GRB 230228A
GCN Circular 33378
Subject
GRB 230228A: Swift detection of a possibly short burst
Date
2023-02-28T06:03:29Z (2 years ago)
From
David Palmer at LANL <palmer@lanl.gov>
S. Dichiara (PSU), J.D. Gropp (PSU), D. M. Palmer (LANL) and
T. M. Parsotan (GSFC/UMBC/CRESSTII) report on behalf of the Neil
Gehrels Swift Observatory Team:
At 05:50:50 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 230228A (trigger=1156572). Swift slewed immediately to the burst.
The BAT on-board calculated location is
RA, Dec 18.403, +44.489 which is
RA(J2000) = 01h 13m 37s
Dec(J2000) = +44d 29' 19"
with an uncertainty of 3 arcmin (radius, 90% containment, including
systematic uncertainty). The BAT light curve showed a single symmetrical
peak structure with a duration of about 1.5 sec. The peak count rate
was ~2000 counts/sec (15-350 keV), at ~0 sec after the trigger.
The XRT began observing the field at 05:52:49.2 UT, 119.0 seconds after
the BAT trigger. Using promptly downlinked data we find a fading,
uncatalogued X-ray source located at RA, Dec 18.37776, 44.48321 which
is equivalent to:
RA(J2000) = 01h 13m 30.66s
Dec(J2000) = +44d 28' 59.6"
with an uncertainty of 3.7 arcseconds (radius, 90% containment). This
location is 68 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.
A power-law fit to a spectrum formed from promptly downlinked event
data gives a column density consistent with the Galactic value of 9.72
x 10^20 cm^-2 (Willingale et al. 2013).
UVOT took a finding chart exposure of 150 seconds with the White filter
starting 122 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
0.085.
Burst Advocate for this burst is S. Dichiara (simonedichiara55 AT gmail.com).
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 33379
Subject
GRB 230228A: Prompt enhanced Swift-XRT position
Date
2023-02-28T06:35:05Z (2 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 230228A, we find an
enhanced XRT position of the afterglow: RA, Dec: 18.37804, 44.48289
which is equivalent to:
RA (J2000) = 01 13 30.73
Dec (J2000) = +44 28 58.4
with an uncertainty of 1.9 arcseconds (radius, 90% confidence).
Analysis of the promptly available data is online at
http://www.swift.ac.uk/sper/1156572.
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 33380
Subject
GRB 230228A: Miryang Arirang Astronomical Observatory (MAAO) 0.7-m telescope optical upper limit
Date
2023-02-28T13:33:13Z (2 years ago)
From
Gu Lim at Seoul National U <lim9gu@gmail.com>
Gu Lim (PNU), Donghyun Kim (PNU), Dohyeong Kim (PNU), Myungshin Im
(SNU ARC/SNU), Gregory S.H. Paek (SNU ARC/SNU), Keun-Hong Park (MAAO),
and Seonghun Lim (MAAO) on behalf of GECKO collaboration
We searched for the optical counterpart of a possible short burst GRB
230228A (Dichiara et al. GCN #33378) with the 0.7-m telescope at Miryang
Arirang Astronomical Observatory (MAAO), located at Miryang, Republic of
Korea. We observed the center of Swift-XRT localization (RA, Dec =
01:13:30.73, +44:28:58.4; Evans et al. GCN #33379) +4.09 hours after
report, but could not find any possible transient within the field of view
(28.2' x 28.2'). We performed flux calibration with the PS1 catalog and
used the AB magnitude system. Each depth means 3 and 5 sigma upper limit
for a point source detection. The magnitudes are not corrected for galactic
extinction.
object exposures date-obs (UT) MJD band Depth(3��) Depth(5
��) FWHM(")
=========================================================================================
GRB230228A 60sx8 2023-02-28T09:56:11 60003.414 V <18.77 <18.21
2.8
Gravitational wave Electromagnetic wave Counterpart Korean Observatory
(GECKO) is a network of 10+ 0.5m to 1m class telescopes over the world.
