TITLE: GCN CIRCULAR
NUMBER: 35485
SUBJECT: IceCube-240105A - IceCube observation of a high-energy neutrino candidate track-like event
DATE: 24/01/05 15:22:16 GMT
FROM: Erik Blaufuss at University of Maryland, College Park <blaufuss(a)umd.edu>
The IceCube Collaboration (http://icecube.wisc.edu/) reports:
On 2024-01-05 at 12:27:42.57 UT IceCube detected a track-like event with a moderate probability of being of astrophysical origin. The event was selected by the ICECUBE_Astrotrack_Bronze alert stream. The average astrophysical neutrino purity
for Bronze alerts is 30%. This alert has an estimated false alarm rate of 2.64 events per year due to atmospheric backgrounds. The IceCube detector was in a normal operating state at the time of detection.
After the initial automated alert (https://gcn.gsfc.nasa.gov/notices_amon_g_b/138821_46175426.amon), more sophisticated reconstruction algorithms have been applied offline, with the direction refined to:
Date: 2024-01-05
Time: 12:27:42.57 UT
RA: 72.69 (+0.53, -0.33 deg 90% PSF containment) J2000
Dec: +11.42 (+0.20, -0.08 deg 90% PSF containment) J2000
We encourage follow-up by ground and space-based instruments to help identify a possible astrophysical source for the candidate neutrino.
One gamma-ray source listed in the 4FGL-DR4 Fermi-LAT catalog is located in the 90% uncertainty of the event. The source is 4FGL J0449.1+112 (associated with PKS 0446+11), located at RA = 72.28 deg and Dec = +11.36 deg (J2000), 0.4 deg away from the best-fit position.
The IceCube Neutrino Observatory is a cubic-kilometer neutrino detector operating at the geographic South Pole, Antarctica. The IceCube realtime alert point of contact can be reached at roc(a)icecube.wisc.edu
View this GCN Circular online at https://gcn.nasa.gov/circulars/35485.
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TITLE: GCN CIRCULAR
NUMBER: 35484
SUBJECT: GRB 240102A: 1.3m DFOT optical upper limit
DATE: 24/01/05 11:20:00 GMT
FROM: Amit Kumar Ror at ARIES <mitturor77894(a)gmail.com>
Amit K. Ror, Rahul Gupta, Amar Aryan, and Shashi B. Pandey (ARIES) report:
We observed the field of GRB 240102A detected by Swift (Gropp et al. 2024,
GCN 35461) with the 1.3m Devasthal Fast Optical Telescope (DFOT), located
at the Devasthal Observatory of the Aryabhatta Research Institute of
Observational Sciences (ARIES), India. The observations were started on
2024-01-02 at 18:23:56 UT, i.e., ~ 49 minutes after the BAT trigger. We
have taken multiple frames with an exposure time of 300 s in the R filter.
We stacked the images after the alignment. We did not detect any optical
afterglow in our stacked image within the enhanced Swift-XRT error box
(Goad et al., 2024, GCN 35471). We obtain the following preliminary 3-sigma
upper limit in the stacked image:
Date Start_UT T_start-T0 (minutes) Filter Exp time (s) Limiting magnitude
=========================================================
2024-01-02 18:23:56 ~49 R 300*20 > 21.5
Our non-detection is consistent with the observations of Hu et al. 2024,
GCN 35465; Strausbaugh et al. 2024, GCN 35467; and Belles et al. 2024, GCN
35475.
The magnitude is not corrected for the Galactic extinction in the direction
of the burst. Photometric calibration is performed using the standard stars
from the USNO-B1.0 catalog. This circular may be cited.
View this GCN Circular online at https://gcn.nasa.gov/circulars/35484.
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TITLE: GCN CIRCULAR
NUMBER: 35483
SUBJECT: GRB 240101B: 1.3m DFOT optical upper limit
DATE: 24/01/05 11:17:13 GMT
FROM: Amit Kumar Ror at ARIES <mitturor77894(a)gmail.com>
Amit K. Ror, Rahul Gupta, Amar Aryan, and Shashi B. Pandey (ARIES) report:
We observed the field of the GRB 240101B detected by Swift (Cenko et al.
