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Discovery of four SN candidates as a part of A Survey for Supernovae in Massive High-Redshift Clusters

ATel #723; K. Sharon (Tel Aviv University), Avishay Gal-Yam (Caltech) and D. Maoz (Tel Aviv University)
on 6 Feb 2006; 18:17 UT
Distributed as an Instant Email Notice Supernovae
Credential Certification: Avishay Gal-Yam (avishay@astro.caltech.edu)

Subjects: Optical, Supernovae

K. Sharon (Tel Aviv U.), A. Gal-Yam (Caltech), and D. Maoz (Tel Aviv U.) report for a larger collaboration, including M. Donahue (MSU), H. Ebeling (IfA), R. Ellis (Caltech), A. Filippenko (UCB), R. Foley (UCB), W. Freedman (OCIW), J.-P. Kneib (Marseille), R. Kirshner (CfA), T. Matheson (NOAO), J. Mulchaey (OCIW), M. Phillips (OCIW), V. Sarajedini (UF) and M. Voit (MSU) (http://www.astro.caltech.edu/~avishay/hst.html):

We have used the Advanced Camera for Surveys (ACS) on board the Hubble Space Telescope (HST), to image the galaxy clusters CL1226+3332 (z=0.888) and MACS 0647+7015 (z=0.584) for one orbit each (2209s and 2584s respectively) with the F814W filter, as part of our cycle 14 survey for SNe in galaxy clusters (GO 10493, PI Gal-Yam).

Comparing our new data for CL1226+3332 (2006 Jan 29.5 UT) with previous archival observations (2003 Apr 13.5 UT, GO 9033, PI Ebeling), and our new data for MACS 0647+7015 (2006 Feb 1.0 UT) with previous archival observations (2004 Dec 5.0 UT, GO 9722, PI Ebeling), we detect 4 transient point sources (two in each cluster). The discovery dates, coordinates and magnitudes are listed in the table below.

Name Coordinates (RA, Dec; J2000.0) Discovery (Date, Mag) Host (RA, Dec, Offset, Mag)
CL1226_1 12:26:54.507 +33:33:58.28 Jan06 25.75 12:26:54.473 +33:33:58.14 0.55''E 0.16''N 20.53
CL1226_2 12:26:55.460 +33:32:14.31 Apr03 24.01 12:26:55.545 +33:32:14.66 1.05''E 0.35''N 20.16
MACS0647_1 06:47:30.025 +70:14:54.71 Feb06 25.84 06:47:29.863 +70:14:54.39 0.82''E 0.32''N 22.54
MACS0647_2 06:47:38.030 +70:16:16.72 Dec04 26.78 06:47:38.041 +70:16:16.10 0.05''E 0.62''N 22.20

We note that the coordinates we cite are based on the HST WCS information and should be regarded as preliminary.

The lack of detectable proper motion over the span of the observations argues against a solar-system origin, and the offsets from galaxy cores clearly rule out AGN. We therefore conclude that these new sources are most likely SNe.

HST cluster SN project webpage