GRB 220730A
GCN Circular 32431
Subject
GRB 220730A: Swift detection of a short hard burst
Date
2022-07-30T16:05:05Z (3 years ago)
From
David Palmer at LANL <palmer@lanl.gov>
S. Dichiara (PSU), J. A. Kennea (PSU),
N. J. Klingler (GSFC/UMBC/CRESSTII), F. E. Marshall (NASA/GSFC),
K. L. Page (U Leicester), D. M. Palmer (LANL),
A. Tohuvavohu (U Toronto) and M. A. Williams (PSU) report on behalf of
the Neil Gehrels Swift Observatory Team:
At 15:48:55 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 220730A (trigger=1118357). Swift slewed immediately to the burst.
The BAT on-board calculated location is
RA, Dec 225.021, -69.497 which is
RA(J2000) = 15h 00m 05s
Dec(J2000) = -69d 29' 48"
with an uncertainty of 3 arcmin (radius, 90% containment, including
systematic uncertainty). The BAT light curve showed a single spike
structure with a duration of about 0.2 sec. The peak count rate
was ~10000 counts/sec (15-350 keV), at ~0 sec after the trigger.
The XRT began observing the field at 15:50:43.0 UT, 108.2 seconds after
the BAT trigger. No source was detected in 446 s of promptly downlinked
data. We are waiting for the full dataset to detect and localise the
XRT counterpart.
UVOT took a finding chart exposure of 150 seconds with the White filter
starting 111 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 25% of
the BAT error circle. The typical 3-sigma upper limit has been about 19.6 mag.
The 8'x8' region for the list of sources generated on-board covers 91% of the
BAT error circle. The list of sources is typically complete to about 18 mag. No
correction has been made for the expected extinction corresponding to E(B-V) of
0.161.
Burst Advocate for this burst is S. Dichiara (simonedichiara55 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 32432
Subject
Swift GRB 220730A: Global MASTER-Net observations report
Date
2022-07-30T17:00:18Z (3 years ago)
From
Vladimir Lipunov at Moscow State U/Krylov Obs <lipunov@xray.sai.msu.ru>
V. Lipunov, V.Kornilov, E.Gorbovskoy, K.Zhirkov, N.Tyurina, P.Balanutsa, A.Kuznetsov, D. Vlasenko,
G.Antipov, D.Zimnukhov, V.Senik, E.Minkina, A.Chasovnikov, V.Topolev, D.Kuvshinov, D.Cheryasov, Ya.Kechin
(Lomonosov Moscow State University, SAI, Physics Department),
R. Podesta, C.Lopez, F. Podesta, C.Francile
(Observatorio Astronomico Felix Aguilar OAFA),
R. Rebolo, M. Serra
(The Instituto de Astrofisica de Canarias),
D. Buckley
(South African Astronomical Observatory),
O.A. Gres, N.M. Budnev
(Irkutsk State University, API),
L.Carrasco, J.R.Valdes, V.Chavushyan, V.M.Patino Alvarez, J.Martinez, A.R.Corella, L.H.Rodriguez
(INAOE, Guillermo Haro Astrophysics Observatory),
A. Tlatov, D. Dormidontov
(Kislovodsk Solar Station of the Pulkovo Observatory),
A. Gabovich, V.Yurkov
(Blagoveschensk Educational State University)
MASTER-SAAO robotic telescope (Global MASTER-Net: http://observ.pereplet.ru, Lipunov et al., 2010, Advances in Astronomy, vol. 2010, 30L) located in South Africa (South African Astronomical Observatory) was pointed to the Swift GRB 220730A ( S. Dichiara et al., GCN 32431) errorbox 3555 sec after notice time and 3568 sec after trigger time at 2022-07-30 16:48:23 UT, with upper limit up to 17.7 mag. Observations started at twilight. The observations began at zenith distance = 38 deg. The sun altitude is -10.3 deg.
The galactic latitude b = -10 deg., longitude l = 314 deg.
Real time updated cover map and OT discovered available here:
https://master.sai.msu.ru/site/master2/observ.php?id=2044932
We obtain a following upper limits.
Tmid-T0 | Site |Filt.| Expt. | Limit| Comment
_________|_____________________|_____|_______|______|________
3659 | MASTER-SAAO | C | 180 | 17.4 |
3870 | MASTER-SAAO | C | 180 | 17.7 |
Filter C is a clear (unfiltred) band.
The observation and reduction will continue.
The message may be cited.
GCN Circular 32434
Subject
GRB 220730A: Swift-XRT observations
Date
2022-07-31T16:16:31Z (3 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), J.A.
Kennea (PSU), K.L. Page (U. Leicester), A.P. Beardmore (U. Leicester),
A. Melandri (INAF-OAB), T. Sbarrato (INAF-OAB) and S. Dichiara (PSU)
report on behalf of the Swift-XRT team:
We have analysed 5.7 ks of Photon Counting (PC) mode XRT data for the
Swift-BAT-detected burst GRB 220730A (Dichiara et al. GCN Circ. 32431),
collected between T0+3.8 ks and T0+51.6 ks.
