LIGO/Virgo/KAGRA S241102br
GCN Circular 38043
Subject
LIGO/Virgo/KAGRA S241102br: Identification of a GW compact binary merger candidate
Date
2024-11-02T13:08:46Z (7 months ago)
From
francesca.bucci@fi.infn.it
Via
Web form
The LIGO Scientific Collaboration, the Virgo Collaboration, and the KAGRA Collaboration report:
We identified the compact binary merger candidate S241102br during real-time processing of data from LIGO Hanford Observatory (H1), LIGO Livingston Observatory (L1), and Virgo Observatory (V1) at 2024-11-02 12:40:58.788 UTC (GPS time: 1414586476.788). The candidate was found by the cWB [1], cWB BBH [2], GstLAL [3], MBTA [4], PyCBC Live [5], and SPIIR [6] analysis pipelines.
S241102br is an event of interest because its false alarm rate, as estimated by the online analysis, is 1.1e-41 Hz, or about one in 1e33 years. The event's properties can be found at this URL:
https://gracedb.ligo.org/superevents/S241102br
The classification of the GW signal, in order of descending probability, is BBH (>99%), NSBH (<1%), Terrestrial (<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%. [7] Using the masses and spins inferred from the signal, the probability of matter outside the final compact object (HasRemnant) is <1%. [7] Both HasNS and HasRemnant consider the support of several neutron star equations of state for maximum neutron star mass. The probability that either of the binary components lies between 3 and 5 solar masses (HasMassGap) is 14%.
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 [8], distributed via GCN notice about 28 seconds after the candidate event time.
* bayestar.multiorder.fits,1, an initial localization generated by BAYESTAR [8], 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 well fit by an ellipse with an area of 47 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(23h00m, +40d28m, 7.08d, 2.10d, 96.84d)
Marginalized over the whole sky, the a posteriori luminosity distance estimate is 354 +/- 63 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] Klimenko et al. PRD 93, 042004 (2016) doi:10.1103/PhysRevD.93.042004
[2] T. Mishra et al. PRD 105, 083018 (2022) doi:10.1103/PhysRevD.105.083018
[3] Tsukada et al. PRD 108, 043004 (2023) doi:10.1103/PhysRevD.108.043004 and Ewing et al. (2023) arXiv:2305.05625
[4] Aubin et al. CQG 38, 095004 (2021) doi:10.1088/1361-6382/abe913
[5] Dal Canton et al. ApJ 923, 254 (2021) doi:10.3847/1538-4357/ac2f9a
[6] Chu et al. PRD 105, 024023 (2022) doi:10.1103/PhysRevD.105.024023
[7] Chatterjee et al. ApJ 896, 54 (2020) doi:10.3847/1538-4357/ab8dbe
[8] Singer & Price PRD 93, 024013 (2016) doi:10.1103/PhysRevD.93.024013
GCN Circular 38044
Subject
LIGO/Virgo/KAGRA S241102br: NED Galaxies in the Localization Volume
Date
2024-11-02T15:28:58Z (7 months ago)
From
David Cook at Caltech/IPAC-NED <dcook@ipac.caltech.edu>
Via
Web form
David O. Cook (Caltech/IPAC), Rick Ebert (Caltech/IPAC), George Helou (Caltech/IPAC), Joseph M. Mazzarella (Caltech/IPAC), Marion Schmitz (Caltech/IPAC), and Leo Singer (NASA/GSFC)
On behalf of the NASA/IPAC Extragalactic Database (NED) Team.
