GRB 201229A
GCN Circular 29213
Subject
GRB 201229A: Swift/UVOT Detection
Date
2021-01-01T02:06:07Z (5 years ago)
From
Mike Siegel at PSU/Swift MOC <mhs18@psu.edu>
M. H. Siegel (PSU) and B. Sbarufatti (PSU)
report on behalf of the Swift/UVOT team:
The Swift/UVOT began settled observations of the field of GRB 201229A
117 s after the BAT trigger (Sbarufatti et al., GCN Circ. 29192).
A source consistent with the XRT position
(Osborne et al. GCN Circ. 29193) is detected in the initial UVOT exposures, consistent
with the optical transient reported in the initial circular and confirmed by
SAO (Moskvitin et al., GCN Circ. 29203) and AbAO (Pankov et al., GCN Circ. 29205).
The preliminary UVOT position is:
RA (J2000) = 14:02:45.40 = 210.68916 (deg.)
Dec (J2000) = +48:11:53.3 = 48.19814 (deg.)
with an estimated uncertainty of 0.44 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
white (fc) 117 266 147 18.22 +/- 0.05
white 555 749 38 18.50+/-0.13
white 879 1029 147 19.17+/-0.13
white 1182 1548 58 19.42+/-0.34
white 23280 24102 801 20.88+/-0.22
v 605 1597 116 >18.48
v 17146 34853 1217 >20.39
b 531 1523 97 >19.33
b 22367 23274 885 >21.24
u (fc) 275 525 245 18.13+/-0.09
u 680 5086 107 18.57+/-0.25
u 12362 29756 1220 20.54+/-0.34
uvw1 654 5071 254 19.04+/-0.25
uvw1 28021 28921 885 >20.45
uvw2 16239 34408 1771 20.27+/-0.21
The magnitudes in the table are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 0.01 in the direction of the burst
(Schlegel et al. 1998).
GCN Circular 29205
Subject
GRB 201229A: AbAO optical afterglow detection, TSHAO optical upper limit
Date
2020-12-30T11:31:43Z (5 years ago)
From
Alexei Pozanenko at IKI, Moscow <apozanen@iki.rssi.ru>
N. Pankov (IKI, HSE), A. Pozanenko (IKI), R. Ya. Inasaridze (AbAO), I.
Reva (FAI), V. R. Ayvazian (AbAO), G. V. Kapanadze (AbAO), S. Belkin
(IKI) report on behalf of IKI-GRB-FuN:
We observed the field of GRB 201229A (Sbarufatti et al., GCN 29192)
with AS-32 telescope of Abastumani observatory (AbAO), and Zeiss-1000
telescope of TSHAO in R-filter. We detected the optical object at the
edge of enhanced XRT position (Osborne et al., GCN 29193). An optical
afterglow candidate (Sbarufatti et al., GCN 29192; Moskvitin at al.,
GCN 29204) is detected in AbAO observations and not detected in TSHAO
observations with shallow upper limit. Coordinates of the optical object
(J2000) 14:02:45.36 +48:11:53.5 with uncertainty of 0.3 arcsec (in
both coordinates) are consistent with coordinates reported by UVOT
(Sbarufatti et al., GCN 29192) and SAO RAS (Moskvitin at al., GCN
29204). Preliminary photometry of the object is following
Date UT start t-T0 Filter Exp. OT Err. UL(3sigma)
(mid, days) (s)
2020-12-29 20:38:18 0.42095 R 23*120 n/d n/d 20.2 Zeiss-1000
2020-12-30 01:52:12 0.64354 R 68*60 21.1 0.2 21.3 AS-32
The photometry is based on SDSS DR12 star (Lupton transformations)
RA DEC R(Lupton)
210.720000 48.157954 18.28
The non-detection of the object by Zeiss-1000 is consistent with
Nanshan/NEXT optical upper limit (Fu et al., GCN 29203).
The object is absent in SDSS DR12 and we confirm the afterglow of GRB
201229A.
GCN Circular 29204
Subject
GRB 201229A: SAO RAS optical observations
Date
2020-12-30T10:47:31Z (5 years ago)
From
Moskvitin Alexander at SAO RAS <mosk@sao.ru>
A. S. Moskvitin, O. I. Spiridonova (SAO RAS)
on behalf of GRB follow-up team report.
