GRB 200224A
GCN Circular 27173
Subject
GRB 200224A: Swift detection of a burst
Date
2020-02-24T03:41:23Z (5 years ago)
From
David Palmer at LANL <palmer@lanl.gov>
T. N. Ukwatta (LANL), E. Ambrosi (INAF-IASFPA), A. D'Ai (INAF-IASFPA),
V. D'Elia (SSDC), J. A. Kennea (PSU), N. J. Klingler (PSU),
S. Laha (GSFC/UMBC/CRESST), A. Y. Lien (GSFC/UMBC) and
D. M. Palmer (LANL) report on behalf of the Neil Gehrels Swift
Observatory Team:
At 03:24:49 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 200224A (trigger=958141). Swift slewed immediately to the burst.
The BAT on-board calculated location is
RA, Dec 248.794, +41.675 which is
RA(J2000) = 16h 35m 11s
Dec(J2000) = +41d 40' 31"
with an uncertainty of 3 arcmin (radius, 90% containment, including
systematic uncertainty). The BAT light curve showed a complex
structure with a duration of about 30 sec. The peak count rate
was ~1000 counts/sec (15-350 keV), at ~3 sec after the trigger.
The XRT began observing the field at 03:26:26.9 UT, 97.7 seconds after
the BAT trigger. Using promptly downlinked data we find an uncatalogued
X-ray source with an enhanced position: RA, Dec 248.7668, 41.6123 which
is equivalent to:
RA(J2000) = 16h 35m 04.04s
Dec(J2000) = +41d 36' 44.1"
with an uncertainty of 2.9 arcseconds (radius, 90% containment). This
location is 237 arcseconds from the BAT onboard position. This position
may be improved as more data are received; the latest position is
available at https://www.swift.ac.uk/sper. We cannot determine whether
the source is fading at the present time.
A power-law fit to a spectrum formed from promptly downlinked event
data gives a column density consistent with the Galactic value of 8.91
x 10^19 cm^-2 (Willingale et al. 2013).
UVOT results will be reported later.
Burst Advocate for this burst is T. N. Ukwatta (tilan.ukwatta 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 OPS NOTE(24feb20): This is the second Circular in the sequence of 8 circulars
which were all labeled A because of the sequence assigner being offline.
This circular was correctly labelled A.]
GCN Circular 27176
Subject
GRB 200224A: BOOTES-1 and 1.5m OSN optical observations
Date
2020-02-24T06:37:24Z (5 years ago)
From
Alberto J. Castro-Tirado at IAA-CSIC <ajct@iaa.es>
A. Sota, E. Fernandez-Garcia, Y.-D. Hu and A. J. Castro-Tirado
(IAA-CSIC), A. Castellon, I. Carrasco-Garcia and C. Perez del Pulgar
(UMA), on behalf of a larger collaboration, report:
Following the detection of GRB 200224A by Swift (Ukwatta�� et al., GCNC
27173), the 0.3cm robotic telescope at the BOOTES-1 astronomical station
at INTA-CEDEA in Huelva (Spain) started gathering images at 03:26:27 UT,
40s after the alert and 118s after the onset of the burst. No optical
transient is detected in the single images with a limiting magnitude of
14 (consistent with the MASTER upper limit, Lipunov et al., GCNC 27172).
Further data reduction is ongoing.
Deeper exposures were obtained with the 1.5m telescope at Observatorio
de Sierra Nevada starting at 05:35 UT (i.e. 2.1 h post burst).�� We find
an optical source consistent with the Swift/XRT position,�� at
coordinates (RA & Dec, J2000)�� = 16:35:04.11 +41:36:42 (+/- 1���). The
preliminary magnitude is R = 22. Further observations are planned to
confirm whether this is the optical afterglow to GRB 200224A.
This message can be quoted.
[GCN OPS NOTE(24feb20): This is the fifth Circular in the sequence of 8 circulars
which were all labeled A because of the sequence assigner being offline.
