GRB 221120A
GCN Circular 32982
Subject
GRB 221120A: Detection by VZLUSAT-2
Date
2022-11-25T13:43:19Z (3 years ago)
From
Jakub Ripa at Masaryk University <245487@mail.muni.cz>
J. Ripa (Masaryk U.), A. Pal (Konkoly Observatory),�� N. Werner (Masaryk
U.), M. Ohno (Hiroshima U.),�� L. Meszaros, B. Csak (Konkoly
Observatory), H. Takahashi (Hiroshima U.), F. Munz , M. Topinka, F.
Hroch, M. Dafcikova, N. Husarikova, J.-P. Breuer (Masaryk U.), J. Hudec,
J. Kapus, M. Frajt, M. Rezenov (Spacemanic s.r.o), R. Laszlo
(Needronix), G. Galgoczi (Wigner Research Center/Eotvos U.), N. Uchida
(ISAS/JAXA), T. Enoto (Kyoto U.), Zs. Frei (Eotvos U.), Y. Fukazawa, K.
Hirose, H. Matake (Hiroshima U.), S. Hisadomi (Nagoya U.), Y. Ichinohe
(Rikkyo U.), L. L. Kiss (Konkoly Observatory),�� T. Mizuno (Hiroshima
U.), K. Nakazawa (Nagoya U.), H. Odaka (Univ of Tokyo), K. Torigoe
(Hiroshima U.), P. Svoboda, V. Daniel, J. Dudas, M. Junas, J. Gromes
(VZLU), I. Vertat (FEL ZCU)�� -- the VZLUSAT-2/GRB payload collaboration.
A short-duration GRB 221120A (Swift/BAT detection: Eyles-Ferris et al.,
GCN Circ. 32955; Fermi/GBM detection: Veres and Meegan et al., GCN Circ.
32964; GECAM-B detection trig. num. 75; INTEGRAL/SPI-ACS detection peak
at 2022-11-20 21:29:28 UT) was detected by the GRB detector on board of
the VZLUSAT-2 3U CubeSat (https://www.vzlusat2.cz/en/).
The data acquisition was performed by GRB detector unit no. 1 and the
subthreshold detection was confirmed at the peak time 2022-11-20
21:29:27 UTC. The T90 duration was measured to be 2 s with the light
curve cadence of 1 s. The overall significance during T90 reaches 4.4 sigma.
The light curve obtained by VZLUSAT-2 is available here:
https://vzlusat2.konkoly.hu/static/share/GRB221120A_GCN_VZLUSAT2.pdf
GRB detectors on VZLUSAT-2 are a demonstration payload for a future
CubeSats constellation (Werner et al. Proc. SPIE 2018). Two GRB modules
of VZLUSAT-2 are placed in a perpendicular manner and each consists of a
75 x 75 x 5 mm3 CsI scintillator read out by a SiPM array, covering the
energy range from ~30 keV to ~1000 keV. VZLUSAT-2 was launched on 2022
January 13 from Cape Canaveral.
GCN Circular 32978
Subject
GRB 221120A: TURBO Optical Upper Limit
Date
2022-11-23T21:10:38Z (3 years ago)
From
Robert Strausbaugh at University of Minnesota <rstrausb@umn.edu>
R. Strausbaugh (UMN), D. Warshofsky (UMN), P. L. Kelly (UMN) report on
behalf of a larger collaboration:
We observed the GRB 221120A (Eyles-Ferris et al., GCN 32955) field with the
Total-Coverage Ultrafast Response to Binary-Mergers Observatory (TURBO)
prototype telescope in St. Paul, Minnesota on November 21, from 01:34 to
01:36 UT (corresponding to 4.08 hours after GRB trigger) in SDSS g-band and
from 02:45 to 02:47 UT (5.25 hours after GRB trigger) in SDSS r-band
filters.
