GRB 220930A
GCN Circular 32617
Subject
GRB 220930A: AbAO Optical Upper Limit
Date
2022-10-02T22:48:28Z (3 years ago)
From
Alexei Pozanenko at IKI, Moscow <apozanen@iki.rssi.ru>
N. Pankov (IKI), R. Ya. Inasaridze (AbAO), A. Pozanenko (IKI), S. Belkin
(IKI, HSE), V. R. Ayvazian (AbAO), D. Datashvili (AbAO), G. V.
Kapanadze (AbAO) report on behalf of GRB IKI FuN:
We observed the field of GRB 220930A (Cenko et. al, GCN 32603) with
AS-32 telescope of Abastumani Observatory (AbAO). We do not detect any
objects within enhanced Swift-XRT error region (Evans et. al, GCN
32608). The 3-sigma upper limit is following:
Date, UT start, t-T0, Exp., Filter, OT, Err, UL(3 sigma)
(mid, days)
2022-09-30 22:09:17 0.48085 70*60 R n/d n/d 22.3
The photometry is based on nearby USNO-B1.0 stars
USNO_B10_id R2
1033-0057261 16.60
1033-0057239 17.39
The obtained result is consistent with non-detections reported earlier
(Watson et. al, GCN 32604; Hu et al, GCN 32606; Lipunov et al, GCN
32607; Belles and Cenko, GCN 32609; Strausbaugh and Cucchiara, GCN 32610).
GCN Circular 32614
Subject
Konus-Wind detection of GRB 220930A
Date
2022-10-02T17:09:27Z (3 years ago)
From
Anna Ridnaia at Ioffe Institute <ridnaia@mail.ioffe.ru>
A.Ridnaia, D. Frederiks, A.Lysenko, D. Svinkin,
A. Tsvetkova, M. Ulanov, and T. Cline,
on behalf of the Konus-Wind team, report:
The long-duration GRB 220930A
(Swift-BAT detection: Cenko et al., GCN 32603,
Barthelmy et al., GCN 32612;
AstroSat-CZTI detection: Gopalakrishnan et al., GCN 32613)
triggered Konus-Wind at T0=40312.503 s UT (11:11:52.503).
The burst light curve shows a multipeaked structure
which starts at ~T0-1.5 s and has a total duration of ~76.0 s.
The emission is seen up to ~4 MeV.
The Konus-Wind light curve of this GRB is available at
http://www.ioffe.ru/LEA/GRBs/GRB220930_T40312/
As observed by Konus-Wind, the burst
had a fluence of 1.78(-0.64,+0.98)x10^-5 erg/cm2,
and a 64-ms peak flux, measured from T0+0.960 s,
of 5.39(-2.28,+2.15)x10^-6 erg/cm2/s
(both in the 20 keV - 10 MeV energy range).
The time-averaged spectrum of the burst
(measured from T0 to T0+73.984 s)
is best fit in the 20 keV - 10 MeV range
by the GRB (Band) model with the following parameters:
the low-energy photon index alpha = -0.06(-1.06,+1.43),
the high energy photon index beta = -2.41(-0.51,+0.46),
the peak energy Ep = 198(-58,+181) keV
(chi2 = 91/98 dof).
The spectrum near the maximum count rate
(measured from T0 to T0+8.448 s)
is best fit in the 20 keV - 10 MeV range
by the GRB (Band) model with the following parameters:
the low-energy photon index alpha = -0.38(-0.56,+0.66),
the high energy photon index beta = -2.25(-1.42,+0.23),
the peak energy Ep = 215(-52,+121) keV
(chi2 = 97/96 dof).
All the quoted errors are at the 90% confidence level.
All the quoted values are preliminary.
