; intended to work for WISE L1b headers, not sure if there are other different
; or more general types of SIP WCS that come from different data sets
; and/or telescopes

;IDL> help,astr.distort
;** Structure <78c348>, 5 tags, length=416, data length=416, refs=2:
;   NAME            STRING    'SIP'
;   A               FLOAT     Array[5, 5]
;   B               FLOAT     Array[5, 5]
;   AP              FLOAT     Array[5, 5]
;   BP              FLOAT     Array[5, 5]


function flatten_sip, astr

; to save space, DON'T include distort.name -- will assume it's always SIP

  distort = astr.distort
  addstr = {a: distort.a, b: distort.b, ap: distort.ap, bp: distort.bp}

  astr_flat = struct_trimtags(astr, except=['DISTORT'])

  astr_flat = struct_addtags(astr_flat, addstr)

  return, astr_flat
end


; should test on small number of images from each of W1 and W2, and from
; each mission phase, to make sure nothing about the WISE SIP format
; changed over time

pro test_flatten_sip

  fname = '/project/projectdirs/cosmo/data/wise/allsky/4band_p1bm_frm/0a/03590a/143/03590a143-w1-int-1b.fits'

  h = headfits(fname)
  extast, h, astr

end

; see if anything about the WISE/NEOWISE SIP scheme has changed for
; more recent data
pro test_neo4

  fname = '/project/projectdirs/cosmo/staging/wise/neowiser4/neowiser/p1bm_frm/3b/79673b/072/79673b072-w2-int-1b.fits'

  h = headfits(fname)
  extast, h, astr

end