[vsnet-grb-info 23802] LIGO/Virgo S190930t: Transient found in Swift/UVOT counterpart search

Wed Oct 2 02:26:06 JST 2019

TITLE:   GCN CIRCULAR
NUMBER:  25901
SUBJECT: LIGO/Virgo S190930t: Transient found in Swift/UVOT counterpart search
DATE:    19/10/01 17:25:07 GMT
FROM:    Samantha Oates at MSSL  <sro at mssl.ucl.ac.uk>

S. R. Oates (Uni. of Warwick), A. A. Breeveld (MSSL-UCL), N. P. M. Kuin (UCL-MSSL),
F. E. Marshall (NASA/GSFC), P. Brown (TAMU), C. Gronwall (PSU),
M. J. Page (UCL-MSSL), M. De Pasquale (Istanbul U.), M. H. Siegel (PSU),
A. D'Ai (INAF-IASFPA), P. D'Avanzo (INAF-OAB), S. D. Barthelmy (NASA/GSFC),
A. P. Beardmore (U. Leicester), D. N. Burrows (PSU), S. Campana (INAF-OAB),
S. B. Cenko (NASA/GSFC), G. Cusumano (INAF-IASF PA), V. D'Elia(ASDC),
P. A. Evans (U. Leicester), P. Giommi (ASI), D. Hartmann (Clemson U.),
J. A. Kennea (PSU), H. A. Krimm (NSF), A. Y. Lien (GSFC/UMBC),
D. B. Malesani (DTU Space), A. Melandri (INAF-OAB), J. A. Nousek (PSU),
P. T. O'Brien (U. Leicester), J. P. Osborne (U. Leicester), C. Pagani (U. Leicester),
K. L. Page (U.Leicester), D.M. Palmer (LANL), M. Perri (ASDC),
J. L. Racusin (NASA/GSFC), T. Sakamoto (AGU), B. Sbarufatti (INAF-OAB/PSU),
G. Tagliaferri (INAF-OAB), A. Tohuvavohu (U Toronto), and
E. Troja (NASA/GSFC/UMCP) report on behalf of the Swift team:

We report a candidate transient found in the UVOT search results of the
LVC event S190930t (LIGO/VIRGO Collaboration GCN Circ. 25876).

On 2019-09-30 at 18:33:40 UT Swift UVOT took a 74 s exposure in the
u band with exposure ID uu591561225I (target ID 07021582001). The new source is
not listed in the USNO-B1, Gaia DR1, GSC2.3 or 2MASS and is not listed as a minor planet.

The UVOT position is

    RA (J2000)  22:19:51.82 = 334.96592
   Dec (J2000) -48:42:40.1  = -48.71114

with an estimated uncertainty of 0.7 arcsec (radius, 90% confidence).

The magnitude using the UVOT photometric system  (Breeveld et al. 2011, AIP
Conf. Proc. 1358, 373) is u = 18.47 +/- 0.20 mag (Vega).

A faint unresolved counterpart consistent with this position is identified in
the DSS archival image and in the Dark Energy Camera Legacy Survey (DECaLS; http://legacysurvey.org/decamls/),
with reported magnitudes g = 22.76, r = 21.18, and z = 20.29. A source is also
observed at this position in VISTA archival images with magnitudes of J = 18.82,
H = 18.35, Ks = 17.88. The infra-red archival detection may indicate
that this source is a flare of a red dwarf star.

In 72 s of XRT data, there is no X-ray source detected, with a 3-sigma
upper limit of 0.12 count s^-1 (corresponding to an observed flux of
~5e-12 erg cm^-2 s^-1, assuming a typical power-law spectrum).

This circular is an official product of the Swift team.

On 1 Oct 2019, at 17:59, Aaron Tohuvavohu <aaron.tohu at gmail.com<mailto:aaron.tohu at gmail.com>> wrote:

Again, I don't think we should report on this inconsistent GLADE galaxy. It just adds useless information.

On Tue, Oct 1, 2019 at 12:57 PM Oates, Samantha <S.Oates at warwick.ac.uk<mailto:S.Oates at warwick.ac.uk>> wrote:
Ok so in light of source 2 probably being a planetoid, I have reverted back to the original text.

If there are no further comments I will submit this in 15min.

