LIGO/Virgo S190408an

C. M. Hui (NASA/MSFC)

reports on behalf of the Fermi-GBM Team and the GBM+LIGO/Virgo Working Group:



At the time of S190408an, Fermi was passing through

the South Atlantic Anomaly from 14 minutes prior to 15 minutes after

the trigger time; therefore the GBM detectors were disabled.

The LIGO Scientific Collaboration and the Virgo Collaboration report:

We identified the compact binary merger candidate S190408an during
real-time processing of data from LIGO Hanford Observatory (H1), LIGO
Livingston Observatory (L1), and Virgo Observatory (V1) at 2019-04-08
18:18:02.288 UTC (GPS time: 1238782700.288). The candidate was found by
the GstLAL [1], SPIIR [2], CWB [3], MBTAOnline [4], and PyCBC Live [5]
analysis pipelines.

S190408an is a candidate of interest because its false alarm rate, as
determined by the online analysis, is less than one in 100 years. The
candidate's properties can be found at this URL:

https://gracedb.ligo.org/superevents/S190408an

The classification of the signal, in order of descending probability, is
BBH (>99%), Terrestrial (<1%), BNS (<1%), NSBH (<1%), or MassGap (<1%).

Assuming the candidate is astrophysical in origin, there is strong
evidence against the lighter compact object having a mass < 3 solar masses
(HasNS: <1%). Using the masses and spins inferred from the signal, there
is evidence against matter outside the final compact object(HasRemnant: 12%).
We believe that the latter quantity (HasRemnant) may be overestimated; we
are reviewing it and will provide an update when available.

One skymap is available at this time and can be retrieved from the GraceDB
candidate page:
 * bayestar.fits.gz, a preliminary localization generated by BAYESTAR [6],
   distributed via GCN notice about 34 minutes after the candidate.

For the bayestar.fits.gz skymap, the 90% credible region is 387 deg2.
Marginalized over the whole sky, the luminosity distance estimate is
1473 +/- 358 Mpc (a posteriori mean +/- standard deviation).

For further information about analysis methodology and the contents of
this alert, refer to the LIGO/Virgo Public Alerts User Guide
<https://emfollow.docs.ligo.org/userguide/>.

 [1] Messick et al. PRD 95, 042001 (2017)
 [2] Hooper et al. PRD 86, 024012 (2012)
 [3] Klimenko et al. PRD 93, 042004 (2016)
 [4] Adams et al. CQG 33, 175012 (2016)
 [5] Nitz et al. PRD 98, 024050 (2018)
 [6] Singer & Price PRD 93, 024013 (2016)

V. Lipunov, T.Pogrosheva, E. Gorbovskoy, N.Tyurina, V.Kornilov, D.Vlasenko, V.Vladimirov, D.Zimnukhov,
A.Kuznetsov, P.Balanutsa, I.Gorbunov, A. Chasovnikov, V.Topolev, V.Grinshpun, F.Balakin, K.Zhirkov, D.Kuvshinov, A.Pozdnyakov 
(Lomonosov Moscow State University, SAI, Physics Department),

R. Podesta, C. Lopez, C.Francile, F. Podesta (Observatorio Astronomico  Felix Aguilar OAFA, San Juan National University),

H.Levato (Instituto de Ciencias Astronomicas, de la Tierra y del Espacio ICATE,SJNU)

R. Rebolo, M. Serra, N. Lodieu, G. Israelian, L. Suarez-Andres (The Instituto de Astrofisica de Canarias),

D. Buckley (South African Astronomical Observatory),

O. Gress, N.M. Budnev, O.Ershova (Applied Physics Institute, Irkutsk State University),

V. Yurkov, A. Gabovich, Yu. Sergienko, D. Kobcev (Blagoveschensk Educational State University),

A. Tlatov, V.Senik, A.V. Parhomenko, D. Dormidontov (Kislovodsk Solar  Station of the Pulkovo Observatory),

MASTER Global Robotic Net (http://observ.pereplet.ru, Lipunov et al., 2010, Advances in Astronomy,vol. 2010, 30L)
automatically started inspect of the LIGO/Virgo S190408an error-box after 
receiving probability map.

MASTER synchronousely observed central part of LIGO/Virgo S190408an 
error-box during own survey (at alert time).

  Reduction and observation will be cntinued.

The message may be cited.

Myungshin Im (SNU), Joonho Kim (SNU), Gregory S. H. Paek (SNU), Sungyong
Hwang (SNU), Sophia Kim (SNU), Changsu Choi (SNU), Gu Lim (SNU), Chung-Uk
Lee (KASI), Seung-Lee Kim (KASI), Hyung Mok Lee (KASI), on behalf of a
larger collaboration

We performed the search for the EM counterpart of S190408an (Singer et al.
GCN 24069
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 ) using the KMTNet telescopes, covering about 30 deg^2 area that
encompasses the highest confidence regions observable from the southern
hemisphere. The observation at the South Africa site has been completed,
and the observations are scheduled at the Chile and Australia sites. The
central coordinate of each 2 deg x 2deg pointing is given below.

G329243-0-0(R)  14:51:33.7   -41:24:41        B,R     120
G329243-1-0(R)  14:43:33.8   -41:24:41        B,R     120
G329243-2-0(R)  14:59:33.7   -41:24:41        B,R     120
G329243-3-0(R)  14:51:33.7   -39:24:41        B,R     120
G329243-4-0(R)  14:51:33.7   -43:24:41        B,R     120
G329243-5-0(R)  14:43:33.8   -39:24:41        B,R     120
G329243-6-0(R)  14:59:33.7   -43:24:41        B,R     120
G329243-7-0(R)  14:43:33.8   -43:24:41        B,R     120

The observations and the analysis of the data are ongoing. We thank the
observers at the KMTNet sites for performing the observation.

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

We report the search results in the BAT data within T0 +/- 100 s of the
LVC event S190408an (LIGO/VIRGO Collaboration GCN Circ. 24069
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 ),
where T0 is the LVC trigger time (2019-04-08T18:18:02.288 UTC).

The center of the BAT FOV at T0 is
RA = 133.644 deg,
DEC = 20.099 deg,
ROLL = 291.895 deg.
The BAT Field of View (>10% partial coding) covers 0.02% of the integrated
LVC localization probability.

