GRB 210104A
GCN Circular 29440
Subject
GRB 210104A: LBT observations
Date
2021-02-09T15:09:31Z (5 years ago)
From
Andrea Melandri at INAF-OAB <andrea.melandri@inaf.it>
A. Melandri (INAF-OAB), and A Rossi (INAF-OAS) report on behalf of the CIBO collaboration:
We observed the field of GRB 210104A (Troja et al., GCN 29233; Malacaria et al., GCN 29246) simultaneously in the r' and z' bands with the LBC imager mounted on LBT (Mt Graham, AZ, USA). We obtained 20min of imaging on 2021-02-05, 31.8 days after the burst trigger. Observations were performed under poor seeing (~1.7") conditions but reached a depth of r~25.5 mag.
At the position of the afterglow (Xin et al., GCN 29235; Hu et al., GCN 29236; Kim et al., GCNs 29238, 29265, 29283; Lipunov et al., GCNs 29239, 29248; Horiuchi et al., GCN 29241; Breeveld et al., GCN 29247; Paek et al., GCN 29254; Smartt et al., GCN 29262; Anandagoda et al., GCN 29273; Mao et al., GCN 29275; Moskvitin & Vlasyuk, GCN 29277; Belikin et al., GCN 29286; Nakamura et al., GCN 29291; Kann et al., GCN 29318), we clearly detect the host galaxy in both filters (RA,DEC = 06:55:05.18,+64:40:33.7; J2000).
After removing the halo of a nearby star, we measure the following AB magnitudes:
r = 24.2 +/- 0.3
z = 22.1 +/- 0.2
calibrated against SDSS field stars.
We acknowledge the excellent support from the LBTO and LBT-INAF staff, particularly B. Rothberg, F. Cusano, and D. Paris, in obtaining these observations.
GCN Circular 29337
Subject
GRB 210104A: 3.6m DOT optical upper limit
Date
2021-01-20T11:44:16Z (5 years ago)
From
Dimple Panchal at ARIES, India <dimplepanchal96@gmail.com>
Dimple (ARIES), K. Misra (ARIES), A. Ghosh (ARIES), R. Gupta (ARIES), A.
Kumar (ARIES), S.B. Pandey (ARIES) report:
We observed the field of GRB 210104A (Troja et al. GCN #29233) with Aries
Devasthal Faint Object Spectrograph and Camera (ADFOSC) mounted on the 3.6m
Devasthal Optical Telescope (DOT). The observations started on 2021-01-13
at 19:52:50 UT (9.374 days after the burst). We obtained a set of
consecutive images with short exposure times to avoid saturation from the
nearby bright star. We do not detect any optical counterpart upto a
magnitude limit of 23.2 in the stacked image.
GCN Circular 29318
Subject
GRB 210104A: Late-time CAHA 2.2m detection
Date
2021-01-18T15:51:26Z (5 years ago)
From
Alexander Kann at IAA-CSIC <kann@iaa.es>
D. A. Kann (HETH/IAA-CSIC), A. Rossi (INAF-OAS), A. de Ugarte Postigo
(HETH/IAA-CSIC, DARK/NBI), C. C. Thoene (HETH), M. Blazek, J. F. Agui
Fernandez (both HETH/IAA-CSIC), and J. I. Vico Linares (CAHA) report:
We observed the afterglow position (Troja et al., GCN #29233) of the
bright Swift/Fermi GRB 210104A (Swift detection: Troja et al., GCN
#29233; GBM detection: Fermi GBM Team, GCN #29232; Biltzinger et al.,
GCN #29234; Konus-Wind detection: Frederiks et al., GCN #29258; CALET
detection: Cherry et al., GCN #29268; AstroSat CZTI detection: Nadella
et al., GCN #29299) with CAFOS at the 2.2m telescope at Calar Alto,
Almeria, Spain, in the Rc band. We obtained 6 x 600 s exposures,
centered at 11.4624 days after the GRB, under good conditions but
mediocre seeing.
After removing the halo of a nearby star, the afterglow (Xin et al., GCN
#29235; Hu et al., GCN #29236; Hosokawa et al., GCN #29237; Kim et al.,
GCNs #29238,29265,29283; Horiuchi et al., GCN #29241; Breeveld et al.,
GCN #29247; Lipunov et al., GCN #29248; Zhu et al., GCN #29252; Paek et
al., GCN #29254; Kumar et al., GCN #29257; Smartt et al., GCN #29262;
Anandagoda et al., GCN #29273; Gokuldass et al., GCN #29274; Mao et al.,
GCN #29275; Moskvitin et al., GCN #29277; Belkin et al., GCN #29286;
Nakamura et al., GCN #292291) is faintly but clearly detected.
Against three SDSS comparison stars (transformed to Rc band using the
Lupton 2005 equations, then transformed back to AB magnitude), we
measure Rc = 23.67 +/- 0.14 mag. This value is in agreement with the
extrapolation of the light curve decay reported by Belkin et al., GCN
#29286 (A. Pozanenko, priv. comm.). This implies there is no significant
evidence for a supernova rise, and therefore the redshift of GRB 210104A
is conservatively estimated to be z > 0.4 (e.g., SN 2012eb associated
with GRB 120714B at z ~ 0.4 peaks at r' ~ 22.2 mag 12 days after
trigger, Klose et al. 2019, A&A, 622, A138).
