April 2024 - vsnet-grb-info - ooruri.kusastro.kyoto-u.ac.jp

[vsnet-grb-info 34129] LIGO/Virgo/KAGRA S240422ed: No significant counterpart candidates in HAWC observations
by GCN Circulars 24 Apr '24

24 Apr '24

TITLE: GCN CIRCULAR NUMBER: 36286 SUBJECT: LIGO/Virgo/KAGRA S240422ed: No significant counterpart candidates in HAWC observations DATE: 24/04/24 16:02:42 GMT FROM: Hugo Ayala at Pennsylvania State University <hgayala(a)psu.edu> The HAWC Collaboration (https://www.hawc-observatory.org) reports: The HAWC Collaboration performed a follow-up of the gravitational wave trigger S240422ed (GCN 36236). At the time of the trigger the HAWC local zenith was oriented towards (RA, Dec) = (77.6 deg, 19.0 deg). 36% of the GW candidate sky location probability fell within our observable field of view (0-45 deg zenith angle). We performed a search for a short timescale emission using 6 sliding time windows (dt = 0.3s, 1s, 3s, 10s, 30s and 100s), shifted forward in time by 20% of their width. We searched the 95% probability containment area in a timescale-dependent time period, from t0-5dt to t0+10dt, where t0 is the time of the GW trigger. No significant gamma-ray detection above the background was observed. The sensitivity of this analysis is greatly dependent on zenith angle, ranging from 49.8deg to 60deg for the area searched in this analysis. The 5sigma detection sensitivity to a 1s (100s) burst in the 80-800GeV energy range goes from 9.9e-5 erg/cm^2 to 4.4e-4 erg/cm^2 (5.6e-4 erg/cm^2 to 2.5e-03 erg/cm^2), depending on the zenith angle. A list of some of the hotspots found in the search is shown below. We found that one of the galaxies that are mentioned in GCN 36235 is close to one of the observed hotspots. No hotspot was close to the updated list in GCN 36243. We mark with a “>” the hotspots that still show up in the updated localization of the GW (GCN 36240). Timescale 3 seconds RA Dec Unc. TS Galaxy 126.21 -8.61 0.83 10.97 > 126.91 -16.10 0.85 11.47 Timescale 10 seconds RA Dec Unc. TS Galaxy 124.80 -9.97 0.49 12.31 > 126.65 -16.49 0.71 9.27 Timescale 30 seconds RA Dec Unc. TS Galaxy 124.80 -9.97 0.49 9.01 > 127.53 -15.71 0.64 9.15 Timescale 100 seconds RA Dec Unc. TS Galaxy 110.65 -27.95 0.50 9.23 113.99 -20.42 0.37 10.23 114.08 -19.87 0.50 9.29 114.26 -21.94 0.52 11.29 120.94 -13.32 0.59 13.33 WISEA J080028.14-134847.4 (0.95deg) 128.23 -10.20 0.39 12.79 > 129.46 -16.49 0.55 12.06 HAWC is a TeV gamma ray water Cherenkov array located in the state of Puebla, Mexico. It is sensitive to the energy range ~0.1-100TeV, and monitors 2/3 of the sky every day with an instantaneous field-of-view of ~2 sr. View this GCN Circular online at https://gcn.nasa.gov/circulars/36286. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 34128] LIGO/Virgo/KAGRA S240422ed: Vetting of DECam Candidates Using Real-Time Resources and SAGUARO Infrastructure
by GCN Circulars 24 Apr '24

24 Apr '24

TITLE: GCN CIRCULAR NUMBER: 36285 SUBJECT: LIGO/Virgo/KAGRA S240422ed: Vetting of DECam Candidates Using Real-Time Resources and SAGUARO Infrastructure DATE: 24/04/24 16:01:50 GMT FROM: Jillian Rastinejad at Northwestern Univ. <jillianrastinejad2024(a)u.northwestern.edu> Jillian C. Rastinejad (NU), David J. Sand (UA), Griffin Hosseinzadeh (UA), Charles D. Kilpatrick (NU), Wen-fai Fong (NU), Manisha Shrestha (UA), Jennifer E. Andrews (Gemini), K. Azalee Bostroem (UA), Philip N. Daly (UA), Michael J. Lundquist (Keck), Kerry Paterson (MPIA), Jeniveve Pearson (UA), Samuel D. Wyatt (GSFC) report: We performed a vetting analysis of the candidates reported from the DECam GW-MMADS follow-up (Hu et al. 2024, GCN 36273). Following the methods outlined in Rastinejad et al. (2022) and Hosseinzadeh et al. (2024), we crossmatch each candidate with the TNS (Gal-Yam 2021) and point source catalogs (Tachibana and Miller 2018; Jayasinghe et al. 2019; Flesch et al. 2021; Gaia Collaboration 2023), search public ZTF photometry (Bellm et al. 2019), and run ATLAS forced photometry (Shingles et al. 2021) at the position of the candidate to rule out transients unrelated to the GW event. We determine a most likely host galaxy using the probability of chance coincidence method (Pcc; Bloom et al. 2002) and search for an associated spectroscopic or photometric redshift in public galaxy catalogs (White et al. 2011; Alam et al. 2015; Beck et al. 2016, 2021; Dalya et al. 2021; DESI Collaboration et al. 2023). Candidate | Vetting result —————————————————————————————————— AT2024hdk | Three marginal (~3-sigma) ATLAS forced photometry | detections ~3-5 days prior to GW event. AT2024hdl | Marginal (~4-sigma) ATLAS forced photometry detection ~4 | days prior to GW event. AT2024hdm | Marginal (<5-sigma) ATLAS forced photometry detections ~2 | months to 4 days prior to GW event. AT2024hdn | Five ATLAS forced photometry detections ~4-24 days prior to | GW event. AT2024hdo | Associated (Pcc = 0.002) with host galaxy | WISEJ080327.75-260039.2 from GLADE at z = 0.09 +/- 0.02 | (photometric redshift; D = 404 Mpc). AT2024hdp | Associated (Pcc < 0.001) with host galaxy | WISEJ080210.31-271529.7 from GLADE at z = 0.09 +/- 0.02 | (photometric redshift; D = 411 Mpc). ATLAS forced | photometry detections ~3-18 days prior to GW event. AT2024hdq | ZTF detections indicate periodic behavior since 2022. AT2024hdr | ZTF detections in 2021-2022. ATLAS forced photometry | detections extending >200 days prior to GW event. Overall, we determine that AT2024hdq and AT2024hdr are unrelated to S240422ed. We find candidates AT2024hdn, AT2024hdm, AT2024hdk, AT2024hdl and AT2024hdp to be likely unrelated to the GW event based on detections prior to the GW event, though we note the significance of the detections varies. In particular, combined with previously reported color and spectroscopic information, we strongly disfavor AT2024hdn and AT2024hdm as the counterparts of S240422ed (Tinyanont et al. 2024, GCN 36281; Karambelkar et al. 2024, GCN 36279). Finally, for AT2024hdo, while the most probable host galaxy photometric redshift is inconsistent with the GW-inferred distance, we cannot rule it out as a possible counterpart given large uncertainties in photometric redshift estimates in the Local Universe. SAGUARO stands for Searches After Gravitational-waves Using ARizona's Observatories (Hosseinzadeh et al. 2024). It is a partnership between the University of Arizona and Northwestern University. View this GCN Circular online at https://gcn.nasa.gov/circulars/36285. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 34127] LIGO/Virgo/KAGRA S240422ed: No significant candidates in GRANDMA/FRAM Observations
by GCN Circulars 24 Apr '24