GCN Circular 32613
Subject
GRB 220930A: AstroSat CZTI detection
Date
2022-10-02T05:27:01Z (3 years ago)
From
Gaurav Waratkar at IIT,Bombay <gauravwaratkar@iitb.ac.in>
R. Gopalakrishnan (IUCAA), V. Prasad (IUCAA), G. Waratkar (IITB), A.
Vibhute (IUCAA), V. Bhalerao (IITB), D. Bhattacharya (Ashoka
University/IUCAA), A. R. Rao (IUCAA/TIFR), and S. Vadawale (PRL) report
on behalf of the AstroSat CZTI collaboration:
Analysis of AstroSat CZTI data with the CIFT framework (Sharma et al.,
2021, JApA, 42, 73) showed the detection of a long GRB 220930A which was
also detected by Swift-BAT (Cenko et at., GCN 32603), Swift-XRT (Evans
et al., GCN 32608), and Swift/UVOT (Belles et al., GCN 32609).
The source was clearly detected in the 20-200 keV energy range. The
light curve peaks at 2022-09-30 11:11:52.50 UTC. The measured peak count
rate associated with the burst is 435 (+49, -54) counts/s above the
background in the combined data of all quadrants, with a total of 1508
(+301, -353) counts. The local mean background count rate was 501 (+3,
-3) counts/s. Using cumulative rates, we measure a T90 of 9 (+8, -5) s.
It was also clearly detected in the CsI anticoincidence (Veto) detector
in the 100-500 keV energy range. The light curve peaks at 2022-09-30
11:11:51.80 UTC. The measured peak count rate is 911 (+80, -88) counts/s
above the background in the combined Veto data of all quadrants, with a
total of 3694 (+515, -521) counts. The local mean background count rate
was 1597 (+6, -7) counts/s. We measure a T90 of 13 (+5, -5) s from the
cumulative Veto light curve.
CZTI GRB detections are reported regularly on the payload site at
http://astrosat.iucaa.in/czti/?q=grb. CZTI is built by a TIFR-led
consortium of institutes across India, including VSSC, URSC, IUCAA, SAC,
and PRL. The Indian Space Research Organisation funded, managed, and
facilitated the project.
GCN Circular 32612
Subject
GRB 220930A: Swift-BAT refined analysis
Date
2022-10-02T03:35:10Z (3 years ago)
From
Sibasish Laha at GSFC <sibasish.laha@nasa.gov>
S. D. Barthelmy (GSFC), H. A. Krimm (NSF),
S. Laha (GSFC/UMBC), A. Y. Lien (U Tampa),
C. B. Markwardt (GSFC), 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-239 to T+963 sec from the recent telemetry downlink,
we report further analysis of BAT GRB 220930A (trigger #1125809)
(Cenko et al., GCN Circ. 32603). The BAT ground-calculated position is
RA, Dec = 64.725, 13.353 deg which is
RA(J2000) = 04h 18m 54.0s
Dec(J2000) = +13d 21' 12.0"
with an uncertainty of 1.7 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 11%.
The BAT light curve showed a complex structure with a duration of about 200 sec.
T90 (15-350 keV) is 180.47 +- 104.20 sec (estimated error including systematics).
The time-averaged spectrum from T-0.42 to T+235.67 sec is best fit by a simple
power-law model. The power law index of the time-averaged spectrum is
1.59 +- 0.13. The fluence in the 15-150 keV band is 5.5 +- 0.4 x 10^-06 erg/cm2.
The 1-sec peak photon flux measured from T-0.31 sec in the 15-150 keV band
is 6.2 +- 1.0 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/1125809/BA/
GCN Circular 32611
Subject
GRB 220930A: Swift-XRT refined Analysis
Date
2022-10-01T04:58:30Z (3 years ago)
From
Phil Evans at U of Leicester <pae9@leicester.ac.uk>
V. D'Elia (SSDC & INAF-OAR), B. Sbarufatti (INAF-OAB), D.N. Burrows
(PSU), J. D. Gropp (PSU), S. Dichiara (PSU), K.L. Page (U. Leicester),
A.P. Beardmore (U. Leicester), P.A. Evans (U. Leicester), A. D'Ai
(INAF-IASFPA) and S.B. Cenko report on behalf of the Swift-XRT team:
We have analysed 6.9 ks of XRT data for GRB 220930A (Cenko et al. GCN
Circ. 32603), from 160 s to 35.9 ks after the BAT trigger. The data
comprise 390 s in Windowed Timing (WT) mode (the first 9 s were taken
while Swift was slewing) with the remainder in Photon Counting (PC)
mode. The enhanced XRT position for this burst was given by Evans et
al. (GCN Circ. 32605).
