GRB 210306A
GCN Circular 29597
Subject
GRB 210306A: Swift detection of a burst with a bright optical counterpart
Date
2021-03-06T04:12:28Z (4 years ago)
From
Scott Barthelmy at NASA/GSFC <scott@milkyway.gsfc.nasa.gov>
V. D'Elia (SSDC), E. Ambrosi (INAF-IASFPA), S. D. Barthelmy (GSFC),
A. D'Ai (INAF-IASFPA), J. A. Kennea (PSU), N. J. Klingler (PSU),
S. Laha (GSFC/UMBC/CRESST), F. E. Marshall (NASA/GSFC),
D. M. Palmer (LANL) and A. Tohuvavohu (U Toronto) report on behalf of
the Neil Gehrels Swift Observatory Team:
At 03:53:57 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 210306A (trigger=1035994). Swift slewed immediately to the burst.
The BAT on-board calculated location is
RA, Dec 129.965, +60.196 which is
RA(J2000) = 08h 39m 52s
Dec(J2000) = +60d 11' 46"
with an uncertainty of 3 arcmin (radius, 90% containment, including
systematic uncertainty). The BAT light curve shows multiple peaks in a complex
structure with a duration of about 15 sec. The peak count rate
was ~20,000 counts/sec (15-350 keV), at ~7 sec after the trigger.
The XRT began observing the field at 03:55:12.07 UT, 74.9 seconds after
the BAT trigger. Using promptly downlinked data we find an
uncatalogued X-ray source with a position: RA, Dec 129.96204,
60.203271 which is equivalent to:
RA(J2000) = 08h 39m 50.89s
Dec(J2000) = +60d 12' 11.7"
with an uncertainty of 4.7 arcseconds (radius, 90% containment). This
location is 27 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 http://www.swift.ac.uk/sper.
UVOT took a finding chart exposure of 150 seconds with the White filter
starting 85 seconds after the BAT trigger. There is a candidate afterglow in
the rapidly available 2.7'x2.7' sub-image at
RA(J2000) = 08:39:49.95 = 129.95813
DEC(J2000) = +60:12:19.4 = 60.20538
with a 90%-confidence error radius of about 0.61 arc sec. This position is 13.6
arc sec. from the center of the XRT error circle. The estimated magnitude is
16.22 with a 1-sigma error of about 0.14. No correction has been made for the
expected extinction corresponding to E(B-V) of 0.052.
Burst Advocate for this burst is V. D'Elia (delia AT ssdc.asi.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/)
GCN Circular 29598
Subject
GRB 210306A: DDOTI Afterglow Confirmation
Date
2021-03-06T04:28:38Z (4 years ago)
From
Alan M Watson at UNAM <alan@astro.unam.mx>
Alan M. Watson (UNAM), Nat Butler (ASU), Rosa L. Becerra (UNAM), Simone Dichiara
(GSFC/UMD), Alexander Kutyrev (GSFC/UMD), William H. Lee (UNAM), Oc��lotl Lopez
(UNAM), Diego Gonzalez (UNAM), Margarita Pereyra (UNAM), Srihari Ravi (ASU), and
Eleonora Troja (GSFC/UMD) report:
We observed the field of the Swift/BAT GRB 210306A (D'Elia et al., GCN Circ.
29597) with the DDOTI wide-field imager at the Observatorio Astron��mico Nacional
on Sierra San Pedro Martir (http://ddoti.astroscu.unam.mx) starting at
2021-03-06 04:07 UTC (from 14 minutes after the trigger).
We observed a region covering aproximately 7 degrees in RA and 10 degrees in
declination (about 70 square degrees) centered on the XRT position in the w
filter. We calibrated our images against the APASS catalog.
Compared to the USNO-B1, Pan-STARRS DR1, and APASS DR10 catalogs, we detect a
bright source at 08:39:50.04 +60:12:18.9 (J2000) fading from about w = 17. This
confirms the afterglow reported in UVOT observations by D'Elia et al. (GCN Circ.
29597)
We thank the staff of the Observatorio Astronomico Nacional in San Pedro Martir.
GCN Circular 29599
Subject
GRB 210306A: iTelescope optical afterglow observations
Date
2021-03-06T05:53:48Z (4 years ago)
From
Filipp Dmitrievich Romanov at Amateur astronomer <filipp.romanov.27.04.1997@gmail.com>
I observed the field of GRB 210306A (D'Elia et al., GCN Circ. 29597)
with remote telescope T24 (0.61-m f/6.5 reflector + CCD) of
iTelescope.Net in Sierra Remote Observatory (Auberry, California, USA)
on 2021-03-06. Two images (exposures 300 seconds, BINx1) were obtained
with luminance filter since 04:42:56 UT (2939 seconds after the
trigger) and since 04:48:59 UT (3302 seconds after the trigger). I
clearly detected the optical afterglow in UVOT position. The following
magnitudes were measured from comparison to r magnitudes of nearby
stars from Pan-STARRS DR1 catalogue (Chambers et al., 2016): 17.80
(+/- 0.057) and 17.97 (+/- 0.038).