Four uncatalogued X-ray sources have been detected consistent with
being within 296 arcsec of the Swift-BAT position, however none of them
is above the RASS limit or shows definitive signs of fading. Therefore,
at the present time we cannot identify which, if any, is the afterglow.
Details of these sources are given below:
Source 1:
RA (J2000.0): 224.9153 = 14:59:39.66
Dec (J2000.0): -69.5540 = -69:33:14.4
Error: 6.4 arcsec (radius, 90% conf.)
Count-rate: (1.27 [+0.69, -0.53])e-3 ct s^-1
Distance: 244 arcsec from Swift-BAT position.
Flux: (4.0 [+2.2, -1.7])e-14 erg cm^-2 s^-1 (observed, 0.3-10 keV)
Source 5:
RA (J2000.0): 225.0143 = 15:00:3.43
Dec (J2000.0): -69.4959 = -69:29:45.4
Error: 6.6 arcsec (radius, 90% conf.)
Count-rate: (1.90 [+1.02, -0.77])e-3 ct s^-1
Distance: 9 arcsec from Swift-BAT position.
Flux: (4.0 [+2.2, -1.6])e-13 erg cm^-2 s^-1 (observed, 0.3-10 keV)
Source 7:
RA (J2000.0): 225.0749 = 15:00:17.98
Dec (J2000.0): -69.4908 = -69:29:26.9
Error: 7.3 arcsec (radius, 90% conf.)
Count-rate: (1.68 [+0.79, -0.62])e-3 ct s^-1
Distance: 71 arcsec from Swift-BAT position.
Flux: (1.12 [+0.53, -0.41])e-13 erg cm^-2 s^-1 (observed, 0.3-10 keV)
Source 8:
RA (J2000.0): 224.9654 = 14:59:51.71
Dec (J2000.0): -69.5389 = -69:32:20.2
Error: 7.4 arcsec (radius, 90% conf.)
Count-rate: (2.53 [+0.93, -0.76])e-3 ct s^-1
Distance: 166 arcsec from Swift-BAT position.
Flux: (3.13 [+1.15, -0.94])e-13 erg cm^-2 s^-1 (observed, 0.3-10 keV)
Five uncatalogued sources were also detected too far from the GRB
position to be likely afterglow candidates.
The results of the XRT-team automatic analysis of the XRT observations,
including a position-specific upper limit calculator, are available at
https://www.swift.ac.uk/ToO_GRBs/01118357.
This circular is an official product of the Swift-XRT team.
GCN Circular 32435
Subject
GRB 220730A: Swift/UVOT Upper Limits
Date
2022-08-01T11:50:57Z (3 years ago)
From
Paul Kuin at MSSL <npkuin@gmail.com>
N. P. M. Kuin (UCL-MSSL) and S. Dichiara (PSU)
report on behalf of the Swift/UVOT team:
The Swift/UVOT began settled observations of the field of GRB 220730A
112 s after the BAT trigger (Dichiara et al., GCN Circ. 32431).
No optical afterglow consistent with any of the positions in GCN Circ.
32434 (D'Ai et al.) has been 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
white_FC 112 261 147 >20.5
u_FC 324 574 246 >19.8
white 112 623 167 >20.6
v 655 675 19 >17.8
b 579 599 19 >18.7
u 324 574 246 >19.8
w2 630 650 19 >18.4
The magnitudes in the table are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 0.161 in the direction of the burst
(Schlegel et al. 1998).
GCN Circular 32436
Subject
GRB 220730A: Swift-XRT afterglow detection
Date
2022-08-01T14:07:50Z (3 years ago)
From
Phil Evans at U of Leicester <pae9@leicester.ac.uk>
S. Dichiara (PSU), A. D'Ai (INAF-IASFPA), D.N. Burrows (PSU), J. D.
Gropp (PSU), J.A. Kennea (PSU), K.L. Page (U. Leicester), A.P.
Beardmore (U. Leicester), A. Melandri (INAF-OAB), T. Sbarrato
(INAF-OAB) and P.A. Evans (U. Leicester) report on behalf of the
Swift-XRT team:
Swift-XRT has conducted further observations of the field of the
Swift-BAT-detected burst GRB 220730A (Dichiara et al. GCN Circ. 32431).
The observations now extend from T0+119 s to T0+124.8 ks.
Of the sources reported by D'Ai et al. (GCN Circ. 32434), "Source 5" is
fading with >3-sigma significance and is believed to be the afterglow.
The position of this source is RA, Dec=225.0143, -69.4959 which is
equivalent to:
RA (J2000): 15:00:3.43
Dec(J2000): -69:29:45.4
with an uncertainty of 6.6 arcsec (radius, 90% confidence). This
position is 9.3 arcsec from the Swift-BAT position.
The results of the XRT-team automatic analysis are available at
http://www.swift.ac.uk/xrt_products/01118357.
The results of the full analysis of the XRT observations are available
at https://www.swift.ac.uk/ToO_GRBs/01118357.
This circular is an official product of the Swift-XRT team.