24 Apr '24

TITLE: GCN CIRCULAR NUMBER: 36284 SUBJECT: LIGO/Virgo/KAGRA S240422ed: No significant candidates in GRANDMA/FRAM Observations DATE: 24/04/24 15:45:43 GMT FROM: Cristina Andrade at UMN <andra104(a)umn.edu> C. Andrade (UMN), P. Gokuldass (ERAU), A. Klotz (Les Makes/T60), M. Masek (FZU), Y. Rajabov (UBAI), S. Karpov (FZU), M. Prouza (FZU), S. Antier (OCA), M. Coughlin (UMN), P. Hello (IJCLAB), I. Tosta e Melo (UniCT-DFA), D. Turpin (CEA-Saclay/Irfu), T. Pradier(Unistra/IPHC), P.A Duverne (APC), N. Guessoum (AUS) Report on behalf of the GRANDMA collaboration: We performed tiled observations of LIGO/VIRGO event S240422ed (GCN 36236, 36240, and 36243) with the FRAM-Auger (30cm ODK + CCD MII G4-16000, 60' x 60' field of view, Pierre Auger Observatory, Malargue, Argentina) telescope. Observations were conducted from 2024-04-23 00:02:54 to 2024-04-23 05:16:49, beginning approximately 2.46 hr after the GW trigger time, under moderate weather conditions. Using the Bilby skymap as a reference, we searched 11.5% (65.1 sq deg) of the localization region, acquiring 2 consecutive 2-minute long exposures in Johnson R filter at the individual pointings as described below: +------------+--------------+--------+---------+-------------+-------------+ | Date | Time (UTC) | Filter | Exposure | RA | Dec | |------------+--------------+--------+---------+-------------+-------------+ | 2024-04-23 | 00:02:54.252 | R | 120.0 | 125.79545 | -18.0 | | 2024-04-23 | 00:05:05.859 | R | 120.0 | 125.79545 | -18.0 | | 2024-04-23 | 00:07:27.154 | R | 120.0 | 126.81818 | -18.0 | | 2024-04-23 | 00:09:38.735 | R | 120.0 | 126.81818 | -18.0 | | 2024-04-23 | 00:12:02.014 | R | 120.0 | 126.51429 | -18.97297 | | 2024-04-23 | 00:14:13.631 | R | 120.0 | 126.51429 | -18.97297 | | 2024-04-23 | 00:16:36.403 | R | 120.0 | 126.40449 | -16.05405 | | 2024-04-23 | 00:18:48.019 | R | 120.0 | 126.40449 | -16.05405 | | 2024-04-23 | 00:21:10.954 | R | 120.0 | 127.11864 | -17.02703 | | 2024-04-23 | 00:23:22.559 | R | 120.0 | 127.11864 | -17.02703 | | 2024-04-23 | 00:25:45.930 | R | 120.0 | 124.38202 | -16.05405 | | 2024-04-23 | 00:27:57.467 | R | 120.0 | 124.38202 | -16.05405 | | 2024-04-23 | 00:30:20.097 | R | 120.0 | 127.84091 | -18.0 | | 2024-04-23 | 00:32:31.677 | R | 120.0 | 127.84091 | -18.0 | | 2024-04-23 | 00:34:51.547 | R | 120.0 | 127.41573 | -16.05405 | | 2024-04-23 | 00:37:03.099 | R | 120.0 | 127.41573 | -16.05405 | | 2024-04-23 | 00:39:22.111 | R | 120.0 | 125.08475 | -17.02703 | | 2024-04-23 | 00:41:33.743 | R | 120.0 | 125.08475 | -17.02703 | | 2024-04-23 | 00:43:52.683 | R | 120.0 | 126.10169 | -17.02703 | | 2024-04-23 | 00:46:04.298 | R | 120.0 | 126.10169 | -17.02703 | | 2024-04-23 | 00:48:26.997 | R | 120.0 | 127.54286 | -18.97297 | | 2024-04-23 | 00:50:38.607 | R | 120.0 | 127.54286 | -18.97297 | | 2024-04-23 | 00:53:01.805 | R | 120.0 | 128.42697 | -16.05405 | | 2024-04-23 | 00:55:13.343 | R | 120.0 | 128.42697 | -16.05405 | | 2024-04-23 | 00:57:34.624 | R | 120.0 | 127.24138 | -19.94595 | | 2024-04-23 | 00:59:46.236 | R | 120.0 | 127.24138 | -19.94595 | | 2024-04-23 | 01:02:06.232 | R | 120.0 | 125.39326 | -16.05405 | | 2024-04-23 | 01:04:17.814 | R | 120.0 | 125.39326 | -16.05405 | | 2024-04-23 | 01:06:37.756 | R | 120.0 | 124.77273 | -18.0 | | 2024-04-23 | 01:08:49.323 | R | 120.0 | 124.77273 | -18.0 | | 2024-04-23 | 01:11:10.415 | R | 120.0 | 127.7095 | -15.08108 | | 2024-04-23 | 01:13:22.008 | R | 120.0 | 127.7095 | -15.08108 | | 2024-04-23 | 01:15:45.628 | R | 120.0 | 126.70391 | -15.08108 | | 2024-04-23 | 01:17:57.217 | R | 120.0 | 126.70391 | -15.08108 | | 2024-04-23 | 01:20:17.265 | R | 120.0 | 127.35376 | -14.10811 | | 2024-04-23 | 01:22:28.875 | R | 120.0 | 127.35376 | -14.10811 | | 2024-04-23 | 01:24:50.113 | R | 120.0 | 126.2069 | -19.94595 | | 2024-04-23 | 01:27:01.724 | R | 120.0 | 126.2069 | -19.94595 | | 2024-04-23 | 01:29:22.108 | R | 120.0 | 128.13559 | -17.02703 | | 2024-04-23 | 01:31:33.663 | R | 120.0 | 128.13559 | -17.02703 | | 2024-04-23 | 01:40:09.688 | R | 120.0 | 126.93642 | -20.91892 | | 2024-04-23 | 01:42:21.259 | R | 120.0 | 126.93642 | -20.91892 | | 2024-04-23 | 01:44:45.889 | R | 120.0 | 128.35655 | -14.10811 | | 2024-04-23 | 01:46:57.480 | R | 120.0 | 128.35655 | -14.10811 | | 2024-04-23 | 01:49:29.976 | R | 120.0 | 125.69832 | -15.08108 | | 2024-04-23 | 01:51:41.523 | R | 120.0 | 125.69832 | -15.08108 | | 2024-04-23 | 01:54:02.080 | R | 120.0 | 123.68715 | -15.08108 | | 2024-04-23 | 01:56:13.674 | R | 120.0 | 123.68715 | -15.08108 | | 2024-04-23 | 01:58:37.600 | R | 120.0 | 125.48571 | -18.97297 | | 2024-04-23 | 02:00:49.167 | R | 120.0 | 125.48571 | -18.97297 | | 2024-04-23 | 02:03:13.104 | R | 120.0 | 124.0678 | -17.02703 | | 2024-04-23 | 02:05:24.705 | R | 120.0 | 124.0678 | -17.02703 | | 2024-04-23 | 02:07:49.310 | R | 120.0 | 128.71508 | -15.08108 | | 2024-04-23 | 02:10:00.873 | R | 120.0 | 128.71508 | -15.08108 | | 2024-04-23 | 02:12:19.642 | R | 120.0 | 127.64543 | -13.13514 | | 2024-04-23 | 02:14:31.240 | R | 120.0 | 127.64543 | -13.13514 | | 2024-04-23 | 02:16:51.118 | R | 120.0 | 126.35097 | -14.10811 | | 2024-04-23 | 02:19:02.679 | R | 120.0 | 126.35097 | -14.10811 | | 2024-04-23 | 02:21:26.549 | R | 120.0 | 127.97688 | -20.91892 | | 2024-04-23 | 02:23:38.143 | R | 120.0 | 127.97688 | -20.91892 | | 2024-04-23 | 02:26:03.066 | R | 120.0 | 128.86364 | -18.0 | | 2024-04-23 | 02:28:14.659 | R | 120.0 | 128.86364 | -18.0 | | 2024-04-23 | 02:30:36.400 | R | 120.0 | 124.69274 | -15.08108 | | 2024-04-23 | 02:32:48.004 | R | 120.0 | 124.69274 | -15.08108 | | 2024-04-23 | 02:35:10.945 | R | 120.0 | 125.34819 | -14.10811 | | 2024-04-23 | 02:37:22.567 | R | 120.0 | 125.34819 | -14.10811 | | 2024-04-23 | 02:39:46.984 | R | 120.0 | 128.27586 | -19.94595 | | 2024-04-23 | 02:41:58.649 | R | 120.0 | 128.27586 | -19.94595 | | 2024-04-23 | 02:44:23.686 | R | 120.0 | 123.37079 | -16.05405 | | 2024-04-23 | 02:46:35.316 | R | 120.0 | 123.37079 | -16.05405 | | 2024-04-23 | 02:48:57.258 | R | 120.0 | 123.34262 | -14.10811 | | 2024-04-23 | 02:51:08.875 | R | 120.0 | 123.34262 | -14.10811 | | 2024-04-23 | 02:53:32.133 | R | 120.0 | 129.15254 | -17.02703 | | 2024-04-23 | 02:55:43.756 | R | 120.0 | 129.15254 | -17.02703 | | 2024-04-23 | 02:58:05.908 | R | 120.0 | 128.57143 | -18.97297 | | 2024-04-23 | 03:00:17.452 | R | 120.0 | 128.57143 | -18.97297 | | 2024-04-23 | 03:02:40.433 | R | 120.0 | 128.64266 | -13.13514 | | 2024-04-23 | 03:04:52.081 | R | 120.0 | 128.64266 | -13.13514 | | 2024-04-23 | 03:07:14.331 | R | 120.0 | 126.6482 | -13.13514 | | 2024-04-23 | 03:09:25.895 | R | 120.0 | 126.6482 | -13.13514 | | 2024-04-23 | 03:11:49.170 | R | 120.0 | 129.35933 | -14.10811 | | 2024-04-23 | 03:14:00.841 | R | 120.0 | 129.35933 | -14.10811 | | 2024-04-23 | 03:16:21.686 | R | 120.0 | 129.4382 | -16.05405 | | 2024-04-23 | 03:18:33.310 | R | 120.0 | 129.4382 | -16.05405 | | 2024-04-23 | 03:21:04.900 | R | 120.0 | 124.3454 | -14.10811 | | 2024-04-23 | 03:23:16.484 | R | 120.0 | 124.3454 | -14.10811 | | 2024-04-23 | 03:25:38.595 | R | 120.0 | 127.29282 | -12.16216 | | 2024-04-23 | 03:27:50.170 | R | 120.0 | 127.29282 | -12.16216 | | 2024-04-23 | 03:30:14.245 | R | 120.0 | 127.67442 | -21.89189 | | 2024-04-23 | 03:32:25.803 | R | 120.0 | 127.67442 | -21.89189 | | 2024-04-23 | 03:34:49.897 | R | 120.0 | 129.63989 | -13.13514 | | 2024-04-23 | 03:37:01.519 | R | 120.0 | 129.63989 | -13.13514 | | 2024-04-23 | 03:39:23.962 | R | 120.0 | 129.72067 | -15.08108 | | 2024-04-23 | 03:41:35.580 | R | 120.0 | 129.72067 | -15.08108 | | 2024-04-23 | 03:44:00.564 | R | 120.0 | 128.28729 | -12.16216 | | 2024-04-23 | 03:46:12.151 | R | 120.0 | 128.28729 | -12.16216 | | 2024-04-23 | 03:48:34.757 | R | 120.0 | 125.65097 | -13.13514 | | 2024-04-23 | 03:50:46.322 | R | 120.0 | 125.65097 | -13.13514 | | 2024-04-23 | 03:53:08.426 | R | 120.0 | 124.65374 | -13.13514 | | 2024-04-23 | 03:55:19.996 | R | 120.0 | 124.65374 | -13.13514 | | 2024-04-23 | 03:57:43.547 | R | 120.0 | 130.36212 | -14.10811 | | 2024-04-23 | 03:59:55.102 | R | 120.0 | 130.36212 | -14.10811 | | 2024-04-23 | 04:02:18.466 | R | 120.0 | 129.01734 | -20.91892 | | 2024-04-23 | 04:04:30.035 | R | 120.0 | 129.01734 | -20.91892 | | 2024-04-23 | 04:06:53.404 | R | 120.0 | 122.33983 | -14.10811 | | 2024-04-23 | 04:09:05.024 | R | 120.0 | 122.33983 | -14.10811 | | 2024-04-23 | 04:11:26.495 | R | 120.0 | 129.28177 | -12.16216 | | 2024-04-23 | 04:13:38.099 | R | 120.0 | 129.28177 | -12.16216 | | 2024-04-23 | 04:16:01.140 | R | 120.0 | 123.65651 | -13.13514 | | 2024-04-23 | 04:18:12.733 | R | 120.0 | 123.65651 | -13.13514 | | 2024-04-23 | 04:20:34.944 | R | 120.0 | 129.6 | -18.97297 | | 2024-04-23 | 04:22:46.596 | R | 120.0 | 129.6 | -18.97297 | | 2024-04-23 | 04:25:06.802 | R | 120.0 | 129.31034 | -19.94595 | | 2024-04-23 | 04:27:18.396 | R | 120.0 | 129.31034 | -19.94595 | | 2024-04-23 | 04:29:41.406 | R | 120.0 | 130.44944 | -16.05405 | | 2024-04-23 | 04:31:52.989 | R | 120.0 | 130.44944 | -16.05405 | | 2024-04-23 | 04:34:14.611 | R | 120.0 | 128.72093 | -21.89189 | | 2024-04-23 | 04:36:26.183 | R | 120.0 | 128.72093 | -21.89189 | | 2024-04-23 | 04:38:48.313 | R | 120.0 | 129.88636 | -18.0 | | 2024-04-23 | 04:40:59.927 | R | 120.0 | 129.88636 | -18.0 | | 2024-04-23 | 04:49:43.474 | R | 120.0 | 130.63712 | -13.13514 | | 2024-04-23 | 04:51:55.061 | R | 120.0 | 130.63712 | -13.13514 | | 2024-04-23 | 04:54:16.280 | R | 120.0 | 130.16949 | -17.02703 | | 2024-04-23 | 04:58:49.683 | R | 120.0 | 130.72626 | -15.08108 | | 2024-04-23 | 04:56:27.984 | R | 120.0 | 130.16949 | -17.02703 | | 2024-04-23 | 05:01:01.293 | R | 120.0 | 130.72626 | -15.08108 | | 2024-04-23 | 05:03:26.082 | R | 120.0 | 128.79765 | -22.86486 | | 2024-04-23 | 05:05:37.654 | R | 120.0 | 128.79765 | -22.86486 | | 2024-04-23 | 05:07:59.985 | R | 120.0 | 129.85337 | -22.86486 | | 2024-04-23 | 05:10:11.541 | R | 120.0 | 129.85337 | -22.86486 | | 2024-04-23 | 05:12:32.981 | R | 120.0 | 129.55752 | -23.83784 | | 2024-04-23 | 05:14:44.597 | R | 120.0 | 129.55752 | -23.83784 | +------------+--------------+--------+---------+-------------+-------------+ Our low latency analysis did not reveal any significant candidate down to the R>16.7 (5 sigma, AB system) limit. GRANDMA (Global Rapid Advanced Network Devoted to the Multi-messenger Addicts) is a network of robotic telescopes connected all over the world with both photometry and spectrometry capabilities for Time- domain Astronomy (https://grandma.lal.in2p3.fr/). Details on the FRAM telescopes are available on the GRANDMA web pages or on https://grandma.ijclab.in2p3.fr/fram/ View this GCN Circular online at https://gcn.nasa.gov/circulars/36284. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 34126] IceCube-240424A - IceCube observation of a high-energy neutrino candidate track-like event
by GCN Circulars 24 Apr '24