Magnitudes were not corrected for Galactic extinction.
Stacked image available here:
https://www.flickr.com/photos/filipp-romanov/51007330278
GCN Circular 29600
Subject
GRB 210306A: LCO Optical Afterglow Detection
Date
2021-03-06T07:40:57Z (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 (U. of the Virgin Islands/College of Marin) report on behalf of a larger collaboration:
We observed Swift GRB 210306A (D'Elia et al., GCN 29597) with the LCO 1-m Sinistro instrument at the McDonald Observatory, Texas, USA site, on March 6, from 06:49 to 07:06 UT (corresponding to 2.93 to 3.22 hours from the GRB trigger time) with the Bessel R and I filters.
We performed a series of 4x120s exposures in R and I. We clearly detect an optical source in R and I band in stacked images at a location consistent the initial UVOT detection (D'Elia et al., GCN 29597), in agreement with other optical afterglow detections (Watson et al., GCN 29598; Romanov, GCN 29599). Using the USNO-B.1 catalog as reference, we calculate the following magnitudes:
R = 19.00 +/- 0.02
I = 17.70 +/- 0.03
These magnitudes are not corrected for galactic extinction. The fainter R magnitude could indicate a moderately high redshift.
R.S. is funded by NSF AST grant #1831682
GCN Circular 29602
Subject
GRB 210306A: Fermi-LAT detection
Date
2021-03-06T14:19:02Z (4 years ago)
From
Milena Crnogorcevic at U.of Maryland/NASA-GSFC <milenaGCN@gmail.com>
M. Ohno (Hiroshima Univ. & Eotvos Univ.), M. Axelsson (KTH &
StockholmUniv.), S. Cutini (INFN Perugia), F. Longo (University & INFN
Trieste), and M. Crnogorcevic (Univ. of Maryland & NASA/GSFC)
report on behalf of the Fermi-LAT Collaboration:
On March 06, 2021, Fermi-LAT detected high-energy emission from GRB
210306A, which was also detected by
Fermi-GBM (trigger 636695642), Swift (D'Elia et al.; GCN 29597), and
confirmed the afterglow by ground telescopes
(M. Watson et al.; GCN 29598, Dmitrievich Romanov; GCN 29599,
Strausbaugh and. Cucchiara; GCN 29600).
The best LAT on-ground location is found to be RA, Dec 130.3, 60.2
(degrees, J2000)
with an error radius of 0.38 deg (90% containment, statistical error only).
This was 10 deg from the LAT boresight at the time of the GBM trigger:
T0 = 03:53:57.11 UT.
The data from the Fermi-LAT show a significant increase
in the event rate after the GBM trigger that is spatially correlated with the
GBM emission (5.8 degrees from the GBM location) with high significance.
The photon flux above 100 MeV in the time interval 0-3000 s after the
GBM trigger is (6.6+/-3.5 e-7) ph/cm2/s.
The estimated photon index above 100 MeV is -2.0(+/-0.4).
The highest-energy photon is a 1.9 GeV event which is observed 790 seconds
after the GBM trigger.
The Fermi-LAT point of contact for this burst is
Milena Crnogorcevic (mcrnogor@astro.umd.edu).
The Fermi-LAT is a pair conversion telescope designed to cover
the energy band from 20 MeV to greater than 300 GeV.
It is the product of an international collaboration between
NASA and DOE in the U.S. and many scientific institutions
across France, Italy, Japan and Sweden.
GCN Circular 29603
Subject
GRB 210306A: iTelescope T24 optical observations
Date
2021-03-06T14:23:19Z (4 years ago)
From
Veli-Pekka Hentunen at Taurus Hill Obs,A95 <veli-pekka.hentunen@kassiopeia.net>
Veli-Pekka Hentunen and Markku Nissinen (Taurus Hill Observatory, Varkaus,
Finland) report:
We have detected GRB 210306A optical afterglow using iTelescope T24
(0.61-m f/6.5 + CCD) telescope in Sierra Remote Observatory (Auberry,
California, USA). The observations were started at 2021-03-06 05:02:41 (UT).
We used Luminance filter and 300 sec exposures.
The afterglow was detected at the position RA 08 39 50.11 DEC +60 12 18.8.
The following magnitudes were measured from comparison of a nearby star
(r = 16.974) from Pan-STARRS DR1 catalogue (Chambers et al., 2016):
Tmid (h:min:sec)+T0 Mag Mag_err
01:11:12 18.08 0.08
01:16:55 17.97 0.06
01:22:47 18.13 0.07
02:06:55 18.41 0.10
02:14:53 18.44 0.09
02:18:53 18.52 0.10
02:24:37 18.63 0.10
03:03:34 18.82 0.11
03:09:13 18.85 0.11
03:20:45 18.87 0.12
03:26:56 18.91 0.12
03:32:55 18.84 0.13
04:33:44 19.33 0.19
04:39:39 19.22 0.18
05:03:57 19.33 0.21
05:27:40 19.61 0.38
Magnitudes were not corrected for galactic extinction.
