| Summary table |
|---|
| Variable |
Value |
Source |
| T0 |
13:29:37 UTC |
GCN_circulars,Swift Det |
| ra |
281.3800° |
Swift |
| decl |
26.6558° |
Swift |
| pos_error |
2.98e-04° |
Swift |
| GBM_located |
False |
|
| mjd |
58837.5622337963 |
GCN_circulars,Swift Det |
| IPN table |
|---|
| GRB_name |
GRB191220A |
| ra |
281.3917° |
| decl |
26.6667° |
| pos_error |
5.00e-02° |
| Swift table |
|---|
| GRB_name |
GRB191220A |
| t_trigger |
13:29:37 UTC |
| ra |
281.3800° |
| decl |
26.6558° |
| pos_error |
2.98e-04° |
| GCN 26515 table |
|---|
| GRB_name |
GRB191220A |
| GCN_number |
26515 |
| Detection_method |
Swift-XRT Other |
| ra |
281.3800° |
| decl |
26.6558° |
| Circular_text |
TITLE: GCN CIRCULAR
NUMBER: 26515
SUBJECT: GRB 191220A: Prompt enhanced Swift-XRT position
DATE: 19/12/20 14:02:07 GMT
FROM: Phil Evans at U of Leicester
P.A. Evans (U. Leicester) reports on behalf of the Swift-XRT team:
Using promptly downlinked XRT event data for GRB 191220A, we find an
enhanced XRT position of the afterglow: RA, Dec: 281.3800, 26.6558
which is equivalent to:
RA (J2000) = 18 45 31.19
Dec (J2000) = +26 39 20.9
with an uncertainty of 2.3 arcseconds (radius, 90% confidence).
Analysis of the promptly available data is online at
http://www.swift.ac.uk/sper/945344.
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 26516 table |
|---|
| GRB_name |
GRB191220A |
| GCN_number |
26516 |
| Detection_method |
Swift Det |
| t_trigger |
13:29:37 UTC |
| ra |
281.3910° |
| decl |
26.6670° |
| Circular_text |
TITLE: GCN CIRCULAR
NUMBER: 26516
SUBJECT: GRB 191220A: Swift detection of a burst
DATE: 19/12/20 14:13:01 GMT
FROM: Kim Page at U.of Leicester
S. Laha (GSFC/UMBC/CRESST), D. N. Burrows (PSU), J.D. Gropp (PSU), N. P.
M. Kuin (UCL-MSSL), A. Y. Lien (GSFC/UMBC), K. L. Page (U Leicester), D.
M. Palmer (LANL) and A. Tohuvavohu (U Toronto) report on behalf of the
Neil Gehrels Swift Observatory Team:
At 13:29:37 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 191220A (trigger=945344). Swift slewed immediately to the
burst. The BAT on-board calculated location is
RA, Dec 281.391, +26.667 which is
RA(J2000) = 18h 45m 34s
Dec(J2000) = +26d 40' 02"
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 20 sec. The peak count rate
was ~200 counts/sec (15-350 keV), at ~1 sec after the trigger.
The XRT began observing the field at 13:31:50.2 UT, 132.4 seconds after
the BAT trigger. Using promptly downlinked data we find a bright,
fading, uncatalogued X-ray source located at RA, Dec 281.37924,
26.65599 which is equivalent to:
RA(J2000) = 18h 45m 31.02s
Dec(J2000) = +26d 39' 21.6"
with an uncertainty of 3.8 arcseconds (radius, 90% containment). This
location is 54 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 1.53
x 10^21 cm^-2 (Willingale et al. 2013).
The initial flux in the 2.5 s image was 4.03e-10 erg cm^-2 s^-1 (0.2-10
keV).
UVOT took a finding chart exposure of 250 seconds with the U filter
starting 137 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 19.2 mag. The 8'x8' region for the list of sources
generated on-board covers 0.00% of the XRT error circle. No correction has
been made for the expected extinction corresponding to E(B-V) of 0.14.