24 Apr '24

TITLE: GCN CIRCULAR NUMBER: 36283 SUBJECT: IceCube-240424A - IceCube observation of a high-energy neutrino candidate track-like event DATE: 24/04/24 14:00:19 GMT FROM: A. Zegarelli at Ruhr University Bochum <azegarelli(a)icecube.wisc.edu> The IceCube Collaboration (http://icecube.wisc.edu/) reports: On 2024-04-24 at 01:49:26.0 UT IceCube detected a track-like event with a high probability of being of astrophysical origin. The event was selected by the ICECUBE_Astrotrack_GOLD alert stream. The average astrophysical neutrino purity for Gold alerts is 50%. This alert has an estimated false alarm rate of 1.225 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/139315_50057906.amon), more sophisticated reconstruction algorithms have been applied offline, with the direction refined to: Date: 2024-04-24 Time: 01:49:26.0 UT RA: 327.08 (+2.06, -1.70 deg 90% PSF containment) J2000 Dec: 3.06 (+1.37, -1.33 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. Two Fermi-LAT sources (listed in the 4FGL-DR4 or 3FHL catalogs) are located in the 90% uncertainty region. The nearest gamma-ray source in either catalog is 4FGL J2149.6+0323 (J2149.8+0322 in the 3FHL catalog) at RA: 327.42 deg and DEC: 3.40 deg (0.5 deg away from the best-fit position). The second one is 4FGL J2146.8+0425 at RA: 326.71 deg and DEC: 4.43 deg, 1.4 deg away from the best-fit position. The former source is associated with a BL Lac object, while the latter is a blazar candidate of uncertain type. Additionally, we note that a recent GRB triggered by the Swift Burst Alert Catalog (BAT) on April 19, 2024 (GRB 240419B, detection time 2024-04-19 12:22:52 UT, GCN Circular #36180), is contained within the 90% uncertainty region of the neutrino candidate event, ~1.7 deg from its 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/36283. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 34125] LIGO/Virgo/KAGRA S240422ed: X-ray Upper Limits from EP-WXT for the Potential Electromagnetic Counterparts Reported by Swift and DECam
by GCN Circulars 24 Apr '24

