GRB 201221D
GCN Circular 29311
Subject
GRB 201221D: near-infrared observation with LBT
Date
2021-01-17T15:18:45Z (5 years ago)
From
Andrea Rossi at INAF <andrea.rossi@inaf.it>
A. Rossi (INAF-OAS) reports on behalf of the CIBO collaboration:
We observed the location of the optical afterglow (Malesani et al., GCN
29117) of the short GRB 201221D (Page et al., GCN 29112) simultaneously
in the J and Ks bands with the LUCI near-infrared imager and
spectrograph mounted on the Large Binocular Telescope (LBT, Mt Graham,
AZ, USA). Observations were obtained on 2020-12-24 at the UT midtime
11:40:00, i.e. ~2.5 days after the burst trigger, for a total of 20 min
of exposure in each band.
Inspection of the combined J and K-band images reveals a faint, extended
source in both filters, for which we preliminary measure J=21.7+-0.3
(Vega system), calibrated against 2MASS field stars.
We acknowledge the excellent support from the LBTO and LBT-INAF staff,
particularly A. Cardwell, F. Cusano, and D. Paris, in obtaining these
observations.
GCN Circular 29148
Subject
GRB 201221D: 3.6m DOT optical observations
Date
2020-12-23T12:27:46Z (5 years ago)
From
Rahul Gupta at ARIES, India <rahulbhu.c157@gmail.com>
Dimple (ARIES), A. Panchal (ARIES), A. Gangopadhyay (ARIES), A. Ghosh
(ARIES), R. Gupta (ARIES), A. Kumar (ARIES), K. Misra (ARIES), and S. B.
Pandey (ARIES) report:
We carried out the follow-up observations of GRB 201221D (Page et al., GCN
29112) with Aries Devasthal Faint Object Spectrograph and Camera (ADFOSC)
mounted on the 3.6m Devasthal Optical Telescope (DOT) at Devasthal
observatory of Aryabhatta Research Institute of observational sciencES
(ARIES), India. The observations were started on 2020-12-22 at 23:10:00 UT.
We observed a series of 4 images with the exposure time of 900 seconds each
in r-band. At the position reported by Malesani et al., (GCN 29117), we
detect an uncatalogued source in r-band with a magnitude of 23.46 +- 0.09
(AB mag), calibrated with the nearby PanSTARRS field. However, we remark
that this is an extended source and may contain significant host galaxy
contribution. For further verification, host galaxy subtraction is highly
encouraged.
The magnitude is not corrected for the Galactic extinction in the direction
of the burst.
This circular may be cited.
GCN Circular 29144
Subject
GRB 201221D: SMA submm observation
Date
2020-12-23T02:49:57Z (5 years ago)
From
Yuji Urata at Nat. Central U. <urata@astro.ncu.edu.tw>
Huang, K. (CYCU), Urata, Y. (NCU) and Petitpas, G (SAO). report:
We observed the field of the GRB201221D (Page et al., GCN #29112) at
228 GHz using the Submillimeter Array (SMA). The observation was
started at 2020 December 11:27 UT (12.3 h after the burst). There was
no source at the candidate of optical afterglow (Malesani et al., GCN
#29117; Dichiara et al., GCN #29128; de Ugarte Postigo et al., GCN
#29132; Kilpatrick et al., GCN #29133; Rastinejad et al. GCN #29142).
The preliminary limit of the observation is ~0.2 mJy (rms).
We thank Ramprasad Rao, Mark Gurwell and staff of SMA for the
scheduling and execution of observations.
