GRB 201020B
GCN Circular 29191
Subject
GRB 201020B: Assy, Koshka, Mondy and Maidanak optical observations
Date
2020-12-28T21:53:13Z (5 years ago)
From
Alexei Pozanenko at IKI, Moscow <apozanen@iki.rssi.ru>
S. Belkin (IKI), A. Pozanenko (IKI), V. Kim (FAI, Pulkovo Observatory),
M. Krugov (FAI), A. Novichonok (Petrozavodsk State University, KIAM),
A. Zhornichenko (KIAM), E. Klunko (ISTP), O. Burhonov (UBAI), Sh.
Ehgamberdiev (UBAI) report on behalf of IKI GRB FuN:
We additionally observed the GRB 201020B (Fermi GBM team, GCN 28702;
Malacaria et al., GCN 28710; Arimoto et al., GCN 28716; Ursi et al., GCN
28714; Ridnaia et al., GCN 28723) with AZT-20 telescope of Assy
observatory, Zeiss-1000 of Koshka observatory, AZT-33IK telescope of
Sayan observatory (Mondy), and AZT-22 telescope of Maidanak observatory.
The optical afterglow (Lipunov et al., GCN 28718; Xu et al., GCN 28719;
Belkin et al., GCN 28725; Breeveld & Lien, GCN 28743; Vinko et al., GCN
28750; Kumar et al., GCN 28753; Belkin et al., GCN 28768; Vinko et al.,
GCN 28769; Vinko et al., GCN 28769; Panchal et al., GCN 28772; Nicastro
et al., GCN 28773; Kumar et al., GCN 28776; Kumar et al., GCN 28781)
with redshift of z= 0.804 (Kann et al., GCN 28765) is detected in most
of stacked images of our observations in R-filter.
Preliminary light curve of the afterglow based on our observations
including reported earlier (Belkin et al., GCNs 28725, 28768) can be
found in
http://grb.rssi.ru/GRB201020B/GRB201020B_R_LC.png
The photometry is based on the nearby USNO-B1.0 stars
USNO-B1.0_id R2
1670-0037414 16.74
1670-0037586 16.16
GCN Circular 28781
Subject
GRB 201020B: 1.3m DFOT continued optical follow-up observations
Date
2020-10-26T12:23:26Z (5 years ago)
From
Amit Kumar at ARIES, India <amitkundu515@gmail.com>
Amit Kumar (ARIES), Rahul Gupta (ARIES), Dimple (ARIES), Ankur Ghosh
(ARIES), Kaushal Sharma (ARIES), Amar Aryan (ARIES), Brajesh Kumar
(ARIES), Kuntal Misra (ARIES), and Shashi B. Pandey (ARIES) report:
We followed-up Fermi GBM triggered GRB 201020B (Fermi team, GCN 28702;
Lipunov et al. GCN 28704; Malacaria and Meegan, GCN 28710; Ursi et al.
GCN 28714; Arimoto et al., GCN 28716; Lipunov et al., GCN 28718; Xu et
al., GCN 28719; Kann et al. GCN 28765) using the 1.3m Devasthal Fast
Optical Telescope (DFOT) at Devasthal observatory of Aryabhatta
Research Institute of observational sciencES (ARIES), India.
The observations were carried out on 2020-10-23 (from 19:14:51 to
19:26:16 UT) and 2020-10-24 (from 18:18:43 to 19:24:14 UT) in multiple
bands. We took a series of images with the exposure time of 120
seconds in multiple Bessel filters, covering Swift UVOT position
(Sbarufatti et al. GCN 28740).
The optical transient reported by V. Lipunov et. al. GCN 28718; D. Xu
et. al. GCN 28719 is clearly visible in the stacked images.
The R-band magnitudes of the GRB afterglow estimated from the
photometry of stacked images are as follows:
Date Start_UT T_start-T0 (hrs) Filter Exp time (s)
Magnitude Mag_error
----------------------------------------------------------------------------------------------------------------------------
2020-10-23 19:14:51 73.683 R 15*120 21.34 0.05
2020-10-24 19:24:14 97.839 R 30*120 21.83
0.05
----------------------------------------------------------------------------------------------------------------------------
The estimated magnitudes have not been corrected for the Galactic
extinction in the direction of the GRB. Photometric calibration is
performed using the following standard stars from the USNO-B1.0
catalog:
1670-0037558
1670-0037526
1670-0037460
1670-0037451
1670-0037450
1670-0037447
Our estimated magnitudes in the R-band, along with the measurements
reported by Belkin et al., GCN 28725; Vinko et al. GCN 28750; Belkin
et al. GCN 28768; Vinko et al. GCN 28769; Dimple et al. GCN 28772;
Nicastro et al. GCN 28773, and Kumar et al. GCN 28776, suggest that
the afterglow of GRB 201020B is fading with a power-law index of 1.66
+/- 0.12.
The magnitudes reported by Vinko et al. GCN 28750, Vinko et al. GCN
28769, and Nicastro et al. GCN 28773 are convetred to R-band
magnitudes using the tranformation equations provided by Lupton et al.
(2005).
This power-law index is well consistent with those reported by Kumar
et al. GCN 28753 and Belkin et al. GCN 28768.
This circular may be cited.
