| Summary table |
|---|
| Variable |
Value |
Source |
| T0 |
2:25:37 UTC |
GCN_circulars,Swift Det |
| ra |
173.6950° |
Swift |
| decl |
-49.1342° |
Swift |
| pos_error |
5.18e-04° |
Swift |
| T90 |
2.77 s |
Swift |
| T90_start |
2:25:37 UTC |
Swift |
| fluence |
1.10e-07 erg/cm² |
Swift |
| T100 |
2.77 s |
|
| GBM_located |
False |
|
| mjd |
59403.101122685184 |
GCN_circulars,Swift Det |
| IPN table |
|---|
| GRB_name |
GRB210708A |
| ra |
173.7000° |
| decl |
-49.1833° |
| pos_error |
5.00e-02° |
| Swift table |
|---|
| GRB_name |
GRB210708A |
| t_trigger |
2:25:37 UTC |
| ra |
173.6950° |
| decl |
-49.1342° |
| pos_error |
5.18e-04° |
| T90 |
2.77 s |
| fluence |
1.10e-07 erg/cm² |
| GCN 30413 table |
|---|
| GRB_name |
GRB210708A |
| GCN_number |
30413 |
| Detection_method |
Swift Det |
| t_trigger |
2:25:37 UTC |
| ra |
173.6990° |
| decl |
-49.1870° |
| Circular_text |
TITLE: GCN CIRCULAR
NUMBER: 30413
SUBJECT: GRB 210708A: Swift detection of a burst
DATE: 21/07/08 02:40:32 GMT
FROM: David Palmer at LANL
B. Sbarufatti (PSU), H. A. Krimm (NSF), S. Laha (GSFC/UMBC/CRESST),
A. Y. Lien (GSFC/UMBC), F. E. Marshall (NASA/GSFC),
D. M. Palmer (LANL), M. H. Siegel (PSU) and A. Tohuvavohu (U Toronto)
report on behalf of the Neil Gehrels Swift Observatory Team:
At 02:25:37 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 210708A (trigger=1059460). Swift slewed immediately to the burst.
The BAT on-board calculated location is
RA, Dec 173.699, -49.187 which is
RA(J2000) = 11h 34m 48s
Dec(J2000) = -49d 11' 11"
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 10 sec. The peak count rate
was ~1300 counts/sec (15-350 keV), at ~0 sec after the trigger.
The XRT began observing the field at 02:26:37.5 UT, 60.5 seconds after
the BAT trigger. Using promptly downlinked data we find an uncatalogued
X-ray source located at RA, Dec 173.73706, -49.15179 which is
equivalent to:
RA(J2000) = 11h 34m 56.89s
Dec(J2000) = -49d 09' 06.4"
with an uncertainty of 12.2 arcseconds (radius, 90% containment). 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 in excess of the Galactic value (1.58 x
10^21 cm^-2, Willingale et al. 2013), with an excess column of 3.5
(+3.01/-2.55) x 10^21 cm^-2 (90% confidence).
UVOT data is not immediately available, possibly due to a bright
star (mag=5.5) within 1 arcminute of the XRT location.
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/)
|
| GCN 30416 table |
|---|
| GRB_name |
GRB210708A |
| GCN_number |
30416 |
| Detection_method |
Swift-XRT Other |
| ra |
173.7372° |
| decl |
-49.1515° |
| Circular_text |
TITLE: GCN CIRCULAR
NUMBER: 30416
SUBJECT: GRB 210708A: Swift-XRT refined Analysis
DATE: 21/07/08 10:42:33 GMT
FROM: Phil Evans at U of Leicester
D.N. Burrows (PSU), P.A. Evans (U. Leicester), J.P. Osborne (U.
Leicester), K.L. Page (U. Leicester), T. Sbarrato (INAF-OAB), P.
D'Avanzo (INAF-OAB), M.G. Bernardini (INAF-OAB), J. D. Gropp (PSU) and
B. Sbarufatti report on behalf of the Swift-XRT team:
We have analysed 6.8 ks of XRT data for GRB 210708A (Sbarufatti et al.
GCN Circ. 30413), from 85 s to 22.8 ks after the BAT trigger. The data
are entirely in Photon Counting (PC) mode. The refined XRT position is
RA, Dec = 173.7372, -49.1515 which is equivalent to:
RA (J2000): 11 34 56.92
Dec(J2000): -49 09 05.4
with an uncertainty of 7.0 arcsec (radius, 90% confidence).
The light curve can be modelled with a power-law decay with a decay
index of alpha=1.76 (+0.30, -0.65).
A spectrum formed from the PC mode data can be fitted with an absorbed
power-law with a photon spectral index of 2.5 (+0.4, -0.3). The
best-fitting absorption column is 3.0 (+1.2, -1.0) x 10^21 cm^-2, in
excess of the Galactic value of 1.6 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 3.0 x 10^-11 (5.8 x 10^-11) erg
cm^-2 count^-1.