We acquired a series of 5x30s exposures in each band. We do not detect any
fading uncatalogued sources in the XRT error region in either band, which
is consistent with available optical upper limits (Swain et al., GCN 32956;
Kuin et al., GCN 32958; Gompertz et al., GCN 32966; Odeh et al., GCN 32968;
Querrard et al., GCN 39276).
The following 3-sigma upper limits in AB magnitudes are calculated using
the Pan-STARRS catalog as reference:
g > 16.0
r > 15.4
These magnitudes are not corrected for foreground Galactic extinction.
The TURBO prototype in St. Paul consists of two co-mounted 11-inch
telescopes each with a 6.6 square degree field of view. TURBO will consist
of two arrays of 8 pairs of co-mounted 11-inch telescopes at two dark-sky
sites: Magdalena Ridge Observatory, New Mexico, USA and Skinakas
Observatory, Crete, Greece.
GCN Circular 32976
Subject
GRB 221120A: VIRT Optical Upper Limit
Date
2022-11-23T18:55:14Z (3 years ago)
From
Priyadarshini Gokuldass at U. of the Virgin Islands <priyadass.94@gmail.com>
R. Querrard (UVI), P. Gokuldass (Florida Institute of Technology), N.
Orange (OrangeWave Innovative Science, LLC), K. Noonan (UVI), K. Smith
(UVI), D. Morris (UVI) report:
We observed the field of GRB221120A (R. A. J. Eyles-Ferris et al., GCN
32955) with the 0.5m Virgin Island Robotic Telescope (VIRT) at the
University of the Virgin Islands' Etelman observatory on 11-21-2022
starting at 01:20:09 UT (T+3.8 hrs). We performed a series of exposures in
the R filter with a total exposure of 4000 s. The weather conditions were
partly cloudy to cloudy during the hours of observation with an average
airmass of 1.1.
We detect no new source within the enhanced XRT position error circle (Goad
et al., GCNC 32962) consistent with other non-detections (Swain et al., GCN
32956, O'Connor
et al., GCN 32957, Leonini et al. GCN 32961, Gompertz et al, GCN 32966; and
Odeh et al., GCN 32968) and report the following 5-sigma upper limit:
T_mid ||Exposure ||Filter ||Limit
T+ 4.3 hrs ||4000s ||R ||>20.34
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.
We acknowledge financial support from NASA MUREP MIRO award 80NSSC21M0001,
NASA EPSCoR award 80NSSC22M0063, and NSF EiR award 1901296. R.Q. and N.B.O.
also acknowledge financial support from South Carolina Space Grant award
80NSSC20M0054. This message can be cited.
GCN Circular 32972
Subject
GRB 221120A: GTC Confirmation of an Underlying Galaxy
Date
2022-11-22T23:02:37Z (3 years ago)
From
Brendan O'Connor at UMD <oconnorb@umd.edu>
B. O'Connor (UMD/GWU), N. Butler (ASU), A. Watson (UNAM),
E. Troja (UTV/ASU), S. Dichiara (PSU), on behalf of a
larger collaboration:
We observed the short GRB 221120A (Eyles-Ferris et al., GCN 32955,
Tohuvavohu et al., GCN 32959) using OSIRIS at the 10.4m Gran Telescopio
Canarias (GTC). The observation started on November 22, 2022 at
00:44:32 UTC (~1.13 d) for a total exposure of 540 s in r-band.
At the location of the source reported by O'Connor et al. (GCN 32957)
we detect a source with magnitude r~24.38+/-0.08 AB mag calibrated using
nearby SDSS stars. This serves as confirmation of the underlying galaxy
(Rastinejad et al., GCN 32965) and demonstrates a lack of fading of the
source found by O'Connor et al. (GCN 32957). While the host association
is unclear, if this galaxy is associated to GRB 221120A, the observed
r-J color (Karambelkar et al., GCN 32967) suggests that GRB 221120A was
a distant event (see, e.g., O'Connor et al. 2022, MNRAS, 515, 4890).
We thank the GTC staff for rapidly scheduling and executing these
observations.