URL link for the L filter 300s image:
https://www.kassiopeia.net/2021/03/06/grb-210306a-havainto/
GCN Circular 29604
Subject
GRB 210306A: Tautenburg observations
Date
2021-03-06T17:15:56Z (4 years ago)
From
Sylvio Klose at TLS Tautenburg <klose@tls-tautenburg.de>
B. Stecklum, S. Klose, A. Nicuesa Guelbenzu, S. Melnikov, and S. Hoegner
(all Tautenburg) report:
We observed the field of GRB 210306A (D'Elia et al., GCN 29597) with the
Tautenburg 1.34m Schmidt telescope equipped with the TAUKAM 6kx6k CCD
camera.
Between 4:29 UT and 4:48 UT the afterglow was fading from R=17.33 +/- 0.02
to 17.53 +/- 0.09 mag (Vega), calibrated against the USNO B1 star at R.A.,
Decl. (J2000) = 129.924281, +60.163889 (DS9, R2mag = 15.23) close to the
afterglow position.
GCN Circular 29605
Subject
GRB 210306A: Fermi GBM observation
Date
2021-03-06T19:07:36Z (4 years ago)
From
Peter Veres at UAH <veresp@gmail.com>
P. Veres (UAH)
reports on behalf of the Fermi GBM Team:
"At 03:53:57.11 UT on 6 March 2021, the Fermi Gamma-Ray Burst Monitor (GBM)
triggered and located GRB 210306A (trigger 636695642 / 210306162).
which was also detected by the Swift/BAT (D'Elia et al., GCN 29597)
and Fermi/LAT (Ohno et al., GCN 29602).
The GBM on-ground location is consistent with the Swift position.
The GBM light curve shows multiple overlapping pulses
with a duration (T90) of about 9.5 s (50-300 keV).
The time-averaged spectrum from T0-0.6 s to T0+11.6 s is
best fit by a Band function with Epeak = 59.4 +/- 2.2 keV,
alpha = -0.60 +/- 0.08, and beta = -2.53 +/- 0.06.
The event fluence (10-1000 keV) in this time interval is
(9.82 +/- 0.20)E-6 erg/cm^2. The 1-sec peak photon flux measured
starting from T0+7.6 s in the 10-1000 keV band
is 26.6 +/- 0.4 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 29606
Subject
Swift GRB 210306A: Global MASTER-Net observations report
Date
2021-03-06T20:02:39Z (4 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-Tavrida robotic telescope (Global MASTER-Net: http://observ.pereplet.ru, Lipunov et al., 2010, Advances in Astronomy, vol. 2010, 30L) located in Russia (Lomonosov MSU, SAI Crimea astronomical station) was pointed to the Swift GRB 210306A ( V. D'Elia et al., GCN 29597) errorbox 57322 sec after notice time and 57335 sec after trigger time at 2021-03-06 19:49:32 UT, with upper limit up to 20.0 mag. The observations began at zenith distance = 17 deg. The sun altitude is -42.8 deg.
The galactic latitude b = 37 deg., longitude l = 157 deg.
Real time updated cover map and OT discovered available here:
https://master.sai.msu.ru/site/master2/observ.php?id=1562037
We obtain a following upper limits.
Tmid-T0 | Site |Filt.| Expt. | Limit| Comment
_________|_____________________|_____|_______|______|________
30222 | MASTER- | C | 60 | 18.5 |
31162 | MASTER- | C | 60 | 18.4 |
32113 | MASTER- | C | 60 | 18.9 |
57426 | MASTER-Tavrida | C | 180 | 20.0 |
Filter C is a clear (unfiltred) band.
The observation and reduction will continue.
The message may be cited.
GCN Circular 29607
Subject
GRB 210306A: NEXT optical observations
Date
2021-03-07T04:10:04Z (4 years ago)
From
Dong Xu at NAOC/CAS <dxu@nao.cas.cn>
Z.P. Zhu (NAOC, HUST), S.Y. Fu, X. Liu, D. Xu (NAOC), X. Gao (Urumqi
No.1 Senior High School), J.Z. Liu (XAO) report:
We observed the field of GRB 210306A (D'Elia et al., GCN 29597) using
the NEXT-0.6m optical telescope located at Nanshan, Xinjiang, China.
Observations started at 16:11:33 UT on 2021-03-06, i.e., 12.29 hr after
the BAT trigger. We obtained 15x200 s frames in the Sloan r-filter.
The previously reported optical afterglow (e.g., D'Elia et al., GCN
29597; Watson et al., GCN 29598; Romanov F., GCN 29599; Strausbaugh et
al., GCN 29600; Hentunen et al., GCN 29603; Stecklum et al., GCN 29604)
is clearly detected in our stacked image, with r = 21.0 +/- 0.1 mag at
12.76 hr post-burst, calibrated with nearby PS1 stars.
