- GCN NOTICE
TITLE: GCN/FERMI NOTICE
NOTICE_DATE: Sat 27 Jul 24 06:00:38 UT
NOTICE_TYPE: Fermi-GBM Flight Position
RECORD_NUM: 45
TRIGGER_NUM: 743752813
GRB_RA: 149.283d {+09h 57m 08s} (J2000),
149.440d {+09h 57m 46s} (current),
148.965d {+09h 55m 52s} (1950)
GRB_DEC: -66.200d {-66d 12' 00"} (J2000),
-66.318d {-66d 19' 03"} (current),
-65.961d {-65d 57' 39"} (1950)
GRB_ERROR: 9.47 [deg radius, statistical plus systematic]
GRB_INTEN: 273 [cnts/sec]
DATA_SIGNIF: 6.20 [sigma]
INTEG_TIME: 1.024 [sec]
GRB_DATE: 20518 TJD; 209 DOY; 24/07/27
GRB_TIME: 21608.96 SOD {06:00:08.96} UT
GRB_PHI: 340.00 [deg]
GRB_THETA: 150.00 [deg]
DATA_TIME_SCALE: 1.0240 [sec]
HARD_RATIO: 0.00
LOC_ALGORITHM: 3 (version number of)
MOST_LIKELY: 100% Below horizon
2nd_MOST_LIKELY: 0% n/a
DETECTORS: 0,0,0, 0,1,1, 0,0,0, 0,0,0, 0,0,
SUN_POSTN: 127.05d {+08h 28m 12s} +19.08d {+19d 05' 01"}
SUN_DIST: 87.04 [deg] Sun_angle= -1.5 [hr] (East of Sun)
MOON_POSTN: 21.09d {+01h 24m 21s} +10.14d {+10d 08' 13"}
MOON_DIST: 113.99 [deg]
MOON_ILLUM: 60 [%]
GAL_COORDS: 286.57, -9.03 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS: 206.75,-67.14 [deg] ecliptic lon,lat of the burst (or transient)
LC_URL: http://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2024/bn240727250/quicklook/glg_lc_medres34_bn240727250.gif
COMMENTS: Fermi-GBM Flight-calculated Coordinates.
COMMENTS: This trigger occurred at longitude,latitude = 6.05,24.38 [deg].
COMMENTS: The LC_URL file will not be created until ~15 min after the trigger.
- GCN NOTICE
TITLE: GCN/FERMI NOTICE
NOTICE_DATE: Sat 27 Jul 24 06:00:47 UT
NOTICE_TYPE: Fermi-GBM Flight Position
RECORD_NUM: 58
TRIGGER_NUM: 743752813
GRB_RA: 143.217d {+09h 32m 52s} (J2000),
143.378d {+09h 33m 31s} (current),
142.889d {+09h 31m 33s} (1950)
GRB_DEC: -61.933d {-61d 55' 59"} (J2000),
-62.043d {-62d 02' 34"} (current),
-61.711d {-61d 42' 38"} (1950)
GRB_ERROR: 9.53 [deg radius, statistical plus systematic]
GRB_INTEN: 187 [cnts/sec]
DATA_SIGNIF: 9.40 [sigma]
INTEG_TIME: 4.096 [sec]
GRB_DATE: 20518 TJD; 209 DOY; 24/07/27
GRB_TIME: 21608.96 SOD {06:00:08.96} UT
GRB_PHI: 342.00 [deg]
GRB_THETA: 145.00 [deg]
DATA_TIME_SCALE: 4.0960 [sec]
HARD_RATIO: 0.00
LOC_ALGORITHM: 3 (version number of)
MOST_LIKELY: 100% Below horizon
2nd_MOST_LIKELY: 0% n/a
DETECTORS: 0,0,0, 0,1,1, 0,0,0, 0,0,0, 0,0,
SUN_POSTN: 127.05d {+08h 28m 12s} +19.08d {+19d 05' 01"}
SUN_DIST: 82.16 [deg] Sun_angle= -1.1 [hr] (East of Sun)
MOON_POSTN: 21.09d {+01h 24m 21s} +10.14d {+10d 08' 15"}
MOON_DIST: 113.70 [deg]
MOON_ILLUM: 60 [%]
GAL_COORDS: 281.73, -7.54 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS: 193.79,-67.17 [deg] ecliptic lon,lat of the burst (or transient)
LC_URL: http://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2024/bn240727250/quicklook/glg_lc_medres34_bn240727250.gif
COMMENTS: Fermi-GBM Flight-calculated Coordinates.
COMMENTS: This trigger occurred at longitude,latitude = 6.05,24.38 [deg].
COMMENTS: The LC_URL file will not be created until ~15 min after the trigger.