GCN Circular 28776
Subject
GRB 201020B: HCT and GIT continued optical follow-up observations
Date
2020-10-25T09:04:20Z (5 years ago)
From
Harsh Kumar at Indian Inst of Tech,Bombay <harshkosli13@gmail.com>
H. Kumar(IITB), S. Kiran (IIA), J.Stanzin (IAO), V. Bhalerao(IITB), G. C.
Anupama(IIA), S. Barway(IIA) report on behalf of the HCT team:
We followed-up GRB 201020B reported by Fermi GBM Team (GCN #28702, also
see: V. Lipunov et. al., GCN #28718; D. Xu et. al., GCN #28719) with 2.0m
Himalayan Chandra Telescope (HCT) and 0.7m GROWTH-India Telescope (GIT). We
obtained a series of 300-sec exposures in the Rc, r filters. Afterglow was
clearly detected at a position consistent with V. Lipunov et. al., GCN
#28718; D. Xu et. al., GCN #28719. Here are the photometric results from
HCT & GIT observations:-
-------------------------------------------------------
JD (mid) | T_mid-T0(hrs) | Filter | Mag | Telescope |
-------------------------------------------------------
2459145.40625 | 52.22 | r | 21.01 +/- 0.04 | GIT |
2459146.32699 | 74.80 | Rc | 21.28 +/- 0.04 | HCT |
-------------------------------------------------------
Our results are consistent with the power-law decay of 1.67 reported in S.
Belkin et al. GCN #28768; H. Kumar et al. GCN #28753.
These observations were carried out under the ToO program HCT-2020-C3-P6.
We thank HCT and GIT staff for undertaking the observations.
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 28773
Subject
GRB 201020B: follow-up observations with Savelli Telescope
Date
2020-10-24T19:34:16Z (5 years ago)
From
Luciano Nicastro at INAF-OAS <luciano.nicastro@inaf.it>
L. Nicastro (INAF-OAS), A. Brosio (Osservatorio Astronomico Lilio), S.
Savaglio (UNICAL)
We observed the afterglow
(Lipunov et al., GCN 28718; Xu et al., GCN 28719; Belkin et al., GCN 28725;
Breeveld & Lien, GCN 28743; Vinko et al., GCN 28750; Kumar et al., GCN
28753; Kann et al., GCN 28765; Belkin et al., GCN 28768; Dimple et al.,
GCN 28772)
of GRB 201020B
(Fermi GBM Team, GCN 28702; Fermi GBM detection: Malacaria & Meegan, GCN
28710; Fermi LAT detection: Arimoto et al., GCN 28716; AGILE detection:
Ursi et al., GCN 28714; Konus-Wind detection: Ridnaia et al., GCN 28723)
with the 0.5m telescope of the Osservatorio Astronomico Lilio, located in
Savelli (South Italy).
Date / UT-mid JD T-T0(hr) Exp(s) Filter Mag (AB)
2020-10-21T18:47:48.85 | 2459144.28320 | 25.23 | 5 x 300 | Sloan-r | 19.60
+/- 0.12
2020-10-21T19:35:28.72 | 2459144.31630 | 26.03 | 5 x 300 | Sloan-g | 20.02
+/- 0.15
Magnitudes, calibrated wrt nearby PanSTARRS field stars, are not corrected
for galactic extinction.
Fog prevented us from performing further observations in the following
nights.
GCN Circular 28772
Subject
GRB 201020B: 1.3m DFOT optical observations
Date
2020-10-24T18:24:59Z (5 years ago)
From
Dimple Panchal at ARIES, India <dimple@aries.res.in>
Dimple (ARIES), A. Ghosh (ARIES), Bhavya (ARIES) , R. Gupta (ARIES) , A. Kumar (ARIES), B. Kumar (ARIES), K. Misra (ARIES), and S. B. Pandey (ARIES) report:
We carried out the follow-up observations of GRB 201020B ( Fermi team, GCN 28702; Lipunov et al. GCN 28704; Malacaria and Meegan, GCN 28710; Ursi et al. 28714; Arimoto et al., GCN 28716; Lipunov et al., GCN 28718; Xu et al., GCN 28719; Ridnaia et al., GCN 28723; Belkin et al., GCN 28725; Sbarufatti et al., GCN 28740; Breeveld et al., GCN 28743; Vinko et al. GCN 28750; Kumar et al. GCN 28753; Kann et al. GCN 28765; Belkin et al. GCN 28768; Vinko et al. GCN 28769 ) using 1.3m Devasthal Fast Optical Telescope (DFOT) at Devasthal observatory of Aryabhatta Research Institute of observational sciencES (ARIES), India. The observation was started on 2020-10-21 at 21:41:37 UT. We observed a series of images with the exposure time of 60 seconds in both R and I filters (Johnson-Cousins) covering Swift UVOT position RA, Dec = 05h 01m 52.03s, +77d 04' 05.9" ( Sbarufatti et al. GCN 28740). An uncataloged source is clearly visible in the stacked images in both the bands at the position consistent with V. Lipunov et. al. GCN 28718; D. Xu et. al. GCN 28719.
