GRB 211024A
GCN Circular 30962
Subject
GRB 211024A: Fermi GBM Final Real-time Localization
Date
2021-10-24T01:44:24Z (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 SHORT GRB
At 01:34:11 UT on 24 Oct 2021, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 211024A (trigger 656732056.398738 / 211024065).
The on-ground calculated location, using the Fermi GBM trigger data, is RA = 358.1, Dec = 3.1 (J2000 degrees, equivalent to J2000 23h 52m, 3d 06'), with a statistical uncertainty of 16.9 degrees.
The angle from the Fermi LAT boresight is 88.0 degrees.
The skymap can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2021/bn211024065/quicklook/glg_skymap_all_bn211024065.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/bn211024065/quicklook/glg_healpix_all_bn211024065.fit
The GBM light curve can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2021/bn211024065/quicklook/glg_lc_medres34_bn211024065.gif
GCN Circular 30963
Subject
Fermi GRB 211024A: Global MASTER-Net observations report
Date
2021-10-24T02:30:28Z (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 211024A ( Fermi GBM team, GCN 30962) errorbox 280 sec after notice time and 309 sec after trigger time at 2021-10-24 01:39:20 UT, with upper limit up to 19.1 mag. The observations began at zenith distance = 47 deg. The sun altitude is -32.7 deg.
The galactic latitude b = -57 deg., longitude l = 97 deg.
Real time updated cover map and OT discovered available here:
https://master.sai.msu.ru/site/master2/observ.php?id=1763191
We obtain a following upper limits.
Tmid-T0 | Date Time | Site | Coord (J2000) |Filt.| Expt. | Limit| Comment
_________|_____________________|_____________________|____________________________________|_____|_______|_______|________
339 | 2021-10-24 01:39:20 | MASTER-OAFA | (00h 38m 42.05s , +11d 16m 19.3s) | C | 60 | 19.0 |
419 | 2021-10-24 01:40:40 | MASTER-OAFA | (00h 46m 53.72s , +11d 18m 21.4s) | C | 60 | 19.1 |
501 | 2021-10-24 01:42:02 | MASTER-OAFA | (00h 38m 55.48s , +13d 12m 22.8s) | C | 60 | 18.9 |
580 | 2021-10-24 01:43:21 | MASTER-OAFA | (00h 47m 13.18s , +13d 11m 29.3s) | C | 60 | 18.9 |
660 | 2021-10-24 01:44:41 | MASTER-OAFA | (00h 38m 29.82s , +09d 22m 30.1s) | C | 60 | 19.0 |
739 | 2021-10-24 01:46:00 | MASTER-OAFA | (00h 46m 33.62s , +09d 24m 18.1s) | C | 60 | 19.0 |
819 | 2021-10-24 01:47:20 | MASTER-OAFA | (00h 54m 36.41s , +13d 12m 38.5s) | C | 60 | 18.8 |
978 | 2021-10-24 01:49:59 | MASTER-OAFA | (00h 54m 12.45s , +11d 17m 40.6s) | C | 60 | 18.7 |
1139 | 2021-10-24 01:52:40 | MASTER-OAFA | (00h 53m 50.67s , +09d 24m 40.5s) | C | 60 | 18.6 |
1634 | 2021-10-24 02:00:55 | MASTER-OAFA | (01h 01m 52.87s , +09d 23m 31.2s) | C | 60 | 18.6 |
1714 | 2021-10-24 02:02:15 | MASTER-OAFA | (00h 38m 36.81s , +11d 18m 11.9s) | C | 60 | 18.8 |
1795 | 2021-10-24 02:03:36 | MASTER-OAFA | (00h 46m 51.74s , +11d 17m 19.2s) | C | 60 | 18.8 |
1874 | 2021-10-24 02:04:55 | MASTER-OAFA | (00h 38m 53.73s , +13d 10m 13.7s) | C | 60 | 18.6 |
1956 | 2021-10-24 02:06:17 | MASTER-OAFA | (00h 47m 13.27s , +13d 10m 47.5s) | C | 60 | 18.7 |
2036 | 2021-10-24 02:07:37 | MASTER-OAFA | (00h 38m 26.10s , +09d 23m 54.7s) | C | 60 | 18.8 |
2116 | 2021-10-24 02:08:57 | MASTER-OAFA | (00h 46m 32.07s , +09d 22m 41.4s) | C | 60 | 18.7 |
2196 | 2021-10-24 02:10:17 | MASTER-OAFA | (00h 54m 34.50s , +13d 12m 15.5s) | C | 60 | 18.6 |
2358 | 2021-10-24 02:12:59 | MASTER-OAFA | (00h 54m 06.34s , +11d 18m 29.1s) | C | 60 | 18.4 |
Filter C is a clear (unfiltred) band.