24 Apr '24

TITLE: GCN CIRCULAR NUMBER: 36282 SUBJECT: LIGO/Virgo/KAGRA S240422ed: X-ray Upper Limits from EP-WXT for the Potential Electromagnetic Counterparts Reported by Swift and DECam DATE: 24/04/24 13:14:11 GMT FROM: EP Team at NAOC/CAS <ep_ta(a)bao.ac.cn> H. N. Yang, Y. L. Wang, W. J. Zhang, X. Pan, X. P. Xu, C. C. Jin, D. Y. Li, H. Sun, Y. Liu, Z. X. Ling, C. Zhang, W. Chen, H. Q. Cheng, C. Z. Cui, D. W. Fan, H. B. Hu, J. W. Hu, M. H. Huang, J. J. Jin, T. Y. Lian, H. Y. Liu, M. J. Liu, Z. Z. Lv, X. Mao, H. W. Pan, W. X. Wang, Q. Y. Wu, Y. F. Xu, W. Yuan, M. Zhang, W. D. Zhang, Z. Zhang, D. H. Zhao (NAOC, CAS), Q. C. Shui (IHEP, CAS), E. Kuulkers, A. Santovincenzo (ESA), P. O'Brien (Univ. of Leicester), K. Nandra, A. Rau (MPE), B. Cordier (CEA), on behalf of the Einstein Probe team We report on the X-ray upper limits from the ongoing observations of the Wide-field X-ray Telescope (WXT) on board the Einstein Probe (EP) mission, for the potential electromagnetic counterparts reported by Swift (Evans et al. GCN 36278) and DECam (Hu et al. GCN 36273). Through our preliminary analysis of the WXT data, we found no significant X-ray counterparts at the positions of these sources, except for AT 2024hdq which is associated with a known Seyfert I galaxy LEDA 86073. The detected flux of this Seyfert by EP-WXT is around 2 x 10^-12 erg/s/cm2, consistent with the flux given in eRASS1. Upper limits for the other sources in 0.5-4 keV at the 90% confidence level are derived from the accumulated exposure from 2024-04-23 00:37:26 (UTC) to 2024-04-23 23:48:09 (UTC). The flux upper limits at the 90% confidence level are detailed as follows. Source | R.A | Dec. | Exposure (s) | Upper limit (erg/s/cm2) ---------------------------------------------------------------------------------- AT 2024hdk | 130.625724 | -15.59953 | 20735 | 6.4 x 10^-12 AT 2024hdn | 127.302473 | -21.50639 | 27013 | 5.6 x 10^-12 AT 2024hdm | 126.65801 | -20.83375 | 26785 | 5.6 x 10^-12 AT 2024hdl | 125.472700 | -30.10220 | 39700 | 4.6 x 10^-12 AT 2024hdo | 120.866797 | -26.01212 | 50042 | 4.1 x 10^-12 AT 2024hdr | 120.804560 | -24.33268 | 39477 | 4.6 x 10^-12 AT 2024hdp | 120.543455 | -27.25787 | 42801 | 4.4 x 10^-12 S240422ed_X101 | 122.3954 | -24.3272 | 44192 | 4.4 x 10^-12 S240422ed_X190 | 121.2770 | -26.1203 | 48919 | 4.1 x 10^-12 ---------------------------------------------------------------------------------- Note: the X-ray upper limit from EP-WXT for another potential electromagnetic counterpart of Swift, i.e. S240422ed_X61 has been given in our previous report (GCN 36270). Follow-up observations with the Follow-up X-ray Telescope (FXT) of EP for the potential optical counterparts found by DECam have been carried out. For the two potential electromagnetic counterparts of Swift (S240422ed_X101, S240422ed_X190), we have also triggered quick follow-up observations with EP-FXT. Further results will be reported after the data analysis is completed. The above observations were made with the WXT instrument during the commissioning phase of EP. Launched on January 9, 2024, EP is a space X-ray observatory to monitor the soft X-ray sky with X-ray follow-up capability (Yuan et al. 2022, Handbook of X-ray and Gamma-ray Astrophysics). EP is a mission of the Chinese Academy of Sciences in collaboration with ESA, MPE and CNES. View this GCN Circular online at https://gcn.nasa.gov/circulars/36282. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 34124] LIGO/Virgo/KAGRA S240422ed: MOSFIRE spectroscopy of the DECam GW-MMADS candidate AT 2024hdn
by GCN Circulars 24 Apr '24

24 Apr '24

TITLE: GCN CIRCULAR NUMBER: 36281 SUBJECT: LIGO/Virgo/KAGRA S240422ed: MOSFIRE spectroscopy of the DECam GW-MMADS candidate AT 2024hdn DATE: 24/04/24 10:36:31 GMT FROM: Mansi Kasliwal at Caltech <mansikasliwal(a)gmail.com> Samaporn Tinyanont (NARIT), Jesper Sollerman (OKC), Jacob Jencson (IPAC), Viraj Karambelkar (Caltech), Michael Lundquist (WMKO) and Mansi Kasliwal (Caltech) report on behalf of a larger collaboration We obtained a near-infrared spectrum of the DECam GW-MMADS source AT2024hdn (GCN 36273), reported as a candidate optical counterpart to the LVK gravitational wave event S240422ed (GCN 36236) in the near-IR y-band with MOSFIRE on the Keck-I telescope on UTC 2024-04-24. The signal-to-noise on the transient is low and analysis is underway. In the reduced 2D spectrum, offset from the transient location, we note two prominent emisson lines at approx. 10161 Angstrom and 10679 Angstrom from the possible star formation knot / background galaxy north of the putative host. If these two lines are [SIII], this corresponds to a galaxy redshift of z=0.12 (significantly higher than the photometric redshift estimate of 0.079 from Bilicki et al. 2014). If this knot is at the same redshift as the transient, it would imply that AT 2024hdn has an absolute magnitude that is consistent with a supernova. We thank the WMKO staff and Keck I scheduled observers for their co-operation with these Target of Opportunity observations. View this GCN Circular online at https://gcn.nasa.gov/circulars/36281. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 34123] LIGO/Virgo/KAGRA S240422ed: ATCA follow-up of candidate counterparts
by GCN Circulars 24 Apr '24

24 Apr '24

TITLE: GCN CIRCULAR NUMBER: 36280 SUBJECT: LIGO/Virgo/KAGRA S240422ed: ATCA follow-up of candidate counterparts DATE: 24/04/24 10:32:21 GMT FROM: Dougal Dobie at University of Sydney <ddobie94(a)gmail.com> D. Dobie, A. Gulati, T. Murphy (U. Sydney/OzGrav), J. Freeburn (Swinburne), A. Anumarlapudi, D.L. Kaplan (UWM) on behalf of a larger collaboration. We report observations of Mag24a (GCN #36267) and the GW-MMADS source AT2024hdn (GCN #36273) with the Australia Telescope Compact Array (ATCA) on 2024-04-24 using 2x2048 MHz bands centered on 5.5 and 9 GHz. We observed the position of Mag24a from 03:00-05:34 UTC. We chose to cease observations after independently discovering the red object at the position of the source in archival DECaPS2 data eventually reported in GCN #36274. We then observed the position of AT2024hdn from 05:35-07:40. We do not find radio emission at the location of either optical source. After preliminary analysis of the data we report 3-sigma upper limits of | Source | Frequency (GHz) | Flux density (uJy) | | --------- | --------------- | ------------------ | | Mag24a | 5.5 | < 55 | | Mag24a | 9.0 | < 50 | | AT2024hdn | 5.5 | < 240 | | AT2024hdn | 9.0 | < 60 | We thank CSIRO staff for rapidly scheduling these observations. The Australia Telescope Compact Array is part of the Australia Telescope National Facility (https://ror.org/05qajvd42) which is funded by the Australian Government for operation as a National Facility managed by CSIRO. We acknowledge the Gomeroi people as the Traditional Owners of the Observatory site. View this GCN Circular online at https://gcn.nasa.gov/circulars/36280. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 34122] LIGO/Virgo/KAGRA S240422ed: MOSFIRE imaging of the DECam GW-MMADS candidate AT 2024hdm
by GCN Circulars 24 Apr '24

24 Apr '24

TITLE: GCN CIRCULAR NUMBER: 36279 SUBJECT: LIGO/Virgo/KAGRA S240422ed: MOSFIRE imaging of the DECam GW-MMADS candidate AT 2024hdm DATE: 24/04/24 09:01:56 GMT FROM: Viraj Karambelkar at Indian Inst of Tech,Bombay <karambelkarvraj21197(a)gmail.com> Viraj Karambelkar (Caltech), Jacob Jencson (IPAC), Samaporn Tinyanont (NARIT), Mansi Kasliwal (Caltech) report on behalf of a larger collaboration. We imaged the DECam GW-MMADS source AT2024hdm (GCN 36273), reported as a candidate optical counterpart to the LVK gravitational wave event S240422ed (GCN 36236) in the near-IR J-band with MOSFIRE on the Keck-I telescope on UTC 2024-04-24T07:48:25. This transient is close to a galaxy with photoz ~ 0.048 (Bilicki et al. 2014), suggesting an absolute magnitude of M_r ~ -16 mag at discovery (GCN 36273, https://www.wis-tns.org/object/2024hdm). We detect AT2024hdm in the J-band with m_J ~ 20.4 +/- 0.1 mag (AB). Based on the r-band discovery magnitude, the r - J color of this transient is ~ 0.3 mag. Correcting for Galactic extinction of E(B-V) ~ 0.1 along this direction gives a corrected (r-J)_corr ~ 0.15 +/- 0.1 mag, suggesting that the intrinsic color is not particularly red at this phase. This transient may be consistent with a supernova. We encourage spectroscopic classification to determine the true nature of the source. View this GCN Circular online at https://gcn.nasa.gov/circulars/36279. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 34121] LIGO/Virgo S240422ed: Swift-XRT detection of 3 possible counterparts
by GCN Circulars 24 Apr '24

