GRB 200228B
GCN Circular 27253
Subject
GRB 200228B: Fermi GBM Final Real-time Localization
Date
2020-02-28T11:25:00Z (5 years ago)
From
Fermi GBM Team at MSFC/Fermi-GBM <do_not_reply@GIOC.nsstc.nasa.gov>
The Fermi GBM team reports the detection of a likely LONG GRB
At 11:14:43 UT on 28 Feb 2020, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 200228B (trigger 604581288.894278 / 200228469).
The on-ground calculated location, using the Fermi GBM trigger data, is RA = 258.4, Dec = 9.6 (J2000 degrees, equivalent to J2000 17h 13m, 9d 35'), with a statistical uncertainty of 16.7 degrees.
The angle from the Fermi LAT boresight is 62.0 degrees.
The skymap can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2020/bn200228469/quicklook/glg_skymap_all_bn200228469.png
The HEALPix FITS file, including the estimated localization systematic, can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2020/bn200228469/quicklook/glg_healpix_all_bn200228469.fit
The GBM light curve can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2020/bn200228469/quicklook/glg_lc_medres34_bn200228469.gif
GCN Circular 27254
Subject
GRB 200228B: Swift detection of a burst
Date
2020-02-28T11:27:30Z (5 years ago)
From
Scott Barthelmy at NASA/GSFC <scott@milkyway.gsfc.nasa.gov>
S. Laha (GSFC/UMBC/CRESST), S. D. Barthelmy (GSFC),
P. A. Evans (U Leicester), C. Gronwall (PSU), J.D. Gropp (PSU) and
K. L. Page (U Leicester) report on behalf of the Neil Gehrels Swift
Observatory Team:
At 11:14:41 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 200228B (trigger=958733). Swift slewed immediately to the burst.
The BAT on-board calculated location is
RA, Dec 252.026, +16.960, which is
RA(J2000) = 16h 48m 06s
Dec(J2000) = +16d 57' 37"
with an uncertainty of 3 arcmin (radius, 90% containment, including
systematic uncertainty). The BAT light curve shows a single peak
with a duration of about 25 sec. The peak count rate
was ~2000 counts/sec (15-350 keV), at ~5 sec after the trigger.
The XRT began observing the field at 11:16:56.8 UT, 135.7 seconds after
the BAT trigger. Using promptly downlinked data we find an uncatalogued
X-ray source located at RA, Dec 252.04730, 16.98505 which is equivalent
to:
RA(J2000) = 16h 48m 11.35s
Dec(J2000) = +16d 59' 06.2"
with an uncertainty of 5.7 arcseconds (radius, 90% containment). This
location is 116 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. No spectrum from the promptly downlinked
event data is yet available to determine the column density.
UVOT data are unavailable at this time.
Burst Advocate for this burst is S. Laha (sib.laha 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 27256
Subject
GRB 200228B: Enhanced Swift-XRT position
Date
2020-02-28T14:16:49Z (5 years ago)
From
Phil Evans at U of Leicester <pae9@leicester.ac.uk>
P.A. Evans, M.R. Goad, J.P. Osborne and A.P. Beardmore (U. Leicester)
report on behalf of the Swift-XRT team.
Using 87 s of XRT Photon Counting mode data and 1 UVOT
images for GRB 200228B, 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 = 252.04640, +16.98523 which is equivalent
to:
RA (J2000): 16h 48m 11.14s
Dec (J2000): +16d 59' 06.8"
with an uncertainty of 3.5 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 27263
Subject
GRB 200228B: KAIT Optical Upper Limit
Date
2020-02-28T19:09:52Z (5 years ago)
From
Weikang Zheng at UC Berkeley <weikang@berkeley.edu>
WeiKang Zheng and Alexei V. Filippenko (UC Berkeley) report on
behalf of the KAIT GRB team:
The 0.76-m Katzman Automatic Imaging Telescope (KAIT), located at
Lick Observatory, responded to Swift GRB 200228B (Laha et al.,
GCN 27254) starting at 11:21:06 UT, 395 s after the burst.
Observations were performed with an automatic sequence in the
clear (roughly R), V, and I filters, and the exposure time was 20 s
per image. We do not detect any optical afterglow candidate within
the enhanced XRT position error circle (Evans et al., GCN 27256),
neither in single image, nor in the co-add images.
The typical limiting magnitude of our single clear image is about
18.0 mag calibrated to the Pan-STARRS1 catalog.