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 26519 table |
|---|
| GRB_name |
GRB191220A |
| GCN_number |
26519 |
| Detection_method |
Other |
| Circular_text |
TITLE: GCN CIRCULAR
NUMBER: 26519
SUBJECT: GRB 191220A: SAO RAS possible OT detection
DATE: 19/12/20 17:32:49 GMT
FROM: Moskvitin Alexander at SAO RAS
A. Moskvitin on behalf of larger GRB follow-up team report.
We observed the field of the GRB 191220A with the SAO RAS
Zeiss-1000 telescope equipped with the MMPP (Multi-Mode
Photometer-Polarimeter). The observations were started since
1.419 hours after the trigger (Laha et al., GCNC #26516).
We obtained 8 x 300 sec. frames in Rc band (14:54:44 -- 15:39:44 UT).
Within the enhanced XRT error circle (Evans, GCNC #26515)
we detect single object, possible OT, with the coordinates
R. A. = 18:45:31.10, Decl. = +26:39:20.8, +/- 0".3, Epoch = 2000.
ftp://ftp.sao.ru/pub/grb/GRB191220A/GRB_possibleOT.jpg
Preliminary brightness of the object is R = 20.46 +/- 0.08
(T_mid - T0 = 1.794 h). Photometry were made against the R2
magnitudes of nearby USNO-B1 stars.
|
| GCN 26522 table |
|---|
| GRB_name |
GRB191220A |
| GCN_number |
26522 |
| Detection_method |
Swift-XRT Det |
| ra |
281.3798° |
| decl |
26.6559° |
| Circular_text |
TITLE: GCN CIRCULAR
NUMBER: 26522
SUBJECT: GRB 191220A: Enhanced Swift-XRT position
DATE: 19/12/20 21:43:50 GMT
FROM: Phil Evans at U of Leicester
J.P. Osborne, A.P. Beardmore, P.A. Evans and M.R. Goad (U. Leicester)
report on behalf of the Swift-XRT team.
Using 2496 s of XRT Photon Counting mode data and 10 UVOT
images for GRB 191220A, 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 = 281.37980, +26.65588 which is equivalent
to:
RA (J2000): 18h 45m 31.15s
Dec (J2000): +26d 39' 21.2"
with an uncertainty of 2.3 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 26524 table |
|---|
| GRB_name |
GRB191220A |
| GCN_number |
26524 |
| Detection_method |
Swift-XRT Other |
| Circular_text |
TITLE: GCN CIRCULAR
NUMBER: 26524
SUBJECT: GRB 191220A: Swift-XRT refined Analysis
DATE: 19/12/20 22:52:47 GMT
FROM: Phil Evans at U of Leicester
A. Melandri (INAF-OAB), P. D'Avanzo (INAF-OAB), B. Sbarufatti (PSU),
D.N. Burrows (PSU), J. D. Gropp (PSU), J.P. Osborne (U. Leicester),
K.L. Page (U. Leicester), A.P. Beardmore (U. Leicester), M.G.
Bernardini (INAF-OAB) and S. Laha report on behalf of the Swift-XRT
team:
We have analysed 8.0 ks of XRT data for GRB 191220A (Laha et al. GCN
Circ. 26516), from 138 s to 23.9 ks after the BAT trigger. The data
comprise 38 s in Windowed Timing (WT) mode with the remainder in Photon
Counting (PC) mode. The enhanced XRT position for this burst was given
by Osborne et al. (GCN Circ. 26515).
The light curve can be modelled with an initial power-law decay with an
index of alpha=4.2 (+0.7, -1.5), followed by a break at T+349 s to an
alpha of 0.51 (+0.14, -0.30).
A spectrum formed from the PC mode data can be fitted with an absorbed
power-law with a photon spectral index of 2.01 (+0.18, -0.14). The
best-fitting absorption column is consistent with the Galactic value
of 1.5 x 10^21 cm^-2 (Willingale et al. 2013). The counts to observed
(unabsorbed) 0.3-10 keV flux conversion factor deduced from this
spectrum is 3.4 x 10^-11 (4.1 x 10^-11) erg cm^-2 count^-1.
A summary of the PC-mode spectrum is thus:
Total column: 1.53 (+/-0.25) x 10^21 cm^-2
Galactic foreground: 1.5 x 10^21 cm^-2
Excess significance: <1.6 sigma
Photon index: 2.01 (+0.18, -0.14)
If the light curve continues to decay with a power-law decay index of
0.51, the count rate at T+24 hours will be 9.8 x 10^-3 count s^-1,
corresponding to an observed (unabsorbed) 0.3-10 keV flux of 3.3 x
10^-13 (4.0 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/00945344.