Within T0 +/- 100 s, no significant detections (signal-to-noise ratio >~ 5
sigma)
are found in the BAT raw light curves with time bins of 64 ms, 1 s, and 1.6
s,
respectively. Assuming an on-axis (100% coded) short GRB with a typical
spectrum
in the BAT energy range (i.e., a simple power-law model with a power-law
index of -1.32,
Lien & Sakamoto et al. 2016), the 5-sigma upper limit in the 1-s binned
light
curve corresponds to a flux upper limit (15-350 keV) of ~ 1.49 x 10^-6
erg/s/cm^2.

BAT retains decreased, but significant, sensitivity to rate increases for
gamma-ray events outside of its FOV. About 9.37% of the integrated LVC
localization probability was outside of the BAT FOV but above the Earth's
limb
from Swift's location, and the corresponding flux upper limits for this
region
are within roughly an order of magnitude of those within the FOV.

V. Lipunov, T.Pogrosheva, E. Gorbovskoy, N.Tyurina, V.Kornilov, D.Vlasenko, V.Vladimirov, D.Zimnukhov,
A.Kuznetsov, P.Balanutsa, I.Gorbunov, A. Chasovnikov,  V.Grinshpun, F.Balakin (Lomonosov Moscow State University, SAI, Physics Department),

R. Podesta, C. Lopez, C.Francile, F. Podesta (Observatorio Astronomico  Felix Aguilar OAFA, San Juan National University),

H.Levato (Instituto de Ciencias Astronomicas, de la Tierra y del Espacio ICATE,SJNU)

R. Rebolo, M. Serra, N. Lodieu, G. Israelian, L. Suarez-Andres (The Instituto de Astrofisica de Canarias),

D. Buckley (South African Astronomical Observatory),

O. Gress, N.M. Budnev, O.Ershova (Applied Physics Institute, Irkutsk State University),

V. Yurkov, A. Gabovich, Yu. Sergienko, D. Kobcev (Blagoveschensk EducationState University),

A. Tlatov, V.Senik, A.V. Parhomenko, D. Dormidontov (Kislovodsk Solar  Station of the Pulkovo Observatory),

MASTER Global Robotic Net (http://observ.pereplet.ru, Lipunov et al., 2010, Advances in Astronomy,vol. 2010, 30L)
during  LIGO/Virgo S190408an (Singer et al. GCN 24069
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 ) South Part Error 
Field  Inspection (Lipunov et al. GCN 24070
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 )
at MASTER-OAFA found optical transient (no known sources in VIZIER database inside 5")

MASTER OT J140518.22-395309.9 discovery

MASTER auto-detection system discovered OT source at
(RA,Dec2000) = 14h 05m 18.22s -39d 53m 09.9s on 2019-04-09.07809UT.

The OT unfiltered magnitude is 17.4m (mlim=19.1m).

The OT is seen in 2 MASTER LVC inspect images (Pogrosheva et a., ATel #12644). There is no minor planet at this place.

We have reference image without OT on 2018-05-19.13417 UT with 20.2 
unfiltered magnitude limit.

There is no any sources in VIZIER database.

Spectral observations are required.

The discovery and reference images are available at:

http://master.sai.msu.ru/static/OT/140518.22-395309.9.png

MASTER cover map of Ligo/Virgo S190408an error-field inspection  will be
available on-line at:

http://master.sai.msu.ru/static/LVC/MASTER_S190408an_map.jpg

  Reduction and observation will be cntinued.

The message may be cited.

Q. Luo, C. Cai, C. K. Li, X. B. Li, G. Li, J. Y. Liao, S. L. Xiong, 
C. Z. Liu, X. F. Li, Z. W. Li, Z. Chang, A. M. Zhang, 
Y. F. Zhang, X. F. Lu, C. L. Zou (IHEP), Y. J. Jin, 
Z. Zhang (THU), T. P. Li (IHEP/THU), F. J. Lu, L. M. Song, 
M. Wu, Y. P. Xu, S. N. Zhang (IHEP), 
report on behalf of the Insight-HXMT team: 

Insight-HXMT was taking data normally around the GW trigger time
(T0=2019-04-08 18:18:02.288 UTC). At T0, the LIGO-Virgo localization 
region was fully covered by the Insight-HXMT without occultation
by the Earth.

Within T0 �� 100 s, no significant excess events (SNR > 5 sigma) are 
found in a search of the Insight-HXMT/HE raw light curves.

Assuming the GW counterpart GRB with three typical GRB Band spectral 
models, two typical duration timescales(1 s, 10 s) from the peak 
position of the LIGO-Virgo location probability map, the 5-sigma 
upper-limits fluence (0.2 - 5 MeV, incident energy) are reported below:

Band model 1 (alpha=-1.9, beta=-3.7, Ep=70 keV):
1s:   1.6e-08 erg cm^-2
10s:  5.3e-08 erg cm^-2

Band model 2 (alpha=-1.0, beta=-2.3, Ep=230 keV):
1s:   2.6e-08 erg cm^-2
10s:  8.7e-08 erg cm^-2

Band model 3 (alpha=-0.0, beta=-1.5, Ep=1000 keV):
1s:   7.1e-08 erg cm^-2
10s:  2.9e-07 erg cm^-2

All measurements above are made with the CsI detectors operating in the
regular mode with the energy range of about 80-800 keV (record energy).
Only gamma-rays with energy greater than about 200 keV can penetrate
the spacecraft and leave signals in the CsI detectors installed inside
of the telescope.

Insight-HXMT is the first Chinese space X-ray telescope, which was 
fundedjointly by the China National Space Administration (CNSA) and 
the Chinese Academy of Sciences (CAS). 
More information could be found at: http://www.hxmt.org.

S. J. Smartt, K. W. Smith, D. R. Young, O. McBrien, J. Gillanders. S. Srivastav,
D. O���Neil,  P. Clark, S. Sim (QUB),  L. Denneau, H. Flewelling, A. Heinze, 
J. Tonry, H. Weiland K. C. Chambers , M. Huber,  E. Magnier, 
A. Schultz, (IfA, Univ. Hawaii), A. Rest (STScI),  B. Stalder (LSST), 
C. Stubbs (Harvard)

Lipunov et al (GCN 24076
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 ) reported the discovery of an optical transient 
MASTER OT J140518.22-395309.9  close to the southern part of the 
skymap of LIGO/Virgo source S190408an. 