We spatially cross-matched the LVK S241102br-3-Initial sky localization with the NED Local Volume Sample (NED-LVS; Cook et al. 2023), which is a subset of NED with a redshift or redshift-independent distance less than 1000 Mpc. We find 743 galaxies within the 90% containment volume, and we list here the top 20 galaxies sorted by the joint probability of the 3D localization and the WISE W1 luminosity (an observable proxy for stellar mass). For the full or top 20 list of galaxies in the 90% volume go either to the NED Gravitational Wave Followup service at https://ned.ipac.caltech.edu/uri/NED::GWF/ or click on the following links:
Full List Download: https://ned.ipac.caltech.edu/uri/NED::GWFglist/fits/S241102br/3
Top 20 List Download: https://ned.ipac.caltech.edu/uri/NED::GWFglist/fits/S241102br/3/20
The NED-GWF service provides downloadable galaxy lists and visualizations for candidate host galaxies. For each GW alert, these products are automatically generated and made available within minutes to expedite efficient electromagnetic follow-up observations. The NED top 20 list is sorted by the joint probability of the 3D localization and the WISE W1 luminosity, but users can sort on additional pre-computed prioritization metrics (star formation rate, P_3D * P_SFR; and specific star formation rate, P_3D * P_sSFR; etc.) which are available via downloading the entire galaxy list inside the event's probability volume.
| objname| ra| dec|objtype| DistMpc|DistMpc_unc| m_NUV| m_NUV_unc| m_Ks| m_Ks_unc| m_W1| m_W1_unc| P_3D|P_3D_LumW1|
|-------------------------|--------------|--------------|-------|-----------|-----------|------------|------------|------------|------------|------------|------------|--------|----------|
|WISEA J225919.78+394535.0| 344.83242| 39.75972| G| 390.21| null| null| null| 13.308| 0.159| 9.984| 0.006|7.85e-06| 1.16e-07|
|WISEA J225952.51+442917.7| 344.96871| 44.48825| G| 329.62| null| 20.764| 0.215| 13.099| 0.105| 9.206| 0.006|3.37e-06| 7.37e-08|
|WISEA J230520.33+400018.8| 346.33458| 40.00514| G| 337.02| null| 21.577| 0.315| 13.436| 0.127| 9.974| 0.006|4.63e-06| 5.15e-08|
|WISEA J230012.95+415343.7| 345.05417| 41.89553| G| 408.42| null| null| null| 13.185| 0.148| 10.882| 0.006|5.88e-06| 4.17e-08|
|WISEA J225938.70+415648.8| 344.91125| 41.94689| G| 358.65| null| null| null| 12.637| 0.126| 11.338| 0.006|1.12e-05| 4.04e-08|
|WISEA J230201.05+423126.9| 345.50446| 42.52411| G| 284.80| null| null| null| 12.000| 0.086| 10.462| 0.006|6.81e-06| 3.53e-08|
|WISEA J225743.15+404134.4| 344.42971| 40.69286| G| 336.82| null| null| null| 12.376| 0.107| 11.820| 0.010|1.15e-05| 2.33e-08|
|WISEA J225708.96+394204.3| 344.28733| 39.70117| G| 381.23| null| null| null| 11.820| 0.096| 11.693| 0.008|6.77e-06| 1.99e-08|
|WISEA J225745.81+373140.1| 344.44088| 37.52783| G| 365.05| null| null| null| 12.520| 0.142| 11.189| 0.007|4.52e-06| 1.94e-08|
|WISEA J230533.61+424929.5| 346.39000| 42.82489| G| 300.42| null| null| null| 12.557| 0.115| 10.925| 0.007|4.57e-06| 1.70e-08|
|WISEA J230113.12+354411.0| 345.30462| 35.73639| G| 424.47| null| 21.420| 0.229| 13.349| 0.168| 9.828| 0.006|7.07e-07| 1.42e-08|
|WISEA J230419.52+423037.8| 346.08129| 42.51047| G| 367.41| null| null| null| 12.262| 0.103| 11.938| 0.011|6.38e-06| 1.39e-08|
