Parameters

Select which parameters you want to examine:

Object parameters (e.g. - 'P001', 'P002', etc. tables)
POSS I Field parameters ('plates' table)
Astrometric Fit Parameters ('astrom' table)
Photometric Fit Parameters ('photom' table)
Photometric Standards ('standards' table)
POSS I scanned data removed from MAPS Catalog ('cuts' table)
All the parameters in the MAPS Catalog database (list all of the above)

'astrom' Table Parameters

The 'astrom' database table stores information describing the astrometric fit to each POSS I field in the MAPS Catalog. The following astrometric fit parameters are stored for each field in the MAPS Catalog:

Field Name	Definition
possfield	MAPS POSS I Field Name
possnumber	MAPS POSS I Field Number
catalog	Astrometric catalog used for the data reduction. Either 'lick' for the Lick Northern Proper Motion Catalog or 'acrs' for the Astrographic Catalog of Reference Stars (ACRS).
epoch	Epoch used for astrometric fit. Always '1950'.
x_zpc, y_zpc	The horizontal and vertical zero point corrections applied to data before astrometric reduction (in microns).
init_rot	Initial rotation of astrometric fit (in degrees).
num_cal_stars	The number of calibration stars used in astrometric calibration.
x_ctr, y_ctr	The center of the plate (in ERE).
ra_ctr, decl_ctr	The center of the plate in equatorial B1950.0 coordinates on the FK4 system used for the astrometric fit.
raJ_ctr, declJ_ctr	The center of the plate in ecliptic J2000.0 coordinates on the FK5 system (precessed from ra_ctr, decl_ctr).
l_ctr, b_ctr	The center of the plate in Galactic coordinates on the l^II system (precessed from ra_ctr, decl_ctr).
rarms, declrms	The RMS of the Right Ascension and Declination fit (in arcseconds).
dx, x_x, x_y, x_xr2, dy, y_x, y_y, y_yr2	These are the coefficients of the plate solution used (corresponding to dX, X\|x, X\|y, X\|xr, dY, Y\|x, Y\|y, Y\|yr2 in the equations below). The plate model that maps these modified coordinates, (x,y) to standard coordinates on the celestial sphere (i.e. the focal-length-normalized gnomic projection, (X,Y), of RA and Dec) is given by: X = dX + (X\|x)x + (X\|y)y + (X\|xr2)(r^2) where r^2 = x^2 + y^2 Y = dY + (Y\|x)x + (Y\|y)y + (Y\|yr2)(r^2) dX and dY are given in microns, and represent the difference between the true and nominal plate centers. The remaining terms are dimensionless derivatives. Note that one cannot apply the plate solution coefficients directly to the plate positions in the MAPS catalog because the steps of correcting for distortion, recentering, rotating, flipping, and normalization by focal length are all performed internally in the data reduction before this astrometric fit is applied.