GCN Circular 32970
Subject
GRB 221120A: Swift-BAT refined analysis
Date
2022-11-22T18:45:41Z (3 years ago)
From
Sibasish Laha at GSFC <sibasish.laha@nasa.gov>
T. Sakamoto (AGU), S. D. Barthelmy (GSFC),
H. A. Krimm (NSF), S. Laha (GSFC/UMBC),
A. Y. Lien (U Tampa), C. B. Markwardt (GSFC),
D. M. Palmer (LANL), T. Parsotan (GSFC/UMBC),
M. Stamatikos (OSU) (i.e. the Swift-BAT team):
Using the data set from T-239 to T+963 sec from the recent telemetry downlink,
we report further analysis of BAT GRB 221120A (trigger #1141030)
(Eyles-Ferris et al., GCN Circ. 32955). The BAT ground-calculated position is
RA, Dec = 41.363, 43.241 deg which is
RA(J2000) = 02h 45m 27.1s
Dec(J2000) = +43d 14' 26.5"
with an uncertainty of 1.8 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 97%.
The BAT light curve shows several peaks within a duration of ~1 sec
T90 (15-350 keV) is 0.79 +- 0.16 sec (estimated error including systematics).
The time-averaged spectrum from T-0.60 to T+0.27 sec is best fit by a simple
power-law model. The power law index of the time-averaged spectrum is
0.85 +- 0.27. The fluence in the 15-150 keV band is 1.1 +- 0.2 x 10^-07 erg/cm2.
The 1-sec peak photon flux measured from T-0.67 sec in the 15-150 keV band
is 1.2 +- 0.2 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/1141030/BA/
GCN Circular 32968
Subject
GRB 221120A: AKO Telescope Upper Limits
Date
2022-11-22T04:39:10Z (3 years ago)
From
Mohammad Odeh at Al Khatim Observatory M44 <mshodeh@gmail.com>
Mohammad Odeh of Al-Khatim Observatory (AKO) operated by the International
Astronomical Center, in Abu Dhabi, UAE.
We observed the short GRB 221120A detected by Swift (R. Eyles-Ferris et al.,
GCN 32955), with our 0.35m telescope. The observation was done on 21
November 2022 from 15:36:06 to 15:48:28 (UT), 18.2 hours after the Swift
trigger. We obtained multiple 180-sec exposures in Ic filter. We did not
detect any afterglow within XRT localization (M.R. Goad et al., GCN 32962).
The following upper limit was calculated using Atlas catalogue as a
reference:
----------------------------------------------------------------------------
-
JD (mid), T_mid-T0(hrs), Exposure (sec), Filter, Lim_mag
----------------------------------------------------------------------------
-
2459905.155422, 18.2, 5 x 180 (stacked), Ic, > 19.5
----------------------------------------------------------------------------
-
These magnitudes are not corrected for galactic extinction.
GCN Circular 32967
Subject
GRB221120A: WIRC near-IR imaging of the afterglow candidate
Date
2022-11-22T00:37:56Z (3 years ago)
From
Viraj Karambelkar at Indian Inst of Tech,Bombay <karambelkarvraj21197@gmail.com>
Viraj Karambelkar (Caltech), Zach Vanderbosch (Caltech), Mansi Kasliwal
(Caltech), Igor Andreoni (U. of Maryland)
We observed the location of the short duration GRB 221120A (Eyles-Ferris et
al., GCN 32955, Tohuvavohu et al., GCN 32959) in the NIR J-band with the
Wide-Field Infrared Camera (WIRC, Wilson et al. 2003) on the 200-inch Hale
telescope at Palomar Observatory. Observations began on November 21, 2022
at 06:22:07 UT (approx. 9 hours since the Swift detection), and comprise a
series of 30x45 second exposures.
We detect a faint source centered at RA = 02:45:21.3, Dec = +43:14:35.2
(J2000).
Performing forced aperture photometry at the location of this source
suggests a J-band magnitude of
m_J = 22.0 +/- 0.3 mag (AB).
This source is spatially coincident with that reported by Rastinejad et al.
