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Create Calibration files
There are two calibration steps that are needed including the instrumental position angle and efficiency calibration file. These are currently stored in polcal files in the data/ directory.
The files currently have the format of wavelength, half wave plate efficiency, position angle, quarter wave plate efficiency. In the future, the files should have the following formats: For files with multiple lines (for example wavelength dependance), they each should have their own file for each observation date they are made on. So they should have the following format:
RSSpol_Linear_Efficiency_20151205.txt
If they data are a single value which are measured regularly, they should be kept in their own file which are appended to with the format of observations date, value, and error.
RSSpol_Linear_PAZeropoint.txt
Each calibration that requires a separate observation to have their own file.
These are the standard files that will be required for linear polarization. This assumes that there are not any differences needed for the calibration of data based on the the pupil variations, rho, or gratings.
Efficiency measurements are made by making observations with a lamp and can be done during the day. The block describing the red and blue efficiency observations are available in 2015-2-COM-001. These tests only need to be run when major changes are made to the wave plates. For linear, this will need to be done for the Half-wave plates.
Filename example: RSSPol_HW_Calibrations_20151205.txt
The shape of the position angle is measured using the same data as the efficiency. This can be measured only after major changes or on a scale of 6-12 months. Filename example: RSSPol_Linear_Efficency_20151205.txt
Position angle zeropoints are measured by observing a known, non-variable polarized standard and correcting the observed position angle to the known value. This should be measured monthly. Filename example: RSSPol_Linear_PAZeropoint.txt
Observations of an unpolarized standard are required in order measure the linear polarization zeropoint as a function wavelength. These are required monthly. Filename example: RSSPol_Linear_Zeropoint_20151205.txt
Circular polarization calibration files are still to be determined.