The ATLAS survey (Tonry et al. 2018, Stalder et al. 2016) has detected
this source since MJD=58555 (2019-03-13) at  o = 17.4. It peaked around 
MJD=58569 at o = 17 and has a SN like lightcurve. There is no obvious
catalogued host galaxy. 

In summary, we confirm the discovery of MASTER that this is a real 
optical transient (with no host galaxy) at coordinates : 

14:05:18.21 -39:53:10.0

211.32588 -39.88612

But that it is almost certainly a foreground SN about 1 month old, 
and very unlikely to be related to LIGO/Virgo S190408an.

Michael J. Lundquist (UA), Kerry Paterson, Wen-fai Fong (Northwestern),
David J. Sand (UA), Stefano Valenti (UC Davis), Sheng Yang (INAF-OAPd, UC
Davis), Sam Wyatt (UA), Eric Christensen, Alex Gibbs, Frank Shelly (UA/LPL)
report:

We initiated observations of 3 fields (each 2.26 x 2.26 deg^2) within the
LVC localization region for the GW trigger S190408an (GCN Circ 24069
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 )
starting on 2019-04-09 at 11:45 UT. SAGUARO* uses the 1.5m Catalina Sky
Survey telescope on Mt. Lemmon, AZ and its 5 deg^2 imager to tile the
highest probability regions of the LVC localization that are accessible
from southern Arizona in order to search for electromagnetic counterparts
to gravitational wave events. The typical limiting magnitudes of single
pointings are G~21 mag (calibrated to Gaia DR2). Below are the field
centers observed.

RA DEC
350.4255 56.3125
354.2550 56.3125
349.7730 58.5208

Any interesting transient candidates will be reported as soon as possible.

*SAGUARO stands for Searches After Gravitational-waves Using ARizona's
Observatories. It is a partnership between the University of Arizona and
Northwestern University.

V. Lipunov, T.Pogrosheva, E. Gorbovskoy, N.Tyurina, V.Kornilov, D.Vlasenko, V.Vladimirov, D.Zimnukhov,
A.Kuznetsov, P.Balanutsa, I.Gorbunov, F.Balakin, A. Chasovnikov, V.Grinshpun, K.Zhirkov, A.Pozdnyakov, V.Topolev,
T.Pogrosheva, V.Shumkov (Lomonosov Moscow State University, SAI, Physics Department),

R. Podesta, C. Lopez, C.Francile, F. Podesta (Observatorio Astronomico  Felix Aguilar OAFA, San Juan National University),

H.Levato (Instituto de Ciencias Astronomicas, de la Tierra y del Espacio ICATE,SJNU)

R. Rebolo, M. Serra, N. Lodieu, G. Israelian, L. Suarez-Andres (The Instituto de Astrofisica de Canarias),

D. Buckley (South African Astronomical Observatory),

O. Gress, N.M. Budnev, O.Ershova (Applied Physics Institute, Irkutsk State University),

V. Yurkov, A. Gabovich, Yu. Sergienko, D. Kobcev (Blagoveschensk EducationState University),

A. Tlatov, V.Senik, A.V. Parhomenko, D. Dormidontov (Kislovodsk Solar  Station of the Pulkovo Observatory),

First of all, we must to say that all this OT's not connected with 
gravitational wave source, because real BBH can not produce 
detectable electromgnetic emission.

MASTER Global Robotic Net (http://observ.pereplet.ru, Lipunov et al., 2010,Advances in Astronomy,vol. 2010, 30L)
during  LIGO/Virgo S190408an (Singer et al. GCN 24069
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 )
inspection (Lipunov et al. GCN 24070
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 , GCN 24076
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 )
detected the following optical transients

1) MASTER OT J154209.55-431742.2 discovery - OT, no any sources in VIZIER, ampl>5m

MASTER-OAFA auto-detection system  Lipunov et al., "MASTER Global Robotic Net",Advances in Astronomy, 2010, 30L
  discovered OT source at (RA, Dec) = 15h 42m 09.55s -43d 17m 42.2s on 2019-04-09.06495 UT.

The OT unfiltered magnitude is 17.0m (mlim=17.9m).

The OT is seen in both 2 LVC inspect images (south part). There is no minor planet at this place.
We have reference image without OT on 2017-03-30.32611 UT with 18.6 unfiltered magnitude limit .
There is no any sources in VIZIER, it means 22m POSS limit  in history and 
more then 5m of current outburst amplitude (MASTER W=0.2B+0.8R by thousands USNO-B1 field stars)
Spectral observations are required.
The discovery and reference images are available at: 
http://master.sai.msu.ru/static/OT/154209.55-431742.2.png

2) MASTER OT J231043.63+470956.4 discovery - OT with ampl>7.1m

MASTER-Tavrida auto-detection system discovered OT source at (RA, Dec) = 23h 10m 43.63s +47d 09m 56.4s on 2019-04-09.00417 UT.
The OT unfiltered magnitude is 14.9m (limit 18.9m).
The OT is seen in 8 images. There is no sources in POSS images, it gives more then 7.1mag of current outburst amplitude.
There is PanSTARR source in 4.6", but it's too far for error of localization.

We have reference image without OT on 2019-03-18.10164 UT with unfiltered magnitude limit 18.7m.
Spectral observations are required.

The discovery and reference images are available at

http://observ.pereplet.ru/images/MASTEROTJ231043.63+470956.4.jpg

3) MASTER OT J140518.22-395309.9 discovery (Lipunov et al. GCN24076
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 ) also detected by ATLAS (Smart et al. GCN 24078
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 ) in March


MASTER cover map of Ligo/Virgo S190408an error-field inspection  will be
available on-line at:

http://master.sai.msu.ru/static/LVC/MASTER_S190408an_map.jpg

  Reduction and observation will be cntinued.

The message may be cited.

Dong Xu, Zi-Pei Zhu, Bang-Yao Yu (NAOC), Xing Gao (Urumqi No.1 Senior 
High School), Sheng Yang (INAF-OAPd, UC Davis), Hai-Bin Zhao, Bin Li 
(PMO), Jin-Zhong Liu, Hu-Biao Niu, Jun-Hui Liu, Xuan Zhang (XAO), 
Ji-Rong Mao, Jin-Ming Bai (YNAO), report on behalf of the GWFUNC 
collaboration:

We performed the search for the optical counterpart of LIGO/Virgo 
S190408an (Singer et al. GCN 24069
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 ) using the Half-Meter Telescope (HMT) 
located at Dabancheng, Xinjiang, China. Observations started at 13:50:00 
UT on 2019-04-09 and ended at 22:43:00 UT on 2019-04-09, and the 60x40 
arcmin^2 unfiltered imager scanned the highest probability regions of 
the LVC localization that are accessible to HMT.