The observation and reduction will continue.
The message may be cited.
GCN Circular 30974
Subject
GRB 211024A: GECAM detection
Date
2021-10-24T14:44:10Z (4 years ago)
From
Shuo Xiao at IHEP <xiaoshuo@ihep.ac.cn>
S. Xiao, Yi Zhao, S. L. Xiong, C. Cai, J. J. He, Y. Huang, Z. W. Guo,
C. Y. Li, X. B. Li, J. C. Liu, X. Y. Song, C. W. Wang, P. Wang, S. L. Xie, W. C. Xue,
Q. B. Yi, Y. Q. Zhang, G. Y. Zhao, X. Y. Zhao, C. Zheng, Y. Q. Du, D. Y. Guo,
J. Liang, F. J. Lu, Q. Luo, X. Ma, W. X. Peng, R. Qiao, L. M. Song, J. Wang, H. Wu,
P. Zhang, S. N. Zhang, X. L. Zhang, Z. Zhang, S. J. Zheng (IHEP),
report on behalf of GECAM team:
During the commissioning phase, GECAM-B was triggered ground by a short
bright burst, GRB 211024A, at 2021-10-24T01:34:11.450 UTC (denoted as T0),
which was also detected by Fermi/GBM (GCN 30962).
According to the GECAM-B light curves in about 16-3500 keV, this
burst mainly consists of a broad pulse with a duration of about 0.1 s.
The GECAM light curve could be found here:
http://twiki.ihep.ac.cn/pub/GECAM/GRBList/tn211024_013411_gb.png
GECAM-B localized this burst to the following position (J2000):
Ra: 25.7 deg
Dec: 1.05 deg
Err: 28.73 deg (1-sigma, statistical only)
The current systematic error of location is estimated to be several degrees
which could be minimized by the ongoing calibration.
This location is consistent with Fermi/GBM position within the error.
Please note that all GECAM results here are preliminary. The final analysis
will be published in journal papers or GECAM online catalog.
Gravitational wave high-energy Electromagnetic Counterpart All-sky Monitor
(GECAM) mission consists of two small satellites (GECAM-A and GECAM-B) in
Low Earth Orbit (600 km, 29 deg), launched on Dec 10, 2020 (Beijing Time),
which was funded by the Chinese Academy of Sciences (CAS).
GCN Circular 31006
Subject
GRB 211024A: Swift/BAT-GUANO detection and candidate arcminute localization of a short burst
Date
2021-10-26T13:53:49Z (4 years ago)
From
Aaron Tohuvavohu at U Toronto <aaron.tohu@gmail.com>
Aaron Tohuvavohu (U Toronto), James DeLaunay (UAlabama), Gayathri
Raman (PSU), Jamie A. Kennea (PSU), report:
Swift/BAT did not trigger on GRB 211024A (T0: 2021-10-24T01:34:11.4
UTC, Fermi/GBM trigger # 656732056, GCN 30962), also detected by
GECAM-B (GCN 30974).
The Fermi/GBM notice, distributed in near real-time, triggered the
Swift Mission Operations Center operated Gamma-ray Urgent Archiver for
Novel Opportunities (GUANO; Tohuvavohu et al. 2020, ApJ, 900, 1).
Upon trigger by this notice, GUANO sent a command to the Swift Burst
Alert Telescope (BAT) to save 200 seconds of BAT event-mode data from
[-50,+150] seconds around the time of the burst. All the requested
event mode data was delivered to the ground.