���
GCN Circular 33381
Subject
GRB 230228A: Nanshan/NEXT optical upper limit
Date
2023-02-28T16:50:31Z (2 years ago)
From
Dong Xu at NAOC/CAS <dxu@nao.cas.cn>
T.H. Lu, S.Q. Jiang, S.Y. Fu, X. Liu (NAOC), Z.P. Zhu (NAOC, HUST), D.
Xu (NAOC), X. Gao (Urumqi No.1 Senior High School), J.Z. Liu (XAO) report:
We observed the field of GRB 230228A detected by Swift (Dichiara et al.,
GCN 33378) using the NEXT-0.6m telescope located at Nanshan, Xinjiang,
China. We obtained 12x200 s frames in the Sloan r-band and 12x200 s
frames in the Sloan z-band, starting at 14:37:32 UT on 2023-02-28 (i.e.,
8.77 hr after the BAT trigger).
No optical source is detected in our stacked images at the enhanced XRT
position (Evans, GCN 33379), and preliminary photometric results are as
follows:
T_mid-T0 (hr) Filter Upper limit(3-sigma)
9.86 r >20.6
9.14 z >19.5
calibrated with the nearby PanSTARRS field and not corrected for
Galactic extinction.
GCN Circular 33382
Subject
GRB 230228A: Enhanced Swift-XRT position
Date
2023-02-28T17:09:14Z (2 years ago)
From
Phil Evans at U of Leicester <pae9@leicester.ac.uk>
A.P. Beardmore, P.A. Evans, M.R. Goad and J.P. Osborne (U. Leicester)
report on behalf of the Swift-XRT team.
Using 2720 s of XRT Photon Counting mode data and 3 UVOT
images for GRB 230228A, 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 = 18.37812, +44.48293 which is equivalent
to:
RA (J2000): 01h 13m 30.75s
Dec (J2000): +44d 28' 58.5"
with an uncertainty of 2.1 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 33383
Subject
GRB 230228A: Mondy optical upper limit
Date
2023-02-28T19:12:56Z (2 years ago)
From
XXXX at IKI <alex@cgrsmx.iki.rssi.ru>
S. Belkin (IKI, HSE), E. Klunko (ISTP), A. Pozanenko (IKI), N. Pankov (HSE) report on behalf of GRB IKI FuN:
We observed the field of GRB 230228A (Dichiara et al., GCN 33378) with AZT-33 telescope of Mondy observatory starting on Feb. 28 (UT) 12:46:56. We do not detect any optical counterpart within the enhanced Swift/XRT error box (Beardmore et al., GCN 33382). Preliminary photometry of the field is following
Date UT start t-T0 Filter Exp. OT Err UL(3sigma)
2023-02-28 12:46:56 0.31053 R 30*120 n/d n/d 21.1
The photometry is based on the nearby USNO-B1.0 stars R2
RA DEC R2
01:13:35.3661600 +44:26:54.711600 15.50
01:13:18.4240800 +44:28:30.280800 16.70
The upper limit is not contradict observations reported earlier (Dichiara et al., GCN 33378; Lim et al., GCN 33380; Lu et al., GCN 33381).
GCN Circular 33384
Subject
GRB 230228A: Swift-XRT refined Analysis
Date
2023-03-01T01:07:58Z (2 years ago)
From
Phil Evans at U of Leicester <pae9@leicester.ac.uk>
A. Tohuvavohu (U. Toronto), D.N. Burrows (PSU), J. D. Gropp (PSU), A.P.
Beardmore (U. Leicester), P.A. Evans (U. Leicester), J.P. Osborne (U.
Leicester), M. Perri (SSDC & INAF-OAR), V. D'Elia (SSDC & INAF-OAR), B.
Sbarufatti (INAF-OAB) and S. Dichiara report on behalf of the Swift-XRT
team:
We have analysed 6.9 ks of XRT data for GRB 230228A (Dichiara et al.
GCN Circ. 33378), from 102 s to 63.7 ks after the BAT trigger. The
data comprise 10 s in Windowed Timing (WT) mode (taken while Swift was
slewing), with the remainder in Photon Counting (PC) mode. The enhanced
XRT position for this burst was given by Beardmore et al. (GCN Circ.
33379).
The light curve can be modelled with a power-law decay with a decay
index of alpha=0.94 (+/-0.07).
