short GRB 201006A (Gropp et al., GCN Circ.
28560) using the Large Monolithic Imager (LMI) on the 4.3m Lowell
Discovery Telescope (LDT) at Happy Jack, AZ. Observations started on
October 7, 11:50:54 UT (1.44 days after the Swift trigger) taking 3
exposures of 150 s each with SDSS i filter. Observations were taken at
an airmass of about 1.19 and seeing of about 0.5".
We do not find any source inside the enhanced XRT position (Goad et
al., GCN Circ. 28562) down to a 3-sigma limiting magnitude of i>23.8
AB mag.
Magnitudes are calibrated against the PanSTARRS catalog and not corrected
for Galactic extinction.
We thank the staff of the Lowell Discovery Telescope for assistance with
these observations.
GCN Circular 28571
Subject
GRB 201006A: MITSuME Akeno optical upper limits
Date
2020-10-07T10:07:26Z (5 years ago)
From
Naohiro Ito at Tokyo Tech <n.ito@hp.phys.titech.ac.jp>
N. Ito, R. Hosokawa, K. L. Murata, R. Adachi, M. Niwano, F. Ogawa, N.
Nakamura, 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 201006A (J.D. Gropp et al.,GCN #28560,
S.Mereghetti et al., GCN #28561, R. Hamburg et al., GCN # 28564) 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 started at 13:31:53 UT. Since some images were heavily
affected by bad weather and the moon, we stacked the images with good
conditions. We did not find any new point sources within the enhanced
Swift/XRT circle (M.R. Goad et al., GCN #28562) in all three bands.
We obtained the 5-sigma limits as follows.
T0+[hour] MID-UT T-EXP[sec] 5-sigma limits
------------------------------------------------------------------------------------------------
12.2 16:27:01 4020.0 g'>19.5,Rc>19.4,Ic>18.9
------------------------------------------------------------------------------------------------
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., accepted for publication in PASJ;
arXiv2008.11486
https://github.com/MNiwano/Eclaire)
GCN Circular 28568
Subject
GRB 201006A: Swift-XRT refined Analysis
Date
2020-10-07T01:31:06Z (5 years ago)
From
Phil Evans at U of Leicester <pae9@leicester.ac.uk>
J. D. Gropp (PSU), J.P. Osborne (U. Leicester), K.L. Page (U.
Leicester), A.P. Beardmore (U. Leicester), P. D'Avanzo (INAF-OAB), M.G.
Bernardini (INAF-OAB), E. Ambrosi (INAF-IASFPA) , J.A. Kennea (PSU),
A. Tohuvavohu (U. Toronto) and J.D. Gropp report on behalf of the
Swift-XRT team:
We have analysed 6.0 ks of XRT data for GRB 201006A (Gropp et al. GCN
Circ. 28560), from 91 s to 70.3 ks after the BAT trigger. The data are
entirely in Photon Counting (PC) mode. The enhanced XRT position for
this burst was given by Goad et al. (GCN Circ. 28562).
The light curve can be modelled with a power-law decay with a decay
index of alpha=0.99 (+0.14, -0.13).
A spectrum formed from the PC mode data can be fitted with an absorbed
power-law with a photon spectral index of 2.1 (+/-0.6). The
best-fitting absorption column is 1.3 (+0.7, -0.5) x 10^22 cm^-2, in
excess of the Galactic value of 4.5 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 4.9 x 10^-11 (1.1 x 10^-10) erg
cm^-2 count^-1.
A summary of the PC-mode spectrum is thus:
Total column: 1.3 (+0.7, -0.5) x 10^22 cm^-2
Galactic foreground: 4.5 x 10^21 cm^-2
Excess significance: 2.5 sigma
Photon index: 2.1 (+/-0.6)
If the light curve continues to decay with a power-law decay index of
0.99, the count rate at T+24 hours will be 4.0 x 10^-4 count s^-1,
corresponding to an observed (unabsorbed) 0.3-10 keV flux of 2.0 x
10^-14 (4.3 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/00998907.