(GCN 32965) from archival PS1 images, and also consistent with the position
of the LDT afterglow candidate (O'Connor et al., GCN 32957).
The magnitude reported above is not corrected for Galactic interstellar
reddening E(B-V)~0.08 mag
GCN Circular 32966
Subject
GRB 221120A: Liverpool Telescope Upper Limits
Date
2022-11-21T22:03:04Z (3 years ago)
From
Ben Gompertz at U of Birmingham <b.gompertz@bham.ac.uk>
B. P. Gompertz, M. Nicholl (U. Birmingham), N. Tanvir, G. Lamb, P. O'Brien (U. Leicester) and K. Wiersema (U. Lancaster) report:
We observed short GRB 221120A (Eyles-Ferris et al., GCN 32955) with the IO:O optical camera on the 2m robotic Liverpool Telescope. Observations began on November 20, 2022 at 23:50:33 UT (~2.5h after the Swift trigger) and consist of a series of 10x150s exposures in each of the SDSS r' and i' filters.
We place the following 3-sigma upper limits on an optical source at the location of the the X-ray afterglow (Goad et al., GCN 31962) at the time of observation:
r' > 21.82
i' > 21.88
Magnitudes are in the AB system, calibrated against nearby PS1 stars, and are not corrected for the Galactic reddening of E(B-V) = 0.08 magnitudes along the line of sight (Schlafly & Finkbeiner 2011). Our observations are only weakly constraining to any evolution in the afterglow candidate identified by O'Connor et al. (GCN 32957), precluding power-law decays steeper than ~t^-4 between the two epochs.
GCN Circular 32965
Subject
GRB 221120A: Archival PS1 Imaging of Faint Source near XRT position
Date
2022-11-21T19:18:20Z (3 years ago)
From
Jillian Rastinejad at Northwestern Univ. <jillianrastinejad2024@u.northwestern.edu>
J. Rastinejad, C. D. Kilpatrick, A. E. Nugent and W. Fong (Northwestern) report:
We analyzed stacked images from the Pan-STARRS 3pi Data Release 1 image archive (Flewelling et al. 2016) of the location of the short-duration GRB 221120A (Eyles-Ferris et al., GCN 32955, Tohuvavohu et al., GCN 32959). We detect a faint source in multiple bands centered at
RA (J2000): 02:45:21.31
Dec (J2000): +43:14:35.35
This source is just outside the enhanced XRT position (90% confidence, Goad et al., GCN 32962) and marginally consistent with the optical source reported by O'Connor et al. (GCN 32957) using their reported 0.5'' uncertainty. Performing forced aperture photometry of the source with an aperture approximately equal to the FWHM size (0.9 - 2.0''), we measure the following magnitudes:
g > 23.8 mag
r = 23.2 +/- 0.5 mag
i = 23.1 +/- 0.3 mag
z = 23.5 +/- 0.5 mag
y = 22.0 +/- 0.4 mag
All magnitudes are in the AB system. The source appears extended although the low S/N precludes a firm conclusion. Using the i-band magnitude and an offset of 2.7'' between the centers of this possible galaxy and the XRT position, we calculate a probability of chance coincidence (Pcc; Bloom et al. 2002) of 0.05. The bright, offset galaxy previously reported by O'Connor et al. (GCN 32957), PSO J041.3414+43.242, is also apparent in the PS1 imaging, and for which we measure r_AB = 17.6 mag (similar to the tabulated SDSS magnitude for this source). At an angular offset of 13.2'', we find a Pcc of 0.02.
Thus, it is possible that the optical afterglow candidate reported by GCN 32957 is actually the galaxy apparent in PS1 imaging. Given the comparable Pcc values of both sources, it is difficult to make a clear host association with present information. Confirmation of a fading counterpart is critical to refining the position of the counterpart and determining the true host.