A summary of the PC-mode spectrum is thus:
Total column: 3.0 (+1.2, -1.0) x 10^21 cm^-2
Galactic foreground: 1.6 x 10^21 cm^-2
Excess significance: 2.2 sigma
Photon index: 2.5 (+0.4, -0.3)
If the light curve continues to decay with a power-law decay index of
1.76, the count rate at T+24 hours will be 8.8 x 10^-6 count s^-1,
corresponding to an observed (unabsorbed) 0.3-10 keV flux of 2.6 x
10^-16 (5.1 x 10^-16) erg cm^-2 s^-1.
The results of the XRT-team automatic analysis are available at
http://www.swift.ac.uk/xrt_products/01059460.
This circular is an official product of the Swift-XRT team.
|
| GCN 30421 table |
|---|
| GRB_name |
GRB210708A |
| GCN_number |
30421 |
| Detection_method |
Fermi GBM Other |
| Circular_text |
TITLE: GCN CIRCULAR
NUMBER: 30421
SUBJECT: Fermi GBM Sub-Threshold Detection of GRB 210708A
DATE: 21/07/08 16:52:18 GMT
FROM: Cori Fletcher at USRA
C. Fletcher (USRA) reports on behalf of the Fermi-GBM Team:
Swift-BAT detected GRB 210708A at 02:25:37 UT (GCN 30413). There was no
Fermi-GBM onboard trigger around the event.
An automated, blind search for short gamma-ray bursts below the onboard
triggering threshold in Fermi-GBM identified no counterparts.
The GBM targeted search [1], the most sensitive, coherent search for
GRB-like signals identified a transient most significantly on the 4.096 s
timescale, with a false alarm rate of 1.7e-04 Hz and a location consistent with
the Swift-BAT event, using the standard search protocol with a S/N of 6.
The GBM targeted search event was found with the highest
significance with a "soft" spectrum (Band function with
Epeak = 70 keV, alpha = -1.9, beta = -3.7) for a GRB.
[1] Goldstein et al. 2019 arXiv:1903.12597
|
| GCN 30422 table |
|---|
| GRB_name |
GRB210708A |
| GCN_number |
30422 |
| Detection_method |
Swift-BAT Det |
| ra |
173.7590° |
| decl |
-49.1640° |
| Circular_text |
TITLE: GCN CIRCULAR
NUMBER: 30422
SUBJECT: GRB 210708A: Swift-BAT refined analysis
DATE: 21/07/08 18:08:58 GMT
FROM: Hans Krimm at NSF/NASA-GSFC
T. Sakamoto (AGU), S. D. Barthelmy (GSFC), H. A. Krimm (NSF),
S. Laha (GSFC/UMBC), A. Y. Lien (GSFC/UMBC), C. B. Markwardt (GSFC),
D. M. Palmer (LANL), 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 210708A (trigger #1059460)
(Sbarufatti, et al., GCN Circ. 30413). The BAT ground-calculated position is
RA, Dec = 173.759, -49.164 deg which is
RA(J2000) = 11h 35m 02.3s
Dec(J2000) = -49d 09' 50.2"
with an uncertainty of 2.2 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 94%.
The mask-weighted light curve shows a single peak of duration about 3 seconds,
starting just before T0. T90 (15-350 keV) is 2.77 +- 0.70 sec (estimated error
including systematics).
The time-averaged spectrum from T-0.69 to T+2.44 sec is best fit by a simple
power-law model. The power law index of the time-averaged spectrum is
2.05 +- 0.29. The fluence in the 15-150 keV band is 1.1 +- 0.2 x 10^-7 erg/cm2.
The 1-sec peak photon flux measured from T-0.14 sec in the 15-150 keV band
is 0.8 +- 0.2 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/1059460/BA/
|
| GCN 30425 table |
|---|
| GRB_name |
GRB210708A |
| GCN_number |
30425 |
| Detection_method |
Swift-UVOT Other |
| Circular_text |
TITLE: GCN CIRCULAR
NUMBER: 30425
SUBJECT: GRB 210708A: Swift/UVOT Upper Limits
DATE: 21/07/08 20:24:24 GMT
FROM: Mike Siegel at PSU/Swift MOC
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 210708A
121 s after the BAT trigger (Sbarufatti et al., GCN Circ. 30413).
No optical afterglow consistent with the XRT position
(Sbarufatti et al. GCN Circ. 30413) is detected in the initial UVOT exposures.
We note that the XRT position is close to the bright star HD 100708,
the brightness of which may obscure a faint afterglow.
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 121 370 246 >19.4
v 427 4406 236 >19.6
b 377 5077 108 >19.3
u 121 5021 481 >19.4
w1 476 4816 236 >18.9
m2 452 4611 236 >19.4
w2 403 4201 236 >19.5
The magnitudes in the table are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 0.160 in the direction of the burst
(Schlegel et al. 1998).
|