24 Apr '24

TITLE: GCN CIRCULAR NUMBER: 36278 SUBJECT: LIGO/Virgo S240422ed: Swift-XRT detection of 3 possible counterparts DATE: 24/04/24 08:42:33 GMT FROM: Phil Evans at U of Leicester <pae9(a)star.le.ac.uk> P.A. Evans (U. Leicester), K.L. Page (U. Leicester), J.A. Kennea (PSU), A. Tohuvavohu (U. Toronto), S.B. Cenko (NASA/GSFC), R.A.J. Eyles-Ferris (U. Leicester), A.P. Beardmore (U. Leicester), M.G. Bernardini (INAF-OAB), A.A. Breeveld (UCL-MSSL), S. Campana (INAF-OAB), M. De Pasquale (University of Messina), S. Dichiara (PSU), P. D’Avanzo (INAF-OAB), A. D’Aì (INAF-IASFPA) , V. D’Elia (ASI-SSDC & INAF-OAR), C. Gronwall (PSU), D. Hartmann (Clemson University), N. Klingler (NASA-GSFC / UMBC / CRESST II), N.P.M. Kuin (UCL-MSSL), S. Laha (NASA/GSFC), S.R. Oates (U. Birmingham), J.P. Osborne (U. Leicester), P. O’Brien (U. Leicester), M.J. Page (UCL-MSSL), G. Raman (PSU) S. Ronchini (PSU), T. Sbarrato (INAF-OAB), B. Sbarufatti (INAF-OAB), M.H. Siegel (PSU), G. Tagliaferri (INAF-OAB), E. Troja (U Tor Vergata, INAF) report on behalf of the Swift team: Swift has carried out 92 observations of the LVC error region for the GW trigger S240422ed convolved with the 2MPZ catalogue (Bilicki et al. 2014, ApJS, 210, 9), using 76 fields from the 'BAYESTAR' GW localisation map and 16 fields from the 'ligo-skymap-from-samples' GW localisation map. As these are 3D skymaps, galaxy distances were taken into account in selecting which ones to observe. The observations currently span from 10 ks to 90 ks after the LVC trigger, and the XRT has covered 10.1 deg^2 on the sky (corrected for overlaps). This covers 4.5% of the probability in the 'ligo-skymap-from-samples' (version ligo-skymap-from-samples.fits.gz) skymap, and 19% after convolving with the 2MPZ galaxy catalogue, as described by Evans et al. (2016, MNRAS, 462, 1591). Using the earlier 'BAYESTAR' (version BAYESTAR.fits.gz) skymap our observations cover 5.3% of the probability (19% when convolved). These pointings and associated metadata have been reported to the Treasure Map (Wyatt et al., 2020, ApJ, 894, 127; http://treasuremap.space/alerts?graceids=S240422ed). 3 rank 2 sources have been found. These are candidates to be the counterpart to the GW trigger. Details of these sources are: Source S240422ed_X61: ===================== RA: 120.3245 ( = 08h 01m 17.88s) J2000 Dec: -28.1765 ( = -28d 10' 35.4") J2000 Error: 5.1 (arcsec, radius, 90% confidence). Peak Rate: 8.3e-02 +/- 3.0e-02 ct s^-1 (0.3-10 keV) Peak Flux: 3.5e-12 +/- 1.3e-12 erg cm^-2 s^-1 (0.3-10 keV) Catalogued: No RASS UL: 3.3e-02 ct s^-1 (converted to XRT; 0.3-10 keV) so the source is not above the RASS 3-sigma upper limit. The source IS FADING at the 3.0-sigma level. NOTE: this source is NOT within 200 kpc of a GWGC or 2MPZ galaxy which is consistent (within 3-sigma) with the distance to the GW object. Source S240422ed_X101: ====================== RA: 122.3954 ( = 08h 09m 34.90s) J2000 Dec: -24.3272 ( = -24d 19' 37.9") J2000 Error: 6.6 (arcsec, radius, 90% confidence). Peak Rate: 1.0e-01 +/- 3.1e-02 ct s^-1 (0.3-10 keV) Peak Flux: 4.4e-12 +/- 1.3e-12 erg cm^-2 s^-1 (0.3-10 keV) Catalogued: No RASS UL: 2.6e-02 ct s^-1 (converted to XRT; 0.3-10 keV) so the source is not above the RASS 3-sigma upper limit. The source IS FADING at the 3.5-sigma level. NOTE: this source is NOT within 200 kpc of a GWGC or 2MPZ galaxy which is consistent (within 3-sigma) with the distance to the GW object. Source S240422ed_X190: ====================== RA: 121.2770 ( = 08h 05m 06.48s) J2000 Dec: -26.1203 ( = -26d 07' 13.1") J2000 Error: 5.3 (arcsec, radius, 90% confidence). Peak Rate: 2.0e+00 +/- 5.2e-01 ct s^-1 (0.3-10 keV) Peak Flux: 8.4e-11 +/- 2.2e-11 erg cm^-2 s^-1 (0.3-10 keV) Catalogued: No RASS UL: 2.2e-02 ct s^-1 (converted to XRT; 0.3-10 keV) so the source is not above the RASS 3-sigma upper limit. There is no evidence for fading. NOTE: this source is NOT within 200 kpc of a GWGC or 2MPZ galaxy which is consistent (within 3-sigma) with the distance to the GW object. NOTE: This source is in a very noisy XRT field and it may not be real: we will request a follow-up observation. In total, we have detected 232 X-ray sources. Each source is assigned a rank of 1-4 which describes how likely it is to be related to the GW trigger, with 1 being the most likely and 4 being the least likely. The ranks are described at https://www.swift.ac.uk/ranks.php. We have found: * 0 sources of rank 1 * 3 sources of rank 2 * 221 sources of rank 3 * 8 sources of rank 4 RANK 3 sources ============== These are uncatalogued X-ray sources, however they are not brighter than previous upper limits, so do not stand out as likely counterparts to the GW trigger. | Source ID | RA | Dec | Err90 | | S240422ed_X2 | 08h 04m 43.19s | -23d 37' 24.0" | 6.7" | | S240422ed_X4 | 08h 08m 39.34s | -18d 23' 50.4" | 6.4" | | S240422ed_X5 | 07h 58m 51.02s | -22d 17' 16.6" | 8.4" | | S240422ed_X6 | 07h 58m 47.06s | -22d 19' 26.6" | 7.5" | | S240422ed_X7 | 07h 58m 41.54s | -22d 13' 08.6" | 8.7" | | S240422ed_X8 | 07h 58m 19.82s | -22d 24' 05.6" | 9.0" | | S240422ed_X9 | 07h 58m 00.71s | -22d 21' 34.1" | 6.7" | | S240422ed_X10 | 08h 00m 49.40s | -22d 20' 59.6" | 6.1" | | S240422ed_X11 | 08h 00m 22.80s | -22d 33' 38.2" | 7.5" | | S240422ed_X12 | 08h 07m 15.82s | -15d 17' 34.9" | 6.6" | | S240422ed_X14 | 07h 58m 02.82s | -21d 57' 15.2" | 7.2" | | S240422ed_X16 | 07h 57m 56.03s | -22d 03' 12.6" | 6.2" | | S240422ed_X17 | 07h 58m 19.62s | -22d 11' 25.7" | 6.0" | | S240422ed_X18 | 07h 57m 56.36s | -22d 04' 01.4" | 8.0" | | S240422ed_X21 | 07h 57m 54.83s | -22d 10' 00.4" | 8.5" | | S240422ed_X22 | 08h 15m 58.64s | -17d 22' 35.3" | 5.9" | | S240422ed_X23 | 08h 09m 56.11s | -21d 32' 55.6" | 8.8" | | S240422ed_X24 | 08h 10m 23.64s | -18d 19' 04.7" | 7.6" | | S240422ed_X25 | 08h 10m 14.18s | -18d 21' 09.1" | 10.6" | | S240422ed_X26 | 08h 09m 51.65s | -18d 11' 17.5" | 9.1" | | S240422ed_X27 | 08h 09m 39.34s | -18d 17' 48.1" | 8.2" | | S240422ed_X28 | 08h 09m 41.22s | -18d 25' 48.1" | 7.0" | | S240422ed_X29 | 08h 09m 12.43s | -18d 23' 13.5" | 8.8" | | S240422ed_X30 | 08h 09m 47.31s | -18d 26' 04.3" | 6.9" | | S240422ed_X31 | 08h 09m 33.65s | -18d 24' 32.0" | 6.1" | | S240422ed_X32 | 07h 58m 47.43s | -22d 08' 43.6" | 15.9" | | S240422ed_X33 | 08h 05m 01.75s | -28d 25' 44.4" | 6.8" | | S240422ed_X34 | 08h 04m 34.26s | -28d 12' 37.1" | 9.2" | | S240422ed_X35 | 08h 05m 33.59s | -28d 13' 