GOES-N EUVS field of view sensitivities and modeling

1. GOES-N EUVS field of view sensitivities and modeling Donald R. McMullin, Praxis, Inc., Alexandria, VA, D. J. Strickland, J. S. Evans, W. K. Woo, S. P. Plunkett, and R. Viereck 5th GOES Users’ Conference, New Orleans, LA Paper Number P1.52 ABSTRACT The successful launch of the GOES-N spacecraft will provide the first series of GOES solar EUV irradiance measurements. The new measurements will provide users with detailed observations of the absolute value of solar EUV energy flux and the temporal variance on time scales as short as seconds. Each EUV sensor (EUVS) in the GOES-N series is a transmission grating based instrument, similar to the SOHO/SEM instrument. We have studied the design of the GOES-N EUVS from the EUVS Calibration and Data Handbook with a focus on the Field Of View (FOV) sensitivity to alignment and solar pointing. In this work, we have developed a new algorithm that includes changes in the instrument calibration as a function of solar pointing as well as the spatial distribution of solar intensity across the disk. The new calibration algorithm has been used to develop a new time series of GOES EUVS data collected during the GOES-N Post-Launch Test period (PLT) and these results are reported in the companion paper. Sensitivity to Spatial Distribution Sensitivity to Pointing Dividing solar disk into nine strips of equal width. Corresponding histogram of energy content per strip (relative) for uniform luminosity • Modeling The GOES EUVS Channels • Detector • Grating • Geometry Derived geometry functions for Channel B showing effect of offsets of solar disk within FOV Dependant on the detector location, the geometry of masks and baffles, and any filters used, each channel will produce a measured integrated signal, proportional to the EUV spectrum (wavelengths) that falls on the active area. Results Derived response function for comparison with measured (from handbook) and calculated (provided by SEC) values