This circular is an official product of the Swift-XRT team.
GCN Circular 28567
Subject
GRB 201006A: Swift-BAT refined analysis
Date
2020-10-06T23:22:00Z (5 years ago)
From
Amy Lien at GSFC <amy.y.lien@nasa.gov>
S. D. Barthelmy (GSFC), J. R. Cummings (CPI),
J. D. Gropp (PSU), 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-240 to T+962 sec from the recent telemetry
downlink, we report further analysis of BAT GRB 201006A (trigger #998907)
(Group et al., GCN Circ. 28560). The BAT ground-calculated position is
RA, Dec = 61.917, 65.148 deg which is
RA(J2000) = 04h 07m 40.1s
Dec(J2000) = +65d 08' 53.3"
with an uncertainty of 2.1 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 33%.
The mask-weighted light curve shows a pulse that starts and peaks at ~T0,
and ends at ~T+0.5 s. T90 (15-350 keV) is 0.49 +- 0.09 sec (estimated error
including systematics).
The time-averaged spectrum from T-0.01 to T+0.54 sec is best fit by
a simple power-law model. The power law index of the time-averaged
spectrum is 1.42 +- 0.24. The fluence in the 15-150 keV band is
1.3 +- 0.2 x 10^-7 erg/cm2. The 1-sec peak photon flux measured from
T-0.23 sec in the 15-150 keV band is 2.2 +- 0.3 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/998907/BA/
GCN Circular 28565
Subject
GRB 201006A: Swift/UVOT Upper Limits
Date
2020-10-06T21:07:13Z (5 years ago)
From
Frank Marshall at Swift/UVOT <marshall@milkyway.gsfc.nasa.gov>
F. E. Marshall (NASA/GSFC) and J. D. Gropp (PSU)
report on behalf of the Swift/UVOT team:
The Swift/UVOT began settled observations of the field of GRB 201006A
88 s after the BAT trigger (Gropp et al., GCN Circ. 28560).
No optical afterglow consistent with the XRT position
(Goad et al. GCN Circ. 28562)
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 88 238 147 >21.1
u_FC 300 549 246 >20.2
white 88 1539 385 >21.0
v 629 1423 97 >18.9
b 555 1521 97 >19.8
u 300 722 265 >20.3
w1 678 1472 97 >18.7
w2 1205 1225 19 >17.3
The magnitudes in the table are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 1.27 in the direction of the burst
(Schlegel et al. 1998).
GCN Circular 28564
Subject
GRB 201006A: Fermi GBM detection
Date
2020-10-06T17:14:45Z (5 years ago)
From
Rachel Hamburg at UAH <rkh0007@uah.edu>
R. Hamburg (UAH) and C. Meegan (UAH)
report on behalf of the Fermi GBM Team:
"At 01:17:52.27 UT on 06 October 2020, the Fermi Gamma-Ray Burst Monitor
(GBM)
triggered and located GRB 201006A (trigger 623639877 / 201006054),
which was also detected by the Swift/BAT and the Swift/XRT
(Gropp et al. 2020, GCN 28560). The GBM on-ground location is
consistent with the Swift position.
The angle from the Fermi LAT boresight at the GBM trigger time is 42
degrees.
The GBM light curve consists of one main spike
with a duration (T90) of about 1.7 s (50-300 keV).
The time-averaged spectrum from T0-0.19 s to T0+0.83 s is
best fit by a power law function with an exponential
high-energy cutoff. The power law index is -0.97 +/- 0.19 and
the cutoff energy, parameterized as Epeak, is 130 +/- 26 keV.
