Discussion on FITS tables had a lot of participants, each with different opinions. I see no convergent line of thoughts which would lead to a standard acceptable for all. Therefore I do not propose any standard for the interchange of raw star lists. I will just review some discussions on this subject.
Apparently, only Arne has a strong interest to exchange raw star lists (i.e. star lists which need a lot of further processing) and also a very clear idea how such lists should look like. The criteria in his selection of fields were:
Header ----------- Contains a copy of the IMAGE header JD Julian Day FILTER EXPOSURE exposure time (already in image header) DATE-OBS start of observing (date + time) (already in image header) OBSERVATORY observatory code (MPC) or observatory coordinates RA-CENTER DEC-CENTER CRVAL1, CRVAL2, etc.. PLATE constants APERTURE_SIZE (diameter in pixels) PSFFUNCTION ? (I guess this would be needed) Table ------------ XT, YT image coordinates SXT, SXT error estimates for the above PSFMAG, PSFMAGERR magnitude and error estimate obtained by PSF APERTUREMAG, APERTUREMAGERR magnitude by aperture method FWHMX, FWHMY star shape useful for quality control (NOT WELL-DEFINED YET) ROUNDNESS, SHARPNESS (additional shape parameters, for definition see DAOPHOT) PEAK_DN (to decide whether a star is saturated, etc.) SKY_DN
Other people suggested a number of additional fields, according to their own experience in photometric work. Some suggested that the table should contain required and optional fields, mostly because software packages do not all compute the same quantities. Michael Gutzwiller therefore proposed the following:
Header ----------- Contains a copy the IMAGE header JD Julian Day FILTER EXPOSURE exposure time (already in image header) DATE-OBS start of observing (date + time) (already in image header) OBSERVATORY observatory code (MPC) or observatory coordinates RA-CENTER DEC-CENTER CRVAL1, CRVAL2, etc.. PLATE constants APERTURE_SIZE (diameter in pixels) Table Required ------------ XT, YT image coordinates APERTUREMAG, APERTUREMAGERR magnitude by aperture method FWHMX, FWHMY star shape useful for quality control Table Optional ------------ SXT, SXT error estimates for the above PSFMAG, PSFMAGERR magnitude and error estimate obtained by PSF FWHMX, FWHMY star shape useful for quality control (NOT WELL-DEFINED YET) ROUNDNESS, SHARPNESS (additional shape parameters, for definition see DAOPHOT) PEAK_DN (to decide whether a star is saturated, etc.) SKY_DN GOODNESS_OF_FIT (chi-square/pixel)
Header ----------- Contains a copy the IMAGE header JD Julian Day FILTER EXPOSURE exposure time (already in image header) DATE-OBS start of observing (date + time) (already in image header) OBSERVATORY observatory code (MPC) or observatory coordinates RA-CENTER DEC-CENTER CRVAL1, CRVAL2, etc.. PLATE constants APERTURE_SIZE (diameter in pixels) This would tell a reader the column 3 used an aperture of 3.5 pixels, column 4 used 5.0 pixels and column 5 used PSF fitting. TAPPX3 = 3.5 TAPPY3 = 3.5 TAPPX4 = 5.0 TAPPY4 = 5.0 etc.. TPSF5 = TRUE HISTORY processed by software XXXX version YYYY HISTORY etc... Table Required ------------ XT, YT image coordinates APERTUREMAG, APERTUREMAGERR magnitude by aperture method FWHMX, FWHMY star shape useful for quality control Table Optional ------------ SXT, SXT error estimates for the above PSFMAG, PSFMAGERR magnitude and error estimate obtained by PSF FWHMX, FWHMY star shape useful for quality control (NOT WELL-DEFINED YET) ROUNDNESS, SHARPNESS (additional shape parameters, for definition see DAOPHOT) PEAK_DN (to decide whether a star is saturated, etc.) SKY_DN GOODNESS_OF_FIT (chi-square/pixel) MAGAPP3, MAGAPP5, etc CROWDING (NOT WELL DEFINED) NO_BADPIXELS (Number of bad pixels inside the aperture)
The whole discussion started after Michael Gutzwiller proposed his version of star list format. I only jumped in to propose that the date of observation should be in the header and to exclude some parameters which I did not consider essential. I never thought and I still don't think that exchange of raw star lists will take place on any larger scale even between two individuals, much less between more people. So, I don't think there is a need for a standard for raw star lists.
There is a need for standard for the distribution of the final results, if anybody wants to put them into some database without too much trouble. Michael's proposal was just that and for this a standard should be defined. So, at the end let's show here this, somewhat modified proposal.
Header -------------- Copy the IMAGE header JD Julian Day FILTER EXPOSURE exposure time DATE-OBS start of observing (date + time) OBSERVER observatory code or information how to get observatory coordinates Number of HISTORY keywords indicating the processing steps, like HISTORY ACTION: Calculate sky coordinates HISTORY Performed by XYZ program version 5.3 HISTORY Date of operation 2000-11-29 Table ----------- RA, DEC MAG MAGERR AIRMASS QUALITY flags (probably bit fields)