GCN Circular 32964
Subject
GRB 221120A: Fermi GBM observation
Date
2022-11-21T15:15:14Z (3 years ago)
From
Peter Veres at UAH <veresp@gmail.com>
P. Veres and C. Meegan (both UAH)
report on behalf of the Fermi GBM Team:
"At 21:29:27.85 UT on 20 November 2022, the Fermi Gamma-Ray Burst Monitor (GBM)
triggered and located GRB 221120A (trigger 690672572 / 221120895)
which was also detected by the Swift/BAT (Eyles-Ferris et al., GCN 32955).
The GBM on-ground location is consistent with the Swift position.
The angle from the Fermi LAT boresight at the GBM trigger time is 62 degrees.
The GBM light curve consists of two pulses
with a duration (T90) of about 0.64 s (50-300 keV).
The time-averaged spectrum from T0-0.13 s to T0+0.58 s is
best fit by a power law function with an exponential
high-energy cutoff. The power law index is 0.11 +/- 0.31 and
the cutoff energy, parameterized as Epeak, is 379 +/- 65 keV.
The event fluence (10-1000 keV) in this time interval is
(7.8 +/- 0.9)E-7 erg/cm^2. The 64 ms peak photon flux measured
starting from T0+0.38 s in the 10-1000 keV band
is 7.45 +/- 0.91 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 32963
Subject
GRB 221120A: Swift-XRT refined Analysis
Date
2022-11-21T12:45:58Z (3 years ago)
From
Phil Evans at U of Leicester <pae9@leicester.ac.uk>
S. Dichiara (PSU), J.A. Kennea (PSU), K.L. Page (U. Leicester), A.P.
Beardmore (U. Leicester), P.A. Evans (U. Leicester), A. D'Ai
(INAF-IASFPA), A. Melandri (INAF-OAB), T. Sbarrato (INAF-OAB), A.
Tohuvavohu (U. Toronto) and R.A.J. Eyles-Ferris report on behalf of the
Swift-XRT team:
We have analysed 8.4 ks of XRT data for GRB 221120A (Eyles-Ferris et
al. GCN Circ. 32955), from 103 s to 47.0 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. 32962).
The light curve can be modelled with a power-law decay with a decay
index of alpha=1.6 (+/-0.3).
A spectrum formed from the PC mode data can be fitted with an absorbed
power-law with a photon spectral index of 1.9 (+1.1, -0.9). The
best-fitting absorption column is 3.2 (+2.4, -1.7) x 10^22 cm^-2, in
excess of the Galactic value of 1.2 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 7.9 x 10^-11 (1.8 x 10^-10) erg
cm^-2 count^-1.
A summary of the PC-mode spectrum is thus:
Total column: 3.2 (+2.4, -1.7) x 10^22 cm^-2
Galactic foreground: 1.2 x 10^21 cm^-2
Excess significance: 3.0 sigma
Photon index: 1.9 (+1.1, -0.9)
If the light curve continues to decay with a power-law decay index of
1.6, the count rate at T+24 hours will be 8.2 x 10^-6 count s^-1,
corresponding to an observed (unabsorbed) 0.3-10 keV flux of 6.5 x
10^-16 (1.5 x 10^-15) erg cm^-2 s^-1.
The results of the XRT-team automatic analysis are available at
http://www.swift.ac.uk/xrt_products/01141030.
This circular is an official product of the Swift-XRT team.