- GCN NOTICE
TITLE: GCN/FERMI NOTICE
NOTICE_DATE: Sat 27 Jul 24 06:01:13 UT
NOTICE_TYPE: Fermi-GBM Flight Position
RECORD_NUM: 70
TRIGGER_NUM: 743752813
GRB_RA: 145.767d {+09h 43m 04s} (J2000),
145.899d {+09h 43m 36s} (current),
145.497d {+09h 41m 59s} (1950)
GRB_DEC: -67.167d {-67d 10' 00"} (J2000),
-67.280d {-67d 16' 47"} (current),
-66.937d {-66d 56' 12"} (1950)
GRB_ERROR: 6.40 [deg radius, statistical plus systematic]
GRB_INTEN: 328 [cnts/sec]
DATA_SIGNIF: 14.30 [sigma]
INTEG_TIME: 4.096 [sec]
GRB_DATE: 20518 TJD; 209 DOY; 24/07/27
GRB_TIME: 21608.96 SOD {06:00:08.96} UT
GRB_PHI: 340.00 [deg]
GRB_THETA: 150.00 [deg]
DATA_TIME_SCALE: 4.0960 [sec]
HARD_RATIO: 0.00
LOC_ALGORITHM: 3 (version number of)
MOST_LIKELY: 100% Below horizon
2nd_MOST_LIKELY: 0% n/a
DETECTORS: 0,0,0, 0,1,1, 0,0,0, 0,0,0, 0,0,
SUN_POSTN: 127.05d {+08h 28m 12s} +19.08d {+19d 05' 00"}
SUN_DIST: 87.49 [deg] Sun_angle= -1.3 [hr] (East of Sun)
MOON_POSTN: 21.09d {+01h 24m 22s} +10.14d {+10d 08' 22"}
MOON_DIST: 112.30 [deg]
MOON_ILLUM: 60 [%]
GAL_COORDS: 286.12,-10.67 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS: 207.40,-68.82 [deg] ecliptic lon,lat of the burst (or transient)
LC_URL: http://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2024/bn240727250/quicklook/glg_lc_medres34_bn240727250.gif
COMMENTS: Fermi-GBM Flight-calculated Coordinates.
COMMENTS: This trigger occurred at longitude,latitude = 6.05,24.38 [deg].
COMMENTS: The LC_URL file will not be created until ~15 min after the trigger.
- GCN Circular #36943
G. Waratkar (IITB), J. Joshi (IUCAA), 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-duration GRB 240727B which was also detected by Fermi/GBM (Trigger 743752813). Inspection of INTEGRAL/SPI-ACS data also showed the detection of the burst.
The source was clearly detected in the CsI anticoincidence (Veto) detector in the 100-500 keV energy range. The light curve peaks at 2024-07-27 06:00:15.7 UTC. The measured peak count rate is 353 (+85, -34) counts/s above the background in the combined Veto data of all quadrants, with a total of 3126 (+699, -758) counts. The local mean background count rate was 1440 (+8, -8) counts/s. We measure a T90 of 17 (+10, -7) s from the cumulative Veto light curve.
It was also detected in the CZT detectors in the 20-200 keV energy range. The light curve peaks at 2024-07-27 06:00:18.5 UTC. The measured peak count rate associated with the burst is 72 (+37, -11) counts/s above the background in the combined data of all quadrants, with a total of 468 (+180, -183) counts. The local mean background count rate was 331 (+3, -4) counts/s. Using cumulative rates, we measure a T90 of 12 (+3, -6) s.
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.
CZTI GRB detections are reported regularly on the payload site at:
http://astrosat.iucaa.in/czti/?q=grb
- GCN Circular #36945
FROM: Samuele Ronchini at PSU
Samuele Ronchini (PSU), James DeLaunay (PSU), Aaron Tohuvavohu (U Toronto),
Gayathri Raman (PSU), Jamie A. Kennea (PSU), Tyler Parsotan (NASA GSFC) report:
Swift/BAT did not localize GRB 240727B onboard (T0: 2024-07-27T06:00:08.96
UTC, AstroSat GCN 36943, Fermi trig. 743752813).
The Fermi notice, distributed in near real-time, triggered the Swift Mission
Operations Center operated Gamma-ray Urgent Archiver for Novel Opportunities
(GUANO; Tohuvavohu et al. 2020, ApJ, 900, 1).=20
Upon trigger by this notice, GUANO sent a command to the Swift Burst Alert
Telescope (BAT) to save 200 seconds of BAT event-mode data from [-50,+150]
seconds around the time of the burst. All the requested event mode data was
delivered to the ground.
