GRB 220117A
GCN Circular 31522
Subject
GRB 220117A, GROND observations
Date
2022-01-24T11:56:35Z (4 years ago)
From
Ana Nicuesa at TLS Tautenburg <ana@tls-tautenburg.de>
A. Nicuesa Guelbenzu, S. Klose (both TLS Tautenburg), and A. Rau (MPE
Garching) report:
We observed the field of the short GRB 220117A (Melandri et al., GCN
31466) with GROND mounted at the 2.2m MPG telescope at La Silla
Observatory (Chile).
Observations started at 02:55 UT on January 19, about 34.5 hr after the
GRB trigger. They were performed at an average seeing of 1.3 arcsec and at
an airmass of 1.0.
Inside the XRT error circle (Beardmore et al., GCN 31472), the
reported optical transient (Palmerio et al., GCN 31480; Strausbaugh
et al., GCN 31481) is not detected anymore down to the following upper
limits (AB mags; 3 sigma):
g' > 23.2,
r' > 23.4,
i' > 23.0,
J > 21.4,
H > 21.1,
K > 19.3.
The given limits are derived based on calibrating the optical images
against the Pan-STARRS catalog and the JHK data against 2MASS stars.
We thank Sam Kim for excellent support and for performing the observations.
GCN Circular 31520
Subject
GRB 220117A: Terskol and AbAO optical upper limits
Date
2022-01-23T16:24:09Z (4 years ago)
From
Alexei Pozanenko at IKI, Moscow <apozanen@iki.rssi.ru>
A. Volnova (IKI), I. Sokolov (INASAN, KIAM), I. Izvekova (Institute of
Physics of NAS, ICAMBR of NAS), A. Shein (INASAN), Y. Markus (Institute
of Physics of NAS, ICAMBR NAS), Y. Markelov (KIAM), R. Ya. Inasaridze
(AbAO), N. Pankov (HSE), G. Butenko (ICAMBR NAS), S. Belkin (IKI,
HSE), A. Pozanenko (IKI) report on behalf of GRB IKI:
We observed the field of GRB 220117A (Melandri et al., GCN 31466) also
detected by Fermi GBM Sub-Threshold (Veres, GCN 31487), and Konus-Wind
(Frederiks et al. GCN 31511) with Zeiss-2000, Zeiss-600 and K-800
telescopes of Terskol observatory and with AS-32 telescope of Abastumani
observatory. Within the enhanced XRT Swift-XRT error circle (Beardmore
et al., GCN 31472) we did not find any optical source. In particular we
do not find the afterglow reported by Nanshan/NEXT (Fu et al., GCN
31467), VLT (Palmerio et al., GCN 31480), LCO (Strausbaugh et al., GCN
31481). Preliminary upper limits are following
Date UT start t-T0 Filter Exp. OT Err UL(3sigma) Telescope
2022-01-17 18:32:01 0.12671 R 90*60 n/d n/d 19.3 Zeiss-600
2022-01-17 19:41:36 0.16134 R 19*180 n/d n/d 20.5 Zeiss-2000
2022-01-17 20:53:30 0.20545 R 35*60 n/d n/d 19.4 AS-32
The photometry is based on the nearby PS1 stars.
GCN Circular 31511
Subject
GRB 220117A: Konus-Wind detection and joint Konus-Wind + Swift-BAT spectral analysis
Date
2022-01-21T15:54:26Z (4 years ago)
From
Dmitry Frederiks at Ioffe Institute <fred@mail.ioffe.ru>
D. Frederiks, A.Lysenko, A. Ridnaya, D. Svinkin, A. Tsvetkova, M. Ulanov,
on behalf of the Konus-Wind team;
and A. Melandri (INAF-OAB), A.Y. Lien (U Tampa), D.M. Palmer (LANL), S.D. Barthelmy (GSFC),
on behalf of the Swift-BAT team, report:
The long GRB 220117A (Swift-BAT trigger #1093592, T0 = T0(BAT)= 16:18:51.546 UT:
Melandri et al. GCN 31466; Palmer et al., GCN 31485;
Fermi GBM Sub-Threshold Detection: Veres, GCN 31487)
was detected by Konus-Wind (KW) in the waiting mode.
A Bayesian block analysis of the KW waiting mode data in the 20-400 keV band
reveals a >10 sigma count rate increase over background in the interval
from ~T0+10 s to ~T0+50 s. No statistically significant
emission has been detected above 400 keV throughout the burst.