|WISEA J230200.39+415916.5| 345.50162| 41.98792| G| 373.08| null| null| null| 12.802| 0.127| 12.402| 0.008|9.02e-06| 1.31e-08|
|WISEA J225832.97+415012.0| 344.63725| 41.83658| G| 403.11| null| null| null| 12.759| 0.131| 12.183| 0.007|6.23e-06| 1.30e-08|
|WISEA J230133.36+394404.8| 345.38892| 39.73472| G| 367.20| null| null| null| 12.931| 0.157| 12.509| 0.013|9.15e-06| 1.17e-08|
|WISEA J230257.02+393909.0| 345.73754| 39.65240| G| 287.69| null| null| null| 11.595| 0.087| 11.513| 0.007|5.89e-06| 1.15e-08|
|WISEA J225902.80+411053.6| 344.76171| 41.18158| G| 387.80| null| null| null| 12.465| 0.155| 12.602| 0.018|8.78e-06| 1.15e-08|
|WISEA J225942.19+421403.0| 344.92588| 42.23417| G| 280.20| null| null| null| 11.975| 0.095| 11.825| 0.010|8.01e-06| 1.13e-08|
|WISEA J230431.87+440856.3| 346.13275| 44.14900| G| 395.29| null| null| null| 13.222| 0.146| 11.423| 0.008|2.70e-06| 1.10e-08|
|WISEA J230530.98+394323.1| 346.37912| 39.72308| G| 358.69| null| null| null| 13.320| 0.150| 11.579| 0.006|3.74e-06| 1.07e-08|
Table 1: Top 20 galaxies in NED-LVS that fall in the 90% probability volume for S241102br sorted by the joint probability of 3D position and WISE W1 luminosity (P_3D * P_LumW1). Galaxy is the NED preferred name. RA and Dec are the Equatorial coordinates in degrees (J2000). Objtype is the object type of the galaxy candidate. Distance is the distance to the galaxy in Mpc. m_NUV and mErr_NUV are the apparent magnitude and error from GALEX. m_Ks and mErr_Ks are the apparent magnitude and error from 2MASS. m_W1 and mErr_W1 are the apparent magnitude and error from AllWISE. P_3D is the probability that the galaxy is in the volume given the distance of GW event. P_3D_LumW1 is the joint probability within the volume weighted by the WISE1 luminosity of the galaxy (P_3D * P_LumW1).
GCN Circular 38056
Subject
LIGO/Virgo/KAGRA S241102br: EP-WXT X-ray follow-up and flux limits
Date
2024-11-03T10:19:11Z (7 months ago)
From
EP Team at NAOC/CAS <ep_ta@bao.ac.cn>
Via
Web form
Q. Y. Wu (NAO, CAS), J. Mao(YNAO, CAS), Y. F. Liang (PMO, CAS), Q. C. Liu (THU), R. D. Liang, D. H. Zhao, H. N. Yang, W. Yuan (NAO, CAS) report on behalf of the Einstein Probe team:
Following on the trigger of the detection of the gravitational-wave (GW) event S241102br (LVK Collaboration, GCN 38043), we carried out a target-of-opportunity observation of the GW sky region with the Wide-field X-ray telescope(WXT) on board the Einstein Probe (EP). The observation started at 2024-11-02 15:44:04 (UTC), about 3 hours after the trigger of the GW event, lasting for around 5 hours. The 90% credible region of the event was fully covered by the large field-of-view of WXT, centering at the nominal GW source position at (RA=23h00m, Dec=+40d28m). The total effective exposure time is about 8 ks within the source credible region. No new X-ray source is found in this observation. This observation sets upper limits on the 0.5-4 keV flux in the source credible region to be approximately 2.42 x 10^(-12) erg/cm^2/s (90%. C.L.). Furthermore, we derived upper limits (see the Table below) for the top 20 galaxies from the galaxy list within the 90% volume reported by Cook et al. (GCN 38044). For queries on more information about this observation and the upper limits, please contact Qinyu Wu at the EP science center (ep_ta@nao.cas.cn).