The BAT likelihood search, NITRATES (DeLaunay + Tohuvavohu 2022, ApJ, 941,
169), detects the burst in a 16.384 s analysis time bin starting at T0 s wi=
th a sqrt(TS) of 45.6.
An arcminute localization is found with DeltaLLHOut of 29.3 and a DeltaLLHP=
eak of 49.37.
See Section 9.1 and Figures 10 and 17 in the NITRATES paper for brief descr=
iptions and interpretations of sqrt(TS), DeltaLLHPeak, and DeltaLLHOut.
The BAT position is
RA, Dec =3D 97.786, -37.18 deg which is
RA(J2000) =3D 06h 31m 08.64s
Dec(J2000) =3D -37d 10=E2=80=B2 48.0=E2=80=B3
with an estimated uncertainty of 4 arcmin radius.
XRT and UVOT follow-up has been requested.
Results of follow-up observations will be reported in future circulars.
GUANO is a fully autonomous, extremely low latency, spacecraft
commanding pipeline designed for targeted recovery of BAT event mode
data around the times of compelling astrophysical events to enable
more sensitive GRB searches.
A live reporting of Swift/BAT event data recovered by GUANO can be
found at: https://www.swift.psu.edu/guano/
- GCN Circular #36946
P. A. Evans (U. Leicester) reports on behalf of the Swift team:
Swift has initiated a ToO observation of the Fermi/GBM GRB 240727B.
Automated analysis of the XRT data will be presented online at
https://www.swift.ac.uk/ToO_GRBs/00021701
Any uncatalogued X-ray sources detected in this analysis will be
reported on this website and via GCN COUNTERPART notices. These are
not necessarily related to the Fermi/GBM event. Any X-ray source
considered to be a probable afterglow candidate will be reported via a
GCN Circular after manual consideration.
Details of the XRT automated analysis methods are detailed in Evans et
al. (2007, A&A, 469, 379; 2009, MNRAS, 397, 1177 and 2014, ApJS, 210, 8).
This circular is an official product of the Swift-XRT team.
- GCN Circular #36949
C. Fletcher (USRA), R. Hamburg (CNRS/IJCLab) and C. Meegan (UAH) report on behalf of
the Fermi Gamma-ray Burst Monitor Team:
"At 06:00:08.96 UT on 27 July 2024, the Fermi Gamma-ray Burst Monitor (GBM)
triggered and located GRB 240727B (trigger 743752813/240727250).
which was also detected by Swift/BAT-GUANO (Ronchini et al. 2024, GCN 36945) and AstroSat (Waratkar et al. 2024, GCN 36943).
The Fermi GBM on-ground location is consistent with the Swift/BAT-GUANO position.
The angle from the Fermi LAT boresight is 114 degrees.
The GBM light curve consists of multiple peaks with a duration (T90)
of about 19 s (50-300 keV). The time-averaged spectrum
from T0-3.3 to T0+20.2 s is best fit by
a power law function with an exponential high-energy cutoff.
The power law index is -0.3 +/- 0.1 and the cutoff energy,
parameterized as Epeak, is 850 +/- 90 keV.
The event fluence (10-1000 keV) in this time interval is
(1.52 +/- 0.05)E-05 erg/cm^2. The 1-sec peak photon flux measured
starting from T0+8.7 s in the 10-1000 keV band is 3.4 +/- 0.4 ph/s/cm^2.
A Band function fits the spectrum equally well
with Epeak= 848 +/- 116 keV, alpha = -0.3 +/- 0.1 and beta = -2.5 +/- 0.3.
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 #36970
D.N. Burrows (PSU), J. D. Gropp (PSU), S. Dichiara (PSU), K.L. Page (U.
Leicester), A.P. Beardmore (U. Leicester), B. Sbarufatti (INAF-OAB), C.
Salvaggio (INAF-OAB), M. Ferro (INAF-OAB) and P.A. Evans (U. Leicester)
reports on behalf of the Swift-XRT team:
Swift-XRT has performed follow-up observations of the Fermi/GBM,
Swift/BAT-GUANO and Astrosat/CZTI detected burst GRB 240727B (Fletcher
et al. 2024, GCN 36949; Ronchini et al. 2024, GCN 36945; Waratkar et
al. 2024, GCN 36943), collecting 4.9 ks of Photon Counting (PC) mode
data between T0+33.5 ks and T0+52.2 ks.
No X-ray sources have been detected within 296 arcsec of the
Swift/BAT-GUANO position. The 3-sigma upper limit in the field is 0.003
ct s^-1, corresponding to a 0.3-10 keV observed flux of 1.0e-13 erg
cm^-2 s^-1 (assuming a typical GRB spectrum).
Three uncatalogued sources were 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/00021701.
This circular is an official product of the Swift-XRT team.
Previous IAU Circulars 