The total area is about 48 deg^2, and listed below are the field centers 
observed.

  RA(deg)   DEC(deg)
13.39305	67.41200
13.39305	68.07900
13.39305	68.74600
16.07167	67.41200
16.07167	68.07900
16.07167	68.74600
18.75028	67.41200
18.75028	68.07900
18.75028	68.74600
14.67533	69.41300
14.67533	70.08000
14.67533	70.74700
17.61040	69.41300
17.61040	70.08000
17.61040	70.74700
20.54547	69.41300
20.54547	70.08000
20.54547	70.74700
5.87013	69.41300	
5.87013	70.08000	
5.87013	70.74700	
8.80520	69.41300	
8.80520	70.08000	
8.80520	70.74700	
11.74027	69.41300
11.74027	70.08000
11.74027	70.74700
5.35722	67.41200	
5.35722	68.07900	
5.35722	68.74600	
8.03583	67.41200	
8.03583	68.07900	
8.03583	68.74600	
10.71444	67.41200
10.71444	68.07900
10.71444	68.74600
347.58542	55.40600
347.58542	56.07300
347.58542	56.74000
349.37710	55.40600
349.37710	56.07300
349.37710	56.74000
351.16878	55.40600
351.16878	56.07300
351.16878	56.74000
349.83315	57.40700
349.83315	58.07400
349.83315	58.74100
351.72414	57.40700
351.72414	58.07400
351.72414	58.74100
353.61513	57.40700
353.61513	58.07400
353.61513	58.74100
344.31655	49.40300
344.31655	50.07000
344.31655	50.73700
345.87454	49.40300
345.87454	50.07000
345.87454	50.73700
347.43253	49.40300
347.43253	50.07000
347.43253	50.73700
351.07563	53.40500
351.07563	54.07200
351.07563	54.73900
352.77989	53.40500
352.77989	54.07200
352.77989	54.73900
354.48414	53.40500
354.48414	54.07200
354.48414	54.73900

Optical transient(s) from the above fields, if interesting, will be 
reported later on.

Alan M. Watson (UNAM), Eleonora Troja (GSFC/UMD), Nat Butler (ASU), Rosa
L. Becerra (UNAM), Simone Dichiara (UMD), Diego Gonz��lez (UNAM),
Alexander Kutyrev (GSFC/UMD), William H. Lee (UNAM), Margarita Pereyra
(UNAM), and Tanner Wolfram (ASU) report:

We observed the region of maximum probability of the LIGO/Virgo
candidate S190408an with the DDOTI/OAN wide-field imager at the
Observatorio Astron��mico Nacional on Sierra San Pedro M��rtir
(http://ddoti.astroscu.unam.mx).

We observed a region of approximately 11 degrees in declination by 7
degrees in RA centered on 23:26:00 +54:46:00 2000 from 2019-04-09 11:03
UTC to 12:08 UTC (16.8 to 17.8 hours after trigger) obtaining a total of
42 minutes exposure in the w filter at high airmass.

Analysis is ongoing and interesting transient source will be reported
later.

Jun Mo, Wen-xiong Li, Xiao-feng Wang (THU), Xiao-Jun Jiang, Jie Zheng, Xiao-ming Zhang,Tian-meng Zhang (NAOC), Xing-han Zhang, Li-Ming Rui, Dan-feng Xiang, Zhi-hao Chen, Gao-bo Xi, Han Lin, 
Ji-cheng Zhang, Wei-li Lin, Cheng Miao (THU), Sheng-yu Yan (GU/THU), Ju-jia Zhang (YNAO), and Li-fan Wang (TAMU/PMO) report:

We conducted optical imaging observations for gravitational wave alert S190408an (Singer et al. GCN 24069
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 ) with 4 x 40 cm Tsinghua Ma-huateng Telescopes (TMTS) at Xinglong Observatory in Hebei Province, China (40.40�� N, 117.58�� E). Our observations started at 2019-04-09 19:37 UT and ended at 2019-04-09 20:20 UT, covering about 90% credible region of S190408an observable from Xinglong.  The total sky area scanned by the TMTS  is about 450 deg^2, with each exposure covering the field of view of about 18 deg^2. Our 3�� detection limit is ~19.5 mag for 60s explosure. The center coordinates of our observations are listed below. 
-----------         -------------
RA(hmd) DEC(dms)
22:20:04.00 +38:00:00.00
22:36:23.87 +42:00:00.00
22:38:56.48 +46:00:00.00
23:01:58.45 +46:00:00.00
22:49:02.22 +50:00:00.00
23:13:55.71 +50:00:00.00
23:38:49.20 +50:00:00.00
23:08:15.72 +54:00:00.00
23:35:28.97 +54:00:00.00
23:08:53.45 +58:00:00.00
23:39:05.05 +58:00:00.00
00:00:00.00 +62:00:00.00
00:34:04.85 +62:00:00.00
23:17:18.93 +62:00:00.00
23:51:23.79 +62:00:00.00
00:00:00.00 +66:00:00.00
00:39:20.25 +66:00:00.00
01:18:40.50 +66:00:00.00
00:00:00.00 +70:00:00.00
00:46:46.85 +70:00:00.00
01:33:33.70 +70:00:00.00
00:00:00.00 +74:00:00.00
00:58:02.84 +74:00:00.00
01:56:05.67 +74:00:00.00
01:16:57.35 +78:00:00.00
02:33:54.69 +78:00:00.00
------------      -------------
Detailed data analysis is still in progress and any interesting transients will be reported later.