The KW light curve of this burst is available
at http://www.ioffe.ru/LEA/GRBs/GRB220117A/
To derive broad-band spectral parameters of this burst, we performed
a joint spectral analysis of the Swift/BAT data (15-150 keV) and
the KW 3-channel spectral data (20-1500 keV).
A fit to the time-averaged spectrum, measured from T0+10.557 s to T0+48.829 s,
by a power law with an exponential cutoff (CPL) model gives a photon index
alpha = -1.14 (-0.32,+0.37), and Ep = 71 (-11,+17) keV, chi^2 = 65.0/ 58 dof.
The Band GRB function fits this spectrum equally well, with alpha = -1.04 (-0.40,+0.58),
Ep = 65 (-14,+20) keV, and beta = -2.59 (-7.41, +0.43), chi^2 = 64.7/57 dof.
A fit to a simple power law gives a photon index of 1.89 (-0.08, +0.09), chi^2 = 72.4/ 59 dof.
In the 15-1500 keV band, the total burst fluence, estimated from the Band model,
is (2.8 �� 0.7)x10^-6 erg/cm^2, and the 2.944 s peak energy flux is (1.7 �� 0.4)x10^-7 erg/cm^2/s.
Assuming the redshift z=4.961 (Palmero et al., GCN 31480)
and a standard cosmology with H_0 = 67.3 km/s/Mpc, Omega_M = 0.315,
and Omega_Lambda = 0.685 (Planck Collaboration, 2014),
we estimate the isotropic energy release E_iso to (1.26 �� 0.31)x10^53 erg,
which is consistent with that estimated from the GBM detection (GCN 31487),
the isotropic peak luminosity L_iso to (4.5 �� 1.2)x10^52 erg/s,
and the rest-frame peak energy of the time-integrated spectrum Ep,z to 387(-84,+120) keV.
With the obtained estimates, GRB 220117A lies inside 68% prediction bands
for both 'Amati' and 'Yonetoku' relations for the sample of >300 long KW GRBs
with known redshifts (Tsvetkova et al., 2017; Tsvetkova et al., 2021),
see http://www.ioffe.ru/LEA/GRBs/GRB220117A/GRB220117A_rest_frame.pdf
GCN Circular 31488
Subject
GRB 220117A: MITSuME Akeno optical upper limits
Date
2022-01-18T17:30:21Z (4 years ago)
From
Naohiro Ito at Tokyo Tech <n.ito@hp.phys.titech.ac.jp>
N. Ito, R. Hosokawa, K. L. Murata, M. Niwano, Y. Imai, Y. Takamatsu,
R. Yamaguchi, R. Noto, S. Sato, M. Takaku, Y. Yatsu, and N. Kawai
(Tokyo Tech) report on behalf of the MITSuME collaboration:
We observed the field of GRB 220117A (A. Melandri et al. GCN Circular
#31466, S.Y. Fu et al. GCN Circular #31467, V. Lipunov et al. GCN
Circular #31470, A.P. Beardmore et al. GCN Circular #31472, J.A.
Kennea et al. GCN Circular #31477, J. Palmerio et al. GCN Circular
#31480, R. Strausbaugh et al. GCN Circular #31481, A. A. Breeveld et
al. GCN Circular #31482, D. M. Palmer et al. GCN Circular #31485, P.
Veres et al. GCN Circular #31487) 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 started at
2022-01-18 10:26:37 UT (18.1 hours after Swift trigger). We stacked
the images with good conditions. We did not detect any sources within
the XRT error region (A.P. Beardmore et al. GCN Circular #31472). We
obtained the 5-sigma limits of the stacked images as follows.
T0+[hours] MID-UT T-EXP[sec] 5-sigma limits
------------------------------------------------------------------------------------------------
21.3 2022-01-18 13:34:36 7740 g'>19.0, Rc>19.5, Ic>19.2
------------------------------------------------------------------------------------------------
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).
GCN Circular 31487
Subject
Fermi GBM Sub-Threshold Detection of GRB 220117A
Date
2022-01-18T16:53:23Z (4 years ago)
From
Peter Veres at UAH <veresp@gmail.com>
P. Veres (UAH)
reports on behalf of the Fermi-GBM Team:
���Swift-BAT detected GRB 220117A at T0=2022-01-17T16:18:51.5 UT
(Melandri et al, GCN 31466). There was no Fermi-GBM onboard trigger
around the event.