2024, GCN 35449) with the 1.3m Devasthal Fast Optical Telescope (DFOT),
located at the Devasthal Observatory of the Aryabhatta Research Institute
of Observational Sciences (ARIES), India. The observations were started on
2024-01-02 at 12:43:55 UT, i.e., ~ 0.68 days after the BAT trigger. We have
taken multiple frames with an exposure time of 300 s in the R filter. We
stacked the images after the alignment. We did not detect any optical
afterglow in our stacked image within the enhanced Swift-XRT error box
(Evans et al., 2024, GCN 35455). We obtain the following preliminary
3-sigma upper limit in the stacked image:
Date Start_UT T_start-T0 (days) Filter Exp time (s) Limiting magnitude
=========================================================
2024-01-02 12:43:55 ~0.68 R 300*12 > 21.7
Our non-detection is consistent with Zheng et al. 2024, GCN 35454; Kuin et
al. 2024, GCN 35458; and Peretto 2024, GCN 35463.
The magnitude is not corrected for the Galactic extinction in the direction
of the burst. Photometric calibration is performed using the standard stars
from the USNO-B1.0 catalog. This circular may be cited.
View this GCN Circular online at https://gcn.nasa.gov/circulars/35483.
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TITLE: GCN CIRCULAR
NUMBER: 35482
SUBJECT: GRB 240101C: Swift/BAT-GUANO detection of a short burst
DATE: 24/01/05 02:17:35 GMT
FROM: Jimmy DeLaunay at Penn State <delauj2(a)gmail.com>
James DeLaunay (PSU), Gayathri Raman (PSU), Samuele Ronchini (PSU), Aaron Tohuvavohu (U Toronto), Jamie A. Kennea (PSU), Tyler Parsotan (NASA GSFC) report:
Swift/BAT did not localize GRB 240101C onboard (T0: 2024-01-01T12:57:23.76 UTC, Fermi GBM Trig 725806648, GRBAlpha GCN 35459, AstroSat CZTI GCN 35478).
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).
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), performed on the temporal window [T0-20 s, T0+20 s], detects the burst with a sqrt(TS) of 11.2 in a 0.128 s analysis time bin, starting at T0 s.
NITRATES results, independently, are ambiguous with respect to whether this burst originates from in or outside the BAT coded FOV, with a DeltaLLHOut of 4.2.
See Section 9.1 and Figures 10 and 17 in the NITRATES paper for brief descriptions and interpretation of sqrt(TS), DeltaLLHPeak, and DeltaLLHOut.
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/
View this GCN Circular online at https://gcn.nasa.gov/circulars/35482.
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TITLE: GCN CIRCULAR
NUMBER: 35481
SUBJECT: LIGO/Virgo/KAGRA S240104bl: Updated Sky localization
DATE: 24/01/05 01:00:31 GMT
FROM: Soichiro Morisaki at U. of Tokyo <soichiro.morisaki(a)ligo.org>
The LIGO Scientific Collaboration, the Virgo Collaboration, and the KAGRA Collaboration report:
We have conducted further analysis of the LIGO Hanford Observatory (H1) data around the time of the compact binary merger (CBC) candidate S240104bl (GCN Circular 35480). Parameter estimation has been performed using Bilby [1] and a new sky map, Bilby.multiorder.fits,0, distributed via GCN Notice, is available for retrieval from the GraceDB event page:
https://gracedb.ligo.org/superevents/S240104bl
After parameter estimation by RapidPE-RIFT [2], the updated classification of the GW signal, in order of descending probability, is BBH (>99%), Terrestrial (<1%), NSBH (<1%), or BNS (<1%).
For the Bilby.multiorder.fits,0 sky map, the 90% credible region is 27949 deg2. Marginalized over the whole sky, the a posteriori luminosity distance estimate is 1978 +/- 618 Mpc (a posteriori mean +/- standard deviation).
For further information about analysis methodology and the contents of this alert, refer to the LIGO/Virgo/KAGRA Public Alerts User Guide https://emfollow.docs.ligo.org/userguide/.