Preliminary photometry of the optical transient in the combined images is following
Date Start_UT T_start-T0 (hrs) Filter Exp time (s) Magnitude Mag_error
----------------------------------------------------------------------------------------------------------------------------
2020-10-21 21:41:37 28.280 R 15*60 19.741 0.0262
2020-10-21 22:00:04 28.588 I 15*60 19.298 0.0468
----------------------------------------------------------------------------------------------------------------------------
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 28769
Subject
GRB 201020B: follow-up observations at Konkoly
Date
2020-10-24T11:11:02Z (5 years ago)
From
Jozsef Vinko at Konkoly Observatory <vinko@konkoly.hu>
J. Vinko (Konkoly/ELTE/U Szeged), A. Pal, L. Kriskovics, R. Szakats, A. Ordasi and K. Vida (Konkoly)
report on behalf of the "Transient Astrophysical Objects" project:
Follow-up observations of the optical afterglow of GRB 201020B
(Fermi team, GCN 28702; Lipunov et al. GCN 28704;
Malacaria and Meegan, GCN 28710; Ursi et al. 28714; Arimoto et al., GCN 28716;
Lipunov et al., GCN 28718; Xu et al., GCN 28719; Ridnaia et al., GCN 28723;
Belkin et al., GCN 28725; Sbarufatti et al., GCN 28740; Breeveld et al., GCN 28743;
Vinko et al. GCN 28750; Kumar et al. GCN 28753; Kann et al. GCN 28765; Belkin et al.
GCN 28768) with the 0.8m RC80 telescope at Konkoly Observatory yielded the following magnitudes
for the transient:
Date UT-mid t-T0(hr) Exp(s) Filter AB mag Err
2020-10-22 19:31:01 49.94 6 x 300 SDSS-r 20.592 0.172
2020-10-22 19:36:07 50.04 6 x 300 SDSS-i 20.566 0.264
tied to local PS1 stars.
Our data are consistent with the magnitudes reported by Belkin et al. (GCN 28768).
At the redshift of z=0.8 (Kann et al. GCN 28765) these correspond to
M ~ -22.9 absolute mag.
GCN Circular 28768
Subject
GRB 201020B: continued Mondy optical observations
Date
2020-10-24T09:51:25Z (5 years ago)
From
Alexei Pozanenko at IKI, Moscow <apozanen@iki.rssi.ru>
S. Belkin (IKI), A. Pozanenko (IKI), E. Klunko (ISTP), N. Pankov (HSE)
report on behalf of IKI GRB FuN:
We continued observations of the GRB 201020B (Fermi GBM team, GCN 28702;
Malacaria et al., GCN 28710; Arimoto et al., GCN 28716; Ursi et al., GCN
28714; Ridnaia et al., GCN 28723) with AZT-33IK telescope of Sayan
observatory (Mondy) on Oct. 22, 23. The optical afterglow (Lipunov et
al., GCN 28718; Xu et al., GCN 28719; Belkin et al., GCN 28725; Breeveld
& Lien, GCN 28743; Vinko et al., GCN 28750; Kumar et al., GCN 28753)
with redshift of z= 0.804 (Kann et al., GCN 28765) is detected in our
stacked images in R-filter.
Preliminary photometry of the optical transient in a combined image is
following
Date UT start t-T0 Filter Exp. OT Err. UL(3sigma)
(mid, days) (s)
2020-10-22 17:35:31 2.02195 R 60*60 20.40 0.05 23.0
2020-10-23 14:33:52 2.89719 R 32*120 20.99 0.26 21.1
The photometry is based on the nearby USNO-B1.0 stars
USNO-B1.0_id R2
1670-0037414 16.74
1670-0037586 16.16
GCN Circular 28765
Subject
GRB 201020B: Redshift from GTC/OSIRIS
Date
2020-10-24T06:29:31Z (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, J. F. Agui Fernandez, C. C. Thoene (all
HETH/IAA-CSIC), S. Geier, and M. Rivero (both GRANTECAN) report:
We observed the afterglow (Lipunov et al., GCN#28718; Xu et al.,
GCN#28719; Belkin et al., GCN#28725; Breeveld & Lien, GCN#28743; Vinko
et al., GCN#28750; Kumar et al., GCN#28753) of GRB 201020B (Fermi GBM
Team, GCN#28702; Fermi GBM detection: Malacaria & Meegan, GCN#28710;
Fermi LAT detection: Arimoto et al., GCN#28716; AGILE detection: Ursi et
al., GCN#28714; Konus-Wind detection: Ridnaia et al., GCN#28723) with
the 10.4m GTC telescope, at Roque de los Muchachos Observatory (La
Palma, Spain) equipped with OSIRIS. The observation started on 24
October 2020 at 04:05:16 UT (3.438 days after the GRB trigger, following
a period of inclement weather) and consisted of 4 x 1200 s with the
R1000B grism, covering the wavelength range between 3700 and 7800 AA.
Observations were taken under good conditions.
At the afterglow position, a source is clearly detected. We measure i' ~
21.45 mag (AB) vs. a nearby PanSTARRS field star. This represents a
significant decay compared to the value reported by Vinko et al.
(GCN#28750). The afterglow is seen to decay with a slope of 1.68, in
full agreement with Kumar et al. (GCN#28753).
A preliminary reduction of the spectrum shows a clear but featureless
continuum. There is an emission feature, which we identify as due to the
[OII]3727 doublet at z = 0.804. Other interpretations (as Hbeta, [OIII]
or Halpha) would imply other emission lines should be visible, which
they are not. At the same redshift there could be marginal, weak
features consistent with FeII, MgII, and MgI. Therefore, we suggest z =
0.804 as the redshift of the GRB.
GCN Circular 28753
Subject
GRB 201020B: GROWTH-India Telescope optical observations
Date
2020-10-22T20:37:16Z (5 years ago)
From
Harsh Kumar at Indian Inst of Tech,Bombay <harshkosli13@gmail.com>
H. Kumar(IITB), K. Sharma(IITB), J. Stanzin(IAO), V. Bhalerao(IITB), G. C.
Anupama(IIA), S. Barway(IIA), report on behalf of the GROWTH-India
collaboration:
We followed-up GRB 201020B reported by Fermi GBM Team (GCN #28702, also
see: V. Lipunov et. al., GCN #28718; D. Xu et. al., GCN #28719) with 0.7m
GROWTH-India telescope. We obtained 300-sec exposures in the SDSS r��� filter
starting at 2020-10-21T14:53:24.42 UT (~ 21.4 hrs after the burst detection
by Fermi-GBM). We clearly detected uncataloged sources at a position
consistent with V. Lipunov et. al., GCN #28718; D. Xu et. al., GCN #28719.
