The Zwicky Transient Facility Begins Nightly Concurrent Observations of TESS Northern Fields

ATel #12952; Lin Yan, T. Prince, S. R. Kulkarni, M. J. Graham, D. Duev, C. Fremling (Caltech), E. Bellm (UW), F. Masci (IPAC)
on 23 Jul 2019; 16:37 UT
Credential Certification: Lin Yan (lyan@caltech.edu)

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The Zwicky Transient Facility (ZTF) has begun nightly concurrent observations of TESS sector 14 on July 18, 2019. Most of this sector is covered by ZTF except TESS Camera 4 due to the visibility limits from Palomar. Each ZTF pointing has one exposure each for g and r filter. Based on the first three night observations, we found the following four transient candidates. Followup spectral classifications are encouraged.

 
Name         | IAUNAME    | R.A.        | Dec.        | t_1st [1]  | mag_1st[2] | band | Note 
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ZTF19abfwtkw | 2019lcn    | 17:03:21.38 | +55:43:35.4 | 2019-07-10 | 20.4       | g    | [3] 
ZTF19abgnuri | 2019lkt    | 16:28:55.52 | +70:01:59.2 | 2019-07-14 | 20.14      | g    | [3] 
ZTF19abgncfz | 2019liw    | 13:25:45.62 | +59:01:06.9 | 2019-07-16 | 19.16      | r    | [3] 
ZTF19abgndlf | 2019lkr    | 16:05:08.03 | +37:35:03.8 | 2019-07-16 | 19.08      | r    | [3,4] 
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[1] t_1st: the date of the first detection 
[2] mag_1st: the magnitude of the first detection 
[3] All four transients were first reported to TNS by ZTF (AMPEL) 
[4] 2019lkr was also reported by ATLAS 

ZTF plans to conduct a public, nightly concurrent survey of all 13 TESS northern sectors in 2019-2020. The ZTF transient alerts in the TESS fields will have the keyword "programpi" in the candidate block set to "TESS". In addition to the ZTF alert streams provided by various alert brokers, all ZTF-TESS alerts will be released nightly to the public via ZTF's bucket on Google Cloud in a compressed tarball with the alert packets converted into JSON format. Details on how to access these alerts are given in the following Jupyter notebook: https://colab.research.google.com/github/dmitryduev/kowalski/blob/master/nb/tess.ipynb. ZTF-TESS alerts will also be cross-matched against a number of external catalogs, including 2MASS PSC, AllWISE, IPHAS DR2 and Gaia DR2. While nightly observations are planned, in the event of bad weather or system problems, no tarball will be generated.

We anticipate that ZTF light curves for all objects observed concurrently by TESS and ZTF will be made available publicly within one month of the end of a TESS sector observation campaign. Details on how to access the ZTF light curve data will be given in the same Jupyter notebook as mentioned above. These light curves are constructed from sources extracted from the undifferenced epochal science images, using seed detections from the deeper reference images (co-adds).

Supernova candidates identified using a combination of automated filters and human vetting will be automatically posted to the Transient Name Server (TNS) at https://wis-tns.weizmann.ac.il with the "sender" keyword set to "ZTF_TESS". These will include bright (<19 mag) candidates, which are also selected by the ongoing ZTF Bright Transient Survey (BTS; ATEL #11688). We encourage spectroscopic followup of these candidates as quickly as possible to maximize the potential science return from the ZTF-TESS combination.

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 the support from the Heising-Simons Foundation under Grant No. 12540303.