GCN Circular 29142
Subject
GRB 201221D: MMT MMIRS detection of marginally extended source
Date
2020-12-22T22:39:03Z (5 years ago)
From
Jillian Rastinejad at Northwestern Univ. <jillianrastinejad2024@u.northwestern.edu>
J. Rastinejad, K. Paterson, C. D. Kilpatrick, W. Fong (Northwestern) report:
We observed the location of the Swift GRB 201221D (Page et al., GCN 29112) with the MMT and Magellan Infrared Spectrograph (MMIRS) mounted on the MMT 6.5-meter telescope on Mount Hopkins, Arizona. We obtained 25x60-sec imaging in J-band at a mid-time of 2020 December 22.36 UT (0.40 days post-burst). Within the vicinity of the XRT position (Evans et al., GCN 29113; Evans et al., GCN 29119), we detect a marginally extended source, consistent with the location of emission detected in previously reported optical follow up and archival imaging (Malesani et al., GCN 29117; Dichiara et al., GCN 29128; de Ugarte Postigo et al., GCN 29132; Kilpatrick et al., GCN 29133).
After calibrating our stacked image to isolated stars detected in the 2MASS photometric catalog (Cutri et al., 2003, NASA/IPAC), we applied a 3 arcsecond aperture and measure a magnitude of J = 21.8 +/- 0.2 mag (AB and not corrected for Milky Way extinction).
Further observations are planned to assess any variability of the source. We thank Ryan Howie and Joannah Hinz at the MMT for the rapid scheduling and execution of these observations.
GCN Circular 29141
Subject
GRB 201221D: LCOGT upper limits
Date
2020-12-22T19:18:16Z (5 years ago)
From
Igor Andreoni at Caltech <igor.andreoni@gmail.com>
Igor Andreoni (Caltech), Michael M. Coughlin (UMN)
on behalf of the Global Relay of Observatories Watching Transients Happen
(GROWTH) collaboration
We used the Sinistro camera on the 1-m LCO Global Telescope Network (LCOGT,
Brown et al., 2013) to observe the afterglow of short-duration GRB 201221D
(Page et al., GCN #29112).
Two sets of 300s exposures were acquired in g-r-i bands between
2020-12-22T07:57 and 2020-12-22T08:47 UTC. The observations were performed
under proposal IDs TOM2020A-008 (PI Andreoni) and NOAO2020B-005 (PI
Coughlin).
We do not identify any source within 3.9 arcsec of the enhanced Swift-XRT
position (Evans et al., GCN #29119). Photometric upper limits, calibrated
against Pan-STARRS DR1 magnitudes (Chambers et al., 2016), were measured to
be g > 22.8, r > 22.2, and i > 21.5 mag (5-sigma) after image stacking.
The candidate optical counterpart (transient or host galaxy: Malesani et
al., GCN #29117; Dichiara et al., GCN #29128; de Ugarte Postigo et al., GCN
#29132; Kilpatrick et al., GCN #29133) is too faint to be detectable in our
observations, which did not show any significant brightening, as expected.
We thank the TOM Community Development Program and the TOM Toolkit Workshop
organizers for the generous LCOGT time allocation. GROWTH is a worldwide
collaboration comprising Caltech, USA; IPAC, USA, WIS, Israel; OKC, Sweden;
JSI/UMd, USA; U Washington, USA; DESY, Germany; MOST, Taiwan; UW Milwaukee,
USA; LANL USA; Tokyo Tech, Japan; IIT-B, India; IIA, India; LJMU, TTU,
USyd, Australia, and SDSU, USA. GROWTH acknowledges generous support of the
NSF under PIRE Grant No 1545949.
GCN Circular 29140
Subject
GRB 201221D: Fermi GBM detection
Date
2020-12-22T18:52:47Z (5 years ago)
From
Rachel Hamburg at UAH <rkh0007@uah.edu>
R. Hamburg (UAH), C. Malacaria (NASA-MSFC/USRA), and C. Meegan (UAH)
report on behalf of the Fermi GBM Team:
"At 23:06:34.33 UT on 21 December 2020, the Fermi Gamma-Ray Burst Monitor
(GBM)
triggered and located GRB 201221D (trigger 630284799 / 201221963)
which was also detected by the Swift/BAT and Swift/XRT
(Page et al. 2020, GCN 29112) and Konus-Wind (Frederiks et al. 2020,
GCN 29130). This trigger was initially classified as a particle event by
the flight software, but is in fact a GRB. The GBM on-ground location is
consistent with the Swift position.
