Implement conversion from RHESSI stacked calibrated event list to RHESSI visibilities

[samaloney]

A stacked calibrated event list (SCEL) is basically a visibility in a different format. The transformation from SCEL to visibly essentially only require a linear regression between the phase and count data which are already binned in the SCEL

[dpshelio]

@samaloney - is that an event list that needs to be downloaded from a particular place? a new file format we need to read?

[samaloney]

@dpshelio No same file format as used currently - a fits file with some bin table extensions.