TITLE: GCN CIRCULAR
NUMBER: 36592
SUBJECT: GRB 240529A: AKO Optical Afterglow Follow-Up Observations
DATE: 24/06/01 12:17:07 GMT
FROM: Mohammad Odeh at Al Khatim Observatory M44 <mshodeh(a)gmail.com>
Mohammad Odeh (Al-Khatim Observatory, AKO, operated by the International
Astronomical Center in Abu Dhabi, UAE), Nidhal Guessoum, Dalya Akl, Ilmah
Aabdi, and Shaikha AlShamsi (American University of Sharjah, UAE), report:
As a follow-up to our first observation performed on May 29, 2024 (GCN 36573
<https://gcn.nasa.gov/circulars/36573>), we report further observations of
the field of GRB 240529A (Eyles-Ferris et al., GCN 36556) with our 0.36m
f/7.7 robotic telescope, on May. 30, starting at 22:09 UT.
We obtained multiple 180-sec exposures in the Ic filter, where we
marginally detected the GRB afterglow.
Our detection is consistent with the results of (Kumar et al., GCN 36559;
Fu et al., GCN 36561; Shilling et al., GCN 36562; Perez-Garcia et al., GCN
36563; Dutton et al., GCN 36568; Mo et al., GCN 36569; Odeh et al. GCN
36573; Adami et al., GCN 36575; Mohan et al., GCN 36576; Vinko et al., GCN
36577; Gu et al., GCN 36579; Moskvitin et al., GCN 36582; Pankov et al.,
GCN 36585; Ror et al., GCN 36589).
The following table summarizes the results of the two nights, calculated
using the Atlas catalog as a reference:
-----------------------------------------------------------------
ObsTime (mid), Exposure, Filter, Mag, S/N, Lim. Mag.
-----------------------------------------------------------------
2024-05-29T23:08:00Z, 24 x 180s (stacked), Ic, 17.9 +/- 0.10, 16.1, 19.8
2024-05-30T23:15:55Z, 21 x 180s (stacked), Ic, 18.8 +/- 0.17, 8.0, 19.7
-----------------------------------------------------------------
The magnitudes are not corrected for galactic extinction.
For reference, cutouts of the GRB, as visible in our images for both
nights, can be found below:
Night 1
<https://astronomycenter.net/images/GRB/GRB%20240529A_Seen_20240529.png>
Night 2
<https://astronomycenter.net/images/GRB/GRB%20240529A_Seen_20240530.png>
View this GCN Circular online at https://gcn.nasa.gov/circulars/36592.
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TITLE: GCN CIRCULAR
NUMBER: 36591
SUBJECT: LIGO/Virgo/KAGRA S240530a: Updated Sky localization
DATE: 24/06/01 11:47:06 GMT
FROM: carl.haster(a)unlv.edu
The LIGO Scientific Collaboration, the Virgo Collaboration, and the KAGRA Collaboration report:
We have conducted further analysis of the LIGO Hanford Observatory (H1), LIGO Livingston Observatory (L1), and Virgo Observatory (V1) data around the time of the compact binary merger (CBC) candidate S240530a (GCN Circular 36572). Parameter estimation has been performed using Bilby [1] and a new sky map, Bilby.offline0.multiorder.fits,0, distributed via GCN Notice, is available for retrieval from the GraceDB event page:
https://gracedb.ligo.org/superevents/S240530a
For the Bilby.offline0.multiorder.fits,0 sky map, the 90% credible region is well fit by an ellipse with an area of 207 deg2 described by the following DS9 region (right ascension, declination, semi-major axis, semi-minor axis, position angle of the semi-minor axis):
icrs; ellipse(21h34m, +05d16m, 21.91d, 3.03d, 64.85d)
Marginalized over the whole sky, the a posteriori luminosity distance estimate is 1066 +/- 226 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/.
[1] Ashton et al. ApJS 241, 27 (2019) doi:10.3847/1538-4365/ab06fc and Morisaki et al. (2023) arXiv:2307.13380
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TITLE: GCN CIRCULAR
NUMBER: 36590
SUBJECT: LXT 240528A: GSP optical upper limit
DATE: 24/06/01 11:45:21 GMT
FROM: Wenxiong Li <liwenxiong1992(a)gmail.com>
W. X. Li, S. J. Xue (NAOC), M. Andrews, J. Farrah, D. A. Howell, M. Newsome, E. Padilla Gonzalez, C. McCully, and G. Terreran (Las Cumbres Observatory), on behalf of a larger collaboration, report:
Following the detection of the fast X-ray transient LXT 240528A by the Lobster Eye Imager for Astronomy (LEIA) (Lian et al. GCN 36567), we initiated observations of the transient's location in the g and r bands on May 30 at 3:39 UT, ~39 hours after the trigger. These observations were conducted using the 1-meter telescope at the Las Cumbres Observatory node located at Tenerife in Spain.
