First Total Solar Irradiance Model based on PSPT Data

Authors: Angie M.Cookson, D.G.Preminger, S.R.Walton
Affiliation: CSUN/San Fernando Observatory

At the San Fernando Observatory (SFO), photometric images are taken in two sizes and several wavelengths. CFDT1 produces 512x512 pixel images in red (672.3 nm), blue (472.3 nm), and CaII K-line (393.4 nm) wavelengths. CFDT2 produces 1024x1024 pixel images in red (672.3 nm), blue (470.8 nm), wide and narrow band CaII K (393.4 nm), near infrared (780 nm), and infrared (997 nm) wavelengths. We have developed fairly robust algorithms for determining solar surface brightness measurements (sunspot and faculae) from these images. We now apply the same algorithms to photometric images from the Precision Solar Photometric Telescope (PSPT) in order to construct one of the first Total Solar Irradiance (TSI) models based on PSPT data. These images are larger (2048x2048) than SFO's but taken at similar wavelengths (607 nm, 409.45 nm, and Ca K). We compare this to ground-based TSI models developed using SFO data, as well as to satellite TSI measurements.

We wish to acknowledge the assistance of the PSPT team at HAO for making their data available to us. This research was supported through NSF grant ATM9912312.