The BAT likelihood search, NITRATES (DeLaunay + Tohuvavohu, in prep),
confidently detects the burst with a duration of ~0.1 seconds and
sqrt(TS) of 10.4.
A candidate localization is found with DeltaLLHOut of 13 and an
ambiguous DeltaLLHPeak of 2.5. For this reason we can confidently
claim detection, and some preference for an in-FOV origin, but the
best fit arcmin localization is not strongly preferred over other
positions.
Conventional imaging does not find a location for this burst.
The best BAT position is
RA, Dec = 28.053 -6.973 deg which is
RA(J2000) = 1h 52m 12.61s
Dec(J2000) = -6d 58��� 23���
with an estimated uncertainty of 6 arcmin.
This position is consistent with the Fermi/GBM localization.
XRT and UVOT follow-up has been requested.
Results of follow-up observations will be reported in future circulars.
GUANO is a fully autonomous, extremely low latency, spacecraft
commanding pipeline designed for targeted recovery of BAT event mode
data around the times of compelling astrophysical events to enable
more sensitive GRB searches.
A live reporting of Swift/BAT event data recovered by GUANO can be
found at: https://www.swift.psu.edu/guano/
GCN Circular 31007
Subject
GRB 211024A: Swift ToO observations
Date
2021-10-26T15:12:57Z (4 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 Swift/BAT GRB 211024A.
Automated analysis of the XRT data will be presented online at
https://www.swift.ac.uk/ToO_GRBs/00021464
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 Swift/BAT 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 31011
Subject
GRB 211024A: Fermi GBM detection
Date
2021-10-26T22:38:14Z (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 01:34:11.40 UT on 24 October 2021, the Fermi Gamma-Ray Burst Monitor
(GBM)
triggered and located GRB 211024A (trigger 656732056 / 211024065)
which was also detected by the Swift/BAT-GUANO (Tohuvavohu et al. 2021, GCN
31006).
The GBM on-ground location is consistent with the Swift/BAT-GUANO position.
The angle from the Fermi LAT boresight at the GBM trigger time is 119
degrees.
The GBM light curve consists of a single emission episode
with a duration (T90) of about 0.06 s (50-300 keV).
The time-averaged spectrum from T0-0.128 s to T0+0.128 s
is best fit by a power law function with an exponential
high-energy cutoff. The power law index is -0.23 +/- 0.39 and
the cutoff energy, parameterized as Epeak, is 145 +/- 27 keV.
The event fluence (10-1000 keV) in this time interval is
(1.95 +/- 0.28)E-07 erg/cm^2. The 64-ms peak photon flux measured
starting from T0 s in the 10-1000 keV band
is 10.4 +/- 1.4 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 31013
Subject
GRB 211024A: Swift-XRT observations
Date
2021-10-27T06:33:32Z (4 years ago)
From
Phil Evans at U of Leicester <pae9@leicester.ac.uk>
M. Perri (SSDC & INAF-OAR), V. D'Elia (SSDC & INAF-OAR), A. D'Ai
(INAF-IASFPA), A. Tohuvavohu (U. Toronto), B. Sbarufatti (PSU), D.N.
Burrows (PSU), K.L. Page (U. Leicester), A.P. Beardmore (U. Leicester)
and P.A. Evans (U. Leicester) report on behalf of the Swift-XRT team:
Swift-XRT has performed follow-up observations of the
Swift/BAT-detected burst GRB 211024A (Aaron Tohuvavohu et al. GCN Circ.
31006), collecting 5.1 ks of Photon Counting (PC) mode data between
T0+221.8 ks and T0+234.5 ks.
Four uncatalogued X-ray sources have been detected, however none of
them is above the RASS limit or shows definitive signs of fading.
Therefore, at the present time we cannot identify which, if any, is the
afterglow. Details of these sources are given below:
Source 3:
RA (J2000.0): 27.9803 = 01:51:55.28
Dec (J2000.0): -6.9611 = -06:57:39.9
Error: 9.0 arcsec (radius, 90% conf.)
