A Repository of Precision Flat Fields for High-Resolution MDI Continuum Data

Abstract

We describe an archive of high-precision MDI flat fields that can be used to refine most MDI high-resolution continuum data. The archive consists of many flat-field images representing different time ranges over the full operating period of SOHO. The residual flat-field error on the standard level 1.5/1.8 calibrated continuum images represents a significant proportion (25% - 100%) of the true data variation data on the quiet sun. Using the flat fields in this archive will reduce that error by a factor of 10 - 30, greatly increasing the accuracy of any tracking or photometric operations. The access, use and accuracy of these flat fields are described in this paper.