Dark correction

[mgalloy]

The requirements for the dark to be used for dark subtraction:

• use closest dark in time (no interpolation)
• darks must match exposure time

Tasks

• [ ] validate that darks don't vary with wavelength and polarization state
• [ ] find/retrieve closest dark to a time
• [ ] dark subtraction

Questions

• [x] How do I tell if a file is a dark? OBJECT is "Dark"