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ZTF Observations of the Galactic Transient ASASSN-19yt

ATel #13196; Eric C. Bellm (UW), Amruta Jaodand (Caltech), Kevin Burdge (Caltech), and Paula Szkody (UW) on behalf of the Zwicky Transient Facility Collaboration
on 16 Oct 2019; 19:23 UT
Credential Certification: Eric Bellm (ecbellm@uw.edu)

Subjects: Optical, X-ray, Binary, Cataclysmic Variable, Transient, Variables

We report serendipitous observations of the Galactic transient ASASSN-19yt (ATel #13176) with the Zwicky Transient Facility (ZTF; Bellm et. al 2019). ZTF detected the object (internally designated ZTF17aaagnwn) in difference imaging at a near-quiescient magnitude of m_r = 20.6 on 2019-09-30.50. Between 2019-10-07 and 2019-10-10 the outburst peaked at m_r ~ 15.6 before beginning to fade back to quiescence; the most recent detection on 2019-10-14 was at m_r = 18.5 mag.

In archival ZTF data beginning in 2018, the source shows irregular variability with 1-1.5 mag peak to peak variations. The mean magnitudes are m_g ~ 20.6 and m_r ~ 19.8.

We obtained a 600 sec observation with the FLOYDS spectrograph on the Faulkes Telescope North on 2019-10-12. Relatively weak, double-peaked H-alpha is seen in emission with FWHM ~ 18.5 Angstrom.

The hardness of the archival X-ray source combined with the intermediate duration of the outburst are suggestive of a dwarf nova outburst from an intermediate polar; such outbursts are relatively rare (e.g., Hameury & Lasota 2017). Further observations are encouraged.

Public ZTF alerts for this object can be obtained through community alert brokers; the Lasair (Smith et al. 2019) object page for ZTF17aaagnwn is available at https://lasair.roe.ac.uk/object/ZTF17aaagnwn/.

Archival data release lightcurves can be obtained through the IRSA catalog search.

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 grants 181277 and 1812779 and the Heising-Simons Foundation under grant nos. 12540303 and 2018-0908.