Here are the photometric results from GIT observations:-
------------------------------------------------------------------
JD (mid) | T_mid-T0(hrs) | Filter | Mag |
------------------------------------------------------------------
2459144.12392 | 21.45 | r | 19.36 +/- 0.07
2459144.12752 | 21.53 | r | 19.49 +/- 0.08
2459144.13110 | 21.62 | r | 19.37 +/- 0.07
2459144.27999 | 25.15 | r | 19.64 +/- 0.02
2459144.30582 | 25.77 | r | 19.79 +/- 0.02
2459144.35140 | 26.86 | r | 19.83 +/- 0.03
2459144.39582 | 27.91 | r | 19.83 +/- 0.03
2459144.42656 | 28.67 | r | 19.89 +/- 0.02
-----------------------------------------------------------------
Combining our photometric results with r band measurements of D. Xu et.
al., GCN #28719, we conclude that the source is fading with a power-law
index of 1.65 +/- 0.21. The magnitudes are calibrated against PanSTARRs PS1
data release, (Flewelling et al., 2018) and not corrected for galactic
extinction. Extrapolating backwards to the epoch of MASTER observations (t0
+ 3.2 min), the expected r magnitude is approximately 8.6, significantly
higher than the measured clear band magnitude of 13.7. This may be
indicative of a break in the afterglow. Further observations are strongly
encouraged.
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 28750
Subject
GRB 201020B: Konkoly Obs. optical detection
Date
2020-10-22T18:48:16Z (5 years ago)
From
Jozsef Vinko at Konkoly Observatory <vinko@konkoly.hu>
J. Vinko (Konkoly/ELTE/U Szeged), A. Pal, L. Kriskovics, R. Szakats, A. Ordasi and K. Vida (Konkoly)
report on behalf of the "Transient Astrophysical Objects" project:
We observed the field of GRB 201020B (Fermi team, GCN 28702; Lipunov et al. GCN 28704;
Malacaria and Meegan, GCN 28710; Ursi et al. 28714; Arimoto et al., GCN 28716;
Lipunov et al., GCN 28718; Xu et al., GCN 28719; Ridnaia et al., GCN 28723;
Belkin et al., GCN 28725; Sbarufatti et al., GCN 28740; Breeveld et al., GCN 28743)
with the 0.8m RC80 robotic telescope at Piszkesteto Mountain Station of Konkoly Observatory
through SDSS r' and i' filters (exposure time 3 x 300 sec per filter)
on 2020 Oct 21.807 UT (MJD 59143.807; 25.8 hours = 92880 s after the trigger).
The frames were tied to PS1-photometry of local stellar sources.
An optical afterglow of the GRB has been detected with the following AB-magnitudes:
r' = 20.869 +/- 2.311 AB mag
i' = 19.368 +/- 0.696 AB mag
which are consistent with previous detections of the fading afterglow.
GCN Circular 28743
Subject
GRB 201020B: Swift/UVOT Detection
Date
2020-10-22T12:34:19Z (5 years ago)
From
Alice Breeveld at MSSL-UCL <a.breeveld@ucl.ac.uk>
A. A. Breeveld (UCL-MSSL) 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 201020B 72102 s after the Fermi
GMB/LAT trigger (Fermi GBM team, GCN Circ. 28702; Malacaria and Meegan, GCN Circ. 28710; Arimoto et
al., GCN Circ. 28716).
A source consistent with the Master position (Lipunov et al., GCN Circ. 28718), also detected by Xu
et al., (GCN Circ. 28719), Ridnaia et al. (GCN Circ. 28723), Belkin et al. (GCN Circ. 28723) and
Sbarufatti et al. (GCN Circ. 28740), is detected in the initial UVOT exposures. We note there is a
faint USNO-B1.0 source (1670-0037526, Bmag ~21.7) 5.2" away from this position.
Preliminary detections 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 73636 73973 332 19.54 �� 0.09
v 73979 74316 331 19.30 �� 0.28
u 72102 72821 708 19.12 �� 0.11
u 73293 73631 332 19.41 �� 0.19
The magnitudes in the table are not corrected for the Galactic extinction due to the reddening of
E(B-V) = 0.15 in the direction of the burst (Schlegel et al. 1998).
GCN Circular 28740
Subject
GRB 201020B: Swift-XRT afterglow detection
Date
2020-10-22T09:04:39Z (5 years ago)
From
Paolo D'Avanzo at INAF - OAB <paolo.davanzo@inaf.it>
B. Sbarufatti (PSU), D.N. Burrows (PSU), J.P. Osborne (U. Leicester),
K.L. Page (U. Leicester), A.P. Beardmore (U. Leicester), T. Sbarrato
(INAF-OAB), P. D'Avanzo (INAF-OAB), M.G. Bernardini (INAF-OAB), J. D.
Gropp (PSU) and P.A. Evans (U. Leicester) report on behalf of the
Swift-XRT team:
Swift-XRT has performed follow-up observations of the
Fermi/LAT-detected burst GRB 201020B (Arimoto et al. GCN Circ. 28716),
collecting 1.7 ks of Photon Counting (PC) mode data between T0+72.1 ks
and T0+74.3 ks.
