GRB 210321A
GCN Circular 29725
Subject
GRB 210321A: OSN Upper Limit
Date
2021-03-24T23:41:30Z (6 years ago)
From
Alexander Kann at IAA-CSIC <kann@iaa.es>
D. A. Kann (HETH/IAA-CSIC), A. de Ugarte Postigo (HETH/IAA-CSIC,
DARK/NBI), C. C. Thoene, M. Blazek, J. F. Agui Fernandez (all
HETH/IAA-CSIC), and F. Aceituno (IAA-CSIC) report:
We observed the optical afterglow (Perri et al. GCN #29678; Siegel et
al. GCN #29679; Butler et al. GCN #29680; Heintz et al. GCN #29684; Xin
et al., GCN #29687; Pankov et al., GCNs #29689, #29692; Laporte et al.,
GCN #29697) of GRB 210321A (Swift detection: Dichiara et al., GCN
#29677) with the 1.5m T150 telescope of the Observatorio de Sierra
Nevada (OSN), Granada, Spain. Observations could not be taken due to
high winds in the first night after the GRB. We obtained 11 x 180 s
exposures in Rc starting at 2021-03-22 19:59:44.93 UT, before high winds
shut the telescope down again. The afterglow is not detected in the
combined image.
We determine an upper limit Rc > 23.3 mag (AB mag, vs. a nearby
Pan-STARRS star converted to Rc following the Lupton transformations,
then transformed back to AB mag) at 1.5437 days after the GRB.
GCN Circular 29697
Subject
GRB 210321A: Swift/UVOT Detection
Date
2021-03-23T14:17:59Z (6 years ago)
From
Sam LaPorte at PSU <sjl5346@psu.edu>
GRB 210321A: Swift/UVOT Detection
S. J. Laporte (PSU) and S. Dichiara (NASA/GSFC/UMCP)
report on behalf of the Swift/UVOT team:
The Swift/UVOT began settled observations of the field of GRB 210321A
2735 s after the BAT trigger (Dichiara et al., GCN Circ. 29677).
A source consistent with the XRT position
(Beardmore et al. GCN Circ. 29681)
is detected in the initial UVOT exposures.
The preliminary UVOT position is:
RA (J2000) = 05:51:34.75 = 87.89479 (deg.)
Dec (J2000) = +70:07:49.8 = 70.13051 (deg.)
with an estimated uncertainty of 0.49 arc sec. (radius, 90% confidence).
Preliminary detections and 3-sigma upper limits using the UVOT photometric
system
(Breeveld et al. 2011, AIP Conf. Proc. 1358, 373) for the early exposures
are:
Filter T_start(s) T_stop(s) Exp(s) Mag
white 2735 2885 147 18.69 +/- 0.09
v 2892 4465 331 18.44 +/- 0.16
b 3713 3913 197 18.64 +/- 0.11
u 3507 3706 197 18.29 +/- 0.12
w1 3302 3502 197 18.48 +/- 0.17
m2 3097 3296 197 >18.9
w2 4124 4324 197 >19.8
The magnitudes in the table are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 0.118 in the direction of the burst
(Schlegel et al. 1998).
GCN Circular 29696
Subject
Konus-Wind detection of GRB 210321A
Date
2021-03-23T12:37:30Z (6 years ago)
From
Dmitry Frederiks at Ioffe Institute <fred@mail.ioffe.ru>
D. Frederiks, S. Golenetskii, A.Lysenko, D. Svinkin, A. Ridnaya,
A. Tsvetkova, M. Ulanov, and T. Cline, report:
The long GRB 210321A (Swift-BAT trigger #1037828, T0(BAT)= 07:13:51.023 UT:
Dichiara, et al., GCN 29677; Ukwatta, et al., GCN 29691)
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(BAT)-6.430 s to ~T0(BAT)+2.402 s.
A fit to the KW 3-cannel waiting mode spectrum with by a power law with
an exponential cutoff (CPL) yields alpha~-2 and doesn't constrain Ep.
A fit with a simple power law (PL) gives a photon index of (2.19 �� 0.17), chi^2 = 0.78/ 1 dof.
This result is consistent with the Swift-BAT refined analysis (GCN 29691).
In the 10 keV-10 MeV band, standard for the KW spectral analysis, the total burst fluence,
estimated from the PL model, is (1.6 �� 0.3)x10^-6 erg/cm^2,
and the 2.944 s peak energy flux is (2.2 �� 0.4)x10^-7 erg/cm^2.
Assuming the redshift z=1.487 (de Ugarte Postigo, et al., GCN 29685)
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 burst isotropic energy release E_iso to ~9.7x10^51 erg
and the isotropic luminosity L_iso to ~3.2x10^51 erg/s.
The KW light curve of this burst is available
at http://www.ioffe.ru/LEA/GRBs/GRB210321A/
GCN Circular 29694
Subject
GRB 210321A: DDOTI Position Correction
Date
2021-03-22T19:42:51Z (6 years ago)
From
Nat Butler at Az State U <natbutler@asu.edu>
The afterglow position quoted by Butler et al. (GCN 29680) was typed
incorrectly. The correct position is 05:51:34.82, +70:07:50.4 (J2000).
GCN Circular 29692
Subject
GRB 210321A: CrAO optical upper limit
Date
2021-03-22T19:02:33Z (6 years ago)
From
Alexei Pozanenko at IKI, Moscow <apozanen@iki.rssi.ru>
N. Pankov (HSE), S. Nazarov (CrAO), A. Pozanenko (IKI), S. Belkin (IKI)
report on behalf of GRB IKI FuN:
We observed the field of GRB 210321A (Dichiara et al., GCN 29677) with
AZT-8 telescope of CrAO observatory starting on 2021-03-21 (UT)
19:04:11. The optical afterglow (Siegel et al., GCN 29679; Butler et
al., GCN 29680; Lipunov et al., GCN 29683; Heintz et al., GCN 29684