GRB 210312B
GCN Circular 29650
Subject
GRB 210312B: A long GRB detected by INTEGRAL
Date
2021-03-12T22:02:02Z (4 years ago)
From
Sandro Mereghetti at IASF-Milano/INAF <sandro.mereghetti@inaf.it>
S.Mereghetti (INAF, IASF-Milano), D.Gotz (CEA, Saclay), C.Ferrigno,
E.Bozzo, V.Savchenko (ISDC, Versoix), L.Ducci (IAAT, Germany and ISDC,
Versoix) and J.Borkowski (CAMK, Torun) report:
a gamma ray burst lasting about 5 s has been detected by IBAS in the
IBIS/ISGRI data at 20:52:17 UT of March 12, 2021
The refined coordinates (J2000) are:
R.A.= 155.8431 deg
DEC.= +76.8714 deg
with an uncertainty of 2 arcmin (90% c.l.).
The burst had a peak flux of about 1.5 ph/cm2/s (20-200 keV, 1-s
integration time) and a fluence in the same energy range of about 2e-7
erg/cm2
A plot of the light curve will be posted at
http://ibas.iasf-milano.inaf.it/IBAS_Results.html
GCN Circular 29651
Subject
GRB210312B (Integral alert 9073): Candidate optical afterglow by Ondrejov D50
Date
2021-03-12T22:05:41Z (4 years ago)
From
Martin Jelinek at Astro.Inst-AVCR,Ondrejov <martin.jelinek@asu.cas.cz>
M. Jelinek, J. Strobl, S. Trcka, R. Hudec, C. Polasek (ASU CAS Ondrejov)
report:
We observed the position of the Integral trigger 9073 (GRB 210312.87 or B)
with the D50 robotic telescope of the Astronomical Institute Ondrejov, near
Prague, Czech Republic. We performed a series of 10s and 20s unfiltered
exposures starting 23.8 s after the trigger.
In the first images we detect a rapidly fading object not present in the
DSS catalogue at 10:23:15.312 +76:52:06.96 J2000. The preliminary
magnitude of the
object in the earliest images was R~18m.
GCN Circular 29652
Subject
GRB 210312B: MASTER OT confirmation
Date
2021-03-12T22:55:02Z (4 years ago)
From
Vladimir Lipunov at Moscow State U/Krylov Obs <lipunov@xray.sai.msu.ru>
V. Lipunov, V.Kornilov, E.Gorbovskoy,N.Tiurina,P.Balanutsa,F.Balakin, V.Vladimirov, A.Kuznetsov,K.Zhirkov,D. Vlasenko, I.Gorbunov, D.Zimnukhov,
V.Senik, A.Chasovnikov,A.Pozdnyakov,V.Topolev, D.Cheryasov(Lomonosov Moscow State University, SAI, Physics Department),
D. Buckley (South African Astronomical Observatory),
R. Podesta, C.Lopez, F. Podesta, C.Francile (Observatorio Astronomico FelixAguilar OAFA),
R. Rebolo, M. Serra(The Instituto de Astrofisica de Canarias),
O.A. Gres, N.M. Budnev (Irkutsk State University, API),
A. Tlatov, D. Dormidontov (Kislovodsk Solar Station of the Pulkovo Observatory),
A. Gabovich, V.Yurkov (Blagoveschensk Educational StateUniversity)
MASTER Global robotic net (MASTER-Net:http://observ.pereplet.ru Lipunov et al.,2010,Advances in Astronomy,2010,30L)
automatically started (Lipunov et al. GCN 29649)
Integral GRB 210312B (Mereghetti et al. GCN 29650,Ttrigger=20:52:17UT)
optical observations at MASTER-Kislovodsk at 2021-03-12 20:52:58 UT
27s after notice time(41s after trigger time),
and
at MASTER-Tunka at 2021-03-12 20:52:58UT with mli18.7 at first 10s images.
We confirm Jelinek et al. GCN 29651 (Ondrejov) optical counterpart with
unfiltered m_OT=18.2 at first image.
This message may be cited.
GCN Circular 29653
Subject
GRB 210312B: GTC photometry
Date
2021-03-13T00:51:28Z (4 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 R. Scarpa (GTC) report:
We observed the afterglow (Jelinek et al., GCN #29651; Lipunov et al.,
GCN #29652) of INTEGRAL GRB 210312B (Mereghetti et al., GCN #29650) with
OSIRIS at the 10.4m Gran Telescopio Canarias (Roque de los Muchachos
Observatory, La Palma, Canary Islands, Spain), starting at 2021-03-12
22:57:10.834 UT. We obtained a 60 s finding chart exposure under adverse
conditions (2" seeing, bad transparency because of Calima).