An uncatalogued X-ray source is detected and is above the RASS limit,
and is therefore likely the GRB afterglow. Using 1015 s of PC mode data
and 2 UVOT images, we find an enhanced XRT position (using the XRT-UVOT
alignment and matching UVOT field sources to the USNO-B1 catalogue):
RA, Dec = 75.46680, +77.06830 which is equivalent to:
RA (J2000): 05h 01m 52.03s
Dec(J2000): +77d 04' 05.9"
with an uncertainty of 2.0 arcsec (radius, 90% confidence). This
position is 9.6 arcmin from the Fermi/LAT position and consistent with
the optical counterpart detected by MASTER (Lipunov et al. GCN Circ.
28718). The light curve is consistent with a constant source of mean
count rate 1.5e-01 ct/sec. With the currently available dataset we
cannot constrain the temporal evolution.
A spectrum formed from the PC mode data can be fitted with an absorbed
power-law with a photon spectral index of 2.2 (+0.4, -0.3). The
best-fitting absorption column is 4.0 (+1.7, -1.4) x 10^21 cm^-2, in
excess of the Galactic value of 1.4 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 3.3 x 10^-11 (5.7 x 10^-11) erg
cm^-2 count^-1.
A summary of the PC-mode spectrum is thus:
Total column: 4.0 (+1.7, -1.4) x 10^21 cm^-2
Galactic foreground: 1.4 x 10^21 cm^-2
Excess significance: 3.0 sigma
Photon index: 2.2 (+0.4, -0.3)
The results of the XRT-team automatic analysis of the likely afterglow
are at https://www.swift.ac.uk/ToO_GRBs/00021035/Source1.php.
The results of the full analysis of the XRT observations are available
at https://www.swift.ac.uk/ToO_GRBs/00021035.
This circular is an official product of the Swift-XRT team.
GCN Circular 28725
Subject
GRB 201020B: Mondy optical observations
Date
2020-10-21T17:09:41Z (5 years ago)
From
Alexei Pozanenko at IKI, Moscow <apozanen@iki.rssi.ru>
S. Belkin (IKI), A. Pozanenko (IKI), E. Klunko (ISTP), N. Pankov
(HSE), A. Volnova (IKI) report on behalf of IKI GRB FuN:
We observed the field of GRB 201020B (Fermi GBM team, GCN 28702;
Malacaria et al., GCN 28710; Arimoto et al., GCN 28716; Ursi et al., GCN
28714; Ridnaia et al., GCN 28723) with AZT-33IK telescope of Sayan
observatory (Mondy) starting on Oct. 21 (UT) 14:20:10. The optical
transient (Lipunov et al. GCN 28718; Xu et al. GCN 28719) is well
detected in our images in R-filter.
Preliminary photometry of the optical transient in a combined image is
following
Date UT start t-T0 Filter Exp. OT Err. UL(3sigma)
(mid, days) (s)
2020-10-21 14:20:10 0.88629 R 60*60 18.99 0.03 22.7
The photometry is based on the nearby USNO-B1.0 stars
USNO-B1.0_id R2
1670-0037414 16.74
1670-0037586 16.16
GCN Circular 28723
Subject
Konus-Wind detection of GRB 201020B
Date
2020-10-21T16:18:09Z (5 years ago)
From
Anna Ridnaia at Ioffe Institute <ridnaia@mail.ioffe.ru>
A. Ridnaia, S. Golenetskii, R. Aptekar, D. Frederiks,
M. Ulanov, D. Svinkin, A. Tsvetkova, A. Lysenko, and T. Cline
on behalf of the Konus-Wind team, report:
The long-duration GRB 201020B
(Fermi-GBM detection: The Fermi GBM team, GCN Circ. 28702,
Malacaria & Meegan, GCN Circ. 28710;
AGILE detection: Ursi et al., GCN Circ. 28714;
Fermi-LAT detection: Arimoto et al., GCN Circ. 28716)
triggered Konus-Wind at T0=63237.477 s UT (17:33:57.477).
The burst light curve shows a multipeaked structure
started at ~T0-5.6 s with a total duration of ~53.7 s.
The emission is seen up to ~6 MeV.
The Konus-Wind light curve of this GRB is available at
http://www.ioffe.ru/LEA/GRBs/GRB201020_T63237/
As observed by Konus-Wind, the burst
had a fluence of 4.72(-0.61,+0.70)x10^-5 erg/cm2,
and a 64-ms peak flux, measured from T0+8.016 s,
of 1.38(-0.25,+0.25)x10^-5 erg/cm2/s
(both in the 20 keV - 10 MeV energy range).
The time-averaged spectrum of the burst
(measured from T0 to T0+50.432 s)
is best fit in the 20 keV - 6 MeV range
by the GRB (Band) model with the following parameters:
the low-energy photon index alpha = -1.12(-0.09,+0.10),
the high energy photon index beta = -2.55(-0.56,+0.26),
the peak energy Ep = 193(-23,+23) keV
(chi2 = 72/97 dof).
The spectrum near the maximum count rate
(measured from T0+7.424 to T0+8.448 s)
is best fit in the 20 keV - 6 MeV range
by the GRB (Band) model with the following parameters:
the low-energy photon index alpha = -0.85(-0.13,+0.14),
the high energy photon index beta = -2.78(-3.16,+0.36),
the peak energy Ep = 259(-35,+44) keV
(chi2 = 41/52 dof).
All the quoted errors are at the 90% confidence level.
