GOES-15 is no longer sending data
As scheduled, GOES-15 has sent its last image (More information from NOAA’s Office of Satellite and Product Operations OSPO) . The final image sent was a 1552 UTC Southern Hemisphere sector, shown above (courtesy Tim Schmit). (One of the final Sounder images is here). However, the satellite is not gone for good: it is scheduled to transmit data again in August of this year, when the GOES-17 Loop Heat Pipe issue again renders GOES-West imagery incomplete during the eastern/central Pacific Ocean Hurricane season. (This website shows more specifics)
GOES-15 became the operational GOES-West satellite — replacing GOES-11 — back in early December 2011 (Blog Post; GOES-11 replaced GOES-10 as GOES-West back in 2006 (Blog Post)). GOES-15 ceased being the operational GOES-West when GOES-17 became operational (February 12, 2017), but GOES-15 has continued to transmit data to supplement imagery lost because of the GOES-17’s Loop Heat Pipe.
Added: The Science Test for GOES-15 is available here.