GCN Circular 32437
Subject
GRB 220730A: Fermi GBM detection
Date
2022-08-02T15:36:47Z (3 years ago)
From
Suraj Poolakkil at UAH <sp0076@uah.edu>
S. Poolakkil (UAH) and C. Meegan (UAH)
report on behalf of the Fermi GBM Team:
"At 15:48:55.032 UT on 30 July 2022, the Fermi Gamma-Ray Burst Monitor (GBM)
triggered and located GRB 220730A (trigger 680888940 / 220730659)
which was also detected by the Swift/BAT (Dichiara et al. 2022, GCN 32431).
The angle from the Fermi LAT boresight at the GBM trigger time is 121
degrees.
The GBM light curve consists of a single peak followed
by some extended emission with a duration (T90) of about 0.16 s (50-300
keV).
The time-averaged spectrum from T0-0.064 s to T0+0.192 s
is best fit by a power law function with an exponential
high-energy cutoff. The power law index is -0.34 +/- 0.18 and
the cutoff energy, parameterized as Epeak, is 488 +/- 84 keV.
A Band function fits equally well, with Epeak = 412 +/- 97 keV,
alpha = -0.21 +/- 0.25 and beta = -2.47 +/- 0.68.
The event fluence (10-1000 keV) in this time interval is
(1.06 +/- 0.09)E-06 erg/cm^2. The 64-ms peak photon flux measured
starting from T0 s in the 10-1000 keV band
is 24.9 +/- 2.2 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 32438
Subject
GRB 220730A: Swift-BAT refined analysis
Date
2022-08-02T15:40:32Z (3 years ago)
From
Hans Krimm at NSF/NASA-GSFC <hkrimm@nsf.gov>
C. B. Markwardt (GSFC), S. D. Barthelmy (GSFC), S. Dichiara (PSU),
H. A. Krimm (NSF), S. Laha (GSFC/UMBC), A. Y. Lien (U Tampa),
D. M. Palmer (LANL), T. Parsotan (GSFC/UMBC), T. Sakamoto (AGU),
M. Stamatikos (OSU) (i.e. the Swift-BAT team):
Using the data set from T-240 to T+700 sec from the recent telemetry downlink,
we report further analysis of BAT GRB 220730A (trigger #1118357)
(Dichiara, et al., GCN Circ. 32431). The BAT ground-calculated position is
RA, Dec = 224.988, -69.496 deg which is
RA(J2000) = 14h 59m 57.1s
Dec(J2000) = -69d 29' 44.5"
with an uncertainty of 1.7 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 60%.
The mask-weighted light curve shows a single FRED-shaped pulse from
approximately T-0.05 to T+0.25 seconds. T90 (15-350 keV) is 0.19 +- 0.20 sec
(estimated error including systematics).
The time-averaged spectrum from T-0.04 to T+0.28 sec is best fit by a simple
power-law model. The power law index of the time-averaged spectrum is
0.61 +- 0.25. The fluence in the 15-150 keV band is 1.6 +- 0.2 x 10^-7 erg/cm2.
The 1-sec peak photon flux measured from T-0.35 sec in the 15-150 keV band
is 1.6 +- 0.3 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/1118357/BA/
GCN Circular 32439
Subject
Konus-Wind detection of GRB 220730A (short)
Date
2022-08-02T16:48:45Z (3 years ago)
From
Dmitry Frederiks at Ioffe Institute <fred@mail.ioffe.ru>
D. Frederiks, A.Lysenko, A. Ridnaia, D. Svinkin,
A. Tsvetkova, M. Ulanov, and T. Cline,
on behalf of the Konus-Wind team, report:
The short GRB 220730A (Swift detection: Dichiara et al., GCN Circ 32431;
Swift-BAT refined analysis: Markwardt et al., GCN Circ 32438;
Fermi GBM detection: Poolakkil & Meegan, GCN Circ 32437)
triggered Konus-Wind (KW) at T0=56937.381 s UT (15:48:57.381).
The burst light curve shows a single emission pulse
which starts at ~T0-0.032 s and has a duration of ~0.1 s.
The emission is seen up to ~2 MeV.
The Konus-Wind light curve of this GRB is available at
http://www.ioffe.ru/LEA/GRBs/GRB220730_T56937/
As observed by Konus-Wind, the burst had
a total fluence of (1.20 �� 0.38)x10^-6 erg/cm^2 and
a 16-ms peak energy flux, measured from T0,
of (1.62 �� 0.51)x10^-5 erg/cm^2/s (both in the 20 keV - 10 MeV energy range).
The spectrum of the burst (measured from T0 to T0+0.064 s)
is best fit in the 20 keV - 15 MeV range by a power law with exponential
cutoff (CPL) model: dN/dE ~ (E^alpha)*exp(-E*(2+alpha)/Ep)
with alpha = -0.14(-0.34,+0.40) and Ep = 369(-59,+92) keV (pgstat = 50/54 dof).
A Band function fits the spectrum equally well with alpha = -0.08 (-0.36,+0.42),
beta = -2.61(-1.33, + 0.45), and Ep = 347 (-54, +86) keV (pgstat = 48/53 dof).
All the quoted errors are estimated at the 68% confidence level.
All the presented results are preliminary.