We observed the field of the GRB 201229A (B. Sbarufatti et al.,
GCN #29192) with the SAO RAS 1m telescope Zeiss-1000 equipped
with CCD photometer on December 30, 00:43:31 -- 01:40:03 UT
(T_mid - T0 = 0.59186 days).
The possible OT reported by Swift team is clearly detected
in the stacked 6 x 300 sec. Rc band image with the coordinates
R.A. = 14:02:45.38, Dec. = +48:11:53.5 +/- 0".1 (J2000).
Preliminary photometry of the object is R = 21.29 +/- 0.1
(based on R2 magnitudes of nearby USNO-B1 stars).
Using UVOT and NEXT-0.6m results (S.Y. Fu et al., GCN# 29203)
we confirm the GRB OT.
GCN Circular 29203
Subject
GRB 201229A: Nanshan/NEXT optical upper limit
Date
2020-12-30T03:53:43Z (5 years ago)
From
Dong Xu at NAOC/CAS <dxu@nao.cas.cn>
S.Y. Fu (NAOC), Z.P. Zhu (HUST,NAOC), X. Liu, D. Xu (NAOC), X. Gao
(Urumqi No.1 Senior High School), J.Z. Liu (XAO) report:
We observed the field of GRB 201229A (Sbarufatti et al., GCN 29192)
using the NEXT-0.6m telescope located at Nanshan, Xinjiang, China. We
obtained 5 x 200 s frames in the Sloan r-band, starting at 19:52:23 UT
on 2020-12-29, i.e., 8.88 hr after the burst.
No optical source is detected in our stacked image at the Swift/UVOT
position (Sbarufatti et al., GCN 29192), down to a upper limiting of
r~20.4, calibrated with the nearby PanSTARRS field.
GCN Circular 29200
Subject
GRB 201229A: Swift-XRT refined Analysis
Date
2020-12-30T00:06:20Z (5 years ago)
From
Phil Evans at U of Leicester <pae9@leicester.ac.uk>
A. D'Ai (INAF-IASFPA), D.N. Burrows (PSU), J. D. Gropp (PSU), A.P.
Beardmore (U. Leicester), P.A. Evans (U. Leicester), J.P. Osborne (U.
Leicester), A. Melandri (INAF-OAB), T. Sbarrato (INAF-OAB) and B.
Sbarufatti report on behalf of the Swift-XRT team:
We have analysed 8.6 ks of XRT data for GRB 201229A (Sbarufatti et al.
GCN Circ. 29192), from 114 s to 34.8 ks after the BAT trigger. The
data comprise 22 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. 29193).
The light curve can be modelled with an initial power-law decay with an
index of alpha=2.2 (+0.5, -0.3), followed by a break at T+262 s to an
alpha of 0.49 (+/-0.03).
A spectrum formed from the PC mode data can be fitted with an absorbed
power-law with a photon spectral index of 1.80 (+/-0.12). The
best-fitting absorption column is 1.3 (+/-0.4) x 10^21 cm^-2, in
excess of the Galactic value of 1.8 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 3.8 x 10^-11 (3.9 x 10^-11) erg
cm^-2 count^-1.
A summary of the PC-mode spectrum is thus:
Total column: 1.3 (+/-0.4) x 10^21 cm^-2
Galactic foreground: 1.8 x 10^20 cm^-2
Excess significance: 5.2 sigma
Photon index: 1.80 (+/-0.12)
If the light curve continues to decay with a power-law decay index of
0.49, the count rate at T+24 hours will be 0.048 count s^-1,
corresponding to an observed (unabsorbed) 0.3-10 keV flux of 1.8 x
10^-12 (1.9 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/01015088.
This circular is an official product of the Swift-XRT team.