S. Torii (Waseda U), A. Yoshida, T. Sakamoto, V. Pal'shin, S. Sugita (AGU),
Y. Kawakubo (LSU),K. Yamaoka (Nagoya U), S. Nakahira (RIKEN),
I. Takahashi (IPMU), Y. Asaoka, S. Ozawa, (Waseda U),
Y. Shimizu, T. Tamura (Kanagawa U), W. Ishizaki (ICRR), M. L. Cherry (LSU),
S. Ricciarini (U of Florence), A. V. Penacchioni, P. S. Marrocchesi (U of Siena)
and the CALET collaboration:

The CALET Gamma-ray Burst Monitor (CGBM) was operating at the trigger time
of S190408an (The LIGO Scientific Collaboration and Virgo Collaboration,
GCN Circ. 24069
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 ).  No CGBM on-board trigger occurred around the event time.
Based on the LIGO-Virgo localization sky map, most of the part of
the high probability area was in the field-of-view of CGBM.  The summed LIGO
probabilities inside the HXM and the SGM field of view are 91% and 95%.

Based on the analysis of the light curve data with 0.125 sec time resolution
from -60 sec to 60 sec from the trigger time, we found no significant excess
around the trigger time in either the HXM (7-3000 keV) or the SGM (40 keV -28 MeV)
data.

The CALET Calorimeter (CAL) was operating in low energy trigger mode at the trigger
time of S190408an.  Using CAL data, we have searched for gamma-ray events in
the 1-10 GeV band from -60 sec to +60 sec from the GW trigger time and found no
candidates.  The 90% upper limit of CAL is 2.3 x 10^-6 erg/cm2/s (1-10 GeV) when
the summed LIGO-Virgo probabilities reaches at 80%.

F. Onori (INAF-IAPS Roma), M. Turatto (INAF-OAPd), S. Benetti (INAF-OAPd), L. Tomasella (INAF-OAPd), L. Nicastro (INAF-OAS), E. Palazzi (INAF-OAS), A. Melandri (INAF-OAB), S. Piranomonte (INAF-OAR), S. Yang (INAF-OAPd), P. D���Avanzo (INAF-OAB), M. Cecconi (INAF-TNG), A. Ghedina (INAF-TNG), H. Stoev (INAF-TNG), A. Brosio (Osservatorio Astronomico Lilio), S. Savaglio (UniCal) on behalf of GRAWITA report:

We carried out follow-up observations of the optical transient MASTER OT J231043.63+470956.4, discovered by Lipunov et al. (GCN Circ. #24084
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 ) during observations of the skymap of the LIGO/Virgo event S190408an (LVC, GCN Circ. #24069
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 ). 

Optical imaging observations were obtained with the 0.5m telescope of the Osservatorio Astronomico Lilio, located in Savelli (Italy) starting on 2019-04-10 at 02:08:51 UT with the g-sdss, r-sdss, i-sdss filter. The OT is clearly detected with r~15.59+/- 0.02 mag (AB).

We observed the transient with the 3.6m Italian TNG telescope (Canary Islands, Spain), equipped with the DOLORES camera in spectroscopic mode starting on 2019-04-10 at 04-57-48 UT. A total of 3 optical spectra, each one lasting 180 s, were obtained using the grism LR-B (wavelength range ~ 400-800 nm, resolution 1.05 nm). The spectrum shows a weak Halpha emission and other Balmer lines in absorption at z=0, superposed on a bright continuum.

These results are consistent with MASTER OT J231043.63+470956.4 being a Galactic transient (likely a CV). The transient is therefore unrelated with the LIGO/Virgo GW event S190804an (as already proposed by  Lipunov et al. GCN Circ 24084
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 ).

H. Negoro (Nihon U.), M. Serino, S. Sugita (AGU), M. Sugizaki, N. Kawai (Tokyo Tech),
M. Nakajima, W. Maruyama, M. Aoki, K. Kobayashi (Nihon U.),
S. Nakahira, T. Mihara, M. Matsuoka (RIKEN), T. Sakamoto, A. Yoshida (AGU),
Y. Tsuboi, W. Iwakiri, R. Sasaki, H. Kawai, T. Sato (Chuo U.), M. Shidatsu (Ehime U.), 
Y. Tachibana, K. Morita, M. Oeda, K. Shiraishi (Tokyo Tech), 
S. Ueno, H. Tomida, M. Ishikawa, Y. Sugawara, N.Isobe, R. Shimomukai,
M. Tominaga (JAXA), Y. Ueda, A. Tanimoto, T. Morita, S. Yamada, 
S. Ogawa (Kyoto U.), H. Tsunemi, T. Yoneyama, K. Asakura, S. Ide (Osaka U.),
M. Yamauchi, S. Iwahori, Y. Kurihara (Miyazaki U.), T. Kawamuro (NAOJ),
K. Yamaoka (Nagoya U.), Y. Kawakubo (LSU)
report on behalf of the MAXI team:

At the LVC trigger time of S190408an, 18:18:02.29 UT on 2019 April 8 
(LIGO/Virgo Collaboration, GCN Circ. 24069
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 ), MAXI/GSC was scanning a part of 
the 50% credible region, centered around (R.A., Dec) = (333 deg, 20 deg),
but no flaring event was detected.
For one orbital period about 92 min, MAXI covered about 82% of the 90% 
credible region. Any enhancement was recognized in the region, and a typical 
(averaged) 1-sigma upper limit was 28 mCrab at 2-20 keV. MAXI observed 
the whole 90% credible region in 6 hours, and we put upper limits
of typically about 15 mCrab, and partially about 50 mCrab for the regions 
observed with the degraded GSC_3 camera.

Finally we note that MAXI detected GRB 190408A prior to the LVC trigger by 
12 min (Sugita et al. GCN Circ. 24072
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 ). The burst was relatively short 
(~ 10 sec) and soft, but the GRB location, (R.A., Dec) = (47.3 deg, 1.8 deg), 
is far from the GW localization region.
Thus, an association between these events is likely low.

A. F. Valeev, I. V. Sokolov and V. V. Sokolov (SAO-RAS), Y.-D. Hu, X.-Y. 
Li and A. J. Castro-Tirado (IAA-CSIC), I. Carrasco (UMA), R. 
Sanchez-Ramirez (INAF-IAPS), M. D. Caballero-Garcia (ASU-CAS) and P. 
Pessev (GRANTECAN, IAC, ULL), on behalf�� of a larger collaboration, report:

Following the new optical transient MASTER OT J231043.63+470956.4 
(Lipunov et al. GCNC 24084) within the LIGO/Virgo error box (GCNC 
24069), we have followed it up with the BOOTES-4/MET 0.6m robotic 
telescope in Lijiang (China) confirming its brightness (r = 15.3 mag on 
Apr 9, 21UT). Furthermore, we have taken a 300s spectrum with the 10.4m 
GTC (+OSIRIS) telescope in La Palma (Spain). The spectrum shows a blue 
continuum with Balmer lines in absorption with the exception of H-alpha 
in emission, all at zero redshift. This is consistent with a dwarf nova 
spectrum undergoing a superoutburst, taking into account the > 7 mag 
amplitude in optical brightness with respect to the quiescence phase. 
Therefore this OT is unrelated to S190408an, in agreement with the Onori 
et al. findings (GCNC 24090).