27.9" | 7.3" | | S240422ed_X36 | 08h 05m 42.68s | -28d 19' 58.0" | 7.6" | | S240422ed_X37 | 08h 05m 09.97s | -28d 16' 48.6" | 5.7" | | S240422ed_X38 | 08h 05m 45.16s | -28d 21' 01.4" | 6.6" | | S240422ed_X39 | 08h 05m 52.57s | -28d 18' 46.9" | 6.0" | | S240422ed_X40 | 08h 04m 41.41s | -28d 11' 57.8" | 5.5" | | S240422ed_X41 | 08h 05m 42.43s | -28d 24' 19.3" | 6.5" | | S240422ed_X42 | 08h 04m 52.35s | -28d 28' 09.7" | 5.7" | | S240422ed_X43 | 08h 04m 53.26s | -28d 10' 57.2" | 5.6" | | S240422ed_X44 | 08h 09m 09.81s | -18d 14' 19.8" | 7.3" | | S240422ed_X45 | 08h 09m 23.24s | -18d 20' 00.8" | 6.1" | | S240422ed_X46 | 07h 57m 28.64s | -22d 12' 32.3" | 6.0" | | S240422ed_X47 | 07h 58m 40.23s | -22d 22' 38.5" | 13.7" | | S240422ed_X48 | 07h 59m 34.40s | -22d 17' 46.2" | 11.7" | | S240422ed_X49 | 07h 58m 24.50s | -22d 23' 26.8" | 6.8" | | S240422ed_X50 | 08h 00m 13.07s | -22d 32' 47.5" | 6.5" | | S240422ed_X51 | 08h 05m 21.65s | -23d 53' 32.3" | 17.6" | | S240422ed_X52 | 08h 04m 21.05s | -27d 51' 35.2" | 7.2" | | S240422ed_X53 | 08h 03m 36.15s | -27d 42' 01.7" | 6.4" | | S240422ed_X54 | 08h 03m 47.04s | -27d 55' 19.2" | 9.0" | | S240422ed_X55 | 08h 02m 01.17s | -28d 22' 57.3" | 5.1" | | S240422ed_X56 | 08h 05m 41.74s | -28d 14' 26.6" | 6.3" | | S240422ed_X57 | 08h 01m 49.87s | -29d 25' 59.9" | 18.1" | | S240422ed_X58 | 08h 02m 57.63s | -29d 26' 03.6" | 8.8" | | S240422ed_X59 | 08h 01m 50.05s | -28d 18' 01.6" | 5.9" | | S240422ed_X60 | 08h 02m 04.53s | -29d 20' 01.5" | 8.0" | | S240422ed_X62 | 08h 01m 53.82s | -28d 22' 53.5" | 5.9" | | S240422ed_X63 | 08h 00m 50.67s | -30d 30' 24.5" | 7.6" | | S240422ed_X64 | 08h 05m 05.17s | -28d 28' 42.9" | 5.7" | | S240422ed_X65 | 08h 01m 23.18s | -28d 27' 21.4" | 13.0" | | S240422ed_X66 | 08h 02m 40.39s | -22d 35' 42.0" | 5.8" | | S240422ed_X67 | 08h 02m 29.38s | -25d 57' 49.1" | 10.4" | | S240422ed_X68 | 08h 08m 43.37s | -23d 37' 34.1" | 5.5" | | S240422ed_X69 | 08h 07m 30.28s | -23d 34' 03.4" | 6.6" | | S240422ed_X70 | 08h 07m 46.09s | -23d 33' 27.0" | 21.2" | | S240422ed_X71 | 08h 03m 12.73s | -27d 44' 20.2" | 5.6" | | S240422ed_X72 | 08h 03m 50.59s | -27d 40' 12.6" | 6.0" | | S240422ed_X73 | 08h 04m 15.34s | -27d 48' 20.9" | 6.5" | | S240422ed_X74 | 08h 03m 42.64s | -27d 47' 17.4" | 9.3" | | S240422ed_X75 | 08h 03m 39.57s | -27d 40' 24.7" | 5.5" | | S240422ed_X76 | 08h 03m 09.92s | -27d 51' 26.5" | 5.8" | | S240422ed_X78 | 08h 03m 44.46s | -27d 38' 25.0" | 6.0" | | S240422ed_X79 | 08h 04m 19.22s | -27d 45' 54.7" | 14.0" | | S240422ed_X81 | 08h 03m 55.28s | -27d 39' 33.2" | 5.5" | | S240422ed_X83 | 08h 03m 22.60s | -27d 40' 46.2" | 5.1" | | S240422ed_X84 | 08h 04m 20.06s | -25d 14' 47.2" | 6.6" | | S240422ed_X85 | 08h 04m 09.38s | -25d 09' 29.1" | 6.0" | | S240422ed_X86 | 08h 05m 05.57s | -25d 13' 20.9" | 6.2" | | S240422ed_X87 | 08h 05m 07.42s | -25d 10' 46.8" | 6.2" | | S240422ed_X88 | 08h 04m 49.42s | -25d 20' 49.6" | 5.6" | | S240422ed_X89 | 08h 06m 24.02s | -25d 57' 50.6" | 5.9" | | S240422ed_X90 | 08h 05m 30.96s | -25d 52' 08.9" | 6.9" | | S240422ed_X91 | 08h 05m 53.97s | -26d 07' 17.3" | 5.4" | | S240422ed_X92 | 08h 06m 26.93s | -26d 02' 22.8" | 6.6" | | S240422ed_X93 | 08h 05m 50.43s | -25d 50' 09.4" | 6.5" | | S240422ed_X94 | 08h 05m 17.51s | -26d 01' 16.5" | 5.6" | | S240422ed_X95 | 08h 05m 17.32s | -25d 57' 33.6" | 7.9" | | S240422ed_X96 | 08h 05m 46.88s | -25d 50' 22.5" | 7.9" | | S240422ed_X97 | 08h 05m 44.78s | -25d 49' 06.8" | 7.4" | | S240422ed_X98 | 08h 06m 22.66s | -26d 00' 00.5" | 9.0" | | S240422ed_X99 | 08h 06m 29.45s | -26d 00' 10.6" | 8.8" | | S240422ed_X100 | 08h 05m 02.54s | -25d 56' 13.9" | 8.1" | | S240422ed_X103 | 08h 02m 37.62s | -26d 04' 28.5" | 7.8" | | S240422ed_X104 | 08h 02m 52.95s | -25d 52' 07.3" | 5.9" | | S240422ed_X105 | 08h 07m 25.94s | -23d 38' 14.9" | 9.5" | | S240422ed_X106 | 08h 08m 06.73s | -23d 27' 56.3" | 6.7" | | S240422ed_X107 | 08h 05m 17.75s | -25d 56' 42.1" | 5.7" | | S240422ed_X113 | 08h 25m 27.91s | -20d 20' 51.8" | 5.4" | | S240422ed_X114 | 08h 24m 06.00s | -20d 17' 30.8" | 6.1" | | S240422ed_X115 | 08h 17m 16.80s | -18d 34' 49.1" | 6.5" | | S240422ed_X116 | 08h 16m 57.94s | -18d 36' 35.4" | 6.1" | | S240422ed_X117 | 08h 10m 17.16s | -18d 08' 25.3" | 6.5" | | S240422ed_X119 | 08h 11m 02.83s | -18d 06' 30.8" | 6.4" | | S240422ed_X120 | 08h 10m 40.03s | -17d 57' 24.6" | 7.9" | | S240422ed_X121 | 08h 10m 18.17s | -18d 16' 06.4" | 6.7" | | S240422ed_X122 | 08h 10m 03.03s | -18d 11' 37.4" | 15.7" | | S240422ed_X123 | 08h 10m 16.23s | -18d 19' 39.6" | 6.8" | | S240422ed_X124 | 08h 10m 24.70s | -18d 16' 17.7" | 6.1" | | S240422ed_X125 | 08h 11m 35.67s | -17d 56' 05.8" | 5.8" | | S240422ed_X126 | 08h 10m 38.19s | -18d 22' 21.0" | 5.8" | | S240422ed_X127 | 08h 09m 55.62s | -18d 18' 02.4" | 9.0" | | S240422ed_X128 | 08h 11m 19.81s | -18d 00' 36.6" | 6.0" | | S240422ed_X129 | 08h 09m 56.24s | -18d 15' 51.5" | 8.6" | | S240422ed_X130 | 08h 10m 14.29s | -18d 15' 08.6" | 7.2" | | S240422ed_X131 | 08h 10m 05.28s | -18d 16' 22.0" | 6.6" | | S240422ed_X132 | 08h 10m 54.98s | -17d 46' 59.2" | 6.0" | | S240422ed_X133 | 08h 10m 55.47s | -17d 55' 36.3" | 5.3" | | S240422ed_X134 | 08h 09m 48.80s | -18d 09' 58.4" | 6.8" | | S240422ed_X135 | 08h 10m 02.96s | -18d 16' 16.8" | 6.5" | | S240422ed_X136 | 08h 11m 40.95s | -18d 00' 38.9" | 5.0" | | S240422ed_X137 | 08h 10m 59.88s | -17d 47' 27.4" | 6.2" | | S240422ed_X138 | 08h 10m 21.49s | -18d 20' 23.1" | 5.7" | | S240422ed_X140 | 08h 10m 28.48s | -18d 01' 55.9" | 5.7" | | S240422ed_X141 | 08h 11m 20.29s | -18d 03' 59.4" | 5.7" | | S240422ed_X142 | 08h 10m 13.99s | -18d 09' 21.1" | 6.3" | | S240422ed_X143 | 08h 09m 55.96s | -18d 12' 27.7" | 6.3" | | S240422ed_X144 | 08h 10m 04.29s | -18d 18' 33.4" | 7.1" | | S240422ed_X145 | 08h 10m 12.97s | -18d 16' 47.6" | 6.7" | | S240422ed_X146 | 08h 10m 54.91s | -18d 22' 38.5" | 6.0" | | S240422ed_X147 | 08h 10m 04.19s | -18d 07' 18.2" | 11.3" | | S240422ed_X148 | 08h 10m 08.39s | -18d 18' 15.0" | 6.3" | | S240422ed_X149 | 08h 11m 20.72s | -18d 17' 09.0" | 9.5" | | S240422ed_X150 | 08h 09m 50.26s | -18d 15' 21.7" | 8.8" | | S240422ed_X151 | 08h 10m 01.15s | -18d 19' 55.1" | 6.6" | | S240422ed_X152 | 08h 11m 24.09s | -17d 49' 54.0" | 6.7" | | S240422ed_X153 | 08h 10m 09.02s | -18d 21' 06.4" | 6.1" | | S240422ed_X154 | 08h 12m 14.52s | -18d 48' 29.7" | 8.7" | | S240422ed_X155 | 08h 12m 40.59s | -18d 38' 36.0" | 12.8" | | S240422ed_X156 | 08h 13m 21.01s | -18d 