GCN Circular 29608
Subject
GRB 210306A: MITSuME Akeno optical observation
Date
2021-03-07T06:38:39Z (4 years ago)
From
Ryohei Hosokawa at Tokyo Institute of Technology <hosokawa@hp.phys.titech.ac.jp>
R. Hosokawa, R. Adachi, K. L. Murata, M. Niwano, F. Ogawa, N.
Nakamura, N. Ito, S. Ogata, H. Takamatsu, H. Hara, Y. Yatsu, and N.
Kawai (TokyoTech) report on behalf of the MITSuME collaboration:
We observed the field of GRB 210306A (D'Elia et al. GCN #29597, Watson
et al. GCN 29598, Romanov GCN #29599, Strausbaugh et al. GCN #29600,
Ohno et al. GCN #29602, Hentunen et al. GCN #29603, Stecklum et al.
GCN #29604, Veres et al. GCN #29605, Lipunov et al. GCN #29606, Zhu et
al. GCN #29607) with the optical three color (g', Rc, and Ic) CCD
cameras attached to the MITSuME 50 cm telescope of Akeno Observatory,
Yamanashi, Japan. The observation with a series of 60 sec exposures
started at 2021-03-06 09:12:03 UT (5.3 hours after Swift BAT trigger).
We stacked the images with good conditions. We marginally detected the
point source at the position consistent with the afterglow detected
previously(D'Elia et al. GCN #29597, Watson et al. GCN 29598, Romanov
GCN #29599, Strausbaugh et al. GCN #29600, Hentunen et al. GCN #29603,
Stecklum et al. GCN #29604, Zhu et al. GCN #29607).
We measured the magnitudes as follows.
T0+[hour] MID-UT T-EXP[sec] measured magnitudes
------------------------------------------------------------------------------------------------
5.3 11:38:10 8160 g'=20.0+/-0.4, Rc=20.2+/-0.4, Ic=19.0+/-0.3
------------------------------------------------------------------------------------------------
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 29616
Subject
GRB 210306A: Mondy optical observations
Date
2021-03-07T20:21:30Z (4 years ago)
From
Alexei Pozanenko at IKI, Moscow <apozanen@iki.rssi.ru>
S. Belkin (IKI), A. Pozanenko (IKI), E. Klunko (ISTP), N. Pankov (HSE)
report on behalf of GRB IKI FuN:
We observed the field of GRB 210306A (D'Elia et al., GCN 29597; Ohno et
al., GCN 29602) with AZT-33IK telescope of Sayan observatory (Mondy)
starting on 2021-03-06 (UT) 14:50:30. The optical afterglow (D'Elia et
al., GCN 29597; Watson et al., GCN 29598; Romanov, GCN 29599;
Strausbaugh et al., GCN 29600; Hentunen et al., GCN 29603; Stecklum et
al., GCN 29604; Lipunov et al. GCN 29606, Zhu et al. GCN 29607; Hosokawa
et al., GCN 29608) is clearly detected in a combined image. Preliminary
photometry of the object in a combined image is following
Date UT start t-T0 Filter Exp. OT Err. UL(3sigma)
(mid, days) (s)
2021-03-06 14:50:30 0.47677 R 30*120 20.48 0.05 22.0
The photometry is based on the nearby USNO-B1.0 stars
USNO-B1.0_id R2
1501-0181731 15.23
1502-0183049 17.69
1501-0181697 17.1
GCN Circular 29617
Subject
GRB 210306A: Swift-BAT refined analysis
Date
2021-03-07T22:03:13Z (4 years ago)
From
Takanori Sakamoto at AGU <tsakamoto@phys.aoyama.ac.jp>
S. Laha (GSFC/UMBC), S. D. Barthelmy (GSFC), J. R. Cummings (CPI),
V. D'Elia (SSDC), H. A. Krimm (NSF), A. Y. Lien (GSFC/UMBC),
C. B. Markwardt (GSFC), 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-240 to T+600 sec from the recent telemetry downlink,
we report further analysis of BAT GRB 210306A (trigger #1035994)
(D'Elia, et al., GCN Circ. 29597). The BAT ground-calculated position is
RA, Dec = 129.964, 60.203 deg which is
RA(J2000) = 08h 39m 51.3s
Dec(J2000) = +60d 12' 11.5"
with an uncertainty of 1.0 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 53%.
The BAT light curve showed a complex structure with a duration of about ~10 sec.
T90 (15-350 keV) is 9.12 +- 0.31 sec (estimated error including systematics).