We report that no new optical source was detected in the co-added images within the error box down to a limiting magnitude of ~22.0.
These observations were taken as part of the Global Supernova Project.
View this GCN Circular online at https://gcn.nasa.gov/circulars/36590.
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TITLE: GCN CIRCULAR
NUMBER: 36589
SUBJECT: GRB 240529A: 1.3m DFOT Optical observations
DATE: 24/06/01 10:34:44 GMT
FROM: Amit Kumar Ror at ARIES <mitturor77894(a)gmail.com>
Amit K. Ror, Anshika Gupta, Rishi C., Shashi B. Pandey, and Kuntal Misra
(ARIES) report:
We observed the field of GRB 240529A detected by Swift (Eyles-Ferris et
al., 2024 GCN 36556) 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
2024-05-30 at 21:11:46 UT, i.e., ~ 1.76 days after the BAT trigger. We have
taken multiple frames with an exposure time of 300 s in the R filter. A
similar set of observations was also performed on 2024-05-31 at 20:34:36
UT, i.e., ~ 2.734 days after the BAT trigger. We stacked the images after
the alignment. We clearly detected an optical afterglow in our final
stacked image within the error box of enhanced Swift-XRT and UVOT
observations (Osborne et al., 2024, GCN 36557; Shilling et al., 2024, GCN
36562). The estimated preliminary magnitude is as follows:
Date Start_UT T_start-T0 (days) Filter Exp time (s) Magnitude
=================================================
2024-05-30 21:11:46 UT 1.76 R 300*20 20.15 +/- 0.04
The detection of the GRB afterglow is consistent with the observations of
Kumar et al., 2024, GCN 36559; Fu et al., 2024, GCN 36561; Shilling et al.,
2024, GCN 36562; Perez-Garcia et al., 2024, GCN 36563; Dutton et al., 2024,
GCN 36568; Mo et al., 2024, GCN 36569; Odeh et al., 2024, GCN 36573;
Postigo et al., 2024, GCN 36574; Adami et al., 2024, GCN 36575; Mohan et
al., 2024, GCN 36576; Vinko et al., 2024, GCN 36577; Lim et al., 2024, GCN
36579; Moskvitin et al., 2024, GCN 36582; and Pankov et al., 2024, GCN
36585.
By combining our magnitudes with the observations of Moskvitin et al.
(2024, GCN 36582) and Pankov et al. (2024, GCN 36585), we have calculated
the decay index ~ 1.44 of the R-band light curve at late time.
The given magnitude value is not corrected for the Galactic and host
extinctions in the direction of the GRB afterglow. 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/36589.
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TITLE: GCN CIRCULAR
NUMBER: 36588
SUBJECT: LIGO/Virgo/KAGRA S240527en: Updated Sky localization
DATE: 24/06/01 09:54:12 GMT
FROM: carl.haster(a)unlv.edu
The LIGO Scientific Collaboration, the Virgo Collaboration, and the KAGRA Collaboration report:
We have conducted further analysis of the LIGO Hanford Observatory (H1), LIGO Livingston Observatory (L1), and Virgo Observatory (V1) data around the time of the compact binary merger (CBC) candidate S240527en (GCN Circular 36548). Parameter estimation has been performed using Bilby [1] and a new sky map, Bilby.offline0.multiorder.fits,0, distributed via GCN Notice, is available for retrieval from the GraceDB event page:
https://gracedb.ligo.org/superevents/S240527en
For the Bilby.offline0.multiorder.fits,0 sky map, the 90% credible region is 987 deg2. Marginalized over the whole sky, the a posteriori luminosity distance estimate is 5850 +/- 1907 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/.
[1] Ashton et al. ApJS 241, 27 (2019) doi:10.3847/1538-4365/ab06fc and Morisaki et al. (2023) arXiv:2307.13380
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TITLE: GCN CIRCULAR
NUMBER: 36587
SUBJECT: LIGO/Virgo/KAGRA S240601aj: Identification of a GW compact binary merger candidate
DATE: 24/06/01 08:00:13 GMT
FROM: Jacopo Tissino at GSSI <jacopok(a)gmail.com>
The LIGO Scientific Collaboration, the Virgo Collaboration, and the KAGRA Collaboration report:
We identified the compact binary merger candidate S240601aj during real-time processing of data from LIGO Hanford Observatory (H1) and LIGO Livingston Observatory (L1) at 2024-06-01 06:12:00.359 UTC (GPS time: 1401257538.359). The candidate was found by the CWB [1] and GstLAL [2] analysis pipelines.