GCN Circular 27266
Subject
GRB 200228B: Fermi GBM observation
Date
2020-02-28T20:54:53Z (5 years ago)
From
Joshua Wood at MSFC/Fermi-GBM <joshua.r.wood@nasa.gov>
E. Bissaldi (Politecnico and INFN Bari), C. Meegan (UAH), and J. Wood (NASA/MSFC)
report on behalf of the Fermi GBM Team:
"At 11:14:43.89 UT on 28 February 2020, the Fermi Gamma-Ray Burst Monitor (GBM)
triggered and located GRB 200228B (trigger 604581288 / 200228469),
which was also detected by the Swift/BAT (Laha et al. 2020, GCN 27254).
The GBM on-ground location is consistent with the Swift position.
The angle from the Fermi LAT boresight at the GBM trigger time is 59 degrees.
The GBM light curve shows a single emission episode
with a duration (T90) of about 14 s (50-300 keV).
The time-averaged spectrum from T0-4 s to T0+11 s is
adequately fit by a power law function with an exponential
high-energy cutoff. The power law index is -1.17 +/- 0.33 and
the cutoff energy, parameterized as Epeak, is 76 +/- 16 keV.
The event fluence (10-1000 keV) in this time interval is
(1.30 +/- 0.18)E-07 erg/cm^2. The 1-sec peak photon flux measured
starting from T0-0.3 s in the 10-1000 keV band
is 1.4 +/- 0.2 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 27267
Subject
GRB 200228B: RATIR Optical Observations
Date
2020-02-28T21:07:26Z (5 years ago)
From
Emma Margarita Pereyra Talamantes at IA-UNAM Ensenada <mpereyra@astro.unam.mx>
Margarita Pereyra (UNAM), Nat Butler (ASU), Alan M. Watson (UNAM),
Alexander Kutyrev (GSFC), William H. Lee (UNAM), Michael G. Richer (UNAM),
Ori Fox (STScI), J. Xavier Prochaska (UCSC), Josh Bloom (UCB), Antonino
Cucchiara (UVI), Eleonora Troja (GSFC), Owen Littlejohns (ASU), Enrico
Ramirez-Ruiz (UCSC), Jes��s Gonz��lez (UNAM), Carlos Rom��n-Z����iga (UNAM),
Harvey Moseley (GSFC), John Capone (UMD), V. Zach Golkhou (U. Wash.), and
Vicki Toy (UMD) report:
We observed the field of GRB 200228B (Laha et al., GCN Circ. 27254) with
the Reionization and Transients Infrared Camera (RATIR; www.ratir.org) on
the 1.5m Harold Johnson Telescope at the Observatorio Astron��mico Nacional
on Sierra San Pedro M��rtir from 2020/02 28.48 to 2020/02 28.53 UTC (0.27 to
1.52 hours after the BAT trigger), obtaining a total of 0.62 hours exposure
in the r and i bands.
For a source within the Swift-XRT enhanced error circle (Evans et al., GCN
Circ. 27256), in comparison with the SDSS DR9 and 2MASS catalogs, we obtain
the following upper limits (3-sigma):
r > 21.48
i > 21.40
These magnitudes are in the AB system and are not corrected for Galactic
extinction in the direction of the GRB.
We thank the staff of the Observatorio Astron��mico Nacional in San Pedro
M��rtir.
--
*Dr. Margarita Pereyra *
*FFTF, Schlumberger Foundation Alumnae*
----------------------------------------------------------------------------------------------------------------
*Catedr��tico Conacyt*
*Instituto de Astronom��a de la UNAM,*
*Km. 107 Carretera Tijua**na-Ensenada, *
*Ensenada Baja California, M��xico. C.P. 22860*
Oficina: 405
Skype: margarita-pereyra
GCN Circular 27268
Subject
GRB 200228B: Swift/UVOT Upper Limits
Date
2020-02-28T22:23:32Z (5 years ago)
From
Paul Kuin at MSSL <npkuin@gmail.com>
N. P. M. Kuin (UCL-MSSL) and S. L. Laha (GSFC/UMBC/CRESST)
report on behalf of the Swift/UVOT team:
The Swift/UVOT began settled observations of the field of GRB 200228B
137 s after the BAT trigger (Laha et al., GCN Circ. 27254). No optical
afterglow consistent with the XRT position (Evans et al., GCN Circ.
#27256 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
u_FC 137 387 246 >20.1
v 4992 10685 676 >20.1
b 4580 6012 393 >20.6
u 137 5807 442 >20.4
w1 5402 5602 197 >19.5
m2 5197 5396 197 >19.8
w2 4786 6218 393 >19.4
The magnitudes in the table are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 0.092 in the direction of the burst
(Schlegel et al. 1998).
