TITLE: GCN CIRCULAR
NUMBER: 36296
SUBJECT: LIGO/Virgo/KAGRA S240422ed: Magellan Spectrum of GW-MMADS Candidate AT2024hdo Indicates a Type II SN
DATE: 24/04/25 00:59:38 GMT
FROM: Ryan Foley at UC Santa Cruz <foley(a)ucsc.edu>
A. L. Piro, J. D. Simon (Carnegie), A. Polin (Carnegie/Purdue), D. A. Coulter (STScI), M. R. Drout (Toronto), R. J. Foley, and C. Rojas-Bravo (UC Santa Cruz)
report on behalf of the Carnegie Gravitational wave ElectroMagnetic follow-up (CGEM) and the One-…
[View More]Meter Two-Hemisphere (1M2H) collaborations:
As part of our ongoing search for optical counterparts to the candidate gravitational wave event S240422ed using the 6.5m Magellan Clay telescope with the LDSS-3 spectrograph, we have obtained an optical spectrum of the DECam-reported counterpart candidate AT2024hdo (GCN 36273).
We obtained 2x1200s spectra of AT2024hdo and its presumed host galaxy with the VPH-All grating spanning 4000-10000A. The host galaxy has strong emission lines at z = 0.0658. Examination of the spectrum of AT2024hdo reveals broad P-Cygni H-alpha emission consistent with a Type II SN at z = 0.0658. We therefore conclude that AT2024hdo is unlikely to be associated with S240422ed.
We thank Marcelo Mora, Povilas Palunas, and the rest of the LCO staff for making these observations possible.
View this GCN Circular online at https://gcn.nasa.gov/circulars/36296.
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TITLE: GCN CIRCULAR
NUMBER: 36294
SUBJECT: Fermi trigger No 735697285: Global MASTER-Net observations report
DATE: 24/04/25 00:31:14 GMT
FROM: Vladimir Lipunov at Moscow State U/Krylov Obs <lipunov(a)xray.sai.msu.ru>
V. Lipunov, V.Kornilov, E. Gorbovskoy, K. Zhirkov, N.Tyurina, P.Balanutsa, A.Kuznetsov, V.Senik, D. Vlasenko,
G.Antipov, D.Zimnukhov, E.Minkina, A.Chasovnikov, V.Topolev, D.Kuvshinov, D. Cheryasov, Ya.Kechin, Yu.Tselik, A. Sosnovskij
(Lomonosov Moscow State …
[View More]University, SAI, Physics Department),
R. Podesta, C.Lopez, F. Podesta, C.Francile
(Observatorio Astronomico Felix Aguilar OAFA),
R. Rebolo, M. Serra
(The Instituto de Astrofisica de Canarias),
D. Buckley
(South African Astronomical Observatory),
O.A. Gress, N.M. Budnev, O.Ershova
(Irkutsk State University, API),
L.Carrasco, J.R.Valdes, V.Chavushyan, V.M.Patino Alvarez, J.Martinez,
A.R.Corella, L.H.Rodriguez
(INAOE, Guillermo Haro Astrophysics Observatory),
A. Tlatov, D. Dormidontov
(Kislovodsk Solar Station of the Pulkovo Observatory),
V. Yurkov, A. Gabovich
(Blagoveschensk Educational State University)
MASTER-Tavrida robotic telescope (Global MASTER-Net: http://observ.pereplet.ru, Lipunov et al., 2010, Advances in Astronomy, vol. 2010, 30L) located in Russia (Lomonosov MSU, SAI Crimea astronomical station) started inspect of the Fermi GRB240425.01 (trigger No 735697285,15h 01m 45.60s , +45d 39m 00.0s, R=5.8) errorbox 96 sec after notice time and 128 sec after trigger time at 2024-04-25 00:23:28 UT, with upper limit up to 13.0 mag. The observations began at zenith distance = 20 deg. The sun altitude is -21.9 deg.
MASTER-SAAO robotic telescope located in South Africa (South African Astronomical Observatory) started inspect of the Fermi GRB240425.01 errorbox 109 sec after notice time and 141 sec after trigger time at 2024-04-25 00:23:41 UT, with upper limit up to 17.1 mag. The observations began at zenith distance = 79 deg. The sun altitude is -59.1 deg.
The galactic latitude b = 58 deg., longitude l = 77 deg.
Real time updated cover map and OT discovered available here:
https://master.sai.msu.ru/site/master2/observ.php?id=2434813
We obtain a following upper limits.
