hifast.ref off-source subtraction

Similar to on-source/off-source mode in tracking, hifast.ref in scan mode estimates reference spectra (“off-source”), then subtracts them, reducing the system temperature. Also, hifast.bld -T True can have a similar effect.

Processing Flow

• --method MinMed or --method MedMed

  • Divide all spectra into segments over time ( --npart ), processing each separately.

    • Further divide each segment into sub-segments (based on sub-segment count --nsection or length --nspec),

    • Compute median (Med) along time for each sub-segment,

    • Reference spectrum for a segment is median of medians ( MedMed ) or minimum of medians ( MinMed ),

    • Subtract reference spectrum.

  • Process above steps separately for each frequency.

• Typically, reapply low-order polynomial baseline subtraction to each spectrum (add --post_* parameters or input the output into hifast.bld module)

Parameters

Use command python -m hifast.ref -h | more for more parameter details.