SNEST_IRS2 is the same as SNEST_IRS (see Section 5.1.2) with the following differences:
1. If a sample ends up with negative flux after pedestal subtraction, its flux is set to the median of all the other (pedestal adjusted) fluxes before the uncertainty calculation is made.
2. There is no longer any flagging or processing of "outliers".
3. All points after a rad hit are ignored when computing pedestal level.