Count-rate: (1.24 [+0.76, -0.56])e-3 ct s^-1
Distance: 261 arcsec from Swift/BAT position.
Flux: (4.0 [+2.4, -1.8])e-14 erg cm^-2 s^-1 (observed, 0.3-10 keV)
Source 4:
RA (J2000.0): 28.1958 = 01:52:47.00
Dec (J2000.0): -7.0082 = -07:00:29.4
Error: 3.3 arcsec (radius, 90% conf. [Enhanced position])
Count-rate: 0.0146 [+0.0032, -0.0029] ct s^-1
Distance: 527 arcsec from Swift/BAT position.
Flux: (3.49 [+0.76, -0.70])e-13 erg cm^-2 s^-1 (observed, 0.3-10 keV)
Source 5:
RA (J2000.0): 27.8881 = 01:51:33.14
Dec (J2000.0): -6.9512 = -06:57:04.2
Error: 6.8 arcsec (radius, 90% conf.)
Count-rate: (1.21 [+0.83, -0.59])e-3 ct s^-1
Distance: 592 arcsec from Swift/BAT position.
Source 6:
RA (J2000.0): 28.0277 = 01:52:6.65
Dec (J2000.0): -7.0969 = -07:05:48.8
Error: 7.5 arcsec (radius, 90% conf.)
Count-rate: (1.60 [+0.87, -0.66])e-3 ct s^-1
Distance: 454 arcsec from Swift/BAT position.
A catalogued source was also detected.
The results of the XRT-team automatic analysis of the XRT observations,
including a position-specific upper limit calculator, are available at
https://www.swift.ac.uk/ToO_GRBs/00021464.
This circular is an official product of the Swift-XRT team.
GCN Circular 31014
Subject
GRB 211024A: Possible afterglow candidate from GIT
Date
2021-10-27T11:35:56Z (4 years ago)
From
Harsh Kumar at Indian Inst of Tech,Bombay <harshkosli13@gmail.com>
H. Kumar(IITB), V. Swain (IITB), U. Stanzin (IAO), V. Bhalerao(IITB), G. C.
Anupama(IIA), S. Barway(IIA) report on behalf of the GIT team:
We observed GRB 211024A detected by Fermi GBM (GCN 30962), localisation
further refined by Swift/BAT-GUANO
A. Tohuvavohu et al., (GCN #31006), with 0.7m GROWTH-India Telescope (GIT).
We obtained 2 exposures of 300 sec each in the r' filter, separated by ~15
min. We detected a potential candidate in our subtracted image at R.A.=
1:52:46.98 , DEC.= -7:00:27.30. This is coincident with an X-ray source
(#4) by Swift-XRT ToO observations (M. Perri et al. GCN # 31013). The
photometric results follow as:
-------------------------------------------------------------------
JD (Start) | T_start-T0(days) | Filter | Magnitude (AB) |
-------------------------------------------------------------------
2459514.2264 | 2.66 | r' | 19.83 +/- 0.038|
2459514.2373 | 2.67 | r' | 19.87 +/- 0.046 |
-------------------------------------------------------------------
There was an underlying source at the position of the target in the raw
image which was subtracted using reference images from PanSTARRS. The
source magnitude is 17.86 mag in the r band with phot_z = 0.2108 +/- 0.02
(SDSS Release 12: Alam+, 2015). This may be the host galaxy of the GRB.
There is no minor planet at the location of the candidate in MPC. The gap
between exposures was not sufficient to measure any decay. Further
observations are planned. Follow-up observations for this source are
strongly encouraged.
The magnitudes are calibrated against PanSTARRS (Flewelling et al., 2018)
and not corrected for Galactic extinction.
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 (IIA) and the
Indian Institute of Technology Bombay (IITB) with funding from DST-SERB and
IUSSTF. It is located at the Indian Astronomical Observatory (Hanle),
operated by IIA. We acknowledge funding by the IITB alumni batch of 1994,
which partially supports operations of the telescope. Telescope technical
details are available at https://sites.google.com/view/growthindia/.