This circular was correctly labelled A.]
GCN Circular 27177
Subject
GRB 200224A: Tautenburg observations
Date
2020-02-24T07:37:12Z (5 years ago)
From
Sylvio Klose at TLS Tautenburg <klose@tls-tautenburg.de>
B. Stecklum, S. Klose, A. Nicuesa Guelbenzu, and S. Melnikov (all
Tautenburg) report:
We observed the field of GRB 200224A (T0=03:24:49 UT; Ukwatta et al., GCN
27173) with the Tautenburg 1.34m Schmidt telescope equipped with the
TAUKAM 6k x 6k CCD camera and the wide V-band filter (VB). The
transmission curve of this filter closely follows the Gaia GBP filter.
Observations started at 04:09:53 UT and consisted of 5x3 min exposures.
Based on several Gaia DR2 stars in the field within 1 arcmin radius about
the afterglow position, we measure for the optical transient (Sota et al.,
GCN 27176) at RA, DEC (J2000) = 16:35:04.11, +41:36:42.4 (+/- 0.5 arcsec)
the following preliminary Vega magnitude:
mean time t = Feb 24, 04:18:01 UT; t-T0 = 53m 12s; VB = 21.83 +/- 0.10.
[GCN OPS NOTE(24feb20): This is the sixth Circular in the sequence of 8 circulars
which were all labeled A because of the sequence assigner being offline.
This circular was correctly labelled A.]
GCN Circular 27179
Subject
GRB 200224A: Swift-XRT refined Analysis
Date
2020-02-24T16:21:20Z (5 years ago)
From
Phil Evans at U of Leicester <pae9@leicester.ac.uk>
J. D. Gropp (PSU), J.A. Kennea (PSU), K.L. Page (U. Leicester), A.P.
Beardmore (U. Leicester), T. Sbarrato (INAF-OAB), P. D'Avanzo
(INAF-OAB), M.G. Bernardini (INAF-OAB), A. Tohuvavohu (U. Toronto),
and report on behalf of the Swift-XRT team: report on behalf of the
Swift-XRT team:
We have analysed 12 ks of XRT data for the Swift-detected burst GRB
200224A, from 105 s to 34.0 ks after the Swift trigger. The data are
entirely in Photon Counting (PC) mode. Using 4055 s of PC mode data and
4 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 = 248.76655, +41.61133 which is equivalent to:
RA (J2000): 16h 35m 03.97s
Dec(J2000): +41d 36' 40.8"
with an uncertainty of 1.7 arcsec (radius, 90% confidence). This
position is 4.0 arcmin from the Swift position.
The light curve can be modelled with a power-law decay with a decay
index of alpha=0.86 (+0.10, -0.09).
A spectrum formed from the PC mode data can be fitted with an absorbed
power-law with a photon spectral index of 2.09 (+0.39, -0.29). The
best-fitting absorption column is 3.2 (+7.4, -2.3) x 10^20 cm^-2,
consistent with the Galactic value of 8.9 x 10^19 cm^-2 (Willingale et
al. 2013). The counts to observed (unabsorbed) 0.3-10 keV flux
conversion factor deduced from this spectrum is 3.0 x 10^-11 (3.3 x
10^-11) erg cm^-2 count^-1.
A summary of the PC-mode spectrum is thus:
Total column: 3.2 (+7.4, -2.3) x 10^20 cm^-2
Galactic foreground: 8.9 x 10^19 cm^-2
Excess significance: <1.6 sigma
Photon index: 2.09 (+0.39, -0.29)
If the light curve continues to decay with a power-law decay index of
0.86, the count rate at T+24 hours will be 9.9 x 10^-4 count s^-1,
corresponding to an observed (unabsorbed) 0.3-10 keV flux of 3.0 x
10^-14 (3.3 x 10^-14) erg cm^-2 s^-1.
The results of the XRT-team automatic analysis are available at
http://www.swift.ac.uk/xrt_products/00958141.