Thanks,

Sam

LIGO/Virgo S190930t: Transient found in Swift/UVOT counterpart search

S. R. Oates (Uni. of Warwick), A. A. Breeveld (MSSL-UCL), N. P. M. Kuin (UCL-MSSL),
F. E. Marshall (NASA/GSFC), P. Brown (TAMU), C. Gronwall (PSU),
M. J. Page (UCL-MSSL), M. De Pasquale (Istanbul U.), M. H. Siegel (PSU),
A. D'Ai (INAF-IASFPA), P. D'Avanzo (INAF-OAB), S. D. Barthelmy (NASA/GSFC),
A. P. Beardmore (U. Leicester), D. N. Burrows (PSU), S. Campana (INAF-OAB),
S. B. Cenko (NASA/GSFC), G. Cusumano (INAF-IASF PA), V. D'Elia(ASDC),
P. A. Evans (U. Leicester), P. Giommi (ASI), D. Hartmann (Clemson U.),
J. A. Kennea (PSU), H. A. Krimm (NSF), A. Y. Lien (GSFC/UMBC),
D. B. Malesani (DTU Space), A. Melandri (INAF-OAB), J. A. Nousek (PSU),
P. T. O'Brien (U. Leicester), J. P. Osborne (U. Leicester), C. Pagani (U. Leicester),
K. L. Page (U.Leicester), D.M. Palmer (LANL), M. Perri (ASDC),
J. L. Racusin (NASA/GSFC), T. Sakamoto (AGU), B. Sbarufatti (INAF-OAB/PSU),
G. Tagliaferri (INAF-OAB), A. Tohuvavohu (U Toronto), and
E. Troja (NASA/GSFC/UMCP) report on behalf of the Swift team:

We report a candidate transient found in the UVOT search results of the
LVC event S190930t (LIGO/VIRGO Collaboration GCN Circ. 25876).

On 2019-09-30 at 18:33:40 UT Swift UVOT took a 74 s exposure in the
u band with exposure ID uu591561225I (target ID 07021582001). The new source is
not listed in the USNO-B1, Gaia DR1, GSC2.3 or 2MASS and is not listed as a minor planet.

The UVOT position is

     RA (J2000)  22:19:51.82 = 334.96592
    Dec (J2000) -48:42:40.1  = -48.71114

with an estimated uncertainty of 0.7 arcsec (radius, 90% confidence).

The magnitude using the UVOT photometric system  (Breeveld et al. 2011, AIP
Conf. Proc. 1358, 373) is u = 18.47 +/- 0.20 mag (Vega).

A faint unresolved counterpart consistent with this position is identified in
the DSS archival image and in the Dark Energy Camera Legacy Survey (DECaLS; https://nam01.safelinks.protection.outlook.com/?url=http%3A%2F%2Flegacysurvey.org%2Fdecamls%2F&data=02%7C01%7Cauc444%40psu.edu%7Cae9ccc893bd44c70873008d746908285%7C7cf48d453ddb4389a9c1c115526eb52e%7C0%7C1%7C637055458788709347&sdata=NxcWlLq2h2avRU8ZNw8hPafRkZYlZ2SyGU%2B24N5vu4Y%3D&reserved=0),
with reported magnitudes g = 22.76, r = 21.18, and z = 20.29. A source is also
observed at this position in VISTA archival images with magnitudes of J = 18.82,
H = 18.35, Ks = 17.88. The closest galaxy reported in the GLADE catalogue
(Dálya et al., 2018) is LEDA484504 (D = 419 Mpc, 16.9 mag) at approximately
100 arcsec from the UVOT candidate. The infra-red archival detection may indicate
that this source is a flare of a red dwarf star.

In 72 s of XRT data, there is no X-ray source detected, with a 3-sigma
upper limit of 0.12 count s^-1 (corresponding to an observed flux of
~5e-12 erg cm^-2 s^-1, assuming a typical power-law spectrum).

This circular is an official product of the Swift team.
_______________________________________________
Swiftlv mailing list
Swiftlv at lists.le.ac.uk<mailto:Swiftlv at lists.le.ac.uk>
https://nam01.safelinks.protection.outlook.com/?url=http%3A%2F%2Flists.le.ac.uk%2Fmailman%2Flistinfo%2Fswiftlv&data=02%7C01%7Cauc444%40psu.edu%7Cae9ccc893bd44c70873008d746908285%7C7cf48d453ddb4389a9c1c115526eb52e%7C0%7C1%7C637055458788719350&sdata=99lFxShs%2BNVaWD6vktlS51k3RiFD9Leal1cSCv5UtHQ%3D&reserved=0