The angle from the Fermi LAT boresight at the GBM trigger time is 89
degrees.
The GBM light curve shows a single-peaked structure
with a duration (T90) of about 0.14 s (50-300 keV).
The time-averaged spectrum from T0-0.064 s to T0+0.192 s is
best fit by a power law function with an exponential
high-energy cutoff. The power law index is -0.20 +/- 0.16 and
the cutoff energy, parameterized as Epeak, is 108 +/- 5 keV.
A Band function fits the spectrum equally well with
Epeak = 98 +/- 8 keV, alpha = 0.01 +/- 0.24 and beta = -3.3 +/- 0.5.
The event fluence (10-1000 keV) in this time interval is
(1.076 +/- 0.046)E-06 erg/cm^2. The 64-ms peak photon flux measured
starting from T0+0.00 s in the 10-1000 keV band is 41 +/- 2 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 29139
Subject
GRB 201221D: Swift-BAT refined analysis
Date
2020-12-22T17:44:15Z (5 years ago)
From
Amy Lien at GSFC <amy.y.lien@nasa.gov>
H. A. Krimm (NSF), S. D. Barthelmy (GSFC),
S. Laha (GSFC/UMBC), A. Y. Lien (GSFC/UMBC),
C. B. Markwardt (GSFC), K. L. Page (U Leicester),
D. M. Palmer (LANL), T. Sakamoto (AGU),
M. Stamatikos (OSU), T. N. Ukwatta (LANL)
(i.e. the Swift-BAT team):
Using the data set from T-239 to T+963 sec from the recent telemetry
downlink, we report further analysis of BAT GRB 201221D (trigger #1014037)
(Page et al., GCN Circ. 29112). The BAT ground-calculated position is
RA, Dec = 171.055, 42.152 deg which is
RA(J2000) = 11h 24m 13.2s
Dec(J2000) = +42d 09' 08.4"
with an uncertainty of 1.3 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 23%.
The mask-weighted light curve shows a single-peaked structure that
starts at ~T-0.06 s, peaks at ~T+0.02 s, and ends at ~T+0.2 s.
T90 (15-350 keV) is 0.16 +- 0.04 sec (estimated error including
systematics).
The time-averaged spectrum from T-0.06 to T+0.17 sec is best fit by
a simple power-law model. The power law index of the time-averaged
spectrum is 1.56 +- 0.13. The fluence in the 15-150 keV band is
3.9 +- 0.4 x 10^-7 erg/cm2. The 1-sec peak photon flux measured from
T-0.44 sec in the 15-150 keV band is 5.6 +- 0.5 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/1014037/BA/
GCN Circular 29133
Subject
GRB 201221D: Archival PS1 Imaging of the Putative Host Galaxy
Date
2020-12-22T15:34:10Z (5 years ago)
From
Charles Kilpatrick at UC Santa Cruz <cdkilpat@ucsc.edu>
C. D. Kilpatrick (Northwestern), D. B. Malesani (DTU Space), and W. Fong (Northwestern), report:
���We analyzed stacked images from the PS1 Data Release 1 image archive (Flewelling et al., 2016, arXiv:1612.05243) of the location of the short-duration GRB 201221D (Page et al., GCN 29112). We detected a single source centered at:
RA (J2000): 11:24:14.01
Dec (J2000): +42:08:39.69
in PS1 g-band, 4.6 arcseconds from the latest enhanced XRT position of GRB 201221D (Evans et al., GCN 29119). We note that this places the centroid of the candidate host galaxy just outside the enhanced XRT error circle reported by GCN 29119, which has a radius of 3.9 arcsec (90% confidence), although consistent with the real-time XRT error circle at https://www.swift.ac.uk/xrt_positions/01014037/ <https://www.swift.ac.uk/xrt_positions/01014037/>. Performing forced aperture photometry on this position with an aperture fixed to the FWHM size in all PS1 bands (approximately 1.1 arcseconds), we found that this source has a brightness:
g = 23.2 +/- 0.2 mag
r > 23.2 mag
i > 23.3 mag
z > 22.2 mag
y = 22.6+/-0.2 mag
All magnitudes are given in AB. We note that this source is coincident with emission identified in Malesani & Knudstrup (GCN 29117) who find a source with r = 23.1+/-0.3 mag (AB) in NOT follow up imaging. Similarly, Dichiara et al. (GCN 29128) find r=23.9 mag and i=23.7 mag (AB), all of which are consistent with our limiting magnitudes. Based on this photometry, it is fully plausible that the reported optical candidate (GCN 29117, GCN 29128) is dominated by the host galaxy. However, the detection of absorption features in the spectrum (de Ugarte Postigo et al., GCN 29132), coupled with the possible r-band fading between NOT and DCT observations (reported in GCN 29128) may indicate the presence of an optical afterglow on top of the host emission. Image subtraction will be required to test for fading, and further, deep optical observations are encouraged.
