RELICS Discovery of a Probable Lens-magnified SN behind Galaxy Cluster Abell 1763

ATel #9224; S. Rodney (South Carolina); D. Coe, L. Bradley, L. Strolger, G. Brammer, R. Avila, R. Ryan, S. Ogaz, A. Riess (STScI); K. Sharon, T. Johnson, R. Paterno-Mahler (Michigan); A. Molino (IAG, IAA-CSIC); M. Graham, P. Kelly, A. Filippenko, B. Frye, (UC Berkeley); R. Foley (UC Santa Cruz); K. Schmidt (AIP); K. Umetsu, N. Czakon (ASIAA); B. Weiner, D. Stark, R. Mainali (Arizona); A. Zitrin, I. Sendra (Caltech); O. Graur (CfA); C. Grillo, J. Hjorth, J. Selsing, L. Christensen (DARK); P. Rosati (Ferrara); M. Nonino, I. Balestra (INAF); B. Vulcani (IPMU); C. McCully (LCOGT, UC Santa Barbara); W. Dawson (LLNL); R. Bouwens, D. Lam (Leiden); M. Trenti, D. Carrasco Nunez (Melbourne); T. Matheson (NOAO); J. Merten (Oxford); S. Jha (Rutgers); C. Jones, F. Andrade-Santos (SAO); B. Salmon (TAMU); M. Bradac, A. Hoag, K. Huang (UC Davis); X. Wang (UC Santa Barbara); P. Oesch (Yale)
on 8 Jul 2016; 03:14 UT
Credential Certification: Steven A. Rodney (srodney@sc.edu)

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We report the discovery of a likely supernova (SN) in the background field of the galaxy cluster Abell 1763 (a.k.a. RXC J1335.3+4059, ZwCl 1333.7+4117). The SN candidate was detected in Hubble Space Telescope (HST) observations collected on June 17, 2016 as part of the Reionization Lensing Cluster Survey (RELICS, HST program ID: 14096, PI: D.Coe). The RELICS ID for this object is RLC16Neb (nicknamed "SN Nebra"). Discovery images and a finder chart for follow-up observations may be downloaded from the RELICS public ftp site (links below).

SN Nebra was first detected in data from June 17, 2016 in 4 infrared bands (F105W, F125W, F140W, F160W) from HST's Wide Field Camera 3 Infrared detector (WFC3-IR). The candidate was detected again in F125W and F160W and in the F350LP optical band from the WFC3-UVIS detector on a subsequent visit on July 6, 2016. From June 17 to July 6 the SN increased in brightness by 0.5 mags in the F125W band and by 0.6 mags in the F160W band. The SN candidate is not apparent in any of the four IR bands during the first epoch of RELICS IR imaging collected on May 8, 2016. It is also not detected in the F435W (B) and F814W (I) bands on that date.

The position of Nebra in J2000 coordinates is :
13:35:15.13 +41:00:15.8
203.813052 41.004396

The most likely host galaxy encompasses the SN position and is centered at:
13:35:15.14 +41:00:15.7
203.81308 41.00435

Combining all available HST photometry of the host galaxy (prior to the appearance of the SN candidate), we have estimated the photometric redshift using the BPZ software (Benitez 2000, ApJ, 536, 571). From BPZ we find the host redshift to be z=1.964 with a 95% confidence range of [1.334,2.253]. The foreground cluster Abell 1763 is at z=0.223. Preliminary lensing models for this cluster suggest that if this source is at z~2 then it would be magnified by a factor mu~2.

We have measured the SN brightness (in AB magnitudes) from the July 6, 2016 data as follows:

F350LP ("white" optical) 28.5 +- 0.9
F125W (J) 24.16 +- 0.04
F160W (H) 24.17 +- 0.05


The host galaxy has a surface brightness of 25.5 AB mag / arcsec^2 in optical bands F435W (B) and F814W (I), and 25.2 AB mag / arcsec^2 in the F105W (Y) band.

Additional HST imaging from the RELICS program will be collected on July 18, 2016. Ground-based imaging or spectroscopic observations that could confirm the redshift of the SN candidate or host galaxy are encouraged.

This discovery is based on observations from the RELICS program (HST-GO-14096) using the NASA/ESA Hubble Space Telescope, which were made available by the Mikulski Archive for Space Telescopes at the Space Telescope Science Institute. STScI is operated by the Association of Universities for Research in Astronomy, Inc. under NASA contract NAS 5-26555.

RELICS SN Nebra: Discovery images

Finder Chart for RLC16Neb

The Nebra Sky disk