Cursor readback of flux in user-specified units

[hcferguson]

JWST calibrated data will have flux units will be MJy/steradian. It would be nice to provide a way for users to specify the flux units they would like in their cursor read back. I imagine this would be through the Preferences plugin.

[pllim]

Is the unit provided in image header (e.g., BUNIT)? Does unit name conform to FITS standards or readable by astropy.units? Answers will determine implementation details.

[hcferguson]

I think/hope so for JWST (but I don't know for sure). My thinking here is that if the units are provided in a FITS-conformant way, then Astropy unit conversions can do most of the simple things. For more complex things, one could provide an example in the documentation of how to build a plugin.

[pllim]

I wonder if we can or should piggy back this feature on top of PixTable or Crosshair plugin.

But before we decide where, we need to decide how. I can see things getting complicated when you need some external info for unit conversion. For example, VEGAMAG would need you to provide a spectrum of Vega, and "counts" would need you to provide telescope area. Even just using astropy.units.equivalencies.spectral_density() would need wavelength information for flux conversion.

For the stated use case, what info would be required to convert MJy/sr to the unit that you want?