GCN Circular 32962
Subject
GRB 221120A: Enhanced Swift-XRT position
Date
2022-11-21T08:24:43Z (3 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 1363 s of XRT Photon Counting mode data and 2 UVOT
images for GRB 221120A, 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 = 41.33982, +43.24315 which is equivalent
to:
RA (J2000): 02h 45m 21.56s
Dec (J2000): +43d 14' 35.4"
with an uncertainty of 2.4 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 32961
Subject
GRB221120A: Montarrenti Observatory Upper Limit
Date
2022-11-21T07:30:57Z (3 years ago)
From
Simone Leonini at Monarrenti Obs <s.leonini@iol.it>
<!doctype html>
<html>
<head>
<meta charset="UTF-8">
</head>
<body>
<p class="default-style"></p>
<p dir="ltr">Simone Leonini, M. Conti, P. Rosi and L.M. Tinjaca Ramirez (Montarrenti Observatory, Siena, Italy) report:</p>
<p dir="ltr">We observed the field of the short GRB221120<a href="tel:221120"></a>A (Trigger 1141030, R.A.J. Eyles-Ferris et al., GCN Circ. 32955) with the automatic 0.53m RC telescope + U47 detector at Montarrenti Observatory (Siena, Italy, IAU code C88).</p>
<p dir="ltr">The observations were started under good weather conditions at 2022-11-20 22:35:10 UT (2.240s after notice) stacking 10x30s clear filter CCD exposures.</p>
<p dir="ltr">We have not found optical transient within the error-box of the Neil Gehrels Swift Observatory position (RA 02h 45m 17.00s, Dec +43d 11m 49.0s - J2000).<br> Mag. upper limit R = 19.86+/-0.14</p>
<p dir="ltr">Magnitudes were obtained from USNO-B1 catalogue and are not corrected for galactic extinction.</p>
<p dir="ltr">Observations are consistent with previous upper limits (Swain et al., GCN 32956).<br></p>
</body>
</html>
GCN Circular 32959
Subject
GRB 221120A is a short burst
Date
2022-11-21T05:30:03Z (3 years ago)
From
Aaron Tohuvavohu at U Toronto <aaron.tohu@gmail.com>
Confirming the "likely" classification from GCN 32955, GRB 221120A has a
measured T90 duration of ~0.8 seconds (15-195 keV) in the Swift/BAT data.
Followup is encouraged.
GCN Circular 32958
Subject
GRB 221120A: Swift/UVOT Upper Limits
Date
2022-11-21T04:53:00Z (3 years ago)
From
Paul Kuin at MSSL <npkuin@gmail.com>
Paul Kuin (MSSL/UCL) and Rob Eyles-Ferris (U. Leicester)
report on behalf of the Swift/UVOT team:
The Swift/UVOT began settled observations of the field of GRB 221120A
208 s after the BAT trigger (Eyles-Ferris et al., GCN Circ. 32955).
An optical detection in r' has been reported by O'Connor et al.
(GCN Circ. 32957).
No optical afterglow consistent with the enhanced XRT position 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
u_FC 208 458 246 >19.9
white 761 911 295 >21.0
u 208 458 246 >19.9
The magnitudes in the table are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 0.093 in the direction of the burst
(Schlegel et al. 1998).
GCN Circular 32957
Subject
GRB 221120A: LDT Optical Afterglow Candidate
Date
2022-11-21T02:57:19Z (3 years ago)
From
Brendan O'Connor at UMD <oconnorb@umd.edu>
B. O'Connor (UMD/GWU), I. Andreoni (UMD), S. B. Cenko (NASA/GSFC),
E. Troja (UTV/ASU), S. Dichiara (PSU), A. Kutyrev (NASA/GSFC),
S. Veilleux (UMD), J. Durbak (UMD), on behalf of a larger collaboration:
We performed target of opportunity observations of GRB 221120A
(Eyles-Ferris et al., GCN 32955) with the 4.3m Lowell Discovery
Telescope in Happy Jack, AZ. Observations began on October 21,
2022 at 01:32:08.76 UT corresponding to ~4 hr after the GRB.
We obtained 8x150 s exposures in r-band under good conditions.
At the North-East edge of the XRT localization we detect a faint
source with magnitude r~24.1 AB mag. The source position is:
RA, DEC (J2000) = 02:45:21.36, 43:14:34.9 +/- 0.5"
No other sources are detected within 5" of the GRB localization to
depth r>24.5 AB mag. At present we cannot evaluate whether this
source is the counterpart to GRB 221120A. These results are consistent
with previous upper limits (Swain et al., GCN 32956).
We note the presence of a nearby bright galaxy at an offset of
~16.5" from the center of the XRT localization (Eyles-Ferris et al.,
GCN 32955). The galaxy has a photometric redshift from SDSS of z~0.12.