A spectrum formed from the PC mode data can be fitted with an absorbed
power-law with a photon spectral index of 1.82 (+0.27, -0.25). The
best-fitting absorption column is 2.1 (+1.1, -0.9) x 10^21 cm^-2, in
excess of the Galactic value of 9.7 x 10^20 cm^-2 (Willingale et al.
2013). The counts to observed (unabsorbed) 0.3-10 keV flux conversion
factor deduced from this spectrum is 3.9 x 10^-11 (5.0 x 10^-11) erg
cm^-2 count^-1.
A summary of the PC-mode spectrum is thus:
Total column: 2.1 (+1.1, -0.9) x 10^21 cm^-2
Galactic foreground: 9.7 x 10^20 cm^-2
Excess significance: 1.9 sigma
Photon index: 1.82 (+0.27, -0.25)
If the light curve continues to decay with a power-law decay index of
0.94, the count rate at T+24 hours will be 2.1 x 10^-3 count s^-1,
corresponding to an observed (unabsorbed) 0.3-10 keV flux of 8.1 x
10^-14 (1.0 x 10^-13) erg cm^-2 s^-1.
The results of the XRT-team automatic analysis are available at
http://www.swift.ac.uk/xrt_products/01156572.
This circular is an official product of the Swift-XRT team.
GCN Circular 33387
Subject
GRB 230228A: OSN optical upper limit
Date
2023-03-01T11:21:01Z (2 years ago)
From
Youdong HU at IAA-CSIC <huyoudong072@hotmail.com>
Y.-D. Hu, V. Casanova, E. Fernandez-Garcia, A. J. Castro-Tirado, I. Perez-Garcia, M.D. Caballero-Garcia, R. Sanchez-Ramirez, S. Guziy (IAA-CSIC), on behalf of a larger collaboration, report:
Following the detection of GRB 230228A by Swift (Dichiara et al. GCN 33378), we triggered the 0.9m OSN telescope in Granada (Spain) starting on Feb. 28 at 19:34:03 UT (~13.7 hrs post burst). Ten images covering the burst error region were taken in the I-band. No optical afterglow is detected in the stacked image down to I=20.2 mag. These results are in agreement with the non-detection reported by Lim et al. (GCNC 33380), Lu et al. (GCNC 33381) and Belkin et al. (GCNC 33383).
We thank the staff at OSN for their excellent support.
GCN Circular 33389
Subject
GRB 230228A: Fermi GBM Observation
Date
2023-03-01T16:12:06Z (2 years ago)
From
Cori Fletcher at USRA <cfletcher@usra.edu>
C. Fletcher (USRA), S. Lesage (UAH) and C. Meegan (UAH) report on behalf of
the Fermi Gamma-ray Burst Monitor Team:
"At 05:50:51 UT on 28 February 2023, the Fermi Gamma-ray Burst Monitor (GBM)
triggered and located GRB 230228A (trigger 699256256/230228244).
which was also detected by Swift BAT (S. Dichiara et al. 2023, GCN 33378).
The Fermi GBM on-ground location is consistent with the Swift BAT position.
The angle from the Fermi LAT boresight is 114 degrees.
The GBM light curve consists of a single burst with a duration (T90)
of about 2 s (10-1000 keV). The time-averaged spectrum
from T0-0.9 to T0+1.5 s is best fit by
a power law function with an exponential high-energy cutoff.
The power law index is -0.8 +/- 0.3 and the cutoff energy,
parameterized as Epeak, is 110 +/- 20 keV.
The event fluence (10-1000 keV) in this time interval is
(5.9 +/- 0.6)E-07 erg/cm^2. The 64-ms peak photon flux measured
starting from T0+0 s in the 10-1000 keV band is 6 +/- 1 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 33392
Subject
GRB 230228A: Swift/UVOT Upper Limits
Date
2023-03-02T10:15:52Z (2 years ago)
From
Alice Breeveld at MSSL-UCL <a.breeveld@ucl.ac.uk>
A. A. Breeveld (UCL-MSSL) and S. Dichiara (PSU) report on behalf of the
Swift/UVOT team:
The Swift/UVOT began settled observations of the field of GRB 230228A
122 s after the BAT trigger (Dichiara et al., GCN Circ. 33378).