GCN Circular 29132
Subject
Short GRB201221D: High Redshift from OSIRIS/GTC
Date
2020-12-22T14:49:53Z (5 years ago)
From
Alexander Kann at IAA-CSIC <kann@iaa.es>
A. de Ugarte Postigo (HETH/IAA-CSIC, DARK/NBI), D. A. Kann
(HETH/IAA-CSIC), L. Izzo (DARK/NBI), C.C. Thoene, M. Blazek, J. F. Agui
Fernandez (all HETH/IAA-CSIC) and G. Lombardi (GRANTECAN, IAC) report:
We obtained spectroscopy of the optical counterpart (Malesani et al.,
GCN #29117) of the short GRB 201221D (Page et al., GCN #29112) with
OSIRIS at the 10.4m Gran Telescopio Canarias (Roque de los Muchachos
Observatory, La Palma, Spain), starting at 1:52 UT (2.757 hr after the
burst). The observation consisted of 4 x 1200 s exposures with the
R1000B grism, covering the range between 3700 and 7800 Angstrom.
The spectrum shows a weak continuum over the full spectral range. There
is a prominent emission feature that we identify as the [OII] 3727/3729
doublet at a redshift of 1.046. This line happens to lie in the
atmospheric A band, and therefore must be quite strong to be detectable.
There are also low significance absorption featuress coincident with
FeII and MgII at a similar redshift (z = 1.045). We identify this as the
redshift of GRB 201221D. We note this is a high redshift for a short
GRB, and it represents one of the few short GRB spectra to show
afterglow absorption features.
GCN Circular 29130
Subject
Konus-Wind detection of GRB 201221D (short)
Date
2020-12-22T13:33:30Z (5 years ago)
From
Dmitry Frederiks at Ioffe Institute <fred@mail.ioffe.ru>
D. Frederiks, S. Golenetskii, R.Aptekar, A.Lysenko,
A. Ridnaia, D. Svinkin, A. Tsvetkova, M. Ulanov, and T. Cline,
on behalf of the Konus-Wind team, report:
The short GRB 201221D (Swift detection: Page et al., GCN 29112)
triggered Konus-Wind (KW) at T0=83197.636 s UT (23:06:37.636).
The burst light curve shows a single pulse with the total duration of ~1.9 s (20-1500 keV).
The emission is seen up to ~1 MeV.
The Konus-Wind light curve of this GRB is available at
http://www.ioffe.ru/LEA/GRBs/GRB201221_T83197/
As observed by Konus-Wind, the burst had
a fluence of (5.3 �� 1.1)x10^-7 erg/cm^2 and
a 16-ms peak energy flux, measured from T0-0.016 s,
of (6.6 �� 1.3)x10^-6 erg/cm^2/s (both in the 20 keV - 10 MeV energy range).
The spectrum of the burst (measured from T0 to T0+0.128 s)
is best fit in the 20 keV - 1.5 MeV range
by a power law with exponential cutoff model:
dN/dE ~ (E^alpha)*exp(-E*(2+alpha)/Ep)
with alpha = -0.95(-0.52,+0.64)
and Ep = 148(-37,+86) keV (chi2 = 19/20 dof).