This circular is an official product of the Swift-XRT team.
[GCN OPS NOTE(24feb20): This is the eighth Circular in the sequence of 8 circulars
which were all labeled A because of the sequence assigner being offline.
This circular was correctly labelled A.]
GCN Circular 27182
Subject
GRB 200224A: Swift/UVOT Detection
Date
2020-02-24T21:40:15Z (5 years ago)
From
Frank Marshall at Swift/UVOT <marshall@milkyway.gsfc.nasa.gov>
F. E. Marshall (NASA/GSFC) and T. N. Ukwatta (LANL)
report on behalf of the Swift/UVOT team:
The Swift/UVOT began settled observations of the field of GRB 200224A
101 s after the BAT trigger (Ukwatta et al., GCN Circ. 27173).
A source consistent with the enhanced XRT position
(Gropp et al., GCNC 27179) and the optical positions reported
by Sota et al. (GCNC 27176) and Stecklum et al. (GCNC 27177)
is detected in the initial UVOT exposures.
The source is very close to the edge of the image in the
first exposure at 101 s after the BAT trigger, and further
analysis is required to determine an accurate intensity
for that exposure.
The preliminary UVOT position is:
RA (J2000) = 16:35:04.14 = 248.76727 (deg.)
Dec (J2000) = +41:36:42.3 = 41.61174 (deg.)
with an estimated uncertainty of 0.43 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
u 259 509 246 18.75 +/- 0.10
white 861 1011 147 20.57 +/- 0.20
w1 5978 19265 1098 >20.7
m2 5772 18542 1279 >21.4
w2 5363 30092 1953 >21.9
The magnitudes in the table are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 0.005 in the direction of the burst
(Schlegel et al. 1998).
GCN Circular 27189
Subject
GRB 200224A: RATIR Optical Observations and Confirmation of the Afterglow
Date
2020-02-25T00:49:46Z (5 years ago)
From
Rosa Leticia Becerra Godinez at Inst. de Astronoma,UNAM <rbecerra@astro.unam.mx>
Rosa L. Becerra (UNAM), Margarita Pereyra (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 200224A (Palmer D., et al., GCN 27173) 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 24.36 to 2020/02 24.54 UTC (5.33
to 9.66 hours after the BAT trigger), obtaining a total of 3.44 hours
exposure in the r and i bands.
For a source within the Swift-XRT error circle, in comparison with the SDSS
DR9 and 2MASS catalogs, we obtain the following upper limits (3-sigma):
r > 23.88
i > 23.84
These magnitudes are in the AB system and are not corrected for Galactic
extinction in the direction of the GRB.
Castro-Tirado et al. (GCN 27176)
and Stecklum et al. (GCN 27177) report an afterglow candidate at roughly
magnitude 22 at about 1 and 2 hours after the burst. Our observations show
subsequent fading of this source and confirm that it is the afterglow.
We thank the staff of the Observatorio Astron��mico Nacional in San Pedro
M��rtir.
GCN Circular 27191
Subject
GRB 200224A: LCO Upper Limits
Date
2020-02-25T04:02:07Z (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 200224A (Ukwatta et al., GCN 27173) with the LCO 1-m Sinistro instrument at the McDonald Observatory, Texas, USA site, on February 24, from 12:01 to 12:18 UT (corresponding to 8.62 to 8.90 hours from the GRB trigger time) with the Bessel I and R filters.
We performed a series of 5x120s exposures in I and 3x120s in R. We do not detect any 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:
R > 19.85
I > 19.05
R.S. is funded by NSF AST grant #1831682
GCN Circular 27194
Subject
GRB 200224A: Swift-BAT refined analysis
Date
2020-02-25T06:53:49Z (5 years ago)
From
Amy Lien at GSFC <amy.y.lien@nasa.gov>
A. Y. Lien (GSFC/UMBC), S. D. Barthelmy (GSFC),
J. R. Cummings (CPI), H. A. Krimm (NSF),
S. Laha (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+962 sec from the recent telemetry
downlink,
we report further analysis of BAT GRB 200224A (trigger #958141)
(Ukwatta et al., GCN Circ. 27173). The BAT ground-calculated position is
RA, Dec = 248.743, 41.666 deg which is
RA(J2000) = 16h 34m 58.4s
Dec(J2000) = +41d 39' 57.2"
with an uncertainty of 3.5 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 100%.