The GBM targeted search [1], the most sensitive, coherent search for
GRB-like signals was run from +/-30 s around the BAT trigger time. A
transient source was identified whose most significant timescale according
to the search is 4.096 s with a false alarm rate of 1.9e-5 Hz, and a
location consistent with the Swift-BAT event, using the standard search
protocol with a S/N of 11.4. The GBM targeted search event was found with
the highest significance with a ���soft��� spectral template (Band
function with Epeak = 70 keV, alpha = -1.9, beta = -3.7).
The GBM light curve consists of multiple overlapping pulses. The
time-averaged spectrum from T0 + 11.7 s to T0 + 69.0 s is best fit by
a power law function with an exponential high-energy cutoff. The
power law index is -1.39 +/- 0.20 and the cutoff energy, parameterized
as Epeak, is 40.0 +/- 4.8 keV.
The event fluence (10-1000 keV) in this time interval for the best fitting
model is (2.40 +/- 0.17)E-6 erg/cm^2. Using the redshift z=4.961 reported
by Palmerio et al. (GCN 31480), we derive an isotropic equivalent energy in
the 1-10,000 keV range of (1.56 +/- 0.11)E+53 erg.
This analysis is preliminary.
[1] Goldstein et al. 2019 arXiv:1903.12597
���
GCN Circular 31485
Subject
GRB 220117A: Swift-BAT refined analysis
Date
2022-01-18T15:35:31Z (4 years ago)
From
Amy Lien at GSFC <amy.y.lien@nasa.gov>
D. M. Palmer (LANL), S. D. Barthelmy (GSFC),
H. A. Krimm (NSF), S. Laha (GSFC/UMBC),
A. Y. Lien (U Tampa), C. B. Markwardt (GSFC),
A. Melandri (INAF-OAB), T. Parsotan (GSFC/UMBC),
T. Sakamoto (AGU), M. Stamatikos (OSU)
(i.e. the Swift-BAT team):
Using the data set from T-239 to T+939 sec from the recent telemetry
downlink, we report further analysis of BAT GRB 220117A (trigger #1093592)
(Melandri et al., GCN Circ. 31466). The BAT ground-calculated position is
RA, Dec = 91.590, -28.402 deg which is
RA(J2000) = 06h 06m 21.5s
Dec(J2000) = -28d 24' 08.5"
with an uncertainty of 1.7 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 26%.
The mask-weighted light curve shows a multi-peaked structure that
starts at ~T+15 s and ends at ~T+65 s. The two larger peaks occur
at ~T+15 s and ~T+44 s, respectively. T90 (15-350 keV) is
49.81 +- 2.37 sec (estimated error including systematics).
The time-averaged spectrum from T+14.79 to T+66.14 sec is best fit
by a simple power-law model. The power law index of the time-averaged
spectrum is 1.84 +- 0.18. The fluence in the 15-150 keV band
is 1.6 +- 0.2 x 10^-6 erg/cm2. The 1-sec peak photon flux measured
from T+14.81 sec in the 15-150 keV band is 1.9 +- 0.4 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/1093592/BA/
GCN Circular 31482
Subject
GRB 220117A: Swift/UVOT Upper Limits
Date
2022-01-18T14:13:23Z (4 years ago)
From
Alice Breeveld at MSSL-UCL <a.breeveld@ucl.ac.uk>
A. A. Breeveld (UCL-MSSL) and A. Melandri (INAF-OAB) report on behalf of the Swift/UVOT team:
The Swift/UVOT began settled observations of the field of GRB 220117A 162 s after the BAT trigger
(Melandri et al., GCN Circ. 31466).
No optical afterglow consistent with the XRT position (Beardmore et al. GCN Circ. 31472) 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 162 311 147 >20.5
u_FC 320 570 246 >20.0
white 162 998 306 >20.7
v 650 845 39 >18.4
b 576 770 39 >19.4
u 320 744 265 >20.0
w1 700 720 19 >19.3
m2 675 869 39 >18.7
w2 626 821 39 >18.9
The magnitudes in the table are not corrected for the Galactic extinction due to the reddening of
E(B-V) = 0.028 in the direction of the burst (Schlegel et al. 1998).