At this redshift, the offset from the XRT position is ~37 kpc. The
probability of chance coincidence is Pcc<0.05. Therefore. this is a
plausible host galaxy of GRB221120A.
Magnitudes are calibrated against nearby SDSS stars.
These magnitudes are not corrected for Galactic interstellar
reddening E(B-V)~0.08 mag.
We thank the staff of the Lowell Observatory for assistance with these
observations.
Further observations are planned.
GCN Circular 32956
Subject
GRB 221120A: GIT upper limits on optical afterglow
Date
2022-11-21T01:24:33Z (3 years ago)
From
Varun Bhalerao at Indian Inst of Tech <varunb@iitb.ac.in>
V. Swain (IITB), H. Kumar (IITB), R. Norboo (IAO), V. Bhalerao (IITB), G. C. Anupama (IIA), S. Barway (IIA) report on behalf of the GIT team:
We observed the short GRB 221120A detected by Swift (R. A. J. Eyles-Ferris et al., GCN 32955), with the 0.7m GROWTH-India Telescope (GIT). The observations started at 22:31:28 UT on 2022-11-20, 62 mins after the Swift trigger. We obtained multiple 300-sec exposures in the g', r' and i' filters. We did not detect any new source in our stacked images within the 1.9 arcsec radius circle around R.A.= 02h 45m 21.24s, Dec.= +43d 14' 34.1". The obtained upper limits follow as:
-------------------------------------------------------------------
JD (mid) | T_mid-T0(hrs) | Exposure (sec) | Filter | Lim_mag (5-sigma) |
-------------------------------------------------------------------
2459904.44036416 | 1.08 | 3 x 300 (stacked) | g' | > 21.24 |
2459904.46842522 | 1.75 | 8 x 300 (stacked) | r' | > 21.37 |
2459904.46658235 | 1.70 | 3 x 300 (stacked) | i' | > 20.44 |
-------------------------------------------------------------------
The magnitudes are calibrated against PanSTARRS DR1 (Chambers et al., 2016) and not corrected for Galactic extinction.
The GROWTH India Telescope (GIT; Kumar et al. 2022 <https://iopscience.iop.org/article/10.3847/1538-3881/ac7bea <https://iopscience.iop.org/article/10.3847/1538-3881/ac7bea>>) 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 the telescope���s operations. Telescope technical details are available at https://sites.google.com/view/growthindia/ <https://sites.google.com/view/growthindia/>.
GCN Circular 32955
Subject
GRB 221120A: Swift detection of a likely short burst
Date
2022-11-20T21:57:40Z (3 years ago)
From
David Palmer at LANL <palmer@lanl.gov>
R. A. J. Eyles-Ferris (U Leicester), J.D. Gropp (PSU),
J. A. Kennea (PSU), 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 21:29:28 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 221120A (trigger=1141030). Swift slewed immediately to the burst.
The BAT on-board calculated location is
RA, Dec 41.3225 43.1970 which is
RA(J2000) = 02h 45m 17s
Dec(J2000) = 43d 11' 49"
with an uncertainty of 3 arcmin (radius, 90% containment, including
systematic uncertainty). The BAT trigger duration was 0.256 s, suggesting
a possible short burst. Due to a telemetry gap, no further BAT information
will be available until ground contact.
Using promptly downlinked data we find an uncatalogued X-ray source
with an enhanced position: RA, Dec 41.33852, 43.24280 which is
equivalent to:
RA(J2000) = 02h 45m 21.24s
Dec(J2000) = +43d 14' 34.1"
with an uncertainty of 1.9 arcseconds (radius, 90% containment). 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 does not constrain the column density.
UVOT took a finding chart exposure of 150 seconds with the White
filter. No credible afterglow candidate has been found in the initial
data products. The 2.7'x2.7' sub-image covers 0% of the XRT error
circle. 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.
Burst Advocate for this burst is R. A. J. Eyles-Ferris (raje1 AT leicester.ac.uk).
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/)