The late-time light curve (from T0+5.1 ks) can be modelled with a
power-law decay with a decay index of alpha=1.28 (+/-0.11).
A spectrum formed from the WT mode data can be fitted with an absorbed
power-law with a photon spectral index of 1.59 (+/-0.08). The
best-fitting absorption column is 4.9 (+0.6, -0.5) x 10^21 cm^-2, in
excess of the Galactic value of 2.8 x 10^21 cm^-2 (Willingale et al.
2013). The PC mode spectrum has a photon index of 1.82 (+0.16, -0.15)
and a best-fitting absorption column of 6.4 (+1.2, -1.1) x 10^21 cm^-2.
The counts to observed (unabsorbed) 0.3-10 keV flux conversion factor
deduced from this spectrum is 4.7 x 10^-11 (7.3 x 10^-11) erg cm^-2
count^-1.
A summary of the PC-mode spectrum is thus:
Total column: 6.4 (+1.2, -1.1) x 10^21 cm^-2
Galactic foreground: 2.8 x 10^21 cm^-2
Excess significance: 5.4 sigma
Photon index: 1.82 (+0.16, -0.15)
If the light curve continues to decay with a power-law decay index of
1.28, the count rate at T+24 hours will be 0.017 count s^-1,
corresponding to an observed (unabsorbed) 0.3-10 keV flux of 8.3 x
10^-13 (1.3 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/01125809.
This circular is an official product of the Swift-XRT team.
GCN Circular 32610
Subject
GRB 220930A: LCOGT Optical Upper Limits
Date
2022-10-01T04:03:35Z (3 years ago)
From
Robert Strausbaugh at University of Minnesota <rstrausb@umn.edu>
R. Strausbaugh (University of Minnesota), A. Cucchiara (College of Marin)
report on behalf of a larger collaboration:
We observed the Swift GRB 220930A (Cenko et al., GCN 32603) field with the
LCOGT 1-meter Sinistro instrument at the South African Astronomical
Observatory site, on October 1, from 00:42 to 01:24 (corresponding to 13.52
to 14.22 hours from the GRB trigger time) with the SDSS i and r filters.
We performed a series of 3x300s exposures in i and r bands. We do not
detect any uncatalogued sources in the XRT enhanced error region (Evans et
al., GCN 32608), in either band, consistent with other optical upper limits
(Watson et al., GCN 32604; Hu et al., GCN 32606; Belles et al., GCN 32609).
The following upper limits are calculated using the Pan-STARRS catalog as
reference:
r > 22.08
i > 21.73
These magnitudes are not corrected for galactic extinction.
GCN Circular 32609
Subject
GRB 220930A: Swift/UVOT Upper Limits
Date
2022-09-30T20:39:10Z (3 years ago)
From
Alexander Belles at PSU/Swift <aub1461@psu.edu>
A. Belles (PSU) and S. B. Cenko (GSFC)
report on behalf of the Swift/UVOT team:
The Swift/UVOT began settled observations of the field of GRB 220930A
180 s after the BAT trigger (Cenko et al., GCN Circ. 32603).
