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Astrometry update

Astrometry update. Modifications to astrometry pipeline Transport ldac fits tables python DB precision loss Global astrom algorithm reminiscence from Denis days. Overlap used average position gnomonic grid. Now correct local gnomonic grid Max PV polynome

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Astrometry update

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  1. Astrometry update • Modifications to astrometry pipeline • Transport ldac fits tables python DB precision loss • Global astrom algorithm reminiscence from Denis days. Overlap used average position gnomonic grid. Now correct local gnomonic grid • Max PV polynome • 3d restricted by DB parameters

  2. Astrometric update • Global astrometry boundary condition • X = a0(f) + a1(f) x + a2(f) y + … where ai0(f) = 1, ai1(f) = f, ai2(f) = 2f2 -1, … chebychev polynome ai f dither1 dither2

  3. Astrometric update • Ways to go • Global astrom individual or consecutive dithers • Then combine regridded frames • Global pool • Denser reference grid tighter fit • Multiple determination of same object combined • Alternative • Disjunct chebychev polynomes • Combines overlap information widely different dithers

  4. Astrometry update • The LBC case • Pre-pipeline (needs python mods) • Apply radial deformation on (X,Y) values in catalog • Use this catalog to pre/aplastrom and associate • Use original catalog + pairing for astrom • In-pipeline (needs c-code + algorithm mods) • Implement alternative to AFFINE deformation in pre/aplastrom

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