The mask-weighted light curve shows a weak pulse from ~T0 to ~T+5 s,
followed
by some weaker emission that lasts till ~T+50 s. T90 (15-350 keV)
is 45.0 +- 9.2 sec (estimated error including systematics).
The time-averaged spectrum from T-0.79 to T+49.21 sec is best fit by a
simple
power-law model. The power law index of the time-averaged spectrum is
1.69 +- 0.51. The fluence in the 15-150 keV band is 2.9 +- 0.9 x 10^-7
erg/cm2.
The 1-sec peak photon flux measured from T+2.21 sec in the 15-150 keV band
is 0.4 +- 0.1 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/958141/BA/
GCN Circular 27222
Subject
GRB 200224A: Calar Alto 2.2m optical afterglow detection
Date
2020-02-26T10:47:39Z (5 years ago)
From
Alexander Kann at IAA-CSIC <kann@iaa.es>
J. F. Agui Fernandez, M. Blazek, D. A. Kann (all HETH/IAA-CSIC), A. de
Ugarte Postigo (HETH/IAA-CSIC, DARK/NBI), C. C. Thoene (HETH/IAA-CSIC),
E. Gallego-Cano, and A. Guijarro (both CAHA) report:
We observed the field of the Swift-detected GRB 200224A (Ukwatta et al.,
GCN #21173) with the 2.2m telescope at CAHA, Almeria, Spain. We obtained
5 x 120 s each in Rc and Ic.
At the position of the optical afterglow reported by Sota et al. (GCN
#27176), Stecklum et al. (GCN #21177), and Marshall & Ukwatta (GCN
#27182), we clearly detect a source in each stack image.
We measure Rc = 21.60 +/- 0.06 mag at 0.03702 days after the GRB, and Ic
= 21.31 +/- 0.09 mag at 0.05794 days after the GRB (Vega magnitudes), in
good agreement with the measurements of Tautenburg at an earlier time
(GCN #27177) and OSN at a later time (GCN #27176).
We note the optical afterglow is very faint (see also Becerra et al.,
GCN #27189), but the clear detection in u by Swift/UVOT (GCN #27182) as
well as the blue Rc-Ic color we find indicates this GRB is neither at
high redshift nor particularly extinguished (see also the XRT results,
Gropp et al., GCN #27179), it is likely just intrinsically faint.
GCN Circular 27240
Subject
GRB 200224A: Mondy optical upper limit
Date
2020-02-27T16:28:46Z (5 years ago)
From
Alexei Pozanenko at IKI, Moscow <apozanen@iki.rssi.ru>
S. Belkin (IKI), A. Pozanenko (IKI), E. Klunko (ISTP), E. Mazaeva (IKI),
A. Volnova (IKI) report on behalf of IKI-GRB-FuN:
We observed the field of GRB 200224A (Ukwatta et al., GCN 27173; Fermi
GBM team GCN 27174) with AZT-33IK telescope of Sayan observatory (Mondy)
starting on Feb. 26 (UT) 17:24:49. We did not detect the optical
afterglow (Sota et al., GCN 27176; Stecklum et al., GCN 27177; Marshall
et al., GCN 27182; Becerra et al., GCN 27182; Fernandez et al., GCN
27222). Preliminary photometry of the field is following.
Date UT start, t-T0 Filter Exp. OT UL(3sigma)
(mid, days) (s)
2020-02-26 17:24:49 2.60348 R 29*120 n/d 22.6
Photometry is based on the USNO-B1.0 nearby stars.