galaxy name | ra | dec | flux upper limit (0.5-4 keV)
| deg | deg | ergs/cm^2/s
--------------------------------------------------------------------------------------------------
WISEAJ225919.78+394535.0 | 344.83242 | 39.75972 | 1.42E-12
WISEAJ225952.51+442917.7 | 344.96871 | 44.48825 | 1.51E-12
WISEAJ230520.33+400018.8 | 346.33458 | 40.00514 | 1.88E-12
WISEAJ230012.95+415343.7 | 345.05417 | 41.89553 | 1.86E-12
WISEAJ225938.70+415648.8 | 344.91125 | 41.94689 | 1.51E-12
WISEAJ230201.05+423126.9 | 345.50446 | 42.52411 | 1.09E-12
WISEAJ225743.15+404134.4 | 344.42971 | 40.69286 | 1.19E-12
WISEAJ225708.96+394204.3 | 344.28733 | 39.70117 | 2.25E-12
WISEAJ225745.81+373140.1 | 344.44088 | 37.52783 | 1.63E-12
WISEAJ230533.61+424929.5 | 346.39000 | 42.82489 | 1.91E-12
WISEAJ230113.12+354411.0 | 345.30462 | 35.73639 | 1.65E-12
WISEAJ230419.52+423037.8 | 346.08129 | 42.51047 | 1.07E-12
WISEAJ230200.39+415916.5 | 345.50162 | 41.98792 | 1.35E-12
WISEAJ225832.97+415012.0 | 344.63725 | 41.83658 | 1.95E-12
WISEAJ230133.36+394404.8 | 345.38892 | 39.73472 | 1.13E-12
WISEAJ230257.02+393909.0 | 345.73754 | 39.65240 | 1.99E-12
WISEAJ225902.80+411053.6 | 344.76171 | 41.18158 | 1.49E-12
WISEAJ225942.19+421403.0 | 344.92588 | 42.23417 | 1.17E-12
WISEAJ230431.87+440856.3 | 346.13275 | 44.14900 | 1.77E-12
WISEAJ230530.98+394323.1 | 346.37912 | 39.72308 | 1.73E-12
--------------------------------------------------------------------------------------------------
Launched on January 9, 2024, EP is a space X-ray observatory to monitor the soft X-ray sky with onboard X-ray follow-up capability (Yuan et al. 2022, Handbook of X-ray and Gamma-ray Astrophysics). EP is an international collaborative mission led by the Chinese Academy of Sciences (CAS) and participated by the European Space Agency (ESA), the Max-Planck Institute for Extraterrestrial Physics (MPE) in Germany and the Centre National d’Etudes Spatiales (CNES) in France.
GCN Circular 38057
Subject
LIGO/Virgo/KAGRA S241102br: MASTER observations and OT detection
Date
2024-11-03T10:35:54Z (7 months ago)
From
Vladimir Lipunov at Moscow State U/Krylov Obs <lipunov@xray.sai.msu.ru>
Via
legacy email
P.Balanutsa, V.Lipunov, Ya.Kechin, K.Zhirkov, A.Kuznetsov, P.Balanutsa, A.Chasovnikov, O.Gress, N.Tiurina,E.Gorbovskoy, G.Antipov, D.Vlasenko, V.Senik, V.Topolev, Yu.Tselik, Siyu Wu, V.Vladimirov, D.Cheryasov, T.Pogrosheva, V.Shumkov, K.Vetrov (Lomonosov Moscow State University,
SAI,Physics Department),
D.Buckley (SAAO)
C.Francile, F. Podesta, C.Lopez, R. Podesta (Observatorio Astronomico Felix
Aguilar OAFA),
R. Rebolo (The Instituto de Astrofisica de Canarias),
L.Carrasco, J.R.Valdes, V.Chavushyan, V.M.Patino Alvarez,
J.Martinez,A.Corella,L.H.Rodriguez (INAOE, Guillermo Haro Astrophysics
Observatory),
A. Tlatov, D. Dormidontov (Kislovodsk Solar Station of the Pulkovo Observatory),
A. Gabovich, V.Yurkov (Blagoveschensk Educational State University),
M.Gulyaev, K.Labsina (Lomonosov MSU)
MASTER-Tunka robotic telescope (Global MASTER-Net: http://observ.pereplet.ru, Lipunov et al., 2010, Advances in Astronomy, vol. 2010, 30L)
located in Russia (Applied Physics Institute, Irkutsk State University)
started inspect of the LVC S241102br errorbox 3180 sec after notice time
and 3335 sec after trigger time at 2024-11-02 13:36:33 UT, with upper limit up to 21.5 mag.