GCN Circular 31017
Subject
GRB 211024A: Swift-XRT source 4 is not an afterglow.
Date
2021-10-28T12:09:28Z (4 years ago)
From
Harsh Kumar at Indian Inst of Tech,Bombay <harshkosli13@gmail.com>
H. Kumar(IITB), S. Joharle (IITB), J. Stanzin (IAO), V. Bhalerao(IITB), G.
C. Anupama(IIA), S. Barway(IIA) report on behalf of the GIT team:
We continued the observation of X-ray source (#4) by Swift-XRT ToO
observations (M. Perri et al. GCN # 31013), a candidate for the afterglow
of Fermi GBM GRB 211024A (GCN 30962), A. Tohuvavohu et al., (GCN #31006),
with 0.7m GROWTH-India Telescope (GIT). We obtained multiple exposures of
300 sec each in the g', r' and i' filters. The photometric results follow
as:
-------------------------------------------------------------------
JD (Start) | T_start-T0(days) | Filter | Magnitude (AB) |
-------------------------------------------------------------------
2459515.167376 | 3.60 | g' | 20.25 +/- 0.06
2459515.136124 | 3.57 | i' | 19.68 +/- 0.057
2459515.146851 | 3.58 | r' | 19.85 +/- 0.034
-------------------------------------------------------------------
Comparing magnitude in r' filter with our previous photometry reported in
H. Kumar et al., (GCN #31014), we conclude that the source is not evolving
and is not an afterglow of the GRB 211024A.
We did not detect sources #3,#5,#6 of Swift-XRT ToO observations (M. Perri
et al. GCN # 31013) up to the following upper limits:-
-------------------------------------------------------------------
JD (Start) | T_start-T0(days) | Filter | upper limit |
-------------------------------------------------------------------
2459514.2374 | 2.67 | r' | > 20.26
2459515.1674 | 3.60 | g' | > 21.03
2459515.1361 | 3.58 | i' | > 20.51
-------------------------------------------------------------------
The magnitudes are calibrated against PanSTARRS (Flewelling et al., 2018)
and not corrected for Galactic extinction.
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 (IIA) and the
Indian Institute of Technology Bombay (IITB) with funding from DST-SERB and
IUSSTF. It is located at the Indian Astronomical Observatory (Hanle),
operated by IIA. We acknowledge funding by the IITB alumni batch of 1994,
which partially supports operations of the telescope. Telescope technical
details are available at https://sites.google.com/view/growthindia/.
GCN Circular 31027
Subject
GRB 211024A: 1.3m DFOT observations
Date
2021-11-01T15:36:39Z (4 years ago)
From
Dimple Panchal at ARIES, India <dimplepanchal96@gmail.com>
Ankur Ghosh, Rahul Gupta, Dimple, Amit Kumar, Amit Ror, Amar Aryan, Arvind
K. Dattatrey, Shubham Kishore, Tushar Tripathi, S. B. Pandey, and Kuntal
Misra (ARIES) report:
We observed GRB 211024A which was triggered by Fermi GBM (Fermi GBM Team,
GCN 30962), and further, follow up observations were carried out by
Swift/BAT-GUANO (A. Tohuvavohu et al., GCN 31006)), 0.7m GROWTH-India
Telescope (GIT, Kumar et al,. (GCN 31014)), using 1.3m Devasthal Fast
Optical Telescope (DFOT) located at Devasthal observatory of Aryabhatta
Research Institute of Observational Sciences (ARIES), India. Our
observation was carried out in two epochs. The first epoch observation was
started on 2021-10-26 at 16:22:24, i.e., ~2.62 DAYS post-Fermi trigger
whereas the second epoch observation was started on 2021-10-27 at 17:43:00,
i.e., ~3.68 days the Fermi trigger. Multiple frames in the R filter were
taken in both epochs.
In the first epoch, we started observing the location mentioned in
Swift/BAT-GUANO A. Tohuvavohu et al., (GCN 31006). But we found no
uncatalogued source within the error circle of ~ 6 arcmin up to 22.73 mag.