[1] Ashton et al. ApJS 241, 27 (2019) and Morisaki et al. arXiv:2307.13380 (2023)
[2] Rose et al. arXiv:2201.05263 (2022) and Pankow et al. PRD 92, 023002 (2015)
View this GCN Circular online at https://gcn.nasa.gov/circulars/35481.
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TITLE: GCN CIRCULAR
NUMBER: 35480
SUBJECT: LIGO/Virgo/KAGRA S240104bl: Identification of a GW compact binary merger candidate
DATE: 24/01/04 17:32:19 GMT
FROM: Dana Jones at Australian National University <dana.jones(a)anu.edu.au>
The LIGO Scientific Collaboration, the Virgo Collaboration, and the KAGRA Collaboration report:
We identified the compact binary merger candidate S240104bl during real-time processing of data from LIGO Hanford Observatory (H1) at 2024-01-04 16:49:32.629 UTC (GPS time: 1388422190.629). The candidate was found by the GstLAL [1] analysis pipeline.
S240104bl is an event of interest because its false alarm rate, as estimated by the online analysis, is 3.6e-17 Hz, or about one in 1e9 years. The event's properties can be found at this URL:
https://gracedb.ligo.org/superevents/S240104bl
The classification of the GW signal, in order of descending probability, is BBH (>99%), Terrestrial (<1%), NSBH (<1%), or BNS (<1%).
Assuming the candidate is astrophysical in origin, the probability that the lighter compact object is consistent with a neutron star mass (HasNS) is <1%. [2] Using the masses and spins inferred from the signal, the probability of matter outside the final compact object (HasRemnant) is <1%. [2] Both HasNS and HasRemnant consider the support of several neutron star equations of state. The probability that either of the binary components lies between 3 and 5 solar masses (HasMassgap) is <1%.
Two sky maps are available at this time and can be retrieved from the GraceDB event page:
* bayestar.multiorder.fits,0, an initial localization generated by BAYESTAR [3], distributed via GCN notice about 23 seconds after the candidate event time.
* bayestar.multiorder.fits,1, an initial localization generated by BAYESTAR [3], distributed via GCN notice about 5 minutes after the candidate event time.
The preferred sky map at this time is bayestar.multiorder.fits,1. For the bayestar.multiorder.fits,1 sky map, the 90% credible region is 24219 deg2. Marginalized over the whole sky, the a posteriori luminosity distance estimate is 1777 +/- 565 Mpc (a posteriori mean +/- standard deviation).
For further information about analysis methodology and the contents of this alert, refer to the LIGO/Virgo/KAGRA Public Alerts User Guide https://emfollow.docs.ligo.org/userguide/.
[1] Tsukada et al. PRD 108, 043004 (2023) and Ewing et al. arXiv:2305.05625 (2023)
[2] Chatterjee et al. ApJ 896, 54 (2020)
[3] Singer & Price PRD 93, 024013 (2016)
View this GCN Circular online at https://gcn.nasa.gov/circulars/35480.
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TITLE: GCN CIRCULAR
NUMBER: 35479
SUBJECT: GRB 240102C: AstroSat CZTI detection
DATE: 24/01/04 04:55:12 GMT
FROM: Gaurav Waratkar at IIT Bombay <gauravwaratkar(a)iitb.ac.in>
P. K. Navaneeth (IUCAA), J. Joshi (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-duration GRB 240102C which was also detected by Fermi (Trigger Num. 725857207), and Konus-IPN.
The source was clearly detected in the CZT detectors in the 20-200 keV energy range. The light curve peaks at 2024-01-02 03:00:04.50 UTC. The measured peak count rate associated with the burst is 170 (+35, -32) counts/s above the background in the combined data of all quadrants, with a total of 1021 (+191, -224) counts. The local mean background count rate was 336 (+2, -4) counts/s. Using cumulative rates, we measure a T90 of 10 (+4, -3) s.