GCN Circular 27269
Subject
Swift GRB 200228B: Global MASTER-Net observations report
Date
2020-02-29T00:12:08Z (5 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),
H.Levato
(Instituto de Ciencias Astronomicas, de la Tierra y del Espacio ICATE),
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-Kislovodsk robotic telescope (Global MASTER-Net: http://observ.pereplet.ru, Lipunov et al., 2010, Advances in Astronomy, vol. 2010, 30L) located in Russia (Lomonosov MSU, Kislovodsk Solar Station of Pulkovo observatory) was pointed to the Swift GRB 200228B ( S. Laha et al., GCN 27254) errorbox 45652 sec after trigger time at 2020-02-28 23:55:33 UT, with upper limit up to 18.6 mag. The observations began at zenith distance = 51 deg. The sun altitude is -41.7 deg.
The galactic latitude b = 34 deg., longitude l = 36 deg.
Real time updated cover map and OT discovered available here:
https://master.sai.msu.ru/site/master2/observ.php?id=1300236
We obtain a following upper limits.
Tmid-T0 | Site |Filt.| Expt. | Limit| Comment
_________|_____________________|_____|_______|______|________
45742 | MASTER-Kislovodsk | C | 180 | 18.4 |
45742 | MASTER-Kislovodsk | C | 180 | 18.6 |
Filter C is a clear (unfiltred) band.
The observation and reduction will continue.
The message may be cited.
GCN Circular 27270
Subject
GRB 200228B: Swift-XRT refined Analysis
Date
2020-02-29T05:26:50Z (5 years ago)
From
Kim Page at U.of Leicester <klp5@leicester.ac.uk>
K.L. Page (U. Leicester) and S. Laha (GSFC/UMBC/CRESST) report on
behalf of the Swift-XRT team:
We have analysed 4.6 ks of XRT data for GRB 200228B (Laha et al. GCN
Circ. 27254), from 143 s to 18.2 ks after the BAT trigger. The data
are entirely in Photon Counting (PC) mode. The enhanced XRT position
for this burst was given by Evans et al. (GCN Circ. 27256).
The light curve can be modelled with a power-law decay with a decay
index of alpha=0.65 (+0.10, -0.12).
A spectrum formed from the PC mode data can be fitted with an absorbed
power-law with a photon spectral index of 3.0 (+0.8, -0.7). The
best-fitting absorption column is 1.6 (+0.8, -0.6) x 10^22 cm^-2, in
excess of the Galactic value of 6.4 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 3.5 x 10^-11 (2.3 x 10^-10) erg
cm^-2 count^-1.
A summary of the PC-mode spectrum is thus:
Total column: 1.6 (+0.8, -0.6) x 10^22 cm^-2
Galactic foreground: 6.4 x 10^20 cm^-2
Excess significance: 4.3 sigma
Photon index: 3.0 (+0.8, -0.7)
If the light curve continues to decay with a power-law decay index of
0.65, the count rate at T+24 hours will be 4.9 x 10^-3 count s^-1,
corresponding to an observed (unabsorbed) 0.3-10 keV flux of 1.7 x
10^-13 (1.1 x 10^-12) erg cm^-2 s^-1.
The results of the XRT-team automatic analysis are available at
http://www.swift.ac.uk/xrt_products/00958733.
This circular is an official product of the Swift-XRT team.
GCN Circular 27271
Subject
GRB 200228B: Liverpool Telescope imaging
Date
2020-02-29T13:57:42Z (5 years ago)
From
Daniel Perley at Liverpool JMU <d.a.perley@ljmu.ac.uk>
D. A. Perley and A. M. Cockeram (LJMU) report:
On 2020-02-29 UT we obtained imaging of the position of GRB 200228B
(Fermi GBM team, GCN 27253; Laha et al., GCN 27254) using the 2m robotic
Liverpool Telescope. We collected 3x120s of exposure time in each of
the the i-band and z-band filters, beginning at 05:53:44 and ending at
06:07:33 (UTC).
No unambiguous source is detected in either stacked image, although a
possible marginal (~3-sigma) source is present close to the center of
the latest enhanced XRT error circle in the z-band image. Photometry of
this potential source (calibrating relative to PS1 catalog stars in the
field) gives an approximate magnitude of z = 21.7 +/- 0.3.
3-sigma limits are:
dt(days) filter mag
0.7794 i >22.6
0.7844 z >21.7
We additionally note that Pan-STARRS1 imaging of the field shows several
faint, probably-resolved sources close to the survey detection limit
inside or closely outside the XRT error circle, which could represent a
possible host galaxy or host group.