Tmid-T0 | Date Time | Site | Coord (J2000) |Filt.| Expt. | Limit| Comment
_________|_____________________|_____________________|____________________________________|_____|_______|_______|________
144 | 2024-04-25 00:23:28 | MASTER-Tavrida | (15h 02m 27.12s , +45d 55m 23.3s) | C | 30 | 13.0 |
156 | 2024-04-25 00:23:41 | MASTER-SAAO | (15h 00m 05.69s , +45d 46m 57.7s) | C | 30 | 17.1 |
156 | 2024-04-25 00:23:41 | MASTER-SAAO | (15h 02m 38.82s , +45d 34m 01.6s) | C | 30 | 17.0 |
181 | 2024-04-25 00:24:05 | MASTER-Tavrida | (15h 02m 29.03s , +45d 57m 04.9s) | C | 30 | 12.4 |
206 | 2024-04-25 00:24:31 | MASTER-SAAO | (15h 00m 05.85s , +45d 47m 01.8s) | C | 30 | 17.1 |
206 | 2024-04-25 00:24:31 | MASTER-SAAO | (15h 02m 38.88s , +45d 34m 06.6s) | C | 30 | 17.0 |
Filter C is a clear (unfiltred) band.
The observation and reduction will continue.
The message may be cited.
View this GCN Circular online at https://gcn.nasa.gov/circulars/36294.
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TITLE: GCN CIRCULAR
NUMBER: 36293
SUBJECT: LIGO/Virgo/KAGRA S240422ed: SRG/eROSITA archival upper limits for Swift/XRT candidates
DATE: 24/04/24 23:09:41 GMT
FROM: Arne Rau at MPE <arau(a)mpe.mpg.de>
Zhu Liu, Arne Rau, Chandreyee Maitra (all MPE), Lorenzo Ducci (IAAT), Mirko Krumpe, Axel Schwope (both AIP):
We report constraints on the historical X-ray emission based on archival X-ray observations from the eROSITA X-ray telescope (Predehl et al. A&A 647, A1, 2021) on board …
[View More]the SRG mission for the three potential electromagnetic counterparts of the LIGO/Virgo/KAGRA candidate NSBH event S240422ed (GCN 36236) detected by Swift/XRT (GCN 36278).
The three sources were within the Field-of-View of eROSITA during each of the first four eROSITA all-sky surveys (eRASS) conducted between 2019 December and 2021 December. The three sources were not detected in individual eRASS scans or in the combined eRASS data (hereafter referred to as eRASS:4). Assuming a power-law model with a photon index of 1.7 and a column density of 3.0E20 cm^-2, we derived the following X-ray flux upper limits using the eRASS:4 data (total exposure uncorrected for vignetting is approximately 800s):
-----------------------------------------------------
Name | 0.3-10.0 keV | 0.2-2.3 keV | Total Exp
| ergs/cm^2/s | ergs/cm^2/s | s
-----------------------------------------------------
S240422ed_X101 | < 1.2e-13 | < 5.2e-14 | 816
S240422ed_X61 | < 7.9e-14 | < 3.4e-14 | 881
S240422ed_X190 | < 8.2e-14 | < 3.6E-14 | 853
-----------------------------------------------------
The Galactic neutral hydrogen column density (HI4PI map, N. Ben Bekhti et al., 2016, A&A 594, A116)) for these three sources are much higher than 3E20 cm^-2, we thus also derived the 3 sigma absorbed X-ray flux upper limits with the column density fixed at the value estimated from the HI4PI map:
-------------------------------------------------------------
Name | 0.3-10.0 keV | 0.2-2.3 keV | NH | Total Exp
| ergs/cm^2/s | ergs/cm^2/s | cm**-2 | s
-------------------------------------------------------------
S240422ed_X101 | < 1.8E-13 | < 5.5E-14 | 2.0E21 | 816
S240422ed_X61 | < 1.8E-13 | < 4.1E-14 | 5.0E21 | 881
S240422ed_X190 | < 1.3E-13 | < 3.8E-14 | 2.1E21 | 853
-------------------------------------------------------------
All the Swift/XRT sources show significant X-ray flux increases compared to the eROSITA upper limits, suggesting that they are indeed X-ray transients.
View this GCN Circular online at https://gcn.nasa.gov/circulars/36293.