This circular is an official product of the Swift-XRT team.
|
| GCN 26525 table |
|---|
| GRB_name |
GRB191220A |
| GCN_number |
26525 |
| Detection_method |
Optical |
| Circular_text |
TITLE: GCN CIRCULAR
NUMBER: 26525
SUBJECT: GRB 191220A: AbAO optical observations
DATE: 19/12/20 23:38:38 GMT
FROM: Alexei Pozanenko at IKI, Moscow
S. Belkin (IKI), A. Pozanenko (IKI), R. Ya. Inasaridze (AbAO), V.R.
Ayvazian (AbAO), G. V. Kapanadze (AbAO), E. Mazaeva (IKI), A.
Volnova (IKI), I. Molotov (KIAM) report on behalf of GRB IKI FuN:
We observed the field of GRB 191220A (Evans et al., GCN 26515; Laha et
al., GCN 26516) with AS-32 (0.7m) telescope of Abastumani Observatory
starting on Dec. 20 (UT) 14:40:39. We do no detect any source within
enhanced Swift-XRT position (Osborne et al., GCN 26522). In particular
we do not detect the candidate in the OT (Moskvitin, GCN 26519).
Preliminary photometry of the field is following.
Date UT start t-T0 Filter Exp. OT Err. UL
(mid, days) (s)
2019-12-20 14:40:39 0.05037 R 23*60 n/d n/d 19.8
The photometry is based on nearby USNO-B1.0 stars
UUSNO-B1.0_id R2
1166-0338499 14.74
1166-0338587 15.40
1166-0338614 15.08
|
| GCN 26526 table |
|---|
| GRB_name |
GRB191220A |
| GCN_number |
26526 |
| Detection_method |
Swift-UVOT Other |
| Circular_text |
TITLE: GCN CIRCULAR
NUMBER: 26526
SUBJECT: GRB 191220A: Swift/UVOT Upper Limits
DATE: 19/12/21 02:45:24 GMT
FROM: Paul Kuin at MSSL
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 191220A
138 s after the BAT trigger (Laha et al., GCN Circ. 26516). No optical
afterglow consistent with the XRT position (Laha et al. GCN Circ. 26516)
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 138 387 246 >19.8
u 138 6726 1061 >20.0
w1 446 6521 687 >19.6
m2 420 6316 687 >19.9
w2 396 6766 719 >21.1
The magnitudes in the table are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 0.14 in the direction of the burst
(Schlegel et al. 1998).
|
| GCN 26535 table |
|---|
| GRB_name |
GRB191220A |
| GCN_number |
26535 |
| Detection_method |
Swift-BAT Det |
| ra |
281.3350° |
| decl |
26.6790° |
| Circular_text |
TITLE: GCN CIRCULAR
NUMBER: 26535
SUBJECT: GRB 191220A: Swift-BAT refined analysis
DATE: 19/12/21 21:19:35 GMT
FROM: Sibasish Laha at GSFC
D. M. Palmer (LANL), S. D. Barthelmy (GSFC),
J. R. Cummings (CPI), H. A. Krimm (NSF),
S. Laha (GSFC/UMBC), A. Y. Lien (GSFC/UMBC),
C. B. Markwardt (GSFC), 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 191220A (trigger #945344)
(Laha et al., GCN Circ. 26516). The BAT ground-calculated position is
RA, Dec = 281.335, 26.679 deg which is
RA(J2000) = 18h 45m 20.3s
Dec(J2000) = +26d 40' 43.1"
with an uncertainty of 3.0 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 19%.
The mask weighted light curve shows complex structures with a duration of ~50 sec, with a hint of some weak emission lasting till ~ T+ 240 s.
The overall structure starts at ~ T-2 sec and lasts till ~ T+60 sec.
T90 (15-350 keV) is 175.55 +- 125.93 sec (estimated error including systematics).
The time-averaged spectrum from T-2.46 to T+248.42 sec is best fit by a simple
power-law model. The power law index of the time-averaged spectrum is
2.12 +- 0.40. The fluence in the 15-150 keV band is 1.1 +- 0.3 x 10^-6 erg/cm2.
The 1-sec peak photon flux measured from T+6.69 sec in the 15-150 keV band
is 1.1 +- 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/945344/BA/
|