All the quoted values are preliminary.
GCN Circular 28720
Subject
GRB 201020B: Swift ToO observations
Date
2020-10-21T13:32:38Z (5 years ago)
From
Phil Evans at U of Leicester <pae9@leicester.ac.uk>
P. A. Evans (U. Leicester) reports on behalf of the Swift team:
Swift has initiated a ToO observation of the Fermi/LAT GRB 201020B.
Automated analysis of the XRT data will be presented online at
https://www.swift.ac.uk/ToO_GRBs/00021035
Any uncatalogued X-ray sources detected in this analysis will be
reported on this website and via GCN COUNTERPART notices. These are
not necessarily related to the Fermi/LAT event. Any X-ray source
considered to be a probable afterglow candidate will be reported via a
GCN Circular after manual consideration.
Details of the XRT automated analysis methods are detailed in Evans et
al. (2007, A&A, 469, 379; 2009, MNRAS, 397, 1177 and 2014, ApJS, 210, 8).
This circular is an official product of the Swift-XRT team.
GCN Circular 28719
Subject
GRB 201020B: Nanshan/NEXT optical afterglow confirmation
Date
2020-10-21T13:20:48Z (5 years ago)
From
Dong Xu at NAOC/CAS <dxu@nao.cas.cn>
D. Xu (NAOC), Z.P. Zhu (NAOC, HUST), S.Y. Fu, X. Liu (NAOC), X. Gao
(Urumqi No.1 Senior High School), J.Z. Liu (XAO) report:
We observed the field of GRB 201020B detected by Fermi/GBM, Fermi/LAT,
and AGILE (Fermi GBM team, GCN 28702; Malacaria et al., GCN 28710;
Arimoto et al., GCN 28716; Ursi et al., GCN 28714), starting at 12:35:28
UT on 2020-10-21, i.e., 0.7927 day after the Fermi trigger. Photometry
has been done in Sloan r-filter with 60s for each exposure, and
observations are ongoing.
The optical transient reported by MASTER (Lipunov et al., GCN 28718) is
clearly detected in our single image at improved coordinates
R.A. (J2000) = 5:01:52.80
Dec. (J2000) = +77:04:06.23
with a positional uncertainty of ~0.5 arcsec. It has decayed to m_r =
19.0 +/- 0.1 at T_mid = 0.7944 day post-trigger, calibrated with nearby
PS1 stars.
Based on the quick decay behaviour, we confirm that the source is very
likely the afterglow of the burst.
GCN Circular 28718
Subject
GRB 201020B: MASTER bright optical afterglow detection
Date
2020-10-21T12:19:33Z (5 years ago)
From
Vladimir Lipunov at Moscow State U/Krylov Obs <lipunov@xray.sai.msu.ru>
V. Lipunov, V.Kornilov, E.Gorbovskoy, N.Tiurina, P.Balanutsa, A.Kuznetsov, K.Zhirkov, F.Balakin,
V.Vladimirov, D. Vlasenko, I.Gorbunov, D.Zimnukhov, V.Senik, A.Chasovnikov,
A.Pozdnyakov, D.Cheryasov(Lomonosov Moscow State University, SAI, Physics Department),
R. Podesta, C.Lopez, F. Podesta, C.Francile (Observatorio Astronomico FelixAguilar OAFA),
R. Rebolo, M. Serra(The Instituto de Astrofisica de Canarias),
D. Buckley (South African Astronomical Observatory),
O.A. Gres, N.M. Budnev (Irkutsk State University, API),
A. Tlatov, D. Dormidontov (Kislovodsk Solar Station of the Pulkovo Observatory),
A. Gabovich, V.Yurkov, Yu. Sergienko (Blagoveschensk Educational State University)
MASTER-Tavrida wide field robotic-telescope (Lipunov et al. GCN 28704) and
very wide field cameras observed in alert mode Fermi GRB201020B
(GBM GCN 28703, LAT GCN 28716
https://gcn.gsfc.nasa.gov/other/201020B.gcn3 )
MASTER auto-detection system (Lipunov et al. 2010, Advances in Astronomy, vol. 2010, 30L)
discovered MASTER OT J050152.74+770406.3
with afterglow light curve at
(RA, Dec2000) = 05h 01m 52.74s +77d 04m 06.3s
with m_OT=13.7 at 2020-10-20.73413 UT.
The OT is seen in 35 images with afterglow behaviour.
We have reference image on 2020-01-02.78682 UT with unfiltered mlim=19.5m.
GCN Circular 28716
Subject
GRB 201020B: Fermi-LAT detection
Date
2020-10-21T09:28:52Z (5 years ago)
From
Magnus Axelsson at Stockholm U. <magaxe@kth.se>
M. Arimoto (Kanazawa Univ.), M. Axelsson (KTH and Stockholm Univ.), F. Longo (University and INFN, Trieste) and E. Bissaldi (INFN and Politecnico Bari) report on behalf of the Fermi-LAT Collaboration:
On October 20, 2020, Fermi-LAT detected high-energy emission from GRB 201020B, which was also detected by Fermi-GBM (trigger 624908039.329288 / 201020732; GCN 28702). The best LAT on-ground location is found to be
RA, Dec = 74.9, 77.0 (degrees, J2000)
with an error radius of 0.21 deg (90% containment, statistical error only). This was 67 deg from the LAT boresight at the time of the GBM trigger:
T0 = 17:33:54.33 UT.