In the second epoch, we continued our observation for the 4th X-ray source
given by Swift-XRT ToO observations (M. Perri et al. GCN 31013) which were
assumed to be the afterglow of Fermi GBM GRB 211024A (GCN 30962), A.
Tohuvavohu et al., (GCN #31006), with 0.7m GROWTH-India Telescope (GIT,
Kumar, et al,. (GCN 31014)). We detected one source at R.A.= 1:52:46.98 ,
DEC.= -7:00:27.30 which is coincident with an X-ray source (#4) by
Swift-XRT ToO observations (M. Perri et al. GCN 31013. However, the source
is not variable during our observation period. Hence this is not the optical
counterpart of GRB 211024A. We quote an upper limit of 22.54 mag.
These magnitudes are not corrected for the Galactic extinction in the
direction of the burst. The standard stars from the USNO-B1.0 catalog was
used to get the calibrated magnitude.
This circular may be cited.
GCN Circular 31037
Subject
GRB 211024A: MITSuME Akeno optical observation
Date
2021-11-04T06:14:14Z (4 years ago)
From
Katsuhiro L. Murata at Nagoya U <murata@u.phys.nagoya-u.ac.jp>
Y. Imai, R. Hosokawa, K. L. Murata, N. Ito, Y. Takamatsu, M. Takaku, M.
Niwano, R. Noto, S. Sato, R. Yamaguchi, Y. Yatsu, and N. Kawai (TokyoTech)
report on behalf of the MITSuME collaboration:
We observed the field of GRB 211024A (The Fermi GBM team GCN Circular
#30962, V. Lipunov et al. GCN Circular #30963, S. Xiao et al. GCN Circular
#30974, Aaron Tohuvavohu et al. GCN Circular #31006, P. A. Evans et al. GCN
Circular #31007, S. Poolakkil et al. GCN Circular #31011, M. Perri et al.
GCN Circular #31013, H. Kumar et al. GCN Circular #31014, H. Kumar et al.
GCN Circular #31017) with the optical three color (g', Rc, and Ic) CCD
cameras attached to the MITSuME 50 cm telescope Akeno. The observation with
a series of 60 sec exposures was carried out from 2021-10-27 13:34:50 UT
(~3.5 days after the Fermi trigger) to 2021-10-31. We stacked the images
with good conditions.
We detected the Source 4 reported by the Swift ToO observation (Perri et
al. GCN Circular #31013) and performed aperture photometry. The magnitudes
of the Source 4 and the 5-sigma limits of the stacked images are as follows.
T0+[day] | MID-UT | T-EXP[sec] | Source 4 magnitude | 5-sigma limits
------------------------------------------------------------------------------------------------
3.6 | 2021-10-27 15:18:55 | 4200 | g'=19.2 +/- 0.2, Rc=18.2 +/- 0.1,
Ic=17.6 +/- 0.1| g'>19.9, Rc>20.4, Ic>19.8
4.4 | 2021-10-28 11:42:32 | 10380 | g'=19.3 +/- 0.2, Rc=18.2 +/- 0.1,
Ic=17.7 +/- 0.1 | g'>19.9, Rc>20.2, Ic>19.9
5.4 | 2021-10-29 11:41:30 | 9240 | g'=19.1 +/- 0.2, Rc=18.2 +/- 0.1,
Ic=17.6 +/- 0.1 |g'>19.8, Rc>20.4, Ic>19.9
6.4 | 2021-10-30 10:34:24 | 960 |g'=18.5 +/- 0.3, Rc=18.1 +/- 0.1, Ic=17.5
+/- 0.1 | g'>18.6, Rc>19.1, Ic>18.5
7.4 | 2021-10-31 10:41:48 | 540 | g' no detection, Rc=17.9 +/- 0.2, Ic=17.7
+/- 0.2 | g'>18.6, Rc>18.9, Ic>18.3
------------------------------------------------------------------------------------------------
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. 2021, PASJ, Vol.73, Issue 1, Pages
4-24; https://github.com/MNiwano/Eclaire).