56' 52.6" | 8.6" | | S240422ed_X157 | 08h 12m 48.62s | -18d 59' 37.5" | 7.3" | | S240422ed_X158 | 08h 12m 28.74s | -18d 48' 37.0" | 6.6" | | S240422ed_X161 | 08h 26m 34.51s | -21d 01' 50.6" | 5.9" | | S240422ed_X162 | 08h 25m 20.03s | -20d 21' 21.4" | 6.0" | | S240422ed_X163 | 08h 25m 18.09s | -20d 15' 06.5" | 5.8" | | S240422ed_X164 | 08h 24m 32.58s | -20d 14' 53.8" | 6.8" | | S240422ed_X165 | 08h 25m 50.04s | -20d 59' 25.8" | 5.1" | | S240422ed_X166 | 08h 26m 08.36s | -20d 58' 38.7" | 6.1" | | S240422ed_X167 | 08h 26m 17.04s | -20d 58' 15.6" | 6.3" | | S240422ed_X168 | 08h 25m 34.66s | -20d 18' 29.5" | 5.9" | | S240422ed_X169 | 08h 24m 57.04s | -20d 26' 50.5" | 8.4" | | S240422ed_X170 | 08h 26m 16.63s | -20d 39' 49.0" | 7.1" | | S240422ed_X171 | 08h 24m 52.75s | -20d 26' 15.5" | 5.3" | | S240422ed_X172 | 08h 08m 04.35s | -23d 24' 45.1" | 8.5" | | S240422ed_X173 | 08h 08m 11.03s | -23d 25' 15.4" | 8.8" | | S240422ed_X174 | 08h 03m 49.36s | -26d 13' 42.2" | 9.3" | | S240422ed_X175 | 08h 03m 28.16s | -26d 17' 32.7" | 5.7" | | S240422ed_X176 | 08h 03m 23.77s | -26d 19' 42.3" | 5.9" | | S240422ed_X177 | 08h 05m 10.86s | -25d 58' 40.0" | 12.0" | | S240422ed_X178 | 08h 05m 32.41s | -26d 03' 59.8" | 5.9" | | S240422ed_X179 | 08h 04m 43.40s | -26d 03' 22.6" | 5.6" | | S240422ed_X180 | 08h 02m 45.33s | -26d 25' 14.7" | 5.4" | | S240422ed_X181 | 08h 05m 16.90s | -26d 09' 00.2" | 7.3" | | S240422ed_X182 | 08h 02m 58.18s | -25d 50' 21.3" | 8.6" | | S240422ed_X183 | 08h 03m 40.30s | -26d 03' 00.2" | 6.9" | | S240422ed_X184 | 08h 02m 33.85s | -26d 05' 25.7" | 6.4" | | S240422ed_X185 | 08h 03m 38.73s | -26d 22' 16.1" | 6.2" | | S240422ed_X186 | 08h 03m 05.19s | -25d 50' 21.8" | 7.5" | | S240422ed_X187 | 08h 05m 26.00s | -25d 57' 35.1" | 7.8" | | S240422ed_X188 | 08h 03m 02.65s | -25d 48' 22.2" | 7.9" | | S240422ed_X189 | 08h 02m 43.04s | -25d 49' 50.3" | 6.4" | | S240422ed_X191 | 08h 04m 42.44s | -25d 47' 20.1" | 5.3" | | S240422ed_X192 | 08h 03m 04.32s | -26d 27' 12.7" | 6.8" | | S240422ed_X193 | 08h 02m 56.44s | -26d 07' 22.2" | 6.5" | | S240422ed_X194 | 08h 05m 21.31s | -25d 51' 58.6" | 7.5" | | S240422ed_X195 | 08h 04m 26.43s | -25d 18' 43.9" | 5.6" | | S240422ed_X196 | 08h 04m 39.38s | -25d 50' 26.3" | 6.1" | | S240422ed_X197 | 08h 03m 33.96s | -25d 50' 24.0" | 7.0" | | S240422ed_X198 | 08h 05m 39.81s | -26d 03' 05.6" | 6.0" | | S240422ed_X199 | 08h 05m 24.57s | -26d 04' 33.4" | 6.7" | | S240422ed_X200 | 08h 05m 25.64s | -26d 03' 20.3" | 6.0" | | S240422ed_X201 | 08h 05m 29.95s | -26d 02' 04.2" | 5.9" | | S240422ed_X202 | 08h 04m 46.81s | -25d 52' 01.2" | 7.1" | | S240422ed_X203 | 08h 06m 04.46s | -26d 02' 57.8" | 5.3" | | S240422ed_X204 | 08h 04m 59.49s | -26d 05' 48.9" | 7.4" | | S240422ed_X205 | 08h 03m 42.53s | -26d 13' 58.9" | 5.6" | | S240422ed_X206 | 08h 02m 34.55s | -25d 49' 17.4" | 6.3" | | S240422ed_X207 | 08h 05m 12.38s | -25d 48' 58.6" | 5.5" | | S240422ed_X208 | 08h 02m 22.50s | -26d 24' 00.6" | 6.6" | | S240422ed_X209 | 08h 02m 18.98s | -25d 57' 28.4" | 7.3" | | S240422ed_X210 | 08h 04m 46.12s | -26d 03' 37.3" | 9.4" | | S240422ed_X211 | 08h 03m 16.95s | -25d 53' 01.3" | 6.5" | | S240422ed_X212 | 08h 03m 20.75s | -26d 11' 31.0" | 6.6" | | S240422ed_X213 | 08h 04m 30.57s | -25d 51' 33.7" | 5.9" | | S240422ed_X214 | 08h 03m 15.45s | -26d 02' 27.9" | 6.0" | | S240422ed_X215 | 08h 05m 11.27s | -25d 53' 49.9" | 7.6" | | S240422ed_X216 | 08h 01m 49.79s | -29d 38' 11.0" | 7.3" | | S240422ed_X217 | 08h 03m 17.43s | -27d 52' 09.5" | 5.9" | | S240422ed_X218 | 08h 04m 14.00s | -27d 51' 44.9" | 7.6" | | S240422ed_X219 | 08h 03m 37.04s | -27d 55' 52.6" | 5.3" | | S240422ed_X220 | 08h 03m 23.37s | -27d 46' 53.2" | 6.4" | | S240422ed_X221 | 08h 03m 42.72s | -27d 38' 55.6" | 6.9" | | S240422ed_X222 | 08h 10m 21.80s | -18d 17' 01.0" | 7.0" | | S240422ed_X223 | 08h 08m 49.73s | -24d 31' 22.8" | 5.4" | | S240422ed_X224 | 08h 02m 12.90s | -26d 23' 02.9" | 5.7" | | S240422ed_X225 | 08h 11m 27.69s | -18d 04' 50.0" | 6.6" | | S240422ed_X226 | 08h 10m 08.95s | -18d 12' 17.6" | 7.3" | | S240422ed_X227 | 08h 08m 55.49s | -24d 30' 23.8" | 6.6" | | S240422ed_X229 | 08h 03m 28.50s | -26d 24' 13.0" | 5.5" | | S240422ed_X230 | 08h 10m 22.31s | -18d 19' 53.3" | 11.8" | | S240422ed_X231 | 08h 02m 48.21s | -25d 56' 51.6" | 6.0" | | S240422ed_X232 | 08h 10m 29.42s | -18d 12' 48.5" | 15.2" | | S240422ed_X234 | 08h 10m 04.02s | -18d 08' 27.8" | 9.0" | | S240422ed_X235 | 08h 26m 17.31s | -27d 22' 40.3" | 16.4" | | S240422ed_X236 | 08h 03m 03.62s | -26d 25' 04.6" | 7.4" | | S240422ed_X237 | 08h 04m 45.90s | -26d 09' 23.9" | 7.6" | | S240422ed_X238 | 08h 10m 30.49s | -18d 15' 43.4" | 6.0" | | S240422ed_X239 | 08h 05m 22.47s | -26d 01' 39.7" | 5.6" | | S240422ed_X240 | 08h 08m 53.52s | -24d 31' 51.8" | 5.8" | | S240422ed_X241 | 08h 04m 37.23s | -25d 54' 54.2" | 6.2" | | S240422ed_X242 | 08h 02m 58.11s | -26d 16' 58.3" | 5.9" | | S240422ed_X243 | 08h 05m 23.08s | -25d 59' 52.9" | 6.9" | | S240422ed_X244 | 08h 04m 38.78s | -26d 09' 49.1" | 6.7" | | S240422ed_X245 | 08h 02m 44.53s | -26d 04' 22.9" | 6.7" | RANK 4 sources ============== These are catalogued X-ray sources, showing no signs of outburst compared to previous observations, so they are not likely to be related to the GW trigger. | Source ID | RA | Dec | Err90 | | S240422ed_X3 | 07h 57m 58.98s | -21d 57' 37.8" | 8.4" | | S240422ed_X15 | 07h 58m 49.93s | -22d 00' 19.8" | 4.9" | | S240422ed_X20 | 07h 58m 00.02s | -21d 57' 16.8" | 12.9" | | S240422ed_X102 | 08h 09m 55.15s | -24d 01' 38.6" | 4.8" | | S240422ed_X139 | 08h 10m 27.22s | -18d 11' 38.3" | 9.0" | | S240422ed_X233 | 08h 09m 03.03s | -24d 27' 11.1" | 7.2" | | S240422ed_X247 | 08h 09m 43.99s | -23d 58' 38.1" | 8.4" | | S240422ed_X248 | 08h 13m 04.13s | -29d 01' 53.2" | 6.8" | For all flux conversions and comparisons with catalogues and upper limits from other missions, we assumed a power-law spectrum with NH=3x10^20 cm^-2, and photon index (Gamma)=1.7, unless otherwise stated. The results of the XRT automated analysis, including details of the sources listed above, are online at https://www.swift.ac.uk/LVC/S240422ed This circular is an official product of the Swift XRT team. View this GCN Circular online at https://gcn.nasa.gov/circulars/36278. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 34120] LIGO/Virgo/KAGRA S240422ed: Early X-ray Upper Limits from EP-WXT for the LVK Sky Localization Region
by GCN Circulars 24 Apr '24