Fitting by a GRB (Band) model yields the same alpha and Ep,
and an upper limit on the high energy photon index: beta < -2.1
(chi2 =19/19 dof).
All the quoted errors are estimated at the 90% confidence level.
All the presented results are preliminary.
GCN Circular 29129
Subject
GRB 201221D: Swift/UVOT Upper Limits
Date
2020-12-22T13:27:07Z (5 years ago)
From
Alice Breeveld at MSSL-UCL <a.breeveld@ucl.ac.uk>
A. A. Breeveld (UCL-MSSL) and K. L. Page (U. Leicester) report on behalf of the Swift/UVOT team:
The Swift/UVOT began settled observations of the field of GRB 201221D 92 s after the BAT trigger
(Page et al., GCN Circ. 29112). No optical afterglow consistent with the NOT or XRT position
(Malesani et al. GCN Circ. 29117; Evans et al. GCN Circ. 29119) 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 92 242 147 >20.3
u_FC 305 554 246 >19.3
white 4047 4247 197 >21.0
v 634 4657 216 >19.2
u 305 5110 282 >19.4
w1 684 5068 216 >19.7
m2 4663 4863 197 >19.5
w2 4253 4453 197 >19.9
The magnitudes in the table are not corrected for the Galactic extinction due to the reddening of
E(B-V) = 0.02 in the direction of the burst (Schlegel et al. 1998).
GCN Circular 29128
Subject
GRB 201221D: Lowell Discovery Telescope afterglow observations
Date
2020-12-22T12:59:55Z (5 years ago)
From
Simone Dichiara at UMCP/NASA/GSFC <dichiara@umd.edu>
S.Dichiara (UMD, NASA-GSFC), E. Troja (UMD, NASA-GSFC), S.B. Cenko
(NASA-GSFC), B. O'Connor (GWU, UMD), P. Gatkine (Caltech), J.M. Durbak
(UMD), A. Kutyrev (UMD, NASA-GSFC), S. Veilleux (UMD), report on behalf
of a larger
collaboration:
We observed the short GRB 201221D (Page et al., GCN 29112) using the
Large Monolithic Imager (LMI) on the 4.3m Lowell Discovery Telescope
(LDT) at Happy Jack, AZ. Observations started on December 22, at 09:13:28
UT (about 10.11 hours after the Swift trigger)
with SDSS r, i and z filters. Observations were taken at an airmass of
about 1.3 and seeing of about 0.8".
At the position of the optical candidate counterpart (Malesani et al.,
GCN 29117) we detect a source in all bands with r~23.9 AB mag and i~23.7
AB mag. This is fainter than the value reported by Malesani et al.
(r~23.1 at 1 hr) and may suggest that the source faded between the two
epochs. However, we note that at the same position a weak source is
visible in archival Pan-STARRS images, which we suggest as the putative
GRB host galaxy.
Our observations could be dominated by the galaxy's contribution, and
further observations to determine variability are planned.
We thank the staff of the Lowell Discovery Telescope for assistance with
these observations.
GCN Circular 29125
Subject
GRB 201221D: FRAM-ORM optical limit
Date
2020-12-22T10:25:06Z (5 years ago)
From
Martin Jelinek at Astro.Inst-AVCR,Ondrejov <martin.jelinek@asu.cas.cz>
Martin Jelinek and Jan Strobl (ASU CAS Ondrejov, CZ),
Sergey Karpov, Martin Masek, Petr Janecek, Jakub Jurysek,
Jan Ebr, Ronan Cunniffe, Petr Travnicek and Michael Prouza
(Institute of Physics, Prague, CZ)
report:
The 25cm robotic telescope FRAM-ORM at La Palma (Spain) reacted robotically
to the Swift alert of GRB201221D (Page et al., GCNC 29112 and Evans et al.
GCNC 29113, GCNC 29119 and 29124), obtaining a series of 20s unfiltered
images starting at 23:07:11.9 UT, i.e. 37.6s post trigger.