We acknowledge the excellent support from the GTC staff.

[GCN OPS NOTE(11apr19): Per author's request, the following typos were corrected:
" Peseev" --> "Pessev"; "taking accound the" --> "taking into account".]

K. W. Smith, D. R. Young, M. Huber, K. C. Chambers, S. J. Smartt,
O. McBrien, J. Gillanders. S. Srivastav, D. O'Neil,  P. Clark, 
S. Sim (QUB), E. Magnier, A. Schultz, (IfA, Univ. Hawaii), 
L. Denneau, H. Flewelling, A. Heinze, J. Tonry, H. Weiland,  
A. Rest (STScI),  B. Stalder (LSST), C. Stubbs (Harvard)

We report observations of the BAYESTAR skymap of the BBH event S190804an 
(The LIGO Scientific Collaboration and the Virgo Collaboration, GCN 
24069
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 ) with the Pan-STARRS1 telescope (Chambers et al. 2016, 
arXiv:1612.05560
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 C). Images were taken in the PS1 w,z and y-bands 
(Tonry et al. 2012, ApJ 750, 99) in the standard NEO search sequence. 
At each pointing position a sequence of quads (4 x 45 sec) was taken.
This observing sequence ensures exactly the same pointing position 
for each of the quads. We estimate that the active 
pixel area covered 72 square degrees and a summed probability of 
11% of the BAYESTAR skymap. We began taking data at 2019-04-09
14:30 (UTC) 20hrs after the GW trigger.

The images were processed with the IPP (Magnier et al. 2016, 
arXiv:1612.05240
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 ) and difference images were produced using 
the Pan-STARRS1 Science Consortium 3Pi images as reference 
frames. Transient candidates were run through our standard 
filtering procedures, combined with a machine learning algorithm 
(Wright et al. 2015, MNRAS, 449, 451) were applied and all candidates were
spatially cross-matched with known minor planets, and major 
star, galaxy, AGN and multi-wavelength catalogues (as described in 
Smartt et al. 2016, MNRAS, 462 4094). 

We find 3 new transients. None of which appear to possess any 
peculiar feature that indicates any link to S190804an. 

bPC denotes the percentage probability contour within which 
the transient is found according to the bayestar.fits map. 

Object RA         DEC        Disc Mag  filt MJD         z      bPC  Notes
-------------------------------------------------------------------------
PS19pn 339.15090  +33.16465  20.40 0.21  w  58582.6099  -      60%  (1)
PS19pm 337.33525  +25.26419  19.87 0.14  w  58582.6061  ~0.195 80%  (2)
PS19pl 335.17707  +31.17752  19.44 0.12  w  58582.6086  ~0.083 90%  (3)  

(1) Orphan, no host object 
(2) Nuclear Transient coincident with SDSS J222920.46+251551.0; an r=18.31 
mag galaxy found in the SDSS DR12 PhotoObjAll Table catalogue. It's located 
0.2" from the galaxy core. A host photoZ=0.195 (��0.031) implies absolute
mag of M = -20. There is some variability history at similar flux levels in 
Pan-STARRS data.
(3) Probably associated with SDSS J222042.60+311038.3; an r=17.26 mag
galaxy found in the SDSS DR12 PhotoObjAll Table catalogue. It's located
0.69" N, 1.35" W from the galaxy centre. A host photoZ=0.083 (��0.020)
implies an absolute mag of M = -18.5

T.-W. Chen (MPE, Humboldt Fellow), T. Schweyer (MPE), A. Rossi (INAF-OAS), K. E. Heintz (Univ. of Iceland), M. Gromadzki (Univ. of Warsaw), J. Bolmer (MPE) and P. Schady (Bath)

We observed again the field of the MASTER OT J154209.55-431742.2 (GCN#24084
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 , Lipunov et al.) simultaneously in g'r'i'z'JHK with GROND (Greiner et al. 2008, PASP 120, 405) mounted at the 2.2 m MPG telescope at ESO La Silla Observatory (Chile).

Observations started at 07:23 UT on 10 of April 2019, about 1.25 days after the MASTER OT discovery, and were performed under seeing conditions 1".0, and at an average airmass of 1.0. We detect the candidate and based on 8.3 min of total exposure time.

We derive the following preliminary magnitudes (all in the AB system):

g = 16.70 +/- 0.01 mag,
r = 16.82 +/- 0.01 mag,
i = 17.05 +/- 0.01 mag,
z = 17.14 +/- 0.01 mag,
J = 17.11 +/- 0.01 mag,
H = 17.71 +/- 0.03 mag, and
K = 17.95 +/- 0.07 mag.

Given magnitudes are calibrated against GROND zeropoint as well as 2MASS field stars and are not corrected for the expected Galactic foreground extinction corresponding to a reddening of E_(B-V) = 0.24 mag in the direction of the counterpart (Schlafly & Finkbeiner 2011).

We searched for previous observations. No source is detected in archival DSS and DSS2 red images and IR images. However, we have found that the source was detected in March 2015 by the SkyMapper Southern Sky Survey with vgriz: 17.798 +/- 0.034, 17.588 +/- 0.011, 17.593 +/- 0.030, 17.541 +/- 0.032, 17.703 +/- 0.040 (PSF magnitudes, AB) not corrected for galactic extinction (http://skymapper.anu.edu.au/object-viewer/dr1/179882566/).
We have also searched for previous observations in the VISTA Hemisphere Survey. In images obtained on April 2010 we found a very faint source with J = 20.9 +/- 0.5 mags (Vega), while in K-band we can only provide an upperlimit K>19.0 mag, calibrated against 2MASS field stars.

The SED obtained from archival images points to a very blue star. The late photometry from GROND, shows a ~5 magnitude brightening in the J band. These findings support the idea that this object is likely a bright infrared nova based on the SED and not related with the GW.