GCN Circular 29199
Subject
GRB 201229A: Swift-BAT refined analysis
Date
2020-12-29T23:12:48Z (5 years ago)
From
Amy Lien at GSFC <amy.y.lien@nasa.gov>
A. Y. Lien (GSFC/UMBC), S. D. Barthelmy (GSFC),
H. A. Krimm (NSF), S. Laha (GSFC/UMBC),
C. B. Markwardt (GSFC), D. M. Palmer (LANL),
T. Sakamoto (AGU), B. Sbarufatti (PSU)
M. Stamatikos (OSU), T. N. Ukwatta (LANL)
(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 201229A (trigger #1015088)
(Sbarufatti et al., GCN Circ. 29192). The BAT ground-calculated position is
RA, Dec = 210.692, 48.209 deg which is
RA(J2000) = 14h 02m 46.1s
Dec(J2000) = +48d 12' 33.0"
with an uncertainty of 2.6 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 26%.
The mask-weighted light curve shows a multi-peaked structure that
starts at ~T-45 s and ends at ~T+15 s. There is a weak pulse occurring
at ~T-40 s, followed by the main peak at ~T0. T90 (15-350 keV)
is 53.3 +- 4.6 sec (estimated error including systematics).
The time-averaged spectrum from T-44.43 to T+13.62 sec is best fit
by a simple power-law model. The power law index of the time-averaged
spectrum is 1.40 +- 0.29. The fluence in the 15-150 keV band is
1.3 +- 0.2 x 10^-6 erg/cm2. The 1-sec peak photon flux measured from
T+0.41 sec in the 15-150 keV band is 1.7 +- 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/1015088/BA/
GCN Circular 29193
Subject
GRB 201229A: Enhanced Swift-XRT position
Date
2020-12-29T14:53:01Z (5 years ago)
From
Phil Evans at U of Leicester <pae9@leicester.ac.uk>
J.P. Osborne, A.P. Beardmore, P.A. Evans and M.R. Goad (U. Leicester)
report on behalf of the Swift-XRT team.
Using 1463 s of XRT Photon Counting mode data and 2 UVOT
images for GRB 201229A, 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 = 210.68844, +48.19775 which is equivalent
to:
RA (J2000): 14h 02m 45.23s
Dec (J2000): +48d 11' 51.9"
with an uncertainty of 1.7 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 29192
Subject
GRB 201229A: Swift detection of a burst with a possible optical counterpart
Date
2020-12-29T11:23:17Z (5 years ago)
From
Scott Barthelmy at NASA/GSFC <scott@milkyway.gsfc.nasa.gov>
B. Sbarufatti (PSU), S. D. Barthelmy (GSFC), J.D. Gropp (PSU) and
A. Y. Lien (GSFC/UMBC) report on behalf of the Neil Gehrels Swift
Observatory Team:
At 10:59:30 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 201229A (trigger=1015088). Swift slewed immediately to the burst.
The BAT on-board calculated location is
RA, Dec 210.708, +48.197 which is
RA(J2000) = 14h 02m 50s
Dec(J2000) = +48d 11' 50"
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 7 sec. The peak count rate
was ~500 counts/sec (15-350 keV), at ~2 sec after the trigger.
The XRT began observing the field at 11:01:22.2 UT, 111.4 seconds after
the BAT trigger. Using promptly downlinked data we find a fading,
uncatalogued X-ray source with an enhanced position: RA, Dec 210.6891,
48.1976 which is equivalent to:
RA(J2000) = 14h 02m 45.39s
Dec(J2000) = +48d 11' 51.2"
with an uncertainty of 2.2 arcseconds (radius, 90% containment). This
location is 45 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 1.78
x 10^20 cm^-2 (Willingale et al. 2013).
UVOT took a finding chart exposure of 150 seconds with the White filter
starting 116 seconds after the BAT trigger. There is a candidate afterglow in
the rapidly available 2.7'x2.7' sub-image at
RA(J2000) = 14:02:45.41 = 210.68921
DEC(J2000) = +48:11:53.8 = 48.19828
with a 90%-confidence error radius of about 0.62 arc sec. This position is 3.1
arc sec. from the center of the XRT error circle. The estimated magnitude is
18.19 with a 1-sigma error of about 0.14. No correction has been made for the
expected extinction corresponding to E(B-V) of 0.01.
Burst Advocate for this burst is B. Sbarufatti (bxs60 AT psu.edu).
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/)