At the time of the trigger, the source was outside the field of view of the LAT. Observations began at T0+2300s and the data from the Fermi-LAT show a significant increase in the event rate in the interval T0+2300 to T0+4600s that is spatially correlated with the GBM emission with high significance. The photon flux above 100 MeV in this time interval is 6.5e-7 +/- 3.3e-7 ph/cm2/s. The estimated photon index above 100 MeV is -1.6+/-0.3.
The highest-energy photon is a 6 GeV event which is observed ~2700 seconds after the GBM trigger.
The Fermi-LAT point of contact for this burst is
Elisabetta Bissaldi (Elisabetta.Bissaldi@ba.infn.it<http://ba.infn.it>).
The Fermi-LAT is a pair conversion telescope designed to cover the energy band from 20 MeV to greater than 300 GeV. It is the product of an international collaboration between NASA and DOE in the U.S. and many scientific institutions across France, Italy, Japan and Sweden.
GCN Circular 28714
Subject
GRB 201020B: AGILE detection
Date
2020-10-21T08:43:31Z (5 years ago)
From
Alessandro Ursi at INAF/IAPS <alessandro.ursi@gmail.com>
A. Ursi (INAF/IAPS), M. Pilia (INAF/OA-Cagliari), M. Tavani (INAF/IAPS, and
Univ. Roma Tor Vergata), A. Argan, M. Cardillo, C. Casentini, Y.
Evangelista, G. Piano (INAF/IAPS), F. Lucarelli, C. Pittori, F. Verrecchia
(SSDC, and INAF/OAR), A. Bulgarelli, V. Fioretti, F. Fuschino, N.
Parmiggiani (INAF/OAS-Bologna), M. Marisaldi (INAF/OAS-Bologna, and Bergen
University), A. Trois (INAF/OA-Cagliari), I. Donnarumma (ASI), F. Longo
(Univ. Trieste and INFN Trieste), A. Giuliani (INAF/IASF-Mi), report on
behalf of the AGILE Team:
The AGILE Mini-CALorimeter (MCAL) detected GRB 201020B at T0 = 2020-10-20
17:34:03.78 +/- 0.01 s (UTC), reported by Fermi/GBM (GCNs #28702 and
#28710).
The event lasted about 5 s and released a total number of 3250 counts in
the detector (in the 0.4-100 MeV energy range), above an average background
rate of 550 Hz. The MCAL light curve can be found at
http://www.agilescienceapp.it/notices/GRB_069336_525794310.907011.png .
The time-integrated spectrum of the burst can be fitted in the energy range
0.4-20 MeV with a single power-law with ph.ind. = -2.78 -0.03/+0.04,
resulting in a reduced chi-squared of 1.05 (89 d.o.f.) and a fluence of
4.56e-06 ergs/cm^2 (90% confidence level), in the same energy range.
The burst is clearly visible in the AGILE scientific ratemeters of the
SuperAGILE (SA; 20-60 keV), MiniCALorimeter (MCAL; 0.4-100 MeV), and
AntiCoincidence (AC; 50-200 keV) detectors. The event lasted ~27 s and
released a total number of 5856 counts in the SA detector (above a
background rate of 80 Hz); it lasted ~17.5 s and released a total number of
66750 counts in the AC detector (above a background rate of 3670 Hz); it
lasted ~5 s and released a total number of 7506 counts in the MCAL detector
(above a background rate of 1260 Hz). The AGILE ratemeter light curves can
be found at http://www.agilescienceapp.it/notices/GRB_201020B_AGILE_RM.png .
The AGILE-MCAL detector is a CsI detector with a 4 pi FoV, sensitive in the
energy range 0.4-100 MeV. Additional analysis of AGILE data is in progress.
Automatic MCAL GRB alert Notices can be found at:
https://gcn.gsfc.nasa.gov/agile_mcal.html.
GCN Circular 28710
Subject
GRB 201020B: Fermi GBM detection
Date
2020-10-21T01:14:36Z (5 years ago)
From
Christian Malacaria at NASA-MSFC/USRA <cmalacaria@usra.edu>
C. Malacaria (NASA-MSFC/USRA) and C. Meegan (UAH)
report on behalf of the Fermi GBM Team:
"At 17:33:54.33 UT on 20 October 2020, the Fermi Gamma-Ray Burst Monitor (GBM)
triggered and located GRB 201020B (trigger 624908039 / 201020732).
The Fermi GBM Final Real-time Localization was reported in GCN 28702.
The angle from the Fermi LAT boresight at the GBM trigger time is 69 degrees.
The GBM light curve shows multiple peaks around
the bright, main peak.
The duration (T90) is about 16 s (50-300 keV).
The time-averaged spectrum from T0-5.1 s to T0+23.5 s is
best fit by a Band function with Epeak = 136.9 +/- 3.4 keV,
alpha = -0.71 +/- 0.02, and beta = -2.20 +/- 0.03
The event fluence (10-1000 keV) in this time interval is
(3.929 +/- 0.040)E-05 erg/cm^2. The 1-sec peak photon flux measured
starting from T0+9.4 s in the 10-1000 keV band
is 43.7 +/- 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 28704
Subject
Fermi GRB 201020B: Global MASTER-Net observations report
Date
2020-10-20T19:30:28Z (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),
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) started inspect of the Fermi GRB 201020B ( Fermi GBM team, GCN 28702) errorbox 116 sec after notice time and 145 sec after trigger time at 2020-10-20 17:36:19 UT, with upper limit up to 19.0 mag. The observations began at zenith distance = 51 deg. The sun altitude is -30.3 deg.
The galactic latitude b = 20 deg., longitude l = 135 deg.
