ZTF limits on optical emission from EXO 1846-031
ATel #12991; Eric C. Bellm (UW), Danny Goldstein (Caltech), Yuhan Yao (Caltech) on behalf of the Zwicky Transient Facility Collaboration
on 5 Aug 2019; 23:54 UT
Credential Certification: Eric Bellm (ecbellm@uw.edu)
Subjects: Optical, Black Hole
The Zwicky Transient Facility (ZTF; Bellm et al. 2019, Graham et al. 2019) serendipitiously observed the field of EXO 1846-031 (Parmar and White 1985; Parmer et al. 1992) more than 100 times in r-band since the outburst detected by MAXI (Negoro et al. 2019, ATel #12968). No optical counterpart is detected in the epochal images. We performed forced photometry on the ZTF difference images (Yao et al. in prep) using the radio position reported by Miller-Jones et al. (2019; ATel #12977). Binning the forced fluxes over a five-day window we rule out optical emission brighter than r~23 mag.
The nearby source UKIDSS J184917.09-030355.9 is detected at r=21.3 mag in the coadded ZTF reference image but does not show additional variability at the time of the X-ray outburst.
ZTF is a project led by PI S. R. Kulkarni at Caltech (see ATEL #11266), and includes IPAC; WIS, Israel; OKC, Sweden; JSI/UMd, USA; UW,USA; DESY, Germany; NRC, Taiwan; UW Milwaukee, USA and LANL USA. ZTF acknowledges the generous support of the NSF under AST MSIP Grant No 1440341. Alert distribution service provided by DIRAC@UW. Alert filtering is being undertaken by the GROWTH marshal system, supported by NSF PIRE grant 1545949. We acknowledge further support from the NSF under grant 181277 and the Heising-Simons Foundation under grant nos. 12540303 and 2018-0908.