The observations began at zenith distance = 10 deg. The sun altitude is -37.1 deg.
MASTER-Kislovodsk robotic telescope located in Russia (Lomonosov MSU, Kislovodsk Solar Station of Pulkovo observatory)
started inspect of the LVC S241102br errorbox 7936 sec after notice time and 8090 sec after trigger time at 2024-11-02 14:55:48 UT,
with upper limit up to 17.8 mag. Observations started at twilight.
The observations began at zenith distance = 24 deg. The sun altitude is -10.4 deg.
MASTER-SAAO robotic telescope located in South Africa (South African Astronomical Observatory) started inspect of the LVC S241102br
errorbox 24564 sec after notice time and 24719 sec after trigger time at 2024-11-02 19:32:57 UT, with upper limit up to 17.7 mag.
The observations began at zenith distance = 74 deg. The sun altitude is -28.0 deg.
MASTER-Tavrida robotic telescope located in Russia (Lomonosov MSU, SAI Crimea astronomical station) started
inspect of the LVC S241102br errorbox 35208 sec after notice time and 35363 sec after trigger time at 2024-11-02 22:30:21 UT,
with upper limit up to 18.9 mag. The observations began at zenith distance = 46 deg. The sun altitude is -58.0 deg.
MASTER-OAFA robotic telescope located in Argentina (OAFA observatory of San Juan National University)
started inspect of the LVC S241102br errorbox 41867 sec after notice time and 42022 sec after trigger time
at 2024-11-03 00:21:20 UT, with upper limit up to 19.4 mag. Observations started at twilight.
The observations began at zenith distance = 70 deg. The sun altitude is -16.9 deg.
The galactic latitude b = -15 deg., longitude l = 104 deg.
Real time updated cover map and OT discovered available here:
https://master.sai.msu.ru/site/master2/ligo_1.php?id=23593
MASTER-Tunka auto-detection system ( Lipunov et al., "MASTER Global
Robotic Net", Advances in Astronomy, 2010, 30L )
new sources:
1. MASTER OT J230458.26+422347.1/AT2024aafy on 2024-11-02.57832 UT
(RA, Dec) = 23h 04m 58.26s +42d 23m 47.1s on 2024-11-02.57832 UT.
The OT magnitude in 'clear' filter is 17.6m (mlim= 19.0).
The OT is seen in 2 images. There is no minor planet at this place.
We have reference image on 2024-09-04.61126 UT with 'clear' filter 20.2m.
2.MASTER OT J225647.76+411630.3/AT2024aafw on 2024-11-02.59109 UT.
at (RA, Dec) = 22h 56m 47.76s +41d 16m 30.3s on 2024-11-02.59109 UT.
The OT magnitude in 'clear' filter is 18.8m
(mlim = 20.2).
We have reference image on 2024-06-16.73792 UT with 'clear' filter 19.9m.
The nearest object is J225647.53+411629.0 in the CatWISE2020 catalog (updated version 28-Jan-2021)
(Marocco+, 2021) https://vizier.cds.unistra.fr/viz-bin/VizieR?-source=II/365
This is possibly a red star against a dust cloud.
Real time updated cover map and OT discovered available here:
https://master.sai.msu.ru/site/master2/ligo_1.php?id=23593
The received images are being compiled and processed.