Imaging of the field is available at:
http://www.astro.ljmu.ac.uk/~aridperl/grb/200228b/GRB200228B_LT_PS1.png
(The enhanced XRT error circle is shown in cyan with the marginal
"detection" highlighted in red.)
DisclaimerNone
GCN Circular 27272
Subject
GRB 200228B: RATIR Optical Observations
Date
2020-02-29T15:51:14Z (5 years ago)
From
Rosa Leticia Becerra Godinez at Inst. de Astronoma,UNAM <rbecerra@astro.unam.mx>
Rosa L. Becerra (UNAM), Alan M. Watson (UNAM), Nat Butler (ASU),
Alexander Kutyrev (GSFC), William H. Lee (UNAM), Michael G. Richer (UNAM),
Ori Fox (STScI), J. Xavier Prochaska (UCSC), Josh Bloom (UCB), Antonino
Cucchiara
(UVI), Eleonora Troja (GSFC), Owen Littlejohns (ASU), Enrico
Ramirez-Ruiz (UCSC), Jes��s Gonz��lez (UNAM), Carlos Rom��n-Z����iga (UNAM),
Harvey Moseley (GSFC), John Capone (UMD), V. Zach Golkhou (U. Wash.), and
Vicki Toy (UMD) report:
We observed the field of GRB 200228B (Fermi GBM team, GCN 27253,
Laha, et. al. GCN 27254) with the Reionization and Transients Infrared
Camera (RATIR; www.ratir.org) on the 1.5m Harold Johnson Telescope at the
Observatorio Astron��mico Nacional on Sierra San Pedro M��rtir from 2020/02
29.36
to 2020/02 29.53 UTC (21.40 to 25.38 hours after the BAT trigger), obtaining
a total of 2.27 hours exposure in the r and i bands.
For a source within the Swift-XRT enhanced error circle (Evans et al., GCN
Circ. 27256),
in comparison with the SDSS DR9 and 2MASS catalogs, we obtain the following
upper
limits (3-sigma):
r > 23.19
i > 23.11
These magnitudes are in the AB system and are not corrected for Galactic
extinction in the direction of the GRB.
We thank the staff of the Observatorio Astron��mico Nacional in San Pedro
M��rtir.
GCN Circular 27273
Subject
GRB 200228B: Swift-BAT refined analysis
Date
2020-02-29T23:49:33Z (5 years ago)
From
Amy Lien at GSFC <amy.y.lien@nasa.gov>
C. B. Markwardt (GSFC), S. D. Barthelmy (GSFC),
J. R. Cummings (CPI), H. A. Krimm (NSF),
S. Laha (GSFC/UMBC), A. Y. Lien (GSFC/UMBC),
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+297 sec from the recent telemetry
downlink,
we report further analysis of BAT GRB 200228B (trigger #958733)
(Laha et al., GCN Circ. 27254). The BAT ground-calculated position is
RA, Dec = 252.007, 16.964 deg which is
RA(J2000) = 16h 48m 01.8s
Dec(J2000) = +16d 57' 50.3"
with an uncertainty of 2.5 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 31%.
The mask-weighted light curve shows a weak pulse that starts at ~T-1 s,
peaks at ~T+2 s, and ends at ~T+7 s. T90 (15-350 keV) is 7.37 +- 1.58 sec
(estimated error including systematics).
The time-averaged spectrum from T-0.84 to T+6.97 sec is best fit by a simple
power-law model. The power law index of the time-averaged spectrum is
2.27 +- 0.36. The fluence in the 15-150 keV band is 3.0 +- 0.6 x 10^-7
erg/cm2.
The 1-sec peak photon flux measured from T+1.32 sec in the 15-150 keV band
is 1.0 +- 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/958733/BA/
GCN Circular 27274
Subject
GRB 200228B: LCO Optical Upper Limit
Date
2020-03-01T11:29:15Z (5 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 200228B (Laha et al., GCN 27254) with the LCO 1-m Sinistro instrument at the McDonald Observatory, Texas, USA site, on February 29, from 10:52 to 11:42 UT (corresponding to 23.4 to 24.5 hours after the GRB trigger time) with the Bessel I and R filters.