GCN Circular 31481
Subject
GRB 220117A: LCO Optical Observations
Date
2022-01-18T13:39:22Z (4 years ago)
From
Robert Strausbaugh at U. of the Virgin Islands <robert.strausbaugh@uvi.edu>
R. Strausbaugh (U. of the Virgin Islands), A. Cucchiara (College of Marin) report on behalf of a larger collaboration:
We observed Swift GRB 220117A (Melandri et al., GCN 31466) with the LCO 1-m Sinistro instrument at the Cerro Tololo Interamerican Observatory, Chile site, on January 18, from 01:16 to 01:33 UT (corresponding to 6.97 to 7.25 hours from the GRB trigger time) with the Bessel R and I filters.
We performed a series of 3x320s exposures in I band and 1x152s in R band (the planned observations in R were interrupted). We detect the source at the XRT enhanced coordinates (Beardmore et al., GCN 31472) and VLT observations (Palmerio et al., GCN 31480) in I band, but not R band. The following magnitudes and upper limits are calculated using the USNO-B.1 catalog as reference:
R>19.14
I=20.64+/-0.30
These magnitudes are not corrected for galactic extinction.
R.S. is funded by NSF AST grant #1831682
GCN Circular 31480
Subject
GRB 220117A: VLT/X-shooter optical afterglow and redshift
Date
2022-01-18T12:25:23Z (4 years ago)
From
Daniele B Malesani at Radboud U <d.malesani@astro.ru.nl>
J. Palmerio (CNRS, GEPI - Paris Observatory), D. B. Malesani (Radboud
Univ. and DAWN/NBI), J. P. U. Fynbo (DAWN/NBI), D. Xu (NAOC), L. Izzo
(DARK/NBI), S. Y. Fu (NAOC), Z. P. Zhu (NAOC, HUST), D. A. Kann
(IAA/CSIC), N. R. Tanvir (Univ. Leicester) report on behalf of the
Stargate collaboration:
We observed the field of GRB 220117A (Melandri et al., GCN 31466) using
the ESO VLT UT3 (Melipal) equipped with the X-shooter spectrograph. Our
first observations were carried out using the acquisition camera, using
the g, r and z filters (3x60 s in each band). Inside the XRT error
circle (Beardmore et al., GCN 31472), we detect a new source, not
visible in the archival Pan-STARRS images, which we identify as the GRB
afterglow. The source is very red, being detected strongly in z, only
weakly in r, and completely missing in g. Calibrated against nearby
stars from the Pan-STARRS catalog, we measure z = 20.81 +- 0.12 mag and
z - r ~ 2.1 mag (all AB magnitudes). The afterglow coordinates are
(J2000, 0.2" error):
RA = 06:06:17.409
Dec = -28:26:15.78
A spectrum was secured covering the wavelength range 3000-21000 AA, and
consisting of 4 exposures of 1200 s each. The observation mid time was
2022 Jan 18.15 UT (11.3 hr after the GRB).
In a preliminary reduction, continuum is detected in the red part of the
spectrum down to ~7260 AA. We interpret the break as due to Lyman alpha.
The absorption system is rather weak and, at the present time, we
identify with confidence only the Lyman-alpha trough and the Si II 1260
AA feature, which correspond to a redshift z = 4.961 for GRB 220117A.
We acknowledge excellent support from the ESO observing staff in
Paranal, in particular Michael Abdul-Masih, Diego Parraguez, and
Jonathan Smoker.
GCN Circular 31477
Subject
GRB 220117A: Swift-XRT refined Analysis
Date
2022-01-18T09:06:04Z (4 years ago)
From
Phil Evans at U of Leicester <pae9@leicester.ac.uk>
J.A. Kennea (PSU), P.A. Evans (U. Leicester), J.P. Osborne (U.
Leicester), K.L. Page (U. Leicester), P. D'Avanzo (INAF-OAB), M.G.
Bernardini (INAF-OAB), E. Ambrosi (INAF-IASFPA) , A. Tohuvavohu (U.
Toronto), B. Sbarufatti (PSU) and A. Melandri report on behalf of the
Swift-XRT team:
We have analysed 7.4 ks of XRT data for GRB 220117A (Melandri et al.
GCN Circ. 31466), from 142 s to 51.2 ks after the BAT trigger. The
data comprise 98 s in Windowed Timing (WT) mode (the first 8 s were
taken while Swift was slewing) with the remainder in Photon Counting
(PC) mode. The enhanced XRT position for this burst was given by
Beardmore et al. (GCN Circ. 31472).