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TITLE: GCN CIRCULAR
NUMBER: 36292
SUBJECT: GRB 240419B: Swift-BAT refined analysis
DATE: 24/04/24 21:47:33 GMT
FROM: Sibasish Laha at GSFC <sibasish.laha(a)nasa.gov>
T. Sakamoto (AGU), S. D. Barthelmy (GSFC),
H. A. Krimm (NSF), S. Laha (GSFC/UMBC),
A. Y. Lien (U Tampa), C. B. Markwardt (GSFC),
M. J. Moss (GSFC), D. M. Palmer (LANL),
T. Parsotan (GSFC),(i.e. the Swift-BAT team):
Using the data set from T-61 to T+242 sec from the recent telemetry downlink,
we report further …
[View More]analysis of BAT GRB 240419B (trigger #1223072)
(Dichiara, et al., GCN Circ. 36180). The BAT ground-calculated position is
RA, Dec = 325.853, 4.299 deg which is
RA(J2000) = 21h 43m 24.7s
Dec(J2000) = +04d 17' 58.2"
with an uncertainty of 3.3 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 43%.
The BAT light curve shows a complex structure with a duration of ~ 150 sec.
T90 (15-350 keV) is 132.16 +- 26.29 sec (estimated error including systematics).
The time-averaged spectrum from T-3.3 to T+159.5 sec is best fit by a simple
power-law model. The power law index of the time-averaged spectrum is
1.92 +- 0.09. The fluence in the 15-150 keV band is 4.1 +- 0.2 x 10^-06 erg/cm2.
The 1-sec peak photon flux measured from T+116.36 sec in the 15-150 keV band
is 2.4 +- 0.2 ph/cm2/sec. All the quoted errors are at the 90% confidence
level.
The results of the batgrbproduct analysis are available at
https://swift.gsfc.nasa.gov/results/batgrbcat/BAT_refined_circular/1223072
View this GCN Circular online at https://gcn.nasa.gov/circulars/36292.
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TITLE: GCN CIRCULAR
NUMBER: 36291
SUBJECT: GRB 240421B: Swift-BAT refined analysis
DATE: 24/04/24 21:46:59 GMT
FROM: Sibasish Laha at GSFC <sibasish.laha(a)nasa.gov>
S. D. Barthelmy (GSFC), H. A. Krimm (NSF),
S. Laha (GSFC/UMBC),A. Y. Lien (U Tampa),
C. B. Markwardt (GSFC),M. J. Moss (GSFC),
D. M. Palmer (LANL), T. Parsotan (GSFC),
T. Sakamoto (AGU) (i.e. the Swift-BAT team):
Using the data set from T-239 to T+963 sec from the recent telemetry downlink,
we report further …
[View More]analysis of BAT GRB 240421B (trigger #1223470)
(Williams, et al., GCN Circ. 36208). The BAT ground-calculated position is
RA, Dec = 299.685, -14.878 deg which is
RA(J2000) = 19h 58m 48.03s
Dec(J2000) = -14d 51' 36.4"
with an uncertainty of 1.0 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 4%.
The BAT light curve shows a complex structure with a duration of ~ 40 sec.
T90 (15-350 keV) is 24.00 +- 9.22 sec (estimated error including systematics).
The time-averaged spectrum from T-30.4 to T+7.6 sec is best fit by a power law
with an exponential cutoff. This fit gives a photon index 0.63 +- 0.52,
and Epeak of 81.3 +- 22.3 keV (chi squared 50.17 for 56 d.o.f.). For this
model the total fluence in the 15-150 keV band is 6.4 +- 0.5 x 10^-06 erg/cm2
and the 1-sec peak flux measured from T-0.36 sec in the 15-150 keV band is
14.1 +- 1.6 ph/cm2/sec. A fit to a simple power law gives a photon index
of 1.55 +- 0.10 (chi squared 61.45 for 57 d.o.f.). All the quoted errors
are at the 90% confidence level.
The results of the batgrbproduct analysis are available at
https://swift.gsfc.nasa.gov/results/batgrbcat/BAT_refined_circular/1223470
View this GCN Circular online at https://gcn.nasa.gov/circulars/36291.
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TITLE: GCN CIRCULAR
NUMBER: 36290
SUBJECT: GRB 240422A: Glowbug gamma-ray detection
DATE: 24/04/24 21:13:46 GMT
FROM: C.C. Cheung at Naval Research Lab <Teddy.Cheung(a)nrl.navy.mil>
R. Woolf, C.C. Cheung, M. Kerr, J.E. Grove (NRL), A. Goldstein (USRA), C.A. Wilson-Hodge, D. Kocevski (MSFC), and M.S. Briggs (UAH) report:
The Glowbug gamma-ray telescope [1,2], operating on the International Space Station, reports the detection of GRB 240422A, which was also detected by Fermi/GBM …
[View More](GCN 36222).
