LIGO/Virgo S240422ed
GCN Circular 36247
Subject
LIGO/Virgo S240422ed: No counterpart candidates in INTEGRAL SPI-ACS prompt observation
Date
2024-04-23T07:47:35Z (a year ago)
From
Volodymyr Savchenko at UNIGE, EPFL <volodymyr.savchenko@epfl.ch>
Via
Web form
V. Savchenko, C. Ferrigno (ISDC/UniGE, Switzerland)
J. Rodi (IAPS-Roma, Italy)
A. Coleiro (APC, France)
S. Mereghetti (INAF IASF-Milano, Italy)
on behalf of the INTEGRAL multi-messenger collaboration:
https://www.astro.unige.ch/cdci/integral-multimessenger-collaboration
Using INTEGRAL/SPI-ACS realtime data (following [1]) we have
performed a search for a prompt gamma-ray counterpart of S240422ed (GCN 36236).
At the time of the event (2024-04-22 21:35:13 UTC, hereafter T0),
INTEGRAL was operating in nominal mode. The peak of the event
localization probability was at an angle of 113 deg with respect to
the spacecraft pointing axis. This orientation implies strongly
suppressed (5.6% of optimal) response of ISGRI, strongly suppressed
(27% of optimal) response of IBIS/Veto, and near-optimal (72% of
optimal) response of SPI-ACS.
The background within +/-300 seconds around the event was rather
stable (excess variance 1.3).
We have performed a search for any impulsive events in INTEGRAL SPI-
ACS (as described in [2]) data.
We do not detect any significant counterparts and estimate a 3-sigma
upper limit on the 75-2000 keV fluence of 1.9e-07 erg/cm^2 (within the
50% probability containment region of the source localization) for a
burst lasting less than 1 s with a characteristic short GRB spectrum
(an exponentially cut off power law with alpha=-0.5 and Ep=600 keV)
occurring at any time in the interval within 300 s around T0. For a
typical long GRB spectrum (Band function with alpha=-1, beta=-2.5, and
Ep=300 keV), the derived peak flux upper limit is ~1.7e-07 (5.4e-08)
erg/cm^2/s at 1 s (8 s) time scale in 75-2000 keV energy range.
We report for completeness and in order of FAP, all excesses
identified in the search region. We find: 10 likely background
excesses:
T-T0 | scale | S/N | flux ( x 1e-06 erg/cm2/s) | FAP
-8.75 | 0.35 | 4.2 | 4.54 +/- 0.998 +/- 1.63 | 0.0646
39.6 | 2.5 | 3.2 | 1.3 +/- 0.369 +/- 0.466 | 0.225
14.7 | 0.05 | 5 | 1.47 +/- 0.274 +/- 0.526 | 0.228
46.7 | 0.45 | 3.7 | 3.49 +/- 0.877 +/- 1.25 | 0.485
-112 | 2.55 | 3.3 | 1.33 +/- 0.365 +/- 0.477 | 0.49
-25.5 | 0.5 | 3.3 | 3.03 +/- 0.83 +/- 1.09 | 0.521
-33.7 | 0.3 | 3.7 | 0.44 +/- 0.108 +/- 0.158 | 0.56
-18.7 | 0.05 | 4.1 | 1.19 +/- 0.271 +/- 0.426 | 0.607
-44.1 | 0.3 | 3.7 | 0.438 +/- 0.108 +/- 0.157 | 0.663
-46.7 | 0.5 | 3.4 | 3.08 +/- 0.831 +/- 1.1 | 0.747
Note that FAP estimates (especially at timescales above 2s) may be
possibly further affected by enhanced non-stationary local background
noise. This list excludes any excesses for which FAP is close to
unity.
We note that no independent IBAS alerts happened in the vicinity.
SPI-ACS data can be retrieved and interactively explored in MMODA with this link:
https://www.astro.unige.ch/mmoda/?DEC=-29.74516667&RA=265.97845833&T1=2024-04-22T21%3A35%3A03.000&T2=2024-04-22T21%3A35%3A23.000&T_format=isot&data_level=ordinary&instrument=spi_acs&product_type=spi_acs_lc&query_status=new&query_type=Real&selected_catalog=&src_name=1E+1740.7-2942&time_bin=0.05&time_bin_format=sec
INTEGRAL follow-up alert was distributed to SCIMMA through HERMES few
minutes after the trigger GCN:
https://hermes.lco.global/message/4200a286-c463-437b-8363-6fd6b6df5d73
All results quoted are preliminary.
This circular is an official product of the INTEGRAL Multi-Messenger
team.
Note that we send GCNs Circulars only when one of the following
conditions is met: merger contains at least one neutron star, a
singificant counterpart is reported.
[1] Savchenko et al. 2017, A&A 603, A46
[2] Savchenko et al. 2012, A&A 541A, 122S
GCN Circular 36278
Subject
LIGO/Virgo S240422ed: Swift-XRT detection of 3 possible counterparts
Date
2024-04-24T08:42:33Z (a year ago)
From
Phil Evans at U of Leicester <pae9@star.le.ac.uk>
Via
email
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.
GCN Circular 36332
Subject
LIGO/Virgo S240422ed: Swift XRT observation of EP240426a
Date
2024-04-27T08:41:47Z (a year ago)
From
K.L. Page at U Leicester <klp5@leicester.ac.uk>
Via
email
K.L. Page (U. Leicester), P.A. Evans (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), J.J. Delaunay (PSU), 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 conducted a follow-up observation of the candidate counterpart
EP240426a (GCN Circ. 36313), starting 28.8 ks after the EP-FXT discovery.
We detect an X-ray source 6.2" from, and thus consistent with, the
localisation reported by EP-FXT:
Source S240422ed_X255
=====================
RA: 121.85742 ( = 08h 07m 25.78s) J2000
Dec: -29.4593 ( = -29° 27′ 33.5″) J2000
Error: 5.3 (arcsec, radius, 90% confidence)
Peak Rate: 0.012 +/- 0.003 ct s^-1 (0.3-10 keV)
Peak Flux: 5.1e-13 +/- 1.3e-13 erg cm^-2 s^-1
RASS UL: 0.034 ct s^-1 (converted to XRT; 0.3-10 keV)
so the source is not above the RASS 3-sigma
upper limit
For the flux conversions and comparisons with catalogues and upper limits
from other missions given above, we assumed a power-law spectrum with
NH=3x10^20 cm^-2, and photon index (Gamma)=1.7.
However, for direct comparison with the flux of 9.2 x 10 ^-13 erg cm^-2
s^-1 given in GCN Circ. 36313, we estimate a value of 7.0 x 10^-13 erg
cm^-2 s^-1, calculated over 0.5-10 keV, using Gamma = 2.0, corrected for
the higher Galactic absorption of 4.3x10^21 cm^-2 in this direction.
The results of the XRT automated analysis, including details of the
sources detected during the follow-up of S240422ed, are online at
https://www.swift.ac.uk/LVC/S240422ed/
This circular is an official product of the Swift XRT team.