The time-averaged spectrum from T-0.18 to T+13.16 sec is best fit by a power law
with an exponential cutoff. This fit gives a photon index 1.16 +- 0.19,
and Epeak of 58.4 +- 3.9 keV (chi squared 59.11 for 56 d.o.f.). For this
model the total fluence in the 15-150 keV band is 5.7 +- 0.1 x 10^-6 erg/cm2
and the 1-sec peak flux measured from T+7.50 sec in the 15-150 keV band is
20.9 +- 0.7 ph/cm2/sec. A fit to a simple power law gives a photon index
of 1.91 +- 0.04 (chi squared 111.38 for 57 d.o.f.). 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/1035994/BA/
GCN Circular 29618
Subject
GRB 210306A: 1.3m DFOT observations
Date
2021-03-08T06:40:03Z (4 years ago)
From
Dimple Panchal at ARIES, India <dimplepanchal96@gmail.com>
Dimple (ARIES), A. Ghosh (ARIES), G. Singh (ARIES), R. Gupta (ARIES), A.
Kumar (ARIES), K. Misra (ARIES), S.B. Pandey (ARIES) report:
We observed the afterglow of the GRB 210306A (D'Elia et al. GCN
#29597, Watson et al. GCN 29598, Romanov GCN #29599, Strausbaugh et
al. GCN #29600, Ohno et al. GCN #29602, Hentunen et al. GCN #29603,
Stecklum et al. GCN #29604, Veres et al. GCN #29605, Lipunov et al.
GCN #29606, Zhu et al. GCN #29607) with 1.3m Devasthal Fast Optical
Telescope (DFOT) at Devasthal observatory of Aryabhatta Research
Institute of observational sciencES (ARIES), India. We took
observations in B,V,R,I bands. We detect the optical afterglow with a
magnitude of 20.24 +- 0.13 in R-band at 9.8 hrs after the burst.
Further observations are ongoing with 1.3m DFOT.
The magnitude is not corrected for the Galactic extinction in the
direction of the burst. The photometric calibration is performed using
the standard stars from the USNO-B1.0 catalog.
GCN Circular 29620
Subject
GRB 210306A: continued Mondy optical observations
Date
2021-03-08T11:16:12Z (4 years ago)
From
Alexei Pozanenko at IKI, Moscow <apozanen@iki.rssi.ru>
S. Belkin (IKI), A. Pozanenko (IKI), E. Klunko (ISTP), N. Pankov (HSE)
report on behalf of GRB IKI FuN:
We continue observations (Belkin et al., GCN 29616) the field of GRB
210306A (D'Elia et al., GCN 29597; Ohno et al., GCN 29602) with AZT-33IK
telescope of Sayan observatory (Mondy). The optical afterglow (D'Elia et
al., GCN 29597; Watson et al., GCN 29598; Romanov, GCN 29599;
Strausbaugh et al., GCN 29600; Hentunen et al., GCN 29603; Stecklum et
al., GCN 29604; Lipunov et al. GCN 29606, Zhu et al. GCN 29607; Hosokawa
et al., GCN 29608; Dimple et al., GCN 29618) is still detected in a
combined image. Preliminary photometry of the afterglow in the combined
image is following
Date UT start t-T0 Filter Exp. OT Err. UL(3sigma)
(mid, days) (s)
2021-03-07 13:43:24 1.41281 R 5*120 22.09 0.25 22.1
The photometry is based on the nearby USNO-B1.0 stars
USNO-B1.0_id R2
1501-0181731 15.23
1502-0183049 17.69
1501-0181697 17.1
GCN Circular 29622
Subject
GRB 210306A: Swift-XRT refined Analysis
Date
2021-03-08T16:08:27Z (4 years ago)
From
Valerio D'Elia at ASDC <valerio.delia@ssdc.asi.it>
V. D'Elia (SSDC & INAF-OAR), A. D'Ai (INAF-IASFPA), D.N. Burrows (PSU),
J. D. Gropp (PSU), J.A. Kennea (PSU), J.P. Osborne (U. Leicester), K.L.
Page (U. Leicester), A.P. Beardmore (U. Leicester) and A. Melandri
(INAF-OAB) report on behalf of the Swift-XRT team:
We have analysed 10 ks of XRT data for GRB 210306A (D'Elia et al. GCN
Circ. 29597), from 65 s to 182.6 ks after the BAT trigger. The data
comprise 576 s in Windowed Timing (WT) mode (the first 7 s were taken
while Swift was slewing) with the remainder in Photon Counting (PC)
mode. Using 3375 s of PC mode data and 9 UVOT images, we find an
enhanced XRT position (using the XRT-UVOT alignment and matching UVOT
field sources to the USNO-B1 catalogue): RA, Dec = 129.95774, +60.20523
which is equivalent to:
RA (J2000): 08h 39m 49.86s
Dec(J2000): +60d 12' 18.8"
with an uncertainty of 1.4 arcsec (radius, 90% confidence).
The light curve can be modelled with an initial power-law decay with an
index of alpha=0.435 (+/-0.027), followed by a break at T+1548 s to an
alpha of 1.58 (+/-0.06).