We do not detect any new or strongly variable source neither in single
images (detection limit R>~16.9) nor in a combined 40x20s frame (mean exp
time 560s post trigger, with a limit R>~18.5). While we analysed the entire
25'x25' field of view centred at the XRT localization, we did pay a special
attention to the location of the candidate afterglow mentioned by Malesani
& Knudstrup (GCNC 29117) with a negative outcome.
GCN Circular 29124
Subject
GRB 201221D: Swift-XRT refined Analysis
Date
2020-12-22T09:36:27Z (5 years ago)
From
Phil Evans at U of Leicester <pae9@leicester.ac.uk>
P.A. Evans (U. Leicester), M. Capalbi (INAF-IASFPA), M. Perri (SSDC &
INAF-OAR), V. D'Elia (SSDC & INAF-OAR), J. D. Gropp (PSU), J.A. Kennea
(PSU), A. Tohuvavohu (U. Toronto), J.P. Osborne (U. Leicester) and K.L.
Page report on behalf of the Swift-XRT team:
We have analysed 6.7 ks of XRT data for GRB 201221D (Page et al. GCN
Circ. 29112), from 96 s to 23.5 ks after the BAT trigger. The data are
entirely in Photon Counting (PC) mode. The enhanced XRT position for
this burst was given by Evans et al. (GCN Circ. 29113). The source is
fading with alpha >0.4.
The results of the XRT-team automatic analysis are available at
http://www.swift.ac.uk/xrt_products/01014037.
This circular is an official product of the Swift-XRT team.
GCN Circular 29122
Subject
Swift GRB 201221D: Global MASTER-Net observations report
Date
2020-12-22T08:54:08Z (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-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) was pointed to the Swift GRB 201221D ( K. L. Page et al., GCN 29112) errorbox 33444 sec after notice time and 33517 sec after trigger time at 2020-12-22 08:25:12 UT, with upper limit up to 17.5 mag. Observations started at twilight. The observations began at zenith distance = 75 deg. The sun altitude is -12.3 deg.
The galactic latitude b = 67 deg., longitude l = 167 deg.
Real time updated cover map and OT discovered available here:
https://master.sai.msu.ru/site/master2/observ.php?id=1508187
We obtain a following upper limits.
Tmid-T0 | Site |Filt.| Expt. | Limit| Comment
_________|_____________________|_____|_______|______|________
33608 | MASTER-OAFA | C | 180 | 17.5 |
Filter C is a clear (unfiltred) band.
The observation and reduction will continue.
The message may be cited.
GCN Circular 29119
Subject
GRB 201221D: Enhanced Swift-XRT position
Date
2020-12-22T01:46:49Z (5 years ago)
From
Phil Evans at U of Leicester <pae9@leicester.ac.uk>
P.A. Evans, M.R. Goad, J.P. Osborne and A.P. Beardmore (U. Leicester)
report on behalf of the Swift-XRT team.
Using 651 s of XRT Photon Counting mode data and 1 UVOT
images for GRB 201221D, 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 = 171.05914, +42.14319 which is equivalent
to:
RA (J2000): 11h 24m 14.19s
Dec (J2000): +42d 08' 35.5"
with an uncertainty of 3.9 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 29118
Subject
GRB 201221D: Nanshan/NEXT early optical upper limit
Date
2020-12-22T01:38:32Z (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 201221D (Page et al., GCN 29112) using the
NEXT-0.6m optical telescope located at Nanshan, Xinjiang, China.
Observations automatically started at 23:07:39 UT on 2020-12-21, i.e.,
65 s after the BAT trigger. We obtained 3x40s, 4x60s and 12x90s frames
in the Sloan r-filter.
No optical source is detected in our stacked image at the XRT enhanced
position (Evans et al., GCN 29113), down to a upper limit of r~21.3,
calibrated with the nearby PanSTARRS field.