The source was also clearly detected in the CsI anticoincidence (Veto) detector in the 100-500 keV energy range. The light curve peaks at 2024-01-02 03:00:02.75 UTC. The measured peak count rate associated with the burst is 285 (+52, -45) counts/s above the background in the combined data of two quadrants (out of four), with a total of 2066 (+305, -324) counts. The local mean background count rate was 757 (+3, -4) counts/s. We measure a T90 of 19 (+2, -8) s from the cumulative Veto light curve.
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
View this GCN Circular online at https://gcn.nasa.gov/circulars/35479.
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TITLE: GCN CIRCULAR
NUMBER: 35478
SUBJECT: GRB 240101C: AstroSat CZTI detection
DATE: 24/01/04 04:38:33 GMT
FROM: Gaurav Waratkar at IIT Bombay <gauravwaratkar(a)iitb.ac.in>
P. K. Navaneeth (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 short-duration GRB 240101C which was also detected by Fermi-GBM (Fermi GBM team, GCN Circ. 35451), and GRBAlpha (Dafcikova et al., GCN Circ. 35459).
The source was detected in the CZT detectors in the 20-200 keV energy range. The light curve peaks at 2024-01-01 12:57:23.80 UTC. The measured peak count rate associated with the burst is 881 (+732, -43) counts/s above the background in the combined data of all quadrants, with a total of 69 (+31, -22) counts. The local mean background count rate was 331 (+13, -43) counts/s. Using cumulative rates, we measure a T90 of 0.13 (+0.06, -0.04) 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
View this GCN Circular online at https://gcn.nasa.gov/circulars/35478.
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TITLE: GCN CIRCULAR
NUMBER: 35477
SUBJECT: GRB 231220A: Swift-UVOT upper limit
DATE: 24/01/04 03:26:25 GMT
FROM: noelklin(a)umbc.edu
N. Klingler (UMBC/NASA-GSFC/CRESST II) reports on behalf of the Swift-UVOT team:
Swift-UVOT has performed follow-up observations of the Swift-BAT/GUANO-detected and Fermi-GBM-detected GRB 231220A, collecting 2.6 ks of data between T0+35.2 ks and T0+47.8 ks. No candidate counterpart was detected. The 3 sigma limiting (AB) magnitude in the White filter near the center of the BAT/GUANO localization (GCN 35409) is >23.20.
View this GCN Circular online at https://gcn.nasa.gov/circulars/35477.
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TITLE: GCN CIRCULAR
NUMBER: 35476
SUBJECT: GRB 240102A: Swift-BAT refined analysis
DATE: 24/01/03 23:33:27 GMT
FROM: Amy <yarleen(a)gmail.com>
M. J. Moss (GSFC), S. D. Barthelmy (GSFC),
J.D. Gropp (PSU), H. A. Krimm (NSF),
S. Laha (GSFC/UMBC), A. Y. Lien (U Tampa),
C. B. Markwardt (GSFC), D. M. Palmer (LANL),
T. Parsotan (GSFC), T. Sakamoto (AGU),
M. Stamatikos (OSU) (i.e. the Swift-BAT team):
Using the data set from T-60 to T+243 sec from the recent telemetry
downlink, we report further analysis of BAT GRB 240102A (trigger #1205899)
(Gropp et al., GCN Circ. 35461). The BAT ground-calculated position is
RA, Dec = 96.848, -20.011 deg which is
RA(J2000) = 06h 27m 23.5s
Dec(J2000) = -20d 00' 39.0"
with an uncertainty of 2.4 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 100%.
The mask-weighted light curve show some weak emission that starts at ~T+8 s
and ends at ~T+140 s. T90 (15-350 keV) is 119.00 +- 30.59 sec
(estimated error including systematics).
The time-averaged spectrum from T+8.00 to T+142.00 sec is best fit by a
simple
power-law model. The power law index of the time-averaged spectrum is
2.00 +- 0.22. The fluence in the 15-150 keV band is 8.5 +- 1.3 x 10^-7
erg/cm2.
The 1-sec peak photon flux measured from T+65.00 sec in the 15-150 keV band
is 0.4 +- 0.1 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/1205899/BA/
View this GCN Circular online at https://gcn.nasa.gov/circulars/35476.
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