A spectrum formed from the WT mode data can be fitted with an absorbed
power-law with a photon spectral index of 1.89 (+0.05, -0.04). The
best-fitting absorption column is 1.53 (+0.15, -0.14) x 10^21 cm^-2,
in excess of the Galactic value of 4.2 x 10^20 cm^-2 (Willingale et al.
2013). The PC mode spectrum has a photon index of 1.98 (+0.14, -0.13)
and a best-fitting absorption column of 1.7 (+/-0.4) x 10^21 cm^-2. The
counts to observed (unabsorbed) 0.3-10 keV flux conversion factor
deduced from this spectrum is 3.5 x 10^-11 (4.7 x 10^-11) erg cm^-2
count^-1.
A summary of the PC-mode spectrum is thus:
Total column: 1.7 (+/-0.4) x 10^21 cm^-2
Galactic foreground: 4.2 x 10^20 cm^-2
Excess significance: 5.2 sigma
Photon index: 1.98 (+0.14, -0.13)
The results of the XRT-team automatic analysis are available at
http://www.swift.ac.uk/xrt_products/01035994.
This circular is an official product of the Swift-XRT team.
GCN Circular 29635
Subject
GRB 210306A: continued Mondy optical observations
Date
2021-03-09T06:31:50Z (4 years ago)
From
Alexei Pozanenko at IKI, Moscow <apozanen@iki.rssi.ru>
S. Belkin (IKI), A. Pozanenko (IKI), E. Klunko (ISTP), N. Pankov (HSE)
report on behalf of GRB IKI FuN:
We continue observations (Belkin et al., GCNs 29616,29620) the field of
GRB 210306A (D'Elia et al., GCN 29597; Ohno et al., GCN 29602) with
AZT-33IK telescope of Sayan observatory (Mondy). The optical afterglow
(D'Elia et al., GCN 29597; Watson et al., GCN 29598; Romanov, GCN 29599;
Strausbaugh et al., GCN 29600; Hentunen et al., GCN 29603; Stecklum et
al., GCN 29604; Lipunov et al. GCN 29606, Zhu et al. GCN 29607; Hosokawa
et al., GCN 29608; Dimple et al., GCN 29618) is detected in a combined
image. Preliminary photometry of the afterglow in the combined image is
following
Date UT start t-T0 Filter Exp. OT Err. UL(3sigma)
(mid, days) (s)
2021-03-08 13:47:43 2.43317 R 30*120 22.68 0.18 22.9
The photometry is based on the nearby USNO-B1.0 stars
USNO-B1.0_id R2
1501-0181731 15.23
1502-0183049 17.69
1501-0181697 17.11
GCN Circular 29636
Subject
GRB 210306A: Swift/UVOT Detection
Date
2021-03-09T14:05:28Z (4 years ago)
From
Kira Simpson at PSU <kira.simpson1984@gmail.com>
GRB 210306A: Swift/UVOT Detection
K. K. Simpson (PSU) and V. D'Elia (SSDC)
report on behalf of the Swift/UVOT team:
The Swift/UVOT began settled observations of the field of GRB 210306A
85 s after the BAT trigger (D'Elia et al., GCN Circ. 29597).
A source consistent with the XRT position
(D'Elia et al. GCN Circ. 29597)
is detected in the initial UVOT exposures.
The preliminary UVOT position is:
RA (J2000) = 08:39:49.98 = 129.95824 (deg.)
Dec (J2000) = +60:12:19.2 = 60.20533 (deg.)
with an estimated uncertainty of 0.42 arc sec. (radius, 90% confidence).
Preliminary detections 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 85 235 147 16.23 +/- 0.03
v 628 648 20 17.42 +/- 0.24
b 553 573 20 17.32 +/- 0.13
u 297 547 246 16.86 +/- 0.04
The magnitudes in the table are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 0.052 in the direction of the burst
(Schlegel et al. 1998).
GCN Circular 29638
Subject
GRB 210306A: Early Spectroscopy of the Optical Afterglow
Date
2021-03-09T18:35:39Z (4 years ago)
From
Paul S. Smith at Steward Observatory <psmith@as.arizona.edu>
P.S. Smith, Z. Chen, P. Milne, D. Sand, N. Smith, D. Stark, and G.G.
Williams (Steward Observatory, University of Arizona)
Observations of the optical counterpart of GRB 210306A using the B&C
Spectrograph and the University of Arizona, Steward Observatory 2.3m Bok
Telescope located on Kitt Peak, Arizona began at 07:07:50 on March 6, 2021
UTC and ended at 08:23:13 UT. Three, 1500 s exposures were obtained
centered at 3.384, 3.859, and 4.279 hours after the Swift/BAT detection of
the burst (D�Elia et al.; GCN Circ. 29597). Comparison with a
spectrophotometric standard star observed immediately after the optical
afterglow observations suggest that the counterpart was at an approximate
V magnitude of 19.18, 19.33, and 19.46 for the three exposures,
respectively. All spectra show a featureless blue continuum from 350-760nm.