We also noticed that the source is not detected in GAIA dr1 and 2 down to g=19.5, implying that skymapper and GROND observations were obtained during an outburst.

Z. Kostrzewa-Rutkowska (SRON/RU), S. Hodgkin, A. Delgado, D.L. Harrison, M.
van Leeuwen, G. Rixon, A. Yoldas (IoA Cambridge), D. Eappachen, P.G. Jonker
(SRON/RU) on behalf of Gaia Alerts team report the discovery of a transient
candidate within the probability skymap of S190408an (Singer et al. GCN
24069
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 ):

---------------------------------------------------------------------------
Name      TNSid     Date [TCB]          RaDeg     DecDeg    AlertMag URL
---------------------------------------------------------------------------
Gaia19bhc AT2019ddt
Loading...
 
  2019-04-07 15:17:19 347.68061  47.16521 15.26
  http://gsaweb.ast.cam.ac.uk/alerts/alert/Gaia19bhc/
---------------------------------------------------------------------------

The transient was discovered by the MASTER survey on 2019-04-09.00417 UT
(MASTER OT J231043.63+470956.4; Lipunov et al. GCN 24084
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 ). However, the
transient was observed by Gaia one day before the LIGO/Virgo trigger
thereby re-enforcing the conclusion from Onori et al. (GCN 24090
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 ) and
Valeev et al. (GCN 24092
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 ) that it is unrelated to the GW event S190408an.


Acknowledgements: This work has made use of data from the European Space
Agency (ESA) mission Gaia (https://www.cosmos.esa.int/gaia), processed by
the Gaia Data Processing and Analysis Consortium (DPAC,
https://www.cosmos.esa.int/web/gaia/dpac/consortium). Funding for the DPAC
has been provided by national institutions, in particular the institutions
participating in the Gaia Multilateral Agreement. ZKR, DE, and PGJ
acknowledge support from the European Research Council under ERC
Consolidator Grant agreement no 647208.

H. Weiland (IfA, Univ. of Hawaii), K. W. Smith, D. R. Young, (Queen's 
University Belfast), L. Denneau, H. Flewelling, A. Heinze, J. Tonry 
(IfA), S. Smartt,  O. McBrien, J. Gillanders,nS. Srivastav, D. O'Neil,  
P. Clark, S. Sim (QUB), A. Rest (STScI),  B. Stalder (LSST), 
C. Stubbs (Harvard), E. Magnier, A. Schultz, , M. Huber, 
K. C. Chambers (IfA)

We report observations of the BAYESTAR skymap of the BBH event S190412m 
(The LIGO Scientific Collaboration and the Virgo Collaboration, GCN 
24098
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 ) with the ATLAS telescope system (Tonry et al. 2018, PASP, 13, 
164505). ATLAS is a twin 0.5m telescope system on 
Haleakala and Mauna Loa employing two filters cyan and orange. 
While carrying out the primary mission for Near Earth Objects, we
can adjust the schedule rapidly to point at LVC gravitational wave 
skymaps. 

Sequences of 30 sec images were taken in the ATLAS o/c bands, and 
at each pointing position a sequence of quads (4 x 30 sec) was taken.
The images were processed with the ATLAS pipeline and reference images 
subtracted from each one. Transient candidates were run through our 
standard filtering procedures, combined with machine learning algorithms 
(e.g. Wright et al. 2015, MNRAS, 449, 451). Candidates were 
spatially cross-matched with known minor planets, and 
star, galaxy, AGN and multi-wavelength catalogues (as described in 
Smartt et al. 2016, MNRAS, 462 4094, Stalder et al. 2017, ApJ, 850, 
149). 

We covered 137 square degrees of the bayestar map 90% credible 
region and covered a sky region totalling 91% of the event���s 
full localisation likelihood. Data acquisition began at 58585.300570
or 2019-04-12 07:12:49 (UTC), 41 mins after the PRELIMINARY notice 
and 102 mins after the GW merger event. All data acquisition finished
approximately 4hrs later. 

We found no new transients to magnitudes of o < 19.1 (the median of
the 5 sigma limits of the individual 30 sec images) between 
~40 to ~240 minutes after the BBH merger. 

This work has made use of data from the Asteroid Terrestrial-impact 
Last Alert System (ATLAS) project. ATLAS is primarily funded to search 
for near earth asteroids through NASA grants NN12AR55G, 80NSSC18K0284, 
and 80NSSC18K1575; byproducts of the NEO search include images and 
catalogs from the survey area. The ATLAS science products have been 
made possible through the contributions of the University of Hawaii 
Institute for Astronomy, the Queen's University Belfast, and the 
Space Telescope Science Institute.

Z. Kostrzewa-Rutkowska (SRON/RU), S. Hodgkin, A. Delgado, D.L.
Harrison, M. van Leeuwen, G. Rixon, A. Yoldas (IoA Cambridge), D.
Eappachen, P.G. Jonker (SRON/RU) on behalf of Gaia Alerts team report
the discovery of a transient candidate within the probability skymap
of S190408an (Singer et al. GCN 24069
Loading...
 
 ):

---------------------------------------------------------------------------
Name      TNSid     Date [TCB]          RaDeg     DecDeg    AlertMag URL
---------------------------------------------------------------------------
Gaia19bij AT2019dmx
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  2019-04-10 13:34:31 347.81400 44.91844 18.94
  http://gsaweb.ast.cam.ac.uk/alerts/alert/Gaia19bij/
---------------------------------------------------------------------------



Acknowledgements: This work has made use of data from the European
Space Agency (ESA) mission Gaia (https://www.cosmos.esa.int/gaia),
processed by the Gaia Data Processing and Analysis Consortium (DPAC,
https://www.cosmos.esa.int/web/gaia/dpac/consortium). Funding for the
DPAC has been provided by national institutions, in particular the
institutions participating in the Gaia Multilateral Agreement. ZKR,
DE, and PGJ acknowledge support from the European Research Council
under ERC Consolidator Grant agreement no 647208.

Z. Kostrzewa-Rutkowska (SRON/RU), S. Hodgkin, A. Delgado, D.L. Harrison, M.
van Leeuwen, G. Rixon, A. Yoldas (IoA Cambridge), D. Eappachen, P.G. Jonker
(SRON/RU) on behalf of Gaia Alerts team report the discovery of transient
candidates within the probability skymap of S190408an (Singer et al. GCN
24069
Loading...
 