The detection occurred during a time of high background, thus complicating the analysis. Using an adaptive window with a resolution of 32-ms, the initial peak seen in the GBM light curve was recovered, with a burst onset determined to be 2024-04-22 02:40:55.400 with a duration of 4.1 s and a total significance of about 8.0 sigma.
The analysis results presented here are preliminary and use a response function that lacks a detailed characterization of the surrounding passive structure of the ISS.
Glowbug is a NASA-funded technology demonstrator for sensitive, low-cost gamma-ray transient telescopes developed, built, and operated by the U.S. Naval Research Laboratory (NRL) with support from the University of Alabama in Huntsville, USRA, and NASA MSFC. It was launched on 2023 March 15 aboard the Department of Defense Space Test Program’s STP-H9 to the ISS. The detector comprises 12 large-area (15 cm x 15 cm) CsI:Tl panels covering the surface of a half cube, and two hexagonal (5-cm diameter, 10-cm length) CLLB scintillators, giving it a large field of view (instantaneous FoV ~2/3 sky) over a wide energy band of 50 keV to >2 MeV.
[1] Grove, J.E. et al. 2020, Proc. Yamada Conf. LXXI, arXiv:2009.11959
[2] Woolf, R.S. et al. 2022, Proc. SPIE, 12181, id. 121811O
[3] Goldstein, A. et al. 2020, ApJ 895, 40, arXiv :1909.03006
Distribution Statement A: Approved for public release. Distribution is unlimited.
View this GCN Circular online at https://gcn.nasa.gov/circulars/36290.
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TITLE: GCN CIRCULAR
NUMBER: 36289
SUBJECT: LIGO/Virgo/KAGRA S240422ed: Archival BlackGEM/MeerLICHT detections of AT 2024hdr & AT 2024hdq
DATE: 24/04/24 21:10:06 GMT
FROM: Danielle Pieterse at Radboud U. <d.pieterse(a)astro.ru.nl>
D.L.A. Pieterse (Radboud), H. Tranin (Barcelona), J. van Roestel (Amsterdam), P.J. Groot (Radboud, UCT, SAAO), P.M. Vreeswijk (Radboud), S. Bloemen (Radboud) and P.G. Jonker (Radboud) report on behalf of the BlackGEM/MeerLICHT Consortium:
Following …
[View More]the DECam candidate counterparts to S240422ed reported by (Hu et al., GCN 36273), we looked at archival data of the the 0.6m BlackGEM/MeerLICHT telescope array located at the ESO La Silla, Chile and SAAO Sutherland, South Africa observatories.
We detect DECam candidates AT 2024hdr and AT 2024hdq as nuclear transients in archival 60s q-band (440-720 nm) images of BlackGEM and MeerLICHT. We therefore conclude that these are not the GW counterpart.
No Name night range q_mag range
1 AT 2024hdr 2023/12/06-2024/04/23 19.0-19.5
2 AT 2024hdq 2022/12/31-2024/12/03 18.6-19.2
We report transient limiting magnitudes for the other DECam candidates from (Hu et al., GCN 36273):
No Name limmag filter date-obs
1 AT 2024hdk >19.6 i 2024-04-08 00:12:33
2 AT 2024hdn >19.6 q 2024-04-23 21:25:02
3 AT 2024hdm >19.9 q 2024-04-23 21:20:59
4 AT 2024hdl >20.0 i 2024-04-17 23:46:19
5 AT 2024hdo >20.3 q 2024-04-23 23:26:45
6 AT 2024hdp >19.9 q 2024-04-23 19:39:27
Transient candidates were extracted using the BlackBOX/ZOGY pipeline, where astrophotometric calibrations are performed using Gaia DR3 photometry and astrometry. Possible asteroids are filtered using the daily-updated lists of known asteroids from the Minor Planet Center. All magnitudes quoted are on the AB system.
The BlackGEM/MeerLICHT telescope are designed, installed and operated by a consortium of the following universities and institutions: Radboud University, Netherlands Research School for Astronomy NOVA, KU Leuven, Armagh Observatory and Planetarium, Technical University of Denmark, Hebrew University of Jerusalem, South African Astronomical Observatory, Tel Aviv University, Texas Tech University, University of Amsterdam, University of Barcelona, University of California at Davis, University of Cape Town, University of Durham, University of Hamburg, University of Manchester, University of Oxford, University of Potsdam, University of Valparaiso, University of Warwick, Weizmann Institute
View this GCN Circular online at https://gcn.nasa.gov/circulars/36289.
