Marcelle Soares-Santos, James Annis, Alyssa Garcia, Ken Herner, Antonella Palmese, Douglas Tucker, Sahar Allam, Robert Morgan, Tristan Bachmann, Nora Sherman, Clara Martinez, Tamara Davis
*On behalf of the DESGW Team
As part of our ongoing CTIO Blanco/DECam search program, on the night of August 20 2019 we observed the region of interest of the black hole/neutron star merger S190814bv reported by the LIGO/VIRGO Collaboration in GCN Circular No. 25324, and updated GCN Circular No. 25333. Here we report additional candidate counterparts to those we already reported in GCN Nos. 25336, 25373, & 25398.
Images were processed by our difference imaging pipeline (Herner et al. 2017; see also Soares-Santos et al. 2015, 2017; Doctor et al. 2018; Morgan et al. 2019 for recent applications) using DES images as templates. We employ a machine learning code (autoscan, Goldstein et al. 2015) to reject subtraction artifacts. Candidates were initially selected by requiring at least two high signal to noise detections, rejecting asteroids. We then applied catalog-based vetting to reject variable stars, variable AGNs, using various catalogs including GAIA DR2, and candidates with hosts at redshifts inconsistent (>2sigma, H0=70) with the distance reported by the LVC for S190814bv (276 +/- 56 Mpc) using a variety of photometric and spectroscopic catalogs including DES. The final vetting was done via visual inspection. We matched our remaining candidates using the Transient Name Server to avoid reporting those previously reported by other groups, and the Minor Planet Center to further filter against slow moving asteroids. The following new candidates pass our selection criteria:
Name | TNS Name | RA | Dec | MJD | Mag | MAGERR
desgw-190814j | AT2019nxe | 11.570058 | -24.372554 | 58713.251 | 22.00 (z) | 0.02
desgw-190814m | AT2019nzr | 11.839208 | -24.576827 | 58713.247 | 23.78 (i) | 0.16
desgw-190814o | AT2019oab | 14.747491 | -25.770182 | 58716.220 | 23.54 (i) | 0.07
We encourage spectroscopic followup of these candidates as well as of desgw-190814f / AT2019nte (GCN 25398), our only previously reported counterpart candidate that remains viable after the follow-up described in the GCN archive.
Further analysis is ongoing.
*The DESGW Collaboration:
Sahar Allam (Fermilab), James Annis (Fermilab), Iair Arcavi (Tel Aviv U), Tristan Bachmann (U Chicago), Paulo Barchi (INPE & Brandeis U), Thomas Beatty (U of Arizona) Keith Bechtol (U of Wisconsin-Madison), Federico Berlfein (Brandeis U), Antonio Bernardo (U of Sao Paulo), Dillon Brout (U Penn), Robert Butler (Indiana U), Melissa Butner, (Fermilab), Annalisa Calamida (STScI), Hsin-Yu Chen (Harvard U), Chris Conselice (U of Nottingham), Carlos Contreras (STScI), Jeff Cooke (Swinburne U), Chris D���Andrea (U Penn), Tamara Davis (U Queensland), Reinaldo de Carvalho (UNICSUL), H. Thomas Diehl (Fermilab), Zoheyr Doctor (U Chicago), Alex Drlica-Wagner (Fermilab), Maria Drout (U Toronto), Maya Fishbach (U Chicago), Francisco Forster (U de Chile), Ryan Foley (UCSC), Joshua Frieman (Fermilab & U Chicago), Chris Frohmaier (U of Portsmouth), Ori Fox (STScI), Alyssa Garcia (Brandeis U), Juan Garcia-Bellido (U Autonoma de Madrid), Mandeep Gill (SLAC & Stanford U), Robert Gruendl (NCSA), Will Hartley (U College London), Kenneth Herner (Fermilab), Daniel Holz (U Chicago), Jorge Horvath (U of Sao Paulo), D. Andrew Howell (Las Cumbres Observatory), Richard Kessler (U Chicago), Charles Kilpatrick (UCSC), Nikolay Kuropatkin (Fermilab), Ofer Lahav (U College London), Huan Lin (Fermilab), Andrew Lundgren (U of Portsmouth), Martin Makler (CBPF), Clara Martinez-Vazquez (CTIO/NOAO), Curtis McCully (Las Cumbres Observatory), Mitch McNanna (U of Wisconsin-Madison), Robert Morgan (U of Wisconsin-Madison), Gautham Narayan (STScI), Eric Neilsen (Fermilab), Robert Nichol (U of Portsmouth), Antonella Palmese (Fermilab), Francisco Paz-Chinchon (NCSA & UIUC), Matthew Penny (OSU), Maria Pereira (Brandeis U), Sandro Rembold (UFSM), Armin Rest (STScI & JHU), Livia Rocha (U Sao Paulo), Russell Ryan (STScI), Masao Sako (U Penn), Samir Salim (Indiana U), David Sand (U of Arizona), Luidhy Santana-Silva (Valongo Observatory), Daniel Scolnic (Duke U), Nora Sherman (Fermilab), J. Allyn Smith (Austin Peay State U), Mathew Smith (U of Southampton), Marcelle Soares-Santos (Brandeis U), Lou Strolger (STScI), Riccardo Sturani (UFRN), Mark Sullivan (U of Southampton), Masaomi Tanaka (NAOJ), Nozomu Tominaga (Konan U), Douglas Tucker (Fermilab), Yousuke Utsumi (Stanford U), Stefano Valenti (UC Davis), Kathy Vivas (NOAO/CTIO), Alistair Walker (NOAO/CTIO), Sara Webb (Swinburne U), Matt Wiesner (Benedictine U), Brian Yanny (Fermilab), Michitoshi Yoshida (NAOJ), Alfredo Zenteno (NOAO/CTIO)