We performed a series of 10x120s exposures in I and R. We do not detect any uncatalouged sources in the individual frames (nor in stacked images) in the Swift error region. Using the USNO-B.1 catalog as reference, we obtain the following 3-sigma upper limits in stacked images:
R > 22.08
I > 20.77
R.S. is funded by NSF AST grant #1831682
GCN Circular 27276
Subject
GRB 200228B: Mondy, TSHAO, AbAO and CrAO optical observations, afterglow candidate
Date
2020-03-01T15:21:19Z (5 years ago)
From
Alexei Pozanenko at IKI, Moscow <apozanen@iki.rssi.ru>
A. Pozanenko (IKI), S. Belkin (IKI), E. Klunko (ISTP), A. Kusakin
(FAPHI), I. Reva (FAPHI), V. Rumyantsev (CrAO), R. Ya. Inasaridze
(AbAO), E. Mazaeva (IKI), A. Volnova (IKI) report on behalf of IKI-GRB-FuN:
We observed the field of GRB 200228B (Laha et al., GCN 27254; Fermi GBM
Team, GCN 27253) with AZT-33IK 1.5-m telescope of Sayan observatory
(Mondy) starting on Feb. 28 (UT) 19:24:43. We detected an optical object
near the enhanced XRT position of the XRT afterglow (Evans et al., GCN
27256). The object is absent in the Pan-STARRS DR1 catalog. The
coordinates of the object are (J2000) 16:48:10.88 +16:59:04.5 with
uncertainty of 0.5 arcsec in both coordinates. Next we observed the
filed with Zeiss-1000 1-m telescope of Tien Shan Astronomical
Observatory starting on Feb. 28 (UT) 23:08:56, Abastumani starting on
Feb. 29 (UT) 01:38:45, Tien Shan Astronomical Observatory starting on
Feb. 29 (UT) 23:08:56, and CrAO starting on Mar. 01 (UT) 00:58:28.
Preliminary photometry of the object and the field is following.
Date UT start t-T0 Filter Exp. OT Err UL(3sigma) telescope
(mid, days) (s)
2020-02-28 19:24:43 0.351 R 15*120 21.8 0.3 21.7 AZT-33IK
2020-02-28 23:08:56 0.516 R 3480 n/d n/d 22.3 Z-1000
2020-02-29 01:38:45 0.616 R 46*60 n/d n/d 21.8 AS-32
2020-02-29 22:22:37 n/a R 5040 n/a n/a n/a Z-1000
2020-03-01 00:58:28 1.594 R 31*120 22.05 0.09 23.8 ZTSh
Photometry is based on the USNO-B2.0 nearby stars.
USNO-B1.0 R2
1069-0297786 18.42
1069-0297719 18.25
1069-0297797 14.78
The finding chart is available at
http://193.232.11.154/GRB200228B/GRB200228B_AZT33IK_Z1000_ZTSh_FC.png
(or
http://grb.iki.rssi.ru/GRB200228B/GRB200228B_AZT33IK_Z1000_ZTSh_FC.png ).
We suggest this object is a candidate in the afterglow of GRB 200228B
after at least two epoch detections (see above), possible variability
and absence of the bright object (R ~ 22) in the Pan-STARRS DR1.
We did not detect any object at the position of NIR- candidate (Perley
and Cockeram, GCN 27271).
GCN Circular 27318
Subject
GRB 200228B: continued optical observations
Date
2020-03-05T18:07:39Z (5 years ago)
From
Alexei Pozanenko at IKI, Moscow <apozanen@iki.rssi.ru>
A. Pozanenko (IKI), S. Belkin (IKI), R. Ya. Inasaridze (AbAO), E.
Klunko (ISTP), A. Kusakin (FAPHI), I. Reva (FAPHI), V. Rumyantsev
(CrAO), E. Mazaeva (IKI), A. Volnova (IKI) report on behalf of IKI-GRB-FuN:
We continue observations of the OT (Pozanenko et al., GCN 27276)
associated with GRB 200228B (Laha et al., GCN 27254; Fermi GBM Team, GCN
27253) with AZT-33IK 1.5-m telescope of Sayan observatory (Mondy) and
AS-32 telescope of Abastumani Astrophysical observatory. The OT is well
observable (see photometry below in the table) and current XRT position
( https://www.swift.ac.uk/xrt_positions/00958733/ ) coincides with
position of the OT.
Preliminary photometry of the object following.
Date UT start t-T0 Filter Exp. OT Err UL(3sigma) telescope
(mid, days) (s)
2020-03-03 01:36:36 3.6186 R 58*60 21.65 0.13 22.6 AS-32
2020-03-03 21:03:33 4.4228 R 20*120 22.2 0.4 22.0 AZT-33IK
2020-03-04 23:44:59 5.5488 R 80*60 21.93 0.17 22.6 AS-32
Photometry is based on the USNO-B2.0 nearby stars used in previous
observations (GCN 27276).
The light curve in R-filter is available at
http://grb.rssi.ru/GRB200228B/GRB200228B_lc_2.png
We urge on spectroscopic and multicolor photometry to classify the OT.