(r2) OIFITSTwoProject < Jmmc

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---+ This page is intended as a start page for discussions, whishlists and notes about a Second Version of the [[http://www.mrao.cam.ac.uk/research/OAS/oi_data/oifits.html][OI-FITS format]]

I start with a list of suggestions collected in the [[http://www.jmmc.fr][JMMC]] working groups. 
   1 Correlated Fluxes:
      * needed for, e.g., model fitting.
      * either through the use of VISDATA, VISERR (present in ESO's AMBER format and described [[%ATTACHURL%/OI_FITS.pdf][here]]). These are Double precision Complex values representing the correlated fluxes. Questions:
         * What noise model to adopt (normally same noise model as sketched in the OI-FITS publication)?
         * Normally there should also be a Nchan*Nchan VISCOV representing the covariances?
      * or through the presence of a OI_SPECTRUM table containing the total fluxes such that flux^2*vis2=correlated_flux^2
      * or both? In all cases the noise model should be very precise.
   1 Calibrator vs. Science Object tagging. To have a sequence of calibrators and objects in a OI-FITS. Calibrator may just be that there is a *diameter* in mas in the OI_TARGET, but then:
         * is this a UD or LD
         * if UD, for which lambda, etc...

Comment by JorgUwe.Pott: what about the origin of the diameter above? Comes from a catalog, is subject to change (catalog change or new measurement), should we have an indirection to the originating catalog, etc... To be quite accurate would certainly complicate the OI-FITS. 

Comment by  Gilles.Duvert: yes, but for practical purposes, having the calibrator diameter (say, "implied, supposed or forced diameter by the person responsible of originating the OI-FITS") is very handy for data reduction (especially pipelines like ESO's), model fitting etc... Perhaps it is not necessary to go into more details, and just impose an UD for the observation band. Now that I think of it, the only way to have an UD for multi-band data (AMBER being an example) would be to have an UD vector, one per spectral channel. 

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-- Main.GillesDuvert - 13 Sep 2010
   * [[%ATTACHURL%/OI_FITS.pdf][OI_FITS.pdf]]: ESO's Interferometric data format (contains OI-FITS)
Topic revision: r2 - 2010-09-14 - GillesDuvert