The event fluence (10-1000 keV) in this time interval is
(3.33 +/- 0.38)E-07 erg/cm^2. The 64-ms peak photon flux measured
starting from T0-0.064 s in the 10-1000 keV band
is 6.86 +/- 0.97 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 28563
Subject
GRB 201006A is likely a short burst
Date
2020-10-06T17:04:58Z (5 years ago)
From
Aaron Tohuvavohu at U Toronto <aaron.tohu@gmail.com>
GRB 201006A, detected by Swift/BAT (Gropp et al. GCN 28560),
INTEGRAL/IBAS (Mereghetti et al. GCN 28561) and Fermi/GBM (trig num
623639877), appears likely to be a short burst, despite the real-time
duration estimate (~5s) reported in GCN 28560.
The T90 estimate from downlinked Swift/BAT event data is less than 0.5 seconds.
Follow-up is encouraged.
GCN Circular 28562
Subject
GRB 201006A: Enhanced Swift-XRT position
Date
2020-10-06T09:19:20Z (5 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 1436 s of XRT Photon Counting mode data and 2 UVOT
images for GRB 201006A, 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 = 61.89270, +65.16462 which is equivalent
to:
RA (J2000): 04h 07m 34.25s
Dec (J2000): +65d 09' 52.6"
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 28561
Subject
INTEGRAL sub-threshold detection of GRB 201006A
Date
2020-10-06T07:51:46Z (5 years ago)
From
Sandro Mereghetti at IASF-Milano/INAF <sandro.mereghetti@inaf.it>
S.Mereghetti (INAF, IASF-Milano), D.Gotz (CEA, Saclay), C.Ferrigno,
E.Bozzo, V.Savchenko (ISDC, Versoix), L.Ducci (IAAT, Germany and ISDC,
Versoix)
and J.Borkowski (CAMK, Torun) report:
GRB 201006A detected by Swift (Gropp et al., GCN 28560) has been also
revealed as a sub-threshold GRB by IBAS in the IBIS/ISGRI data. The
corresponding WEAK type Alert Packet with the burst position was
distributed in real time (Alert n. 8745).
The burst coordinates (J2000) obtained with the offline analysis of the
IBIS/ISGRI data are:
R.A.= 61.9045 deg
DEC.= +65.1478 deg
with an uncertainty of 3 arcmin (90% c.l.).
GCN Circular 28560
Subject
GRB 201006A: Swift detection of a burst
Date
2020-10-06T01:31:10Z (5 years ago)
From
Scott Barthelmy at NASA/GSFC <scott@milkyway.gsfc.nasa.gov>
J.D. Gropp (PSU), S. D. Barthelmy (GSFC), S. Laha (GSFC/UMBC/CRESST),
F. E. Marshall (NASA/GSFC), D. M. Palmer (LANL), B. Sbarufatti (PSU),
M. H. Siegel (PSU) and A. Tohuvavohu (U Toronto) report on behalf of
the Neil Gehrels Swift Observatory Team:
At 01:17:52 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 201006A (trigger=998907). Swift slewed immediately to the burst.
The BAT on-board calculated location is
RA, Dec 61.880, +65.150 which is
RA(J2000) = 04h 07m 31s
Dec(J2000) = +65d 08' 59"
with an uncertainty of 3 arcmin (radius, 90% containment, including
systematic uncertainty). The BAT light curve shows a single spike
structure with a duration of about 5 sec. The peak count rate
was ~2500 counts/sec (15-350 keV), at ~0 sec after the trigger.
The XRT began observing the field at 01:19:15.9 UT, 83.9 seconds after
the BAT trigger. Using promptly downlinked data we find an uncatalogued
X-ray source with an enhanced position: RA, Dec 61.8932, 65.1650 which
is equivalent to:
RA(J2000) = 04h 07m 34.36s
Dec(J2000) = +65d 09' 54.0"
with an uncertainty of 2.6 arcseconds (radius, 90% containment). This
location is 57 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 4.50
x 10^21 cm^-2 (Willingale et al. 2013).
UVOT took a finding chart exposure of 150 seconds with the White filter
starting 87 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
1.27.
Burst Advocate for this burst is J.D. Gropp (jdg44 AT psu.edu).
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/)