A fit to the least noisy portion (450-750nm) of the scaled median spectrum
from the three observations yields a slope of about -1.25 in log(F_lambda)
vs. log(wavelength). No corrections for Galactic extinction and reddening
have been made.
GCN Circular 29642
Subject
Konus-Wind detection of GRB 210306A
Date
2021-03-10T10:05:25Z (4 years ago)
From
Anna Ridnaia at Ioffe Institute <ridnaia@mail.ioffe.ru>
A. Ridnaia, S. Golenetskii, D. Frederiks, M. Ulanov,
D. Svinkin, A. Tsvetkova, A. Lysenko, and T. Cline
on behalf of the Konus-Wind team, report:
The long-duration GRB 210306A
(Swift-BAT detection: D'Elia et al., GCN 29597, Laha et al., GCN 29617;
Fermi-LAT detection: Ohno et al., GCN 29602;
Fermi-GBM observation: Veres, GCN 29605)
triggered Konus-Wind at T0=14040.731 s UT (03:54:00.731).
The burst light curve shows a multi-peaked emission complex,
which starts at ~T0-0.2 s and has a total duration of ~11 s.
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/GRB210306_T14040/
As observed by Konus-Wind, the burst
had a fluence of 7.01(-0.45,+0.48)x10^-6 erg/cm2,
and a 64-ms peak flux, measured from T0+7.648 s,
of 3.99(-0.60,+0.67)x10^-6 erg/cm2/s
(both in the 20 keV - 10 MeV energy range).
The time-averaged spectrum of the burst
(measured from T0 to T0+16.640 s)
is best fit in the 20 keV - 1 MeV range
by a power law with exponential cutoff model:
dN/dE ~ (E^alpha)*exp(-E*(2+alpha)/Ep)
with alpha = -1.21(-0.20,+0.22)
and Ep = 77(-7,+7) keV (chi2 = 48/49 dof).
Fitting by a GRB (Band) model yields the same alpha and Ep,
and an upper limit on the high energy photon index: beta < -2.6
(chi2 = 46/48 dof).
The spectrum near the peak count rate
(measured from T0+0.256 to T0+8.448 s)
is best fit in the 20 keV - 1 MeV range
by the GRB (Band) model with the following parameters:
the low-energy photon index alpha = -1.17(-0.23,+0.30),
the high energy photon index beta = -2.97(-1.31,+0.34),
the peak energy Ep = 70(-7,+7) keV
(chi2 = 56/49 dof).
All the quoted errors are at the 90% confidence level.
All the quoted values are preliminary.
GCN Circular 29644
Subject
GRB 210306A: Tautenburg observations
Date
2021-03-10T14:33:10Z (4 years ago)
From
Sylvio Klose at TLS Tautenburg <klose@tls-tautenburg.de>
S. Klose, B. Stecklum, A. Nicuesa Guelbenzu, S. Melnikov, and S. Hoegner
(all Tautenburg) report:
We continued observations of the field of GRB 210306A (D'Elia et al., GCN
29597) with the Tautenburg 1.34m Schmidt telescope. For the optical
afterglow (Simpson & D'Elia, GCN 29636; Belkin et al., GCN 29635, and
references therein) we measure:
March 07, 00:21 UT : Rc = 20.47 +/- 0.13 (Vega mag)
March 07, 02:12 UT : Rc = 20.53 +/- 0.14
March 07, 19:34 UT : Rc > 21.2.
Data calibration followed Stecklum et al. (GCN 29604).
GCN Circular 29645
Subject
GRB 210306A: LBT observations
Date
2021-03-11T12:21:33Z (4 years ago)
From
Andrea Rossi at INAF <andrea.rossi@inaf.it>
A Rossi (INAF-OAS) report on behalf of the CIBO collaboration:
We observed the field of GRB 210306A (D'Elia et al., GCN 29597)
simultaneously in the r' and z' bands with the LBC imager mounted on LBT
(Mt Graham, AZ, USA). We obtained 20min of imaging on 2021-03-11, 5.06
days after the burst trigger. Observations were performed under good
weather conditions with an average seeing of ~1.2".
We clearly detect the afterglow and we preliminary measure
r=24.2+-0.2 (AB system),
calibrated against SDSS field stars. This is still in agreement with the
late decay index alpha~1.1 (after an initial plateau ending at ~2hours
after the burst trigger) obtained modelling the photometry available
(Strausbaugh et al., GCN29600; Zhu et al., GCN 29607; Hentunen &
Nissinen GCN 29603; Hosokawa et al., GCN29608; Dimple et al., GCN 29618;
Belkin et al., GCN 29616, GCN 29620, 29635; Klose et al., GCN 29644).
We acknowledge the excellent support from the LBTO and LBT-INAF staff,
particularly J. Power, J. Williams F. Cusano, and D. Paris, in obtaining
these observations.