The late-time light curve (from T0+4.3 ks) can be modelled with a
power-law decay with a decay index of alpha=1.48 (+0.11, -0.10).
A spectrum formed from the WT mode data can be fitted with an absorbed
power-law with a photon spectral index of 2.69 (+/-0.10). The
best-fitting absorption column is 1.95 (+0.24, -0.23) x 10^21 cm^-2,
in excess of the Galactic value of 2.6 x 10^20 cm^-2 (Willingale et al.
2013). The PC mode spectrum has a photon index of 1.80 (+/-0.11) and a
best-fitting absorption column of 4.5 (+2.6, -1.9) x 10^20 cm^-2. The
counts to observed (unabsorbed) 0.3-10 keV flux conversion factor
deduced from this spectrum is 3.5 x 10^-11 (3.8 x 10^-11) erg cm^-2
count^-1.
A summary of the PC-mode spectrum is thus:
Total column: 4.5 (+2.6, -1.9) x 10^20 cm^-2
Galactic foreground: 2.6 x 10^20 cm^-2
Excess significance: <1.6 sigma
Photon index: 1.80 (+/-0.11)
If the light curve continues to decay with a power-law decay index of
1.48, the count rate at T+24 hours will be 6.5 x 10^-3 count s^-1,
corresponding to an observed (unabsorbed) 0.3-10 keV flux of 2.3 x
10^-13 (2.5 x 10^-13) erg cm^-2 s^-1.
The results of the XRT-team automatic analysis are available at
http://www.swift.ac.uk/xrt_products/01093592.
This circular is an official product of the Swift-XRT team.
GCN Circular 31472
Subject
GRB 220117A: Enhanced Swift-XRT position
Date
2022-01-17T23:36:13Z (4 years ago)
From
Phil Evans at U of Leicester <pae9@leicester.ac.uk>
A.P. Beardmore, P.A. Evans, M.R. Goad and J.P. Osborne (U. Leicester)
report on behalf of the Swift-XRT team.
Using 428 s of XRT Photon Counting mode data and 1 UVOT
images for GRB 220117A, 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 = 91.57218, -28.43765 which is equivalent
to:
RA (J2000): 06h 06m 17.32s
Dec (J2000): -28d 26' 15.5"
with an uncertainty of 2.3 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 31470
Subject
Swift GRB 220117A: Global MASTER-Net observations report
Date
2022-01-17T20:50:22Z (4 years ago)
From
Vladimir Lipunov at Moscow State U/Krylov Obs <lipunov@xray.sai.msu.ru>
V. Lipunov, V.Kornilov, E.Gorbovskoy, K.Zhirkov, N.Tyurina, P.Balanutsa, A.Kuznetsov,
D. Vlasenko, G.Antipov, D.Zimnukhov, V.Senik, T.Pogrosheva, E.Minkina,
A.Chasovnikov, V.Topolev, V.Grinshpun, 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
(Irkutsk State University, API),
B.L.Carrasco, J.R.Valdes,V.Chavushyan, C.J.Martinez, V.M.Patino Alvarez,
M.L.H.Rodriguez (INAOE, OAGH)
A. Tlatov, D. Dormidontov
(Kislovodsk Solar Station of the Pulkovo Observatory),
A. Gabovich, V.Yurkov
(Blagoveschensk Educational State University)
MASTER-SAAO robotic telescope (Global MASTER-Net: http://observ.pereplet.ru, Lipunov et al., 2010, Advances in Astronomy, vol. 2010, 30L) located in South Africa (South African Astronomical Observatory) was pointed to the Swift GRB 220117A ( A. Melandri et al., GCN 31466) errorbox 15547 sec after notice time and 15645 sec after trigger time at 2022-01-17 20:39:37 UT, with upper limit up to 17.5 mag. The observations began at zenith distance = 5 deg. The sun altitude is -28.9 deg.
The galactic latitude b = -21 deg., longitude l = 235 deg.
Real time updated cover map and OT discovered available here:
https://master.sai.msu.ru/site/master2/observ.php?id=1852619
We obtain a following upper limits.
Tmid-T0 | Site |Filt.| Expt. | Limit| Comment
_________|_____________________|_____|_______|______|________
15736 | MASTER-SAAO | C | 180 | 17.5 |
Filter C is a clear (unfiltred) band.
The observation and reduction will continue.
The message may be cited.
