LIGO/VIRGO S190814bv
GCN Circular 25356
Subject
LIGO/VIRGO S190814bv: No candidates from Pan-STARRS and non-detection of AT2019nme
Date
2019-08-15T23:15:05Z (6 years ago)
From
Stephen Smartt at Queen's U/Belfast <s.smartt@qub.ac.uk>
M. Huber (IfA, Univ. of Hawaii), K. W. Smith (QUB), K. Chambers, A.
Schulz (IfA), S. Smartt, D. R. Young, O. McBrien, J. Gillanders. S.
Srivastav, D. O'Neil, P. Clark, S. Sim (QUB), T. de Boer, J. Bulger,
J. Fairlamb, M. Huber, C.-C. Lin, T. Lowe, E. Magnier, R. J.
Wainscoat, M. Willman (IfA, Univ. of Hawaii), T.-W, Chen (MPE), A.
Rest (STScI), C. Stubbs (Harvard)
We report observations of the LALInference skymap of the NSBH event
S190814bv (The LIGO Scientific Collaboration and the Virgo
Collaboration, 25333, 25324) with the Pan-STARRS1 telescope (Chambers
et al. 2016, arXiv:1612.05560C). Images were taken in the PS1 i and z
bands (Tonry et al. 2012, ApJ 750, 99).
Beginning at 2019-08-15 12:40:37 UT (58710.5282) or 15.5hrs after the
detection of S190814bv, observations started in the i-band. We used
the updated LALInference.v1.fits.gz map for pointing coverage.
Observations finished at 2019-08-15 15:13:38 UT.
At each pointing position a dithered sequence of 45 sec i-band and
z-band images were taken. These were combined into a single night
stack, covering the GPC1 camera chip gaps. These dithered sequences
were repeated, with overlaps, to map 18 square degrees of the
LALInference.v1.gz map 90% credible region, corresponding to a summed
probability 89% of the skymap. We did not cover the smaller
probability blob to the south east at DEC=-32.
Conditions were somewhat affected by clouds, and moon, seeing was
around 1.2 - 1.3 arcsec. 5-sigma limiting magnitudes were around i ~
20.8 and z ~ 20.3.
The images were processed with the IPP (Magnier et al. 2016,
arXiv:1612.05240) 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), and already reported transients in the TNS before
S190814by.
After removing these, and requiring detections in BOTH i and z-band
stacks, we were left with two transients. Both of which we discount as
possible counterparts.
Name | TNS Name | RA (J2000) | Dec (J2000) | Disc MJD | i Mag err | z Mag err
PS19epf | AT2019noq | 00 48 47.88 | -25 18 23.4 | 58710.58 | 19.93 0.11 | 20.17 0.16
PS19eph | AT2019nor | 00 49 51.99 | -24 16 17.7 | 58710.59 | 19.69 0.07 | 19.55 0.07
PS19epf is within the inner 20% contour. It is located 0.46"S 3.96"E
from the centre of the galaxy PSO J012.1980-25.3064 (r = 18.3 Kron
mag). The host has no measured photometric or spectroscopic redshift.
However there are 4 separate, single night detections in the ZTF
public stream, from Lasair (Smith et al. 2019;
https://lasair.roe.ac.uk/object/ZTF19abkhnce/), across the last 12
days. Hence it is most probably a SN exploding before the GW.
PS19eph is within the inner 10% contour. However it is coincident with
the core of the B=18.67 galaxy 6dF J0049520-241618 at z = 0.436522
from NED, and hence is not likely related to S190814bv.
We do not recover desgw-190814b (AT2019nme). Reported at i=19.33
z=19.39, (58710.278) by Soares-Santos et al. GCN 25336. This is on the
edge of our stack, but we estimate a 3-sigma limit of i~20.6 z~20.2.
If it is real, it implies a very fast fade in i-band of 1 mag in about
8hrs. Deeper follow-up is required, and confirmation from the DECam
team if it is real.
GCN Circular 25375
Subject
LIGO/VIRGO S190814bv: No candidates from ATLAS observations
Date
2019-08-17T00:01:01Z (6 years ago)
From
Shubham Srivastav at QUB <S.Srivastav@qub.ac.uk>
S. Srivastav, S. J. Smartt, K. W. Smith, D. R. Young (QUB), L. Denneau, H. Flewelling, A. Heinze, J. Tonry, H. Weiland (IfA, Univ. Hawaii), A. Rest (STScI), B. Stalder (LSST), C. Stubbs (Harvard), T.-W. Chen (MPE), O. McBrien, M. Dobson, J. Gillanders, D. O'Neil, P. Clark, S. Sim (QUB)
We report observations of the LALInference skymap of the NSBH event S190814bv (The LIGO Scientific Collaboration and the Virgo Collaboration, GCN 25324, 25333) 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. The survey provides coverage from declination -40 to +80 every 2 nights to typical depths of 19.5 mag in the o-band.
S190814bv was discovered at MJD 58709.88239579 (GCN 25324). ATLAS was observing the whole (99.8% enclosed probability) of the LALInference skymap a few hours before the GW event (and 2 days previously on MJD 58707). The last image of the field, at the end of the night was taken on MJD 58709.63026325 (~6 hrs before S190814bv - see McBrien et al. GCN 25346).
We observed the field again on the two subsequent nights on MJDs ~58710.5 and ~58711.5.
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).
No new candidates were found on any of the 3 nights, either ~6 hrs before the GW event, or ~16 hrs and ~40 hrs later, to limiting magnitudes of o ~ 19.0.
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.
GCN Circular 25392
Subject
LIGO/VIRGO S190814bv: AbAO non-detection of AT2019nme
Date
2019-08-18T06:18:03Z (6 years ago)
From
Alexei Pozanenko at IKI, Moscow <apozanen@iki.rssi.ru>
S. Belkin (IKI), A. Pozanenko (IKI), R. Ya. Inasaridze (AbAO), V.R.
Ayvazian (AbAO), E. Mazaeva (IKI), A. Volnova (IKI), I. Molotov
(KIAM) report on behalf of larger IKI GRB follow-up collaboration:
We observed DESGW candidates desgw-190814a (AT2019nmd), desgw-190814b
(AT2019nme) (Soares-Santos et al., GCN 25336) of the NSBH event
S190814bv (The LIGO/Virgo Scientific Collaboration GCNs 25333, 25324)
with AS-32 (0.7m) telescope of Abastumani Observatory starting on Aug.
16 (UT) 00:12:54. We obtained several 60 s exposures in R-filter per
each candidate.
In particular we do not detect the desgw-190814b (AT2019nme).
Photometry of the field is following
Name, TNS Name, MJD, Exposure (s), R_upper_limit (mag)
desgw-190814b, 2019nme, 58711.03464, 12*60, 18.8
and based on nearby USNO-B1.0 stars (R2 magnitudes).