No optical afterglow consistent with the XRT position
(Evans et al. GCN Circ. 32608)
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
wh_FC 180 330 147 >20.71
u_FC 338 588 245 >19.95
wh 618 1368 225 >20.93
v 669 1418 97 >18.73
b 594 1343 77 >19.59
u 744 1318 58 >18.99
w1 719 1467 77 >18.83
m2 693 1442 77 >18.59
w2 644 1393 97 >19.10
The magnitudes in the table are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 0.639 in the direction of the burst
(Schlegel et al. 1998).
GCN Circular 32608
Subject
GRB 220930A: Enhanced Swift-XRT position
Date
2022-09-30T15:35:59Z (3 years ago)
From
Phil Evans at U of Leicester <pae9@leicester.ac.uk>
P.A. Evans, M.R. Goad, J.P. Osborne and A.P. Beardmore (U. Leicester)
report on behalf of the Swift-XRT team.
Using 892 s of XRT Photon Counting mode data and 1 UVOT
images for GRB 220930A, 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 = 64.71717, +13.34902 which is equivalent
to:
RA (J2000): 04h 18m 52.12s
Dec (J2000): +13d 20' 56.5"
with an uncertainty of 2.2 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 32607
Subject
Swift GRB 220930A: Global MASTER-Net observations report
Date
2022-09-30T15:08:15Z (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-Amur robotic telescope (Global MASTER-Net: http://observ.pereplet.ru, Lipunov et al., 2010, Advances in Astronomy, vol. 2010, 30L) located in Russia (Blagoveshchensk State Pedagogical University) was pointed to the Swift GRB 220930A ( S. B. Cenko et al., GCN 32603) errorbox 11539 sec after notice time and 11568 sec after trigger time at 2022-09-30 14:24:40 UT, with upper limit up to 19.3 mag. The observations began at zenith distance = 69 deg. The sun altitude is -41.3 deg.
The galactic latitude b = -25 deg., longitude l = 181 deg.
Real time updated cover map and OT discovered available here:
https://master.sai.msu.ru/site/master2/observ.php?id=2105765
We obtain a following upper limits.
Tmid-T0 | Site |Filt.| Expt. | Limit| Comment
_________|_____________________|_____|_______|______|________
11659 | MASTER-Amur | C | 180 | 19.3 |
Filter C is a clear (unfiltred) band.
The observation and reduction will continue.
The message may be cited.
GCN Circular 32606
Subject
GRB 220930A: BOOTES-5/JGT early optical upper limit
Date
2022-09-30T13:19:08Z (3 years ago)
From
Youdong HU at IAA-CSIC <huyoudong072@hotmail.com>
Y.-D. Hu, E. Fernandez-Garcia, A. J. Castro-Tirado, I. Perez-Garcia, M.D. Caballero-Garcia, R. Sanchez-Ramirez (IAA-CSIC), D. Hiriart and W. H. Lee (UNAM), C. J. Perez del Pulgar and I. Carrasco (UMA), I. H. Park (SKKU) on behalf of a larger collaboration, report:
Following the detection of GRB 220930A by Swift (Cenko et al. GCNC 32603), the BOOTES-5/JGT 0.6m robotic telescope at Observatorio Astronomico Nacional in San Pedro Martir (Mexico) observed the GRB location starting on Sep. 30, 11:13:05 UT (~ 73 s after trigger). In the early co-added image (18 x 10 s exposures in the clear filter), no optical afterglow is detected within the enhanced Swift/XRT error region (Evans et al. GCNC 32605) down to 21.0 mag, which is consistent with the limits reported by UVOT (Cenko et al. GCNC 32603) and COATLI (Watson et al. GCNC 32604).
We thank the staff at Observatorio Astronomico Nacional in San Pedro Martir for their excellent support.
GCN Circular 32605
Subject
GRB 220930A: Prompt enhanced Swift-XRT position
Date
2022-09-30T12:16:14Z (3 years ago)
From
Phil Evans at U of Leicester <pae9@leicester.ac.uk>
P.A. Evans (U. Leicester) reports on behalf of the Swift-XRT team:
Using promptly downlinked XRT event data for GRB 220930A, we find an
enhanced XRT position of the afterglow: RA, Dec: 64.71723, 13.34924
which is equivalent to:
RA (J2000) = 04 18 52.14
Dec (J2000) = +13 20 57.3
with an uncertainty of 1.9 arcseconds (radius, 90% confidence).
