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The ZTF Bright Transient Survey

ATel #11688; C. Fremling, Y. Sharma, S. R. Kulkarni (Caltech), A. A. Miller (Northwestern), K. Taggart, D. A. Perley (LJMU), A. Goobar (OKC) on behalf of the Zwicky Transient Facility collaboration
on 5 Jun 2018; 21:40 UT
Credential Certification: Christoffer Fremling (fremling@caltech.edu)

Subjects: Optical, Supernovae, Transient

Referred to by ATel #: 11710, 11745, 11746, 11768, 11797, 11798, 11829, 11830, 11861, 11888, 11889, 11911, 11912, 11929, 11930, 11938, 11974, 11986, 11987, 12003, 12021, 12051, 12065, 12213, 12272, 12582, 12952, 13268, 13385, 13418, 13436, 13526, 13596, 14019

As a supplement to the Zwicky Transient Facility (ZTF; ATel #11266) public alerts (ATel #11685) we plan to report (following ATel #11615) bright probable supernovae identified in the raw alert stream from the ZTF Northern Sky Survey ("Celestial Cinematography"; see Bellm & Kulkarni, 2017, Nature Astronomy 1, 71) to the Transient Name Server (https://wis-tns.weizmann.ac.il) on a daily basis; the ZTF Bright Transient Survey (BTS; see Kulkarni et al., 2018; arXiv:1710.04223).

The filtering criteria for BTS transients are the following: (1) Transient candidate brightness < 19 mag (in the most recent g or r band measurement). (2) Transient candidate > 20 arcsec from bright stars (r < 15 mag). (3) Transient candidate has a minimum of two detections separated by > 30 minutes. (4) No star-like source spatially coincident with the transient candidate (we employ a machine-learning star-galaxy separator, based on PS1 data; cf. Miller et al. 2017, AJ, 153, 73). (5) Galactic latitude cut of 7 degrees. There is also a final human vetting step to filter out clearly bogus alerts and stellar alerts that our star-galaxy separator does not catch automatically.

Furthermore, using these filtered alerts, we will carry out an ambitious spectroscopic survey; we will attempt to classify all transients brighter than 18.5 mag using the Spectral Energy Distribution Machine (SEDM; range 350-950nm, spectral resolution R~100) mounted on the Palomar 60-inch (P60) telescope (Blagorodnova et. al. 2018, PASP, 130, 5003). For ambiguous cases we will obtain confirmation spectra using other facilities. These classifications will be periodically announced in future ATels, and on TNS. Here we report classifications obtained since 2018-06-02.

 
Survey Name   | IAU Name   | RA (J2000)   | Dec (J2000)  | Discovery date | Discovery mag | Current mag date    | Current mag | Classification date | Class     | Redshift | Notes  
--------------|------------|--------------|--------------|----------------|---------------|---------------------|-------------|---------------------|-----------|----------|------ 
 ZTF18aavskep |  SN2018bwr | 15:28:26.164 | +08:48:22.16 |  2018-05-20.25 | 18.94     (r) |       2018-06-04.32 | 16.75   (r) |          2018-06-02 |    SN IIn |    0.046 | 
 ZTF18aaxavsk |  SN2018ccn | 17:38:20.079 | +67:50:57.97 |  2018-05-28.32 | 19.58     (r) |       2018-06-03.45 | 18.68   (r) |          2018-06-02 |     SN Ia |     0.08 | 
 ZTF18aaxdrjn |  SN2018cdt | 12:20:01.666 | +56:09:31.88 |  2018-05-31.18 | 18.44     (r) |       2018-06-03.20 | 17.50   (g) |          2018-06-03 |     SN Ia |    0.034 | (1) 
 ZTF18aavrzxp |  SN2018cdu | 14:21:47.851 | +48:09:59.74 |  2018-05-20.28 | 20.26     (g) |       2018-06-03.29 | 18.54   (r) |          2018-06-05 |     SN Ia |     0.07 | 
 ZTF18aawdpnm |  SN2018byi | 14:15:19.137 | +16:53:31.79 |  2018-05-23.30 | 18.71     (r) |       2018-06-01.30 | 17.37   (r) |          2018-06-05 |     SN Ia |    0.044 | 
 ZTF18aaxcxih |  SN2018cco | 18:59:01.022 | +63:45:18.60 |  2018-05-28.35 | 19.65     (r) |       2018-06-03.45 | 18.76   (r) |          2018-06-05 |     SN Ia |     0.07 |

Notes: (1) SEDM spectrum ambiguous. Confirmation from LT/SPRAT.

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 filtering is being undertaken by the GROWTH marshal system, supported by NSF PIRE grant 1545949. Classifications were done with SNID (Blondin & Tonry, 2007, ApJ, 666, 1024). Redshifts are derived from the broad SN features (two decimal points), and from narrow SN features or host galaxy lines (three decimal points).