Real time updated cover map and OT discovered available here:
https://master.sai.msu.ru/site/master2/observ.php?id=1465475
We obtain a following upper limits.
Tmid-T0 | Date Time | Site | Coord (J2000) |Filt.| Expt. | Limit| Comment
_________|_____________________|_____________________|____________________________________|_____|_______|_______|________
160 | 2020-10-20 17:36:19 | MASTER-Tavrida | (05h 02m 15.44s , +77d 01m 50.6s) | C | 30 | 18.1 |
205 | 2020-10-20 17:36:19 | MASTER-Tavrida | (05h 02m 15.47s , +77d 01m 50.6s) | C | 120 | 19.0 | Coadd
216 | 2020-10-20 17:37:09 | MASTER-Tavrida | (05h 02m 09.73s , +77d 00m 53.6s) | C | 40 | 18.4 |
281 | 2020-10-20 17:38:10 | MASTER-Tavrida | (05h 02m 16.10s , +77d 01m 14.1s) | C | 50 | 18.4 |
356 | 2020-10-20 17:39:20 | MASTER-Tavrida | (05h 02m 11.94s , +77d 02m 41.5s) | C | 60 | 18.5 |
447 | 2020-10-20 17:40:41 | MASTER-Tavrida | (05h 02m 11.08s , +77d 01m 36.7s) | C | 80 | 18.7 |
557 | 2020-10-20 17:42:21 | MASTER-Tavrida | (04h 48m 10.21s , +76d 33m 54.4s) | C | 100 | 18.8 |
688 | 2020-10-20 17:44:21 | MASTER-Tavrida | (04h 48m 02.35s , +76d 33m 21.4s) | C | 120 | 18.9 |
843 | 2020-10-20 17:46:42 | MASTER-Tavrida | (04h 48m 00.81s , +76d 34m 32.4s) | C | 150 | 18.6 |
1029 | 2020-10-20 17:49:33 | MASTER-Tavrida | (04h 48m 05.91s , +76d 33m 45.8s) | C | 180 | 18.6 |
1230 | 2020-10-20 17:52:54 | MASTER-Tavrida | (04h 47m 57.59s , +76d 33m 01.0s) | C | 180 | 18.6 |
1431 | 2020-10-20 17:56:14 | MASTER-Tavrida | (04h 48m 03.67s , +76d 33m 39.0s) | C | 180 | 18.6 |
1631 | 2020-10-20 17:59:35 | MASTER-Tavrida | (04h 47m 58.81s , +76d 35m 03.2s) | C | 180 | 18.6 |
1772 | 2020-10-20 18:02:56 | MASTER-Tavrida | (04h 50m 47.49s , +78d 02m 09.0s) | C | 60 | 18.6 |
1852 | 2020-10-20 18:04:16 | MASTER-Tavrida | (04h 09m 27.94s , +76d 03m 59.8s) | C | 60 | 18.8 |
2013 | 2020-10-20 18:06:57 | MASTER-Tavrida | (05h 15m 54.03s , +76d 01m 47.7s) | C | 60 | 18.6 |
4831 | 2020-10-20 18:53:55 | MASTER-Tavrida | (04h 50m 27.27s , +78d 03m 32.9s) | C | 60 | 18.3 |
4912 | 2020-10-20 18:55:16 | MASTER-Tavrida | (05h 29m 10.28s , +78d 03m 58.0s) | C | 60 | 18.6 |
4992 | 2020-10-20 18:56:36 | MASTER-Tavrida | (04h 09m 07.67s , +76d 04m 40.5s) | C | 60 | 18.7 |
5073 | 2020-10-20 18:57:56 | MASTER-Tavrida | (04h 42m 20.94s , +76d 05m 39.8s) | C | 60 | 18.7 |
5233 | 2020-10-20 19:00:37 | MASTER-Tavrida | (05h 01m 52.50s , +80d 03m 12.9s) | C | 60 | 18.9 |
5315 | 2020-10-20 19:01:58 | MASTER-Tavrida | (05h 15m 37.60s , +76d 03m 36.6s) | C | 60 | 18.7 |
5814 | 2020-10-20 19:10:18 | MASTER-Tavrida | (05h 29m 01.57s , +78d 05m 11.8s) | C | 60 | 18.4 |
5895 | 2020-10-20 19:11:38 | MASTER-Tavrida | (04h 42m 17.73s , +76d 04m 03.6s) | C | 60 | 18.6 |
6260 | 2020-10-20 19:17:44 | MASTER-Tavrida | (04h 36m 28.16s , +74d 04m 22.2s) | C | 60 | 18.6 |
Filter C is a clear (unfiltred) band.
The observation and reduction will continue.
The message may be cited.
GCN Circular 28702
Subject
GRB 201020B: Fermi GBM Final Real-time Localization
Date
2020-10-20T17:41:58Z (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 17:33:54 UT on 20 Oct 2020, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 201020B (trigger 624908039.329288 / 201020732).
The on-ground calculated location, using the Fermi GBM trigger data, is RA = 71.6, Dec = 76.6 (J2000 degrees, equivalent to J2000 04h 46m, 76d 35'), with a statistical uncertainty of 1.6 degrees.
The angle from the Fermi LAT boresight is 69.0 degrees.
The skymap can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2020/bn201020732/quicklook/glg_skymap_all_bn201020732.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/bn201020732/quicklook/glg_healpix_all_bn201020732.fit
The GBM light curve can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2020/bn201020732/quicklook/glg_lc_medres34_bn201020732.gif