Analysis of the promptly available data is online at
http://www.swift.ac.uk/sper/1125809.
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 Circular 32604
Subject
GRB 220930A: COATLI Upper Limits
Date
2022-09-30T12:09:45Z (3 years ago)
From
Alan M Watson at UNAM <alan@astro.unam.mx>
Alan M. Watson (UNAM), Nat Butler (ASU), Rosa L. Becerra (UNAM), Simone Dichiara (PSU), Tzveti Dimitrova (ASU), Oc��lotl L��pez (UNAM), Diego Gonz��lez (UNAM), Alexander Kutyrev (GSFC), William H. Lee (UNAM), Margarita Pereyra (UNAM), Eleonora Troja (UTV/ASU) and report:
We observed the field of the Swift/BAT GRB 220930A (Cenko, GCN Circ. 32603) with the COATLI 50-cm telescope and HUITZI f/8 imager at the Observatorio Astron��mico Nacional on the Sierra de San Pedro M��rtir (http://coatli.astroscu.unam.mx) from 2022-09-30 11:22 UTC to 11:59 UTC (10.5 to 48 minutes after the trigger), obtaining a total of 1920 seconds of exposure in the r filter.
We do not detect any uncataloged sources in the XRT error region (Cenko, GCN Circ. 32603) to a 3-sigma limit of r = 22.5.
Our photometry is calibrated against the Pan-STARRS1 catalog, are on an approximate AB system, and are not corrected for Galactic extinction in the direction of the GRB.
We thank the COATLI/HUITZI technical team and the staff of the Observatorio Astron��mico Nacional.
GCN Circular 32603
Subject
GRB 220930A: Swift detection of a burst
Date
2022-09-30T11:36:03Z (3 years ago)
From
Kim Page at U.of Leicester <klp5@leicester.ac.uk>
S. B. Cenko (GSFC), A. P. Beardmore (U Leicester), C. Gronwall (PSU),
J. A. Kennea (PSU), N. P. M. Kuin (UCL-MSSL), K. L. Page (U Leicester)
and T. M. Parsotan (GSFC/UMBC/CRESSTII) report on behalf of the Neil
Gehrels Swift Observatory Team:
At 11:11:52 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 220930A (trigger=1125809). Swift slewed immediately to the
burst.
The BAT on-board calculated location is
RA, Dec 64.737, +13.352 which is
RA(J2000) = 04h 18m 57s
Dec(J2000) = +13d 21' 06"
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 and a secondary peak at about
70 seconds after the trigger time. The peak count rate
was ~3000 counts/sec (15-350 keV), at ~0 sec after the trigger.
The XRT began observing the field at 11:14:42.1 UT, 170.0 seconds after
the BAT trigger. XRT found a bright, uncatalogued X-ray source located
at RA, Dec 64.7149, 13.3500 which is equivalent to:
RA(J2000) = 04h 18m 51.58s
Dec(J2000) = +13d 21' 00.0"
with an uncertainty of 5.0 arcseconds (radius, 90% containment). This
location is 77 arcseconds from the BAT onboard position, within the BAT
error circle. No event data are yet available to determine the column
density using X-ray spectroscopy.
The initial flux in the 2.5 s image was 3.09e-09 erg cm^-2 s^-1 (0.2-10
keV).
UVOT took a finding chart exposure of 150 seconds with the White filter
starting 179 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 19.6 mag. The 8'x8' region for the list of sources
generated on-board covers 100% of the XRT 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 0.639.
Burst Advocate for this burst is S. B. Cenko (brad.cenko AT nasa.gov).
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/)