24 Apr '24

TITLE: GCN CIRCULAR NUMBER: 36277 SUBJECT: LIGO/Virgo/KAGRA S240422ed: Early X-ray Upper Limits from EP-WXT for the LVK Sky Localization Region DATE: 24/04/24 08:17:05 GMT FROM: EP Team at NAOC/CAS <ep_ta(a)bao.ac.cn> W. J. Zhang, Y. L. Wang, H. N. Yang, X. Pan, X. P. Xu, C. C. Jin, D. Y. Li, H. Sun, Y. Liu, Z. X. Ling, C. Zhang, W. Chen, H. Q. Cheng, C. Z. Cui, D. W. Fan, H. B. Hu, J. W. Hu, M. H. Huang, J. J. Jin, T. Y. Lian, H. Y. Liu, M. J. Liu, Z. Z. Lv, X. Mao, H. W. Pan, W. X. Wang, S. X. Wen, Q. Y. Wu, Y. F. Xu, W. Yuan, M. Zhang, W. D. Zhang, Z. Zhang, D. H. Zhao (NAOC, CAS), Q. C. Shui (IHEP, CAS), B. Zhang (UNLV), E. Kuulkers, A. Santovincenzo (ESA), P. O'Brien (Univ. of Leicester), K. Nandra, A. Rau (MPE), B. Cordier (CEA), on behalf of the Einstein Probe team We report on the X-ray upper limits derived from early observations with the Wide-field X-ray Telescope (WXT) on board the Einstein Probe (EP) mission for the sky region of the LIGO/Virgo/KAGRA candidate NSBH event S240422ed (The LIGO-Virgo-KAGRA Collaboration, GCN 36236). A real-time EP-WXT observation serendipitously covered ~90 square degrees in the 90% credible region of the updated LVK sky localization (The LIGO-Virgo-KAGRA Collaboration, GCN 36240) from 2024-04-22 21:21:23 UTC with an exposure time of 5900 seconds, 830 s before the trigger time of the gravitational wave (GW) event (T0). However, this observation was interrupted by the SAA passage from 2024-04-22 21:31:23 UTC to 2024-04-22 22:00:00 UTC, so only the data within [T0-830 s, T0-230 s] (Obs-1a) and [T0+1487 s, T0+36202 s] (Obs-1b) are useful. No significant X-ray counterpart was detected in these good time intervals. Flux upper limits in 0.5-4 keV at the 90% confidence level are derived from good exposure time before and after the interruption of the observation. During the above observation, an EP Target-of-Opportunity observation (Obs-2) was triggered on the LVK sky localization region, with the WXT field-of-view covered almost all of the 90% credible region of GW localization. Through our sebsequent analysis of the WXT data, no significant X-ray counterparts were found. A flux upper limit in 0.5-4 keV at the 90% confidence level is derived from this observation. The flux upper limits at the 90% confidence level are detailed as follows. No. | Start time (UTC) | End time (UTC) | Effective Exposure (s) | Upper limit (erg/s/cm2) -------------------------------------------------------------------------------------------------------------------- Obs-1a | 2024-04-22 21:21:23 | 2024-04-22 21:31:23 | 600 | 4.1 x 10^-11 Obs-1b | 2024-04-22 22:00:00 | 2024-04-23 07:38:35 | 5300 | 1.3 x 10^-11 Obs-2 | 2024-04-23 00:37:26 | 2024-04-23 05:24:11 | 5100 | 1.3 x 10^-11 EP is currently observing a list of galaxies within the 90% GW region with its Follow-up X-ray Telescope (FXT). The WXT field-of-view is covering a large fraction of this GW region simultaneously. The monitoring campaign and subsequent data analysis are ongoing. Further results will be reported later. The above observations were made with the WXT instrument during the commissioning phase of EP. Launched on January 9, 2024, EP is a space X-ray observatory to monitor the soft X-ray sky with X-ray follow-up capability (Yuan et al. 2022, Handbook of X-ray and Gamma-ray Astrophysics). EP is a mission of the Chinese Academy of Sciences in collaboration with ESA, MPE and CNES. View this GCN Circular online at https://gcn.nasa.gov/circulars/36277. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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