GCN Circular 31467
Subject
GRB 220117A: Nanshan/NEXT optical observations and a nearby PanSTARRS source
Date
2022-01-17T18:51:10Z (4 years ago)
From
Dong Xu at NAOC/CAS <dxu@nao.cas.cn>
S.Y. Fu (NAOC), Z.P. Zhu (NAOC,HUST), X. Liu, S.Q. Jiang, D. Xu (NAOC),
X. Gao (Urumqi No.1 Senior High School), J.Z. Liu (XAO) report:
We observed the field of GRB 220117A detected by Swift (Melandri et al.,
GCN 31466) using the NEXT-0.6m telescope located at Nanshan, Xinjiang,
China. Observations automatically started at 16:21:57 UT on 2022-01-17
(i.e., 186 s after the BAT trigger), and a series of 40 s, 60 s, 90 s,
200 s frames were obtained in the Sloan r- and z- filters.
No uncatalogued optical transient is detected in our stacked images at
the Swift-XRT position (GCN 31466), down to limiting magnitudes of
r~19.6 and z~18.7, calibrated with the nearby PanSTARRS field.
Nevertheless, we note that from PanSTARRS there exists a source at the
border of the Swift-XRT error circle at coordinates R.A. (J2000) =
6:06:17.32 and Dec. (J2000) = -28:26:13.07, which has magnitudes of g
~21.51, r~21.05, i~20.99, and z~21.02, rasing the possibility as the
host galaxy of the GRB. This sky area is not covered by SDSS and Legacy
Survey. SkyMapper covered the sky area with upper limits of r~19.0 and
z~19.0, comparable to the NEXT's level. It is thus unclear if the
PanSTARRS source is related to the GRB or not.
GCN Circular 31466
Subject
GRB 220117A: Swift detection of a burst
Date
2022-01-17T16:31:16Z (4 years ago)
From
Kim Page at U.of Leicester <kimlpage1978@gmail.com>
A. Melandri (INAF-OAB), M. G. Bernardini (INAF-OAB),
P. D'Avanzo (INAF-OAB), S. Laha (GSFC/UMBC), A. Y. Lien (U Tampa),
K. L. Page (U Leicester), D. M. Palmer (LANL),
T. M. Parsotan (GSFC/UMBC/CRESSTII), T. Sbarrato (INAF-OAB) and
M. H. Siegel (PSU) report on behalf of the Neil Gehrels Swift
Observatory Team:
At 16:18:51 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 220117A (trigger=1093592). Swift slewed immediately to the burst.
The BAT on-board calculated location is
RA, Dec 91.578, -28.410 which is
RA(J2000) = 06h 06m 19s
Dec(J2000) = -28d 24' 35"
with an uncertainty of 3 arcmin (radius, 90% containment, including
systematic uncertainty). The BAT light curve showed a multi-peaked
structure with a duration of about 65 sec. The peak count rate
was ~900 counts/sec (15-350 keV), at ~15 sec after the trigger.
The XRT began observing the field at 16:21:23.4 UT, 151.9 seconds after
the BAT trigger. Using promptly downlinked data we find a bright,
uncatalogued X-ray source located at RA, Dec 91.57277, -28.43760 which
is equivalent to:
RA(J2000) = 06h 06m 17.46s
Dec(J2000) = -28d 26' 15.4"
with an uncertainty of 3.7 arcseconds (radius, 90% containment). This
location is 100 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 2.57
x 10^20 cm^-2 (Willingale et al. 2013).
The initial flux in the 2.5 s image was 6.01e-10 erg cm^-2 s^-1 (0.2-10
keV).
UVOT took a finding chart exposure of 150 seconds with the White filter
starting 161 seconds after the BAT trigger. No credible afterglow candidate has
been found in the initial data products. The 2.7'x2.7' sub-image covers 100% of
the XRT error circle. The typical 3-sigma upper limit has been about 19.6 mag.
The 8'x8' region for the list of sources generated on-board covers 100% of the
XRT error circle. The list of sources is typically complete to about 18 mag. No
correction has been made for the expected extinction corresponding to E(B-V) of
0.029.
Burst Advocate for this burst is A. Melandri (andrea.melandri AT brera.inaf.it).
Please contact the BA by email if you require additional information
regarding Swift followup of this burst. In extremely urgent cases, after
trying the Burst Advocate, you can contact the Swift PI by phone (see
Swift TOO web site for information: http://www.swift.psu.edu/)