P. L. Kelly, S. A. Rodney, T. Treu, L. G. Strolger, R. J. Foley, S. W. Jha, J. Selsing, G. Brammer, M. Bradač, S. B. Cenko, O. Graur, A. V. Filippenko, J. Hjorth, C. McCully, A. Molino, M. Nonino, A. G. Riess, K. B. Schmidt, B. Tucker, A. Von Der LindenB. J. Weiner, A. Zitrin

Research output: Contribution to journalArticlepeer-review

60 Scopus citations


In Hubble Space Telescope (HST) imaging taken on 2014 November 10, four images of supernova (SN) "Refsdal" (redshift z = 1.49) appeared in an Einstein-cross-like configuration (images S1-S4) around an early-type galaxy in the cluster MACS J1149.5+2223 (z = 0.54). Almost all lens models of the cluster have predicted that the SN should reappear within a year in a second host-galaxy image created by the cluster's potential. In HST observations taken on 2015 December 11, we find a new source at the predicted position of the new image of SN Refsdal approximately 8″ from the previous images S1-S4. This marks the first time the appearance of a SN at a particular time and location in the sky was successfully predicted in advance! We use these data and the light curve from the first four observed images of SN Refsdal to place constraints on the relative time delay and magnification of the new image (SX) compared to images S1-S4. This enables us, for the first time, to test "blind" lens model predictions of both magnifications and time delays for a lensed SN. We find that the timing and brightness of the new image are consistent with the blind predictions of a fraction of the models. The reappearance illustrates the discriminatory power of this blind test and its utility to uncover sources of systematic uncertainty. From planned HST photometry, we expect to reach a precision of 1%-2% on the time delay between S1-S4 and SX.

Original languageEnglish (US)
Article numberL8
JournalAstrophysical Journal Letters
Issue number1
StatePublished - Mar 1 2016

Bibliographical note

Funding Information:
We express our appreciation for the efforts of Program Coordinator Beth Periello and Contact Scientist Norbert Pirzkal of STScI. Support for the analysis in this paper is from HST grant GO-14041. The GLASS program is supported by GO-13459, and the FrontierSN photometric follow-up program has funding through GO-13386. A.Z. is supported by Hubble Fellowship (HF2-51334.001-A) awarded by STScI, which is operated for NASA by the Association of Universities for Research in Astronomy, Inc. under contract NAS 5-26555. R.J.F. gratefully acknowledges support from NSF grant AST-1518052 and the Alfred P. Sloan Foundation. A.V.F.''s group at UC Berkeley has received generous financial assistance from the Christopher R. Redlich Fund, the TABASGO Foundation, and NSF grant AST-1211916. M.N. acknowledges PRININAF 2014 This supernova research at Rutgers University is supported by NSF CAREER award AST-0847157, as well as NASA/Keck JPL RSA 1508337 and 1520634, to S.W.J.

Publisher Copyright:
© 2016. The American Astronomical Society. All rights reserved.


  • galaxies: clusters: general
  • galaxies: individual (MACS J1149.5+2223)
  • gravitational lensing: strong
  • supernovae: general
  • supernovae: individual (SN Refsdal)


Dive into the research topics of 'DEJA VU ALL OVER AGAIN: THE REAPPEARANCE OF SUPERNOVA REFSDAL'. Together they form a unique fingerprint.

Cite this