Early Observations by the GOES-13 Solar Extreme Ultraviolet Sensor (EUVS)

NOAA’s GOES-13 satellite, launched in May 2006, includes a new solar sensor, called EUVS (Extreme UltraViolet Sensor), that measures energy fluxes in five broad-band spectral channels that span the region from 1 to 130 nm. Here, we report on measurements made during the mission’s six-month post-launch test (PLT) period which provided nearly continuous observations from August through November 2006 and the recording of an X9 flare that occurred on 5 December 2006. In this paper, we present a calibration model for the GOES EUVS that incorporates the effects of pointing offsets, cross-disk radiance variability (radiance refers to partial-disk emission), and changes to assumed spectral shapes. Appendices are included that report on the sensitivity to these effects. The main body of the paper gives a description of the model and data recorded during the PLT period. Comparisons are made with time-coincident measurements from TIMED/SEE (Version 10.02), SOHO/SEM, and SORCE/ SOLSTICE for the time period August-November. Comparisons are made with SORCE/XPS for the 5 December flare. In general, there is agreement among the data sets within expected measurement uncertainties. There will be a series of EUVSs extending into the next generation of GOES (starting with GOES-13). The initial performance of GOES-13 EUVS, including 5-channel measurements approximately every 11 s on a nearly continuous basis, suggests that the EUVS series will play a key role over the next many years in monitoring solar EUV variability.