 ):


---------------------------------------------------------------------------

Name      TNSid     Date [TCB]          RaDeg     DecDeg    AlertMag URL

---------------------------------------------------------------------------

Gaia19bkj AT2019dpg
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  2019-04-16T20:07:27 335.67749 19.60641  18.95

       http://gsaweb.ast.cam.ac.uk/alerts/alert/Gaia19bkj/

Gaia19bkd AT2019dma
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  2019-04-16T13:48:35 343.70771 36.54362  17.34

       http://gsaweb.ast.cam.ac.uk/alerts/alert/Gaia19bkd/

Gaia19bju AT2019dmc
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  2019-04-12T09:34:12 338.36352 36.07027  16.19

       http://gsaweb.ast.cam.ac.uk/alerts/alert/Gaia19bju/

Gaia19bji AT2019doo
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  2019-04-12T15:26:12 345.74049 41.71289  18.91

       http://gsaweb.ast.cam.ac.uk/alerts/alert/Gaia19bji/

---------------------------------------------------------------------------



Acknowledgements: This work has made use of data from the European Space
Agency (ESA) mission Gaia (https://www.cosmos.esa.int/gaia), processed by
the Gaia Data Processing and Analysis Consortium (DPAC,
https://www.cosmos.esa.int/web/gaia/dpac/consortium). Funding for the DPAC
has been provided by national institutions, in particular the institutions
participating in the Gaia Multilateral Agreement. ZKR, DE, and PGJ
acknowledge support from the European Research Council under ERC
Consolidator Grant agreement no 647208.

A. Lutovinov, S. Molkov (IKI, Russia)
V. Savchenko, C. Ferrigno, E. Bozzo, T. Courvoisier (ISDC/UniGE, 
Switzerland)
E. Kuulkers (ESTEC/ESA, The Netherlands)
C. Sanchez (ESAC/ESA, Spain)
S. Mereghetti (INAF IASF-Milano, Italy)
D. Götz, Ph. Laurent, S. Schanne, B. Cordier (CEA, France)
S.Antier, A. Coleiro, A. Goldwurm (APC, France)
J. Rodi, A. Bazzano, L. Natalucci, F. Panessa, F. Onori, P. Ubertini 
(IAPS/INAF, Italy)
J. Chenevez, S. Brandt (DTU, Denmark)
R. Diehl, A. von Kienlin (MPE, Germany)
A. Domingo, J. M. Mas-Hesse (CAB/CSIC-INTA, Spain)
L. Hanlon, A. Martin-Carrillo, M.Doyle (UCD, Ireland)
R. Sunyaev (IKI, Russia)
J.-P. Roques, E. Jourdain, P. von Ballmoos (IRAP, France) report:

The INTEGRAL observatory performed follow-up observations of the
LIGO/Virgo compact binary merger candidate S190408an (GCN #24069
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 )
in the form of the fast TOO operational test.

The observations were carried out from 2019-04-10 11:13:07 to 2019-04-10 
17:10:47
in the staring and hexagonal dithering modes with a total observing time of
approximately 18 ks. They were centred on the coordinates RA=350.2, 
Dec=-56.0
and covered ~42% of the LIGO/Virgo localization probability with the 
highest sensitivity.

We do not detect any new sources in the complete IBIS/ISGRI (25-60 keV)�� 
mosaicked image
with the best sensitivity of 16.5 mCrab (1.6e-10 erg/cm2/s, 3-sigma 
upper level) in this energy range.

P.G. Jonker (SRON/RU), M. Fraser (UCD), Manuel Torres (IAC), Pablo
Rodriguez-Gil (University of La Laguna), Kate Maguire (TCD), Z.
Kostrzewa-Rutkowska (SRON/RU), report, on behalf of the International Time
Proposal team, on Liverpool Telescope 3x300 sec r'-band imaging observations
obtained on 2019-04-21T05:47:58 of the transient candidate(s) Gaia19bij found by
the Gaia Alerts team (Kostrzewa-Rutkowska et al. GCN#24124
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 ) in the sky
localisation region of GW190408 / S190408an (Singer et al. GCN 24069
Loading...
 
 ):

Gaia19bij was found at r'~19, approximately 1.5" off-nuclear from a faint host
galaxy.

Acknowledgements: PGJ and ZKR acknowledge support from the European Research
Council under ERC Consolidator Grant agreement no 647208.

Z. Kostrzewa-Rutkowska (SRON/RU), S. Hodgkin, A. Delgado, D.L. Harrison, M.
van Leeuwen, G. Rixon, A. Yoldas (IoA Cambridge), D. Eappachen, P.G. Jonker
(SRON/RU) on behalf of Gaia Alerts team report the discovery of transient
candidates within the probability skymap of S190408an (Singer et al. GCN
24069
Loading...
 
 ):

---------------------------------------------------------------------------

Name      TNSid Date [TCB]          RaDeg DecDeg AlertMag URL

---------------------------------------------------------------------------

Gaia19bla AT2019dpy
Loading...
 
  2019-04-19T01:28:39 357.26858 57.67220 18.66

      http://gsaweb.ast.cam.ac.uk/alerts/alert/Gaia19bla/

Gaia19bmd AT2019dur
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  2019-04-21T01:28:54 352.58222 60.82017 20.16

      http://gsaweb.ast.cam.ac.uk/alerts/alert/Gaia19bmd/

Gaia19bnd AT2019dyn
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  2019-04-15T15:47:08 336.45010 25.41967 16.52
http://gsaweb.ast.cam.ac.uk/alerts/alert/Gaia19bnd/
<http://gsaweb.ast.cam.ac.uk/alerts/alert/Gaia19bmd/>


---------------------------------------------------------------------------

Notes: Gaia19bmd - Gaia source declines by almost 2 mags over 3.5 months



Acknowledgements: This work has made use of data from the European Space
Agency (ESA) mission Gaia (https://www.cosmos.esa.int/gaia), processed by
the Gaia Data Processing and Analysis Consortium (DPAC,
https://www.cosmos.esa.int/web/gaia/dpac/consortium). Funding for the DPAC
has been provided by national institutions, in particular the institutions
participating in the Gaia Multilateral Agreement. ZKR, DE, and PGJ
acknowledge support from the European Research Council under ERC
Consolidator Grant agreement no 647208.