NOAA Solar X-ray and Ultraviolet Imaging

Abstract:

NOAA has provided solar imaging of the lower corona since the early 2000’s and is currently building the spacecraft and instrumentation to continue to do so through 2036. After five million calibrated images, it is appropriate to examine NOAA data as providing consistent context for scientific missions. The first GOES Solar X-ray Imager was launched in 2001 and entered operations in 2003. The current SXIs will remain in operations until approximately 2020, when a new series of Solar (extreme-) Ultraviolet Imagers (SUVIs) will replace them as the current satellites reach their end of life. In the sense that the SXIs are similar to Yokoh’s SXT and Hinode’s XRT, the SUVI instruments will be similar to SOHO’s EIT and SDO’s AIA. The move to narrowband EUV imagers will better support eventual operational estimation of plasma conditions. This work examines the record of GOES Solar X-ray Imager (SXI) observations, including continuity, photometric stability, navigation accuracy, and comparison to other contemporary X-ray imagers. Initial examination of the observing record shows nearly complete coverage since 2001 with the exception of gaps in 2002 and 2008-9. During that span, there are overlaps between all the NOAA instruments to facilitate photometric inter-calibration. Preliminary results of inter-calibration show mostly linear relationships between instruments with exceptions awaiting further investigation. Pointing (navigation) knowledge for the SXIs (particularly GOES 13-15 instruments) will be improved allowing for easier integration of SXI observations into scientific studies. While NOAA’s principal use of these observations is real-time space weather forecasting, they will continue to provide a consistent context measurement for researchers for decades to come.