Observations and analysis are continued.
GCN Circular 38065
Subject
LIGO/Virgo/KAGRA S241102br: Updated Sky localization
Date
2024-11-03T20:08:47Z (7 months ago)
From
carl.haster@unlv.edu
Via
Web form
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 S241102br (GCN Circular 38043). 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/S241102br
For the Bilby.offline0.multiorder.fits,0 sky map, the 90% credible region is well fit by an ellipse with an area of 29 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(22h59m, +40d54m, 5.42d, 1.70d, 93.67d)
Marginalized over the whole sky, the a posteriori luminosity distance estimate is 364 +/- 54 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. PRD 108, 123040 (2023) doi:10.1103/PhysRevD.108.123040
GCN Circular 38068
Subject
LIGO/Virgo/KAGRA S241102br: OHP/T193 optical observations
Date
2024-11-03T21:49:21Z (7 months ago)
From
Christophe Adami at LAM <christophe.adami@lam.fr>
Via
Web form
C. Adami (LAM), B. Schneider (MIT) report on behalf of a larger collaboration:
We observed the field of LIGO/Virgo/KAGRA S241102br and in particular the two possible
OTs pointed by Balanutsa et al. (GCN 38057) using the T193cm telescope at Observatoire
de Haute-Provence (France) equipped with the MISTRAL spectro-imager.
We obtained 3x10 min exposures in the r-band for each of the two MASTER sources
(MASTER OT J230458.26+422347.1 and MASTER OT J225647.76+411630.3) from 2024-11-03
19:15 UT to 2024-11-03 20:14 UT.
No new sources are detected in these two fields at a limiting magnitude of
r > 22.60 AB for MASTER OT J230458.26+422347.1 and r > 22.10 AB for MASTER OT
J225647.76+411630.3.
The photometric calibration was performed using nearby objects from the PanSTARRS
catalog and the magnitudes are not corrected for Galactic extinction.
We acknowledge the excellent support from Observatoire de Haute-Provence, in
particular Stephane Favard.
GCN Circular 38417
Subject
LIGO/Virgo/KAGRA S241102br: GRAWITA wide-field optical observations
Date
2024-12-02T12:09:28Z (6 months ago)
From
Andrea Reguitti at INAF - Osservatorio Astronomico di Brera <andreareguitti@gmail.com>
Via
Web form
*A. Reguitti (INAF-OABr / INAF-OAPd), P. D’Avanzo (INAF-OAB), L. Tomasella (INAF-OAPd), Y. Hu (INAF-OABr), A. Rossi (INAF-OAS), E. Cappellaro (INAF-OAPd) et al. on behalf of the GRAWITA collaboration*
We carried out optical follow-up observations of the well-localized LIGO/Virgo/KAGRA GW trigger S241102br (LVK Collaboration, GCN #38043) with the Schmidt telescope sited at the INAF Asiago observatory (Italy). Observations started on 2024-11-02 at 17:08 UT (~4.5 hours after the GW trigger) with the Sloan-r filter. We covered 12 square degrees within the 90% localisation region of the S241102br GW event, almost covering the totality of the final 7 deg2 50% localisation region. The 12 pointings of 1 square degree each are centered at J2000 celestial coordinates: (344.4023, 38.1139); (344.3944, 39.0544); (344.3862, 39.9948); (344.3775, 40.9352); (344.3684, 41.8757); (344.3589, 42.8161); (345.6411, 42.8161); (345.6316, 41.8757); (345.6225, 40.9352); (345.6138, 39.9948); (345.6056, 39.0544); (345.5977, 38.1139). These observations covered ~ 43% of the final 90% credible region (LVK Collaboration, GCN #38043). The typical 3 sigma limiting AB magnitudes are r ~ 21.1 mag. Preliminary analysis, which includes image subtraction with the template images from the PanSTARRS all-sky survey, shows no clear candidate counterparts.