No optical afterglow consistent with the enhanced XRT position
(Beardmore et al., GCN Circ. 33382) 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 122 272 147 >20.2
u_FC 335 585 246 >19.5
white 122 1706 240 >20.6
v 665 1752 97 >18.8
b 591 1851 88 >19.8
u 335 1830 341 >19.7
w1 714 1806 117 >20.0
m2 689 1780 97 >19.7
w2 640 1731 78 >20.1
The magnitudes in the table are not corrected for the Galactic
extinction due to the reddening of E(B-V) = 0.085 in the direction of
the burst (Schlegel et al. 1998).
GCN Circular 33393
Subject
GRB 230228A: Swift-BAT refined analysis
Date
2023-03-02T13:58:16Z (2 years ago)
From
Tyler Parsotan at UMBC/GSFC/CRESST II <parsotat@umbc.edu>
H. A. Krimm (NSF), S. D. Barthelmy (GSFC),
S. Laha (GSFC/UMBC), A. Y. Lien (U Tampa),
C. B. Markwardt (GSFC), D. M. Palmer (LANL),
T. Parsotan (GSFC/UMBC), T. Sakamoto (AGU),
M. Stamatikos (OSU) (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 230228A (trigger #1156572)
(Dichiara, et al., GCN Circ. 33378). The BAT ground-calculated position is
RA, Dec = 18.397, 44.495 deg which is
RA(J2000) = 01h 13m 35.3s
Dec(J2000) = +44d 29' 41.9"
with an uncertainty of 1.5 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 78%.
The mask-weighted light curve shows a Fast Rise Exponential Decay single
pulse.
T90 (15-350 keV) is 2.18 +- 0.40 sec (estimated error including
systematics).
The time-averaged spectrum from T-0.05 to T+2.53 sec is best fit by a simple
power-law model. The power law index of the time-averaged spectrum is
1.66 +- 0.17. The fluence in the 15-150 keV band is 3.6 +- 0.4 x 10^-07
erg/cm2.
The 1-sec peak photon flux measured from T+0.18 sec in the 15-150 keV band
is 3.0 +- 0.4 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/1156572/BA/
GCN Circular 33394
Subject
GRB 230228A: 6 GHz VLA radio upper limit
Date
2023-03-02T17:55:24Z (2 years ago)
From
Genevieve Schroeder at Northwestern University <genevieveschroeder2023@u.northwestern.edu>
G. Schroeder (Northwestern), T. Laskar (Utah), E. Berger (Harvard) report:
"We observed the position of the possibly short GRB 230228A (Dichiara et
al. GCN 33378; Fletcher GCN 33389) with the Karl G. Jansky Very Large Array
(VLA) under program 23A-296 (PI: Schroeder) beginning on 2023 March 2.02 UT
(1.78 days post-burst) at a mean frequency of 6 GHz.
Based on preliminary analysis, we do not detect any radio emission at or
near the position of the XRT afterglow (Beardmore et al., GCN 33382) to a
3-sigma limit of 12 microJy. Additional followup is planned.
We thank the VLA staff for quickly approving and executing these
observations."
GCN Circular 33426
Subject
GRB 230228A: VIRT Optical Upper Limit
Date
2023-03-08T21:15:43Z (2 years ago)
From
Priya Gokuldass at Florida Tech <pgokuldass2020@my.fit.edu>
K. Noonan (UVI), N. Orange (OrangeWave Innovative Science, LLC), P.
Gokuldass (Florida Tech), D. Morris (UVI), K. Smith (UVI), R. Querrard
(UVI) report:
We observed the field of GRB 230228A (Dichiara et al., GCN 33378) with
the 0.5m Virgin Island Robotic Telescope (VIRT) at the University of
the Virgin Islands' Etelman Observatory on 02-28-2023 starting at
23:29:41 UT (T+17.5 hrs). We performed a series of exposures in the R
filter with a total exposure of 2940s. The weather conditions were
clear during the hours of observation. The GRB was positioned at a
lower altitude with an average airmass of 2.7.
