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GCN Circular 25375

LIGO/VIRGO S190814bv: No candidates from ATLAS observations
2019-08-17T00:01:01Z (5 years ago)
Shubham Srivastav at QUB <>
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.
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