We carried out a specific search for transients in the galaxies located within the S241102br volume. We note that one of the NED galaxies (Cook et al. 2024, GCN #38044) at z = 0.08, a distance consistent with the estimation for the S241102br GW event (0.069<z<0.093), has been proposed in the past as the host galaxy of GRB 051109B (Perley et al. 2006, GCN #5387).
We thank the staff at Padova Astronomical Observatory for their excellent support.
GCN Circular 38493
Subject
LIGO/Virgo/KAGRA S241102br: continued GRAWITA observations and detection of an optical transient (AT2024adip)
Date
2024-12-09T17:09:59Z (6 months ago)
From
Andrea Reguitti at INAF - Osservatorio Astronomico di Brera <andreareguitti@gmail.com>
Via
Web form
A. Reguitti (INAF-OAB / INAF-OAPd), P. D’Avanzo (INAF-OAB), A. Rossi (INAF-OAS), L. Izzo (INAF-OACn / DARK), S. Benetti (INAF-OAPd), R. Brivio (INAF-OAB), S. Campana (INAF-OAB), V. D'Elia (ASI), M. Ferro (INAF-OAB), Y.-D. Hu (INAF-OAB), A. Melandri (INAF-OAR), F. Ragosta (Univ. Napoli / INAF-OACn) et al. on behalf of the GRAWITA collaboration
We continued to carry out optical follow-up observations of the well-localized LIGO/Virgo/KAGRA GW trigger S241102br (LVK Collaboration, GCN Circ. #38043).
Targeted observations carried out with the LBC camera mounted on LBT (Mt. Graham, AZ, USA) on 2024-11-09 at midtime 03:24 UT (~6.4 days after the GW trigger) with the Sloan-r and Sloan-z filters revealed the presence of a bright source located at coordinates RA, Dec = 23:01:50.45, +38:41:39.7" (+/- 0.3") not visible in archival Pan-STARRS images. This source lies on the plane of a bright galaxy seen edge-on, with an offset of about 5" from the host galaxy centre. From preliminary photometry we estimate for this source r=21.2+/-0.2 (AB mag, calibrated against the Pan-STARRS catalogue), confirmed by the subtraction of the template images from the PanSTARRS all-sky survey. Therefore, within the Pan-STARRS limits, suggesting this is a new transient.
Re-inspection of the Asiago Schmidt telescope images (Reguitti et al. 2024, GCN #38417), which includes subtraction of the template images from the PanSTARRS all-sky survey, revealed a possible, low SNR detection of the same source already on 2024-11-02, at r=20.9+/-0.4 AB mag.
Finally, observations carried out with the DOLORES camera mounted on TNG (Roque de los Muchachos, La Palma, Spain) on 2024-12-02 (~ 30 days after the GW trigger) in imaging mode with the Sloan r-band filter revealed the source has clearly faded below the detection threshold at r>22.0 AB mag, which entails a fading of at least 0.8 mag.
On the same night we performed also TNG/DOLORES spectroscopy with the LR-B grism: from the narrow Halpha emission of the host galaxy we derive a redshift z = 0.0815, corresponding to a luminosity distance DL = 373 Mpc (assuming H0=69.6, Wm=0.286, WΛ=0.714), consistent with the distance reported for the GW event S241102br.
Adopting the aforementioned luminosity distance, at the time of LBT observation the source had an absolute magnitude of Mr=-17.0+/-0.2, corrected for the Galactic extinction (Ar=0.38 mag, Schlafly & Finkbeiner 2011).
This new transient source has been loaded into the Transient Name Server with the official IAU name AT 2024adip.
Further observations and analysis of AT 2024adip is in progress.
We thank the staff at LBT Observatory and TNG telescope for their excellent support, in particular the TNG observers Massimo Cecconi, Filippo Ambrosino, Giovanni Mainella, the LBTO staff Alexander Backer, Steve Allanson, and for LBT-Italy Felice Cusano, Ester Marini.