We detect no new source within the enhanced XRT position error circle
(Beardmore et al., GNC 33382) consistent with other non-detections
(Lim et al., GCN 33380, Lu et al., GCN 33381, Belkin et al., GCN
33383, Hu et al., GCN 33387, and Breeveld et al., GCN 33392) and
report the following 3-sigma upper limit:
T_mid ||Exposure ||Filter ||Limit
T+ 18 hrs ||2940s ||R ||>20.6
The limit is estimated from comparison to nearby USNO B1 stars and is
not corrected for Galactic extinction. The VIRT is still in the
commissioning phase.
We acknowledge financial support from NASA MUREP MIRO award
80NSSC21M0001, NASA EPSCoR award 80NSSC22M0063, and NSF EiR award
1901296. R.Q. and N.B.O. also acknowledge financial support from South
Carolina Space Grant award 80NSSC20M0054. This message can be cited.
GCN Circular 33436
Subject
GRB 230228A: NUTTelA-TAO / BSTI Optical Limits
Date
2023-03-09T12:17:48Z (2 years ago)
From
Toktarkhan Komesh at Nazarbayev University <toktarkhan.komesh@nu.edu.kz>
T. Komesh (NU), Zh. Maksut (NU), B. Grossan (UCB, NU), Zh. Abdullayev (NU), M. Krugov (FAI), report on behalf of the Energetic Cosmos Laboratory:
The Nazarbayev University Transient Telescope at Assy-Turgen Astrophysical Observatory (NUTTelA-TAO) observed the field of GRB 230228A, observing in Sloan g', r' and i' bands, with the Burst Simultaneous Three-Channel Imager (BSTI; Grossan, Kumar & Smoot 2019, JHEA, 32, 14).
We obtained 10x300 s frames starting at UT 2023-02-28 14:03:02, 8.2 hours after the BAT trigger. Observations were made under clear conditions, beginning with the target at an altitude of 45 deg. No new or changing sources consistent with the XRT position (Evans 2023, GCN 33379) were detected. Note that these observations provide essentially full-time coverage, simultaneous in all three bands. We report the following results:
start time t-t0(h) end time UL g' UL r' ULi' exposure_time (s)
------------ ----- ----------- ------ ------ ----- ------
14:03:02 8.2 14:53:02 19.9 19.6 19.5 300
start time is in UT. t-t0(h) gives the time since trigger, in hours. UL gives the 5 sigma upper limit sensitivity in magnitudes for images with individual exposure times. The given upper limit values are derived from the average calibration with only 3 standard stars per frame, and no other analysis or corrections.
----------------------------------
NU = Nazarbayev University, Nur-Sultan, Kazakhstan
UCB = University of California, Berkeley, USA
FAI = Fesenkov Astrophysical Institute, Kazakhstan
This research has been funded by the Science Committee of the Ministry of Science and Higher Education of the Republic of Kazakhstan (Grant No. AP14870504). The NUTTelA-TAO Team acknowledges the support of the staff of the Assy-Turgen Astrophysical Observatory, Almaty, Kazakhstan, and the Fesenkov Astrophysical Institute, Almaty, Kazkhstan.
GCN Circular 33557
Subject
GRB 230228A: detection by GTC of the potential host galaxy
Date
2023-04-03T03:19:37Z (2 years ago)
From
Youdong HU at IAA-CSIC <huyoudong072@hotmail.com>
Y.-D. Hu, E. Fernandez-Garcia, A. J. Castro-Tirado, I. Perez-Garcia, M.D. Caballero-Garcia, R. Sanchez-Ramirez (IAA-CSIC), Bin-bin Zhang (NJU) and D. Garcia (GTC, IAC) on behalf of a larger collaboration, report:
Following the detection of short GRB 230228A by Swift (Dichiara et al. GCN 33378), we triggered the 10.4 m Gran Telescopio de Canarias (GTC) in La Palma (Spain) to image the GRB location with the OSIRIS instrument in two epochs (Mar 1 20:16 UT and Mar 3, 20:02 UT, 1.6 and 2.6 days post-burst respectively). Within the XRT error region, a constant brightness (z-band magnitude = 23.6) is found, which we suggest as the potential host galaxy of this burst.
We thank the excellent support from the GTC staff.