[PIPE2D-1028] Wavelengths in bandpass files in obs_pfs should be in vacuum Created: 26/Apr/22  Updated: 06/Jun/22  Resolved: 11/May/22

Status: Done
Project: DRP 2-D Pipeline
Component/s: None
Affects Version/s: None
Fix Version/s: None

Type: Task Priority: Normal
Reporter: sogo.mineo Assignee: sogo.mineo
Resolution: Done Votes: 0
Labels: flux-calibration
Remaining Estimate: Not Specified
Time Spent: Not Specified
Original Estimate: Not Specified

Epic Link: flux calibration
Reviewers: price

 Description   

Bandpass data were added to obs_pfs in tickets/PIPE2D-922, but the wavelength values in these files were in-air values. They should be converted to in-vacuum values.

 Comments   
Comment by sogo.mineo [ 11/May/22 ]

I have decided to use Peck & Reeder (1972):

def vacuum_to_air(wavelength_in_vacuum):
    ss = (1e3 / wavelength_in_vacuum)**2
    n = 1.0000806051 + 0.02480990 / (132.274 - ss) + 0.000174557 / (39.32957 - ss)
    return wavelength_in_vacuum / n

which I quote at second hand from Morton (2003) (Bibcode: 2003ApJS..149..205M).

Because the actual conversion (air to vacuum) is the inverse of this function, I find x such that wavelength_in_air = vacuum_to_air by means of an iterative algorithm.

Comment by sogo.mineo [ 11/May/22 ]

Could you review this change (obs_pfs)?

Comment by price [ 11/May/22 ]

That's great, thanks!

Comment by sogo.mineo [ 11/May/22 ]

Merged. Thanks for the review.

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