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TITLE: GCN CIRCULAR
NUMBER: 36288
SUBJECT: LIGO/Virgo/KAGRA S240413p: DESGW DECam Follow-Up
DATE: 24/04/24 19:39:16 GMT
FROM: norafs(a)umich.edu
Nora Sherman (U. Mich.), Isaac McMahon (UZH), Elise Kesler (U. Mich.), Sean MacBride (U. Mich.), Andre Santos (CBPF), Simran Kaur(U. Mich.), Luidhy Santana-Silva (CBPF), Marcelle Soares-Santos (UZH), Clecio de Bom (CBPF), Ken Herner (FNAL), Kathy Vivas (NOIRLab)
On behalf of the DESGW team:
We report initial results of our DECam search …
[View More]for an optical counterpart of S240413p (LVK, GCN 36075) using DECam. Starting at 2024-04-16 00:33 UTC (~69.25hr post merger), we observed approximately the entirety of the 90% localization region provided in the updated sky map released on April 13, 2024 20:33:39 UTC.
Images were processed by our difference imaging pipeline (Herner et al. 2020) using DES and public DECam images as templates. We employ a machine learning code (autoscan, Goldstein et al. 2015) to reject subtraction artifacts. Candidates were initially selected by requiring at least two high signal to noise detections, which were separated in time in order to reject moving objects. We also require an autoscan score of at least 0.7 on at least one of those detections, and a host redshift consistent with the LVK reported distance within three s.d. We have identified three candidates coinciding with the nuclei of known AGNs, posted below. These are of interest for AGN-driven optical emission for BBH mergers (e.g. Graham et. al 2020).
AGN Name || RA || DEC || Band || Mag
================================================================================
WISEA J105831.80+115457.6 164.632471 11.915976 r 21.89
2MASS J10511539+05482488 162.814215 5.806858 i 18.99
WISEA J105144.54+061108.0 162.935722 6.185632 i 20.32
All magnitudes reported are observed magnitudes. We encourage spectroscopic followup of these candidates.
The DECam Search & Discovery Program for Optical Signatures of Gravitational Wave Events (DESGW) is carried out by the Dark Energy Survey (DES) collaboration in partnership with wide ranging groups in the community. DESGW uses data obtained with the Dark Energy Camera (DECam), which was constructed by the DES collaboration with support from the Department of Energy and member institutions, and utilizes data as distributed by the Science Data Archive at NOAO. NOAO is operated by the Association of Universities for Research in Astronomy (AURA) under a cooperative agreement with the National Science Foundation.
View this GCN Circular online at https://gcn.nasa.gov/circulars/36288.
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TITLE: GCN CIRCULAR
NUMBER: 36287
SUBJECT: LIGO/Virgo/KAGRA S240422ed: Himalayan Chandra Telescope follow-up of the Swift/XRT source S240422ed_X101
DATE: 24/04/24 19:05:49 GMT
FROM: Gaurav Waratkar at IIT Bombay <gauravwaratkar(a)iitb.ac.in>
V. Swain (IITB), G. Waratkar (IITB), U. Pathak (IITB), A. Salgundi (IITB), A. Suresh (IITB), J. Basu (IIA), R.S. Teja (IIA), G. C. Anupama (IIA), S. Barway (IIA), V. Bhalerao (IITB), D.K. Sahu (IIA), A. Suryaprakash (IIA-CREST):
We observed …
[View More]the field of the rank 2 source S240422ed_X101 detected by Swift/XRT (Evans et al., GCN Circ. 36278) with the 2m Himalayan Chandra Telescope (HCT). The observation started at 2024-04-24T14:24:21 UT, i.e., 1.7 days after the LVK trigger (GCN Circ. 36236). We obtained multiple frames in the SDSS i' filter with different exposure times adding up to 55 minutes. Photometry was calibrated against PanSTARRS DR1 (Chambers et al., 2016).
We searched individual images as well as the stacked image but did not detect any afterglow within the Swift/XRT uncertainty circle. We obtain an upper limit of 21.8 mag (5 sigma) in our stacked image.
These observations were carried out under the ToO program HCT-2024-C1-P56. We thank the HCT staff for their support during the observations. The Indian Astronomical Observatory is operated by the Indian Institute of Astrophysics, Bengaluru, India.
View this GCN Circular online at https://gcn.nasa.gov/circulars/36287.
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