Discovery of SSS17a


Members of Ryan Foley’s 1M2H team at UC Santa Cruz (left to right): Charles Kilpatrick, Enia Xhakaj, Matthew Siebert, Ariadna Murguia-Berthier, David Coulter, Enrico Ramírez-Ruiz, Ryan Foley, César Rojas-Bravo. (Missing from photo: Yen-Chen Pan).


Our team, the One-Meter, Two-Hemisphere (1M2H) Collaboration, composed by students and researchers at UC Santa Cruz, Carnegie Observatories and UC Berkeley made the  first discovery of the optical counterpart of the neutron star merger detected by LIGO on August 17, 2017.

When we determined the exact localization of the gravitational wave source, the majority of telescopes and observatories in the world turned to those coordinates and started observing this unprecedented event.

You can check our discovery paper, published in Science:

Swope Supernova Survey 2017a (SSS17a), the optical counterpart to a gravitational wave source. 

The journals Science and Physics World selected the neutron star merger discovery as the 2017 Scientific Breakthrough of the Year.

The journals Nature and Scientific American also selected this discovery as part of their Top Ten Science stories of the year.


Credit: 1M2H Team / UC Santa Cruz & Carnegie Observatories / Ryan Foley

(Left): A Hubble Space Telescope image from 4 months before SSS17a was discovered. (Right): The discovery image of SSS17a obtained from the Henrietta Swope Telescope at Las Campanas Observatory. The image was obtained on 2017 August 17 at 23:33 UT. SSS17a is marked with the red arrow. No object is present in the Hubble image at the position of SSS17a. Taken from



You can check all of our scientific publications in here , and our team’s website here.

You can check UCSC’s group members in here.

In Costa Rica, my home country, the public has been very excited to know that a fellow Costa Rican has been involved in this gravitational/electromagnetic wave breakthrough discovery. You can check all the media coverage here.