In the image, the afterglow is clearly detected. Against a nearby
PanSTARRS star, we measure r' = 21.52 +/- 0.06 mag at 2.0898 hr after
the trigger (0.08708 days).
GCN Circular 29655
Subject
GRB 210312B: Redshift from OSIRIS/GTC
Date
2021-03-13T13:13:31Z (4 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 R. Scarpa (GTC) report:
We observed the afterglow (Jelinek et al., GCN #29651; Lipunov et al.,
GCN #29652) of INTEGRAL GRB 210312B (Mereghetti et al., GCN #29650) with
OSIRIS at the 10.4m Gran Telescopio Canarias (Roque de los Muchachos
Observatory, La Palma, Canary Islands, Spain), starting at 2021-03-12
22:57:10.834 UT under adverse conditions (2" seeing, bad transparency
because of Calima). Following the finding chart exposure (Kann et al.,
GCN #29653), we obtained 2 x 900 s spectroscopic exposures with the
R1000B grism, covering the spectral range from 3700 to 7800 AA, before
the telescope was shut down due to worsening observing conditions. We
detect a faint trace in both images. We resumed observations after an
improvement in weather conditions at 2021-03-13 01:41:40.281 UT,
obtaining two further finding charts and 4 x 900 s spectra with the same
grism.
Using the same comparison star as Kann et al., GCN #29653, we find the
afterglow has faded to r' = 22.36 +/- 0.03 mag (AB) at 4.8316 hrs after
the GRB trigger.
Combining the first spectral exposure and the latter, for a total
exposure of 5 x 900 s, a trace is clearly detected redwards of 4300 AA,
as well as several absorption lines. We identify these as FeII, MgII,
and MgI, at a mean redshift of z = 1.069. At this redshift, we also
detect OII in emission, which allows us to identify this as the redshift
of the GRB.
GCN Circular 29716
Subject
GRB 210312B: OSN Afterglow Observations
Date
2021-03-24T19:45:39Z (4 years ago)
From
Alexander Kann at IAA-CSIC <kann@iaa.es>
D. A. Kann (HETH/IAA-CSIC), M. Jelinek (ASU CAS Ondrejov), A. de Ugarte
Postigo (HETH/IAA-CSIC, DARK/NBI), C. C. Thoene, M. Blazek, J. F. Agui
Fernandez (all HETH/IAA-CSIC), A. Sota, and R. M. Eloy (both IAA-CSIC)
report:
We observed the optical afterglow of GRB 210312B (INTEGRAL detection:
Mereghetti et al., GCN #29650) with both the 1.5m T150 and the 0.9m T90
telescopes of the Observatorio de Sierra Nevada (OSN),
Granada, Spain. We obtained 5 x 90 s exposures in B, V, Rc, and 6 x 90 s
in Ic, followed by 21 x 180 s exposures in Rc with the T150 telescope,
and 18 x 180 s in Rc with the T90 telescope in parallel, starting at
2021-03-12 22:51:28.19 UT. The afterglow is detected in multiple
combined images from T150, and in the complete combined T90 image. We
furthermore obtained 10 x 500 s Rc images in the second night with the
T150. The afterglow is detected in the combined image.
From three stacked images observed from 0.09577 to 0.14106 days after
the GRB, we detect a potential plateau phase, measuring Rc ~ 21.69 mag
(AB mag, vs. a nearby Pan-STARRS star converted to Rc following the
Lupton transformations, then transformed back to AB mag; errors range
from 0.04 to 0.11 mag). Then at 1.0850 days, we find the afterglow has
significantly decayed to Rc = 23.04 +/- 0.07 mag (AB).
Using photometry from our GTC observations (Kann et al., GCNs #29653,
#29655) as well as earlier photometry from the Ondrejov D50, we find a
broken power-law decay with a late slope of alpha ~ 2.2. The second-day
OSN detection is in excess of the extrapolated decay, indicating that
the host galaxy may contribute already, or that another rebrightening
has taken place.
[GCN OPS NOTE(01apr21): The typo in the SUBJECT line "230312B" was
changed to 210312B.]