GCN Circular 29117
Subject
GRB 201221D: candidate optical counterpart from the NOT
Date
2020-12-22T01:34:37Z (5 years ago)
From
Daniele B Malesani at DTU Space <malesani@space.dtu.dk>
D. B. Malesani (DTU Space) and E. Knudstrup (NOT and Aarhus Univ.)
report on behalf of a larger collaboration:
We observed the field of GRB 201221D (Page et al., GCN 29112) using the
Nordic Optical Telescope (NOT) equipped with the ALFOSC imaging camera.
Observations were carried out using the SDSS r (3x300 s) and z (5x200 s)
filters. The data were taken as soon as the target rised, so at quite
high airmass (2.9 to 2.3), yielding a seeing of ~1.5".
Inside or close to the XRT werror circle (current uncertainty 4.2":
https://www.swift.ac.uk/xrt_positions/), a very faint object is detected
in the stack of the r-band images. Calibrating against nearby stars from
the Pan-STARRS catalog, we measure r = 23.1 +- 0.3 (AB), at a mean epoch
2020 Dec 22.032 UT (1.67 hr after the GRB). Its coordinates are:
RA = 11:24:14.02
Dec = +42:08:39.97
No object is visible at this location in the Pan-STARRS r-band image,
which has however a limiting magnitude (r ~ 23.3 AB) comparable to our
measurement. Given the lack of variability and the still relatively
large XRT error circle size, we cannot confirm at the present time
whether this object is associated with GRB 201221D. Further observations
are planned.
GCN Circular 29113
Subject
GRB 201221D: Prompt enhanced Swift-XRT position
Date
2020-12-21T23:32:42Z (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-XRT team:
Using promptly downlinked XRT event data for GRB 201221D, we find an
enhanced XRT position of the afterglow: RA, Dec: 171.0587, 42.1438
which is equivalent to:
RA (J2000) = 11 24 14.09
Dec (J2000) = +42 08 37.5
with an uncertainty of 4.2 arcseconds (radius, 90% confidence).
Analysis of the promptly available data is online at
http://www.swift.ac.uk/sper/1014037.
Position enhancement is is described by Goad et al. (2007, A&A, 476,
1401) and Evans et al. (2009, MNRAS, 397, 1177).
This circular is an official product of the Swift-XRT team.
GCN Circular 29112
Subject
GRB 201221D: Swift detection of a bright short burst
Date
2020-12-21T23:16:01Z (5 years ago)
From
David Palmer at LANL <palmer@lanl.gov>
K. L. Page (U Leicester), S. D. Barthelmy (GSFC), J.D. Gropp (PSU),
J. A. Kennea (PSU), N. J. Klingler (PSU), S. Laha (GSFC/UMBC/CRESST),
A. Y. Lien (GSFC/UMBC), F. E. Marshall (NASA/GSFC),
B. Sbarufatti (PSU), M. H. Siegel (PSU) and A. Tohuvavohu (U Toronto)
report on behalf of the Neil Gehrels Swift Observatory Team:
At 23:06:34 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 201221D (trigger=1014037). Swift slewed immediately to the burst.
The BAT on-board calculated location is
RA, Dec 171.049, +42.144 which is
RA(J2000) = 11h 24m 12s
Dec(J2000) = +42d 08' 39"
with an uncertainty of 3 arcmin (radius, 90% containment, including
systematic uncertainty). The BAT light curve showed a single-peaked
structure with a duration of about 0.3 sec. The peak count rate
was ~9000 counts/sec (15-350 keV), at ~0 sec after the trigger.
The XRT began observing the field at 23:08:01.7 UT, 87.4 seconds after
the BAT trigger. Using promptly downlinked data we find an uncatalogued
X-ray source located at RA, Dec 171.05873, 42.14332 which is equivalent
to:
RA(J2000) = 11h 24m 14.10s
Dec(J2000) = +42d 08' 36.0"
with an uncertainty of 5.7 arcseconds (radius, 90% containment). This
location is 26 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. No
spectrum from the promptly downlinked event data is yet available to
determine the column density.
UVOT took a finding chart exposure of 150 seconds with the White filter
starting 92 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
0.02.
Burst Advocate for this burst is K. L. Page (klp5 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/)