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The Magnificent Five Images of Supernova Refsdal: Time Delay and Magnification Measurements

Kelly, Patrick L.; Rodney, Steven; Treu, Tommaso; Birrer, Simon; Bonvin, Vivien; Dessart, Luc; Foley, Ryan J.; Filippenko, Alexei V.; Gilman, Daniel; Jha, Saurabh; Hjorth, Jens; Mandel, Kaisey; Millon, Martin; Pierel, Justin; Thorp, Stephen; Zitrin, Adi; Broadhurst, Tom; Chen, Wenlei; Diego, Jose M.; Dressler, Alan; Graur, Or; Jauzac, Mathilde; Malkan, Matthew A.; McCully, Curtis; Oguri, Masamune; Postman, Marc; Schmidt, Kasper Borello; Sharon, Keren; Tucker, Brad E.; von der Linden, Anja; Wambsganss, Joachim

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Patrick L. Kelly

Steven Rodney

Tommaso Treu

Simon Birrer

Vivien Bonvin

Luc Dessart

Ryan J. Foley

Alexei V. Filippenko

Daniel Gilman

Saurabh Jha

Jens Hjorth

Kaisey Mandel

Martin Millon

Justin Pierel

Stephen Thorp

Adi Zitrin

Tom Broadhurst

Wenlei Chen

Jose M. Diego

Alan Dressler

Or Graur

Matthew A. Malkan

Curtis McCully

Masamune Oguri

Marc Postman

Kasper Borello Schmidt

Keren Sharon

Brad E. Tucker

Anja von der Linden

Joachim Wambsganss


In late 2014, four images of supernova (SN) "Refsdal," the first known example of a strongly lensed SN with multiple resolved images, were detected in the MACS J1149 galaxy-cluster field. Following the images' discovery, the SN was predicted to reappear within hundreds of days at a new position ∼8'' away in the field. The observed reappearance in late 2015 makes it possible to carry out Refsdal's original proposal to use a multiply imaged SN to measure the Hubble constant H0, since the time delay between appearances should vary inversely with H0. Moreover, the position, brightness, and timing of the reappearance enable a novel test of the blind predictions of galaxy-cluster models, which are typically constrained only by the positions of multiply imaged galaxies. We have developed a new photometry pipeline that uses DOLPHOT to measure the fluxes of the five images of SN Refsdal from difference images. We apply four separate techniques to perform a blind measurement of the relative time delays and magnification ratios between the last image SX and the earlier images S1–S4. We measure the relative time delay of SX–S1 to be $\displaystyle {376.0}_{-5.5}^{+5.6}$ days and the relative magnification to be $\displaystyle {0.30}_{-0.3}^{+0.5}$. This corresponds to a 1.5% precision on the time delay and 17% precision for the magnification ratios and includes uncertainties due to millilensing and microlensing. In an accompanying paper, we place initial and blind constraints on the value of the Hubble constant.


Kelly, P. L., Rodney, S., Treu, T., Birrer, S., Bonvin, V., Dessart, L., …Wambsganss, J. (2023). The Magnificent Five Images of Supernova Refsdal: Time Delay and Magnification Measurements. Astrophysical Journal, 948(2), Article 93.

Journal Article Type Article
Acceptance Date Nov 2, 2021
Online Publication Date May 11, 2023
Publication Date May 10, 2023
Deposit Date May 23, 2023
Publicly Available Date May 23, 2023
Journal Astrophysical Journal
Print ISSN 0004-637X
Electronic ISSN 1538-4357
Publisher American Astronomical Society
Peer Reviewed Peer Reviewed
Volume 948
Issue 2
Article Number 93


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Original content from this work may be used under the terms of the Creative Commons Attribution 4.0 licence. Any further distribution of this work must maintain attribution to the author(s) and the title of the work, journal citation and DOI.

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