S240601aj is an event of interest because its false alarm rate, as estimated by the online analysis, is 3.1e-08 Hz, or about one in 1 year. The event's properties can be found at this URL:
https://gracedb.ligo.org/superevents/S240601aj
The classification of the GW signal, in order of descending probability, is BBH (51%), Terrestrial (49%), BNS (<1%), or NSBH (<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%. [3] Using the masses and spins inferred from the signal, the probability of matter outside the final compact object (HasRemnant) is <1%. [3] 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%.
Three 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 [4], distributed via GCN notice about 36 seconds after the candidate event time.
* cwb.multiorder.fits,0, an initial localization generated by cWB [1], distributed via GCN notice about a minute after the candidate event time.
* cwb.multiorder.fits,1, an initial localization generated by cWB [1], distributed via GCN notice about 6 minutes after the candidate event time.
The preferred sky map at this time is cwb.multiorder.fits,1. For the cwb.multiorder.fits,1 sky map, the 90% credible region is 2468 deg2.
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/.
[1] Klimenko et al. PRD 93, 042004 (2016) doi:10.1103/PhysRevD.93.042004
[2] Tsukada et al. PRD 108, 043004 (2023) doi:10.1103/PhysRevD.108.043004 and Ewing et al. (2023) arXiv:2305.05625
[3] Chatterjee et al. ApJ 896, 54 (2020) doi:10.3847/1538-4357/ab8dbe
[4] Singer & Price PRD 93, 024013 (2016) doi:10.1103/PhysRevD.93.024013
View this GCN Circular online at https://gcn.nasa.gov/circulars/36587.
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TITLE: GCN CIRCULAR
NUMBER: 36586
SUBJECT: GRB 240531A: AstroSat CZTI detection of a short burst
DATE: 24/06/01 05:15:20 GMT
FROM: Gaurav Waratkar at IIT Bombay <gauravwaratkar(a)iitb.ac.in>
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 short-duration GRB 240531A.
The source was clearly detected in the CZT detectors in the 20-200 keV energy range. The light curve showed a single burst of emission that peaked at 2024-05-31 18:54:12.0 UTC. The measured peak count rate associated with the burst is 1140 (+248, -251) counts/s above the background in the combined data of all quadrants, with a total of 202 (+40, -41) counts. The local mean background count rate was 335 (+11, -16) counts/s. Using cumulative rates, we measure a T90 of 0.6 (+0.1, -0.2) s.
It was also clearly detected in the CsI anticoincidence (Veto) detector in the 100-500 keV energy range. The light curve showed a single burst of emission that peaked at 2024-05-31 18:54:11.2 UTC. The measured peak count rate is 292 (+72, -67) counts/s above the background in the combined Veto data of all quadrants, with a total of 264 (+155, -128) counts. The local mean background count rate was 1421 (+8, -14) counts/s. Due to the intrinsic 1 s binning of veto data, we cannot reliably estimate a T90 from it.
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/36586.
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TITLE: GCN CIRCULAR
NUMBER: 36585
SUBJECT: GRB 240529A : Mondy optical observations
DATE: 24/06/01 02:27:03 GMT
FROM: Alexei Pozanenko at IKI, Moscow <apozanen(a)iki.rssi.ru>
N. Pankov (HSE, IKI), A. Pozanenko (IKI), E. Klunko (ISTP), S. Belkin (IKI) report on behalf of GRB IKI FuN:
We observed the field of GRB 240529A (Eyles-Ferris et al.GCN 36556; Osborne et al. GCN 36557; Joshi et al. GCN 36560; Dichiara et al. GCN 36564; Markwardt et al. GCN 36566; Tan et al. GCN 36578) with AZT-33IK telescope of Mondy observatory in R-filter starting 2024-05-30 (UT) 17:12:21. The optical afterglow (Kumar et al. GCN 36559; Fu et al. GCN 36561; Shilling et al.GCN 36562; Perez-Garcia et al. GCN 36563; Dutton et al. GCN 36568; Mo et al. GCN 36569; Odeh et al. GCN 36573; de Ugarte Postigo et al.GCN 36574; Adami et al. GCN 36575; Mohan et al. GCN 36576; Vinko et al., GCN 36577; Lim et al. GCN 36579; Moskvitin et al. GCN 36582) is clearly detected in a stacked image.
Date UT start t-T0 Exp. Filter OT Err. UL(3 sigma)
(mid, days) (s)
2024-05-30 17:12:21 1.61308 29x120 R 19.67 0.11 21.6
The photometry is based on nearby USNO-B1.0 R2 stars.
View this GCN Circular online at https://gcn.nasa.gov/circulars/36585.
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