GCN Circular 29654
Subject
GRB 210306A: HCT optical upper limit
Date
2021-03-13T04:44:34Z (4 years ago)
From
Harsh Kumar at Indian Inst of Tech,Bombay <harshkosli13@gmail.com>
H. Kumar (IITB), A. Dutta (IIA), R. Gupta (ARIES), V. Bhalerao (IITB), G.
C. Anupama (IIA), S. Barway (IIA), D.K. Sahu (IIA), A. Kumar (ARIES),
Dimple (ARIES), A. Ghosh (ARIES), S. B. Pandey (ARIES), and K. Misra
(ARIES) report:
We observed GRB 210306A detected by Swift Burst Alert Telescope (V. D'Elia
et. al., GCN 29597) and optical afterglow confirmed by Alan M. Watson et.
al., (GCN 29598) with the 2.0m Himalayan Chandra Telescope (HCT) of the
Indian Astronomical Observatory. We obtained 6 exposures of 300 sec each in
the Bessell R filter. We did not detect the afterglow in our stacked image.
The photometric upper limit is:
--------------------------------------------------------
JD (mid) | T_mid-T0(hrs) | Filter | Lim_mag (5-sigma) |
--------------------------------------------------------
2459282.110905 | 58.76 | Bessell R | > 23.22 |
--------------------------------------------------------
The magnitudes are in the AB system of magnitude calibrated against PanSTARRS
(Flewelling et al., 2018) using Lupton's transformation equations available
at http://classic.sdss.org/dr4/algorithms/sdssUBVRITransform.html#Lupton2005.
The magnitudes are not corrected for galactic extinction.
These observations were carried out under the ToO program HCT-2021-C1-P2.
We thank the HCT staff for their support during the observations. The
Indian Astronomical Observatory is operated by the Indian Institute of
Astrophysics, Bengaluru, India.
GCN Circular 29657
Subject
GRB 210306A: GIT optical follow-up
Date
2021-03-15T11:34:37Z (4 years ago)
From
Harsh Kumar at Indian Inst of Tech,Bombay <harshkosli13@gmail.com>
H. Kumar(IITB), K. Sharma (IITB), J. Stanzin (IAO), A. Dutta(IIA), V.
Bhalerao(IITB), G. C. Anupama(IIA), S. Barway(IIA) report on behalf of the
GIT team:
We observed GRB 210306A detected by Swift Burst Alert Telescope (V. D'Elia
et. al., GCN 29597) and optical afterglow confirmed by (Alan M. Watson et.
al., GCN 29598), with the 0.7m GROWTH-India Telescope (GIT). We
obtained multiple
exposures in the r' filter. We clearly detected the afterglow in our stacked
image at R.A. = 08:39:49.99, DEC. = +60:12:19.09. The photometric results
follow as:
--------------------------------------------------------
JD (mid) | T_mid-T0(hrs) | Filter | Magnitude (AB) |
--------------------------------------------------------
2459280.20139 | 12.9 | r' | 20.87 +/0.05 |
--------------------------------------------------------
The magnitude is in agreement with that reported by Z.P. Zhu et al., (GCN
29607), around the same time of our observation. The magnitudes are
calibrated against PanSTARRS (Flewelling et al., 2018) and not corrected
for galactic extinction.
The GROWTH India Telescope (GIT) is a 70-cm telescope with a 0.7 degree
field of view, set up by the Indian Institute of Astrophysics and the
Indian Institute of Technology Bombay with support from the Indo-US Science
and Technology Forum (IUSSTF) and the Science and Engineering Research
Board (SERB) of the Department of Science and Technology (DST), Government
of India (https://sites.google.com/view/growthindia/). It is located at the
Indian Astronomical Observatory (Hanle), operated by the Indian Institute
of Astrophysics (IIA).
GCN Circular 30080
Subject
GRB 210306A: LBT observations of the likely host galaxy
Date
2021-05-26T12:33:42Z (4 years ago)
From
Andrea Rossi at INAF <andrea.rossi@inaf.it>
A Rossi (INAF-OAS) and D. B. Malesani (DTU space) report on behalf of
the CIBO collaboration:
We observed the field of GRB 210306A (D'Elia et al., GCN 29597)
simultaneously in the r' and z' bands with the LBC imager mounted on LBT
(Mt Graham, AZ, USA). We obtained 20min of imaging on 2021-05-10, 65
days after the burst trigger and 60 days after our first observation
(Rossi et al., GCN 29645). Observations were performed under good
weather conditions with an average seeing of ~1.3".
At the location of the optical afterglow, we detected an object which is
likely the GRB host galaxy. We measure the following AB magnitudes:
r=24.6+-0.2
z=24.4+-0.4
calibrated against SDSS field stars.
We acknowledge the excellent support from the LBTO and LBT-INAF staff,
particularly A. Cardwell, S. Allanson, F. Cusano, S. Paiano and D.
Paris, in obtaining these observations.