We thank Alexei Pozanenko for discussions.
GCN Circular 29304
Subject
GRB 210104A: JCMT SCUBA-2 sub-mm observations
Date
2021-01-15T21:55:33Z (5 years ago)
From
Ian Smith at Rice U <ian.smith.astronomy@gmail.com>
I.A. Smith (Rice U.), D.A. Perley (LJMU), and N.R. Tanvir
(U. of Leicester) report:
We observed the Swift UVOT location of GRB 210104A (Troja
et al., GCN Circ. 29233) using the SCUBA-2 sub-millimeter
continuum camera on the James Clerk Maxwell Telescope. The
observation started at 08:23 UT on 2021-01-05, with the
mid-point of the run at 0.894 days after the burst trigger.
Exposures totaling 1.0 hours were made in very good weather
conditions. No source was detected, with the RMS background
noise being 1.7 mJy/beam at 850 microns and 14.5 mJy/beam
at 450 microns.
We thank Kevin Silva, Mark Rawlings, and the JCMT staff for
the prompt support of these observations that were taken under
project M20BP026.
GCN Circular 29299
Subject
GRB 210104A: AstroSat CZTI detection
Date
2021-01-13T18:24:27Z (5 years ago)
From
Gaurav Waratkar at IIT Bombay <gauravwaratkar24@gmail.com>
D. Nadella (NITK), G. Waratkar (IITB), A. Vibhute (IUCAA), S. Gupta
(IUCAA), P. Sawant (IUCAA), V. Bhalerao (IITB), D. Bhattacharya (IUCAA), A.
R. Rao (IUCAA/TIFR), and S. Vadawale (PRL) report on behalf of the AstroSat
CZTI collaboration:
Analysis of AstroSat CZTI data with the CIFT framework (Sharma et al, 2020,
arxiv:2011.07067) showed detection of a bright long GRB 210104A, which was
also detected by Fermi-GBM (GCN #29232), Swift-BAT (GCN #29233), Konus-Wind
(GCN #29258) and CALET-CGBM (GCN #29268).
The source was clearly detected in the 20-200 keV energy range. The light
curve showed multiple peaks of emission with the strongest peak at
2021-01-04 11:27:17.5 UT. The measured peak count rate associated with the
burst is 867 (+60, -56) cts/s above the background in the combined data of
four quadrants, with a total of 7003 (+407, -394) cts. The local mean
background count rate was 555 (+2, -2) cts/s. Using cumulative rates, we
measure a T90 of 33 (+7, -1) s.
It was also clearly detected in the CsI anticoincidence (Veto) detector in
the 100-500 keV energy range. The light curve showed multiple peaks of
emission with the strongest peak at 2021-01-04 11:27:17 UT. The measured
peak count rate is 606 (+86, -55) cts/s above the background in the
combined Veto data of four quadrants, with a total of 4520 (+693, -789)
cts. The local mean background count rate was 2009 (+4, -5) cts/s. We
measure a T90 of 35 (+7, -14) s from the cumulative Veto light curve.
CZTI GRB detections are reported regularly on the payload site at
http://astrosat.iucaa.in/czti/?q=grb. CZTI is built by a TIFR-led
consortium of institutes across India, including VSSC, ISAC, IUCAA, SAC and
PRL. The Indian Space Research Organisation funded, managed and facilitated
the project.
GCN Circular 29291
Subject
GRB 210104A: AROMA-N Optical Afterglow Detection
Date
2021-01-12T06:36:42Z (5 years ago)
From
Takanori Sakamoto at AGU <tsakamoto@phys.aoyama.ac.jp>
M. Nakamura, K. Hasuda, T. Sakamoto (AGU)
We observed the field of GRB 210104A (Troja et al., GCN Circ. 29233;
Malacaria et al., GCN Circ. 29246; Frederiks et al., GCN Circ. 29258;
Cherry et al., GCN Circ. 29268) with the 14-inch AGU Robotic Optical
Monitor for Astrophysical object - Narrow (AROMA-N) located at
the Sagamihara campus of Aoyama Gakuin University.
60 images of 60 sec exposures were taken in the R filter starting
from January 4 11:29:50 (UT) about 171 seconds after the trigger and
stopped on January 4 12:45:20 (UT). We detected the optical afterglow
at the consistent position previously reported (Troja et al., GCN Circ. 29233;
Xin et al., GCN Circ. 29235; Hu et al., GCN Circ. 29236; Hosokawa et al.,
GCN Circ. 29237; Kim et al., GCN Circ. 29238, 29265; Lipunov et al.,
GCN Circ. 29239; Horiuchi et al., GCN Circ. 29241; Breeveld et al.,
GCN Circ. 29247; Zhu et al., GCN Circ. 29252; Paek et al., GCN Circ. 29254