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1 files changed, 37 insertions, 0 deletions

diff --git a/vo/votools/gasplib/pixtoeq.x b/vo/votools/gasplib/pixtoeq.x
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+++ b/vo/votools/gasplib/pixtoeq.x
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+include <math.h>
+define	SZ_CDMTX	4
+
+# PHYSTOPIX -- procedure to obtain pixel coordinates from the equatorial
+# ones, giving the center position and scale of the frame.
+
+procedure pixtoeq (plt_ra_cen, plt_dec_cen, plt_x_cen, plt_y_cen,
+	   	     cdmtx, x, y, ra, dec)
+
+double	plt_ra_cen		# Plate centre (radians)
+double	plt_dec_cen		#      "          "
+double	plt_x_cen		# Plate center in x (pixels)
+double	plt_y_cen		# Plate center in y (pixels)
+double	cdmtx[SZ_CDMTX]		# CD Matrix (cd11, cd12, cd21, cd22) 
+double	ra			# Objects RA position (radians)
+double	dec			# Objects DEC position (radians)      
+double	x			# Position from centre (pixels)
+double	y			#      "
+
+double	xi			# Standard coordinate (degrees)
+double	eta			#		"
+double	cd11, cd12, cd21, cd22
+double	xi_arcs, eta_arcs	# Standard coord. in arc seconds.
+
+begin
+
+	cd11 = cdmtx[1]
+	cd12 = cdmtx[2]
+	cd21 = cdmtx[3]
+	cd22 = cdmtx[4]
+
+	xi  = cd11*(x-plt_x_cen) + cd12*(y-plt_y_cen)
+	eta = cd21*(x-plt_x_cen) + cd22*(y-plt_y_cen)
+	xi_arcs = xi*3600.0			# to arcs
+	eta_arcs = eta*3600.0
+	call trsteq (plt_ra_cen, plt_dec_cen, xi_arcs, eta_arcs, ra, dec)
+end