atbound 3 
	set $1 = ($1 < $2) ? $1+360. : $1
	set $1 = ($1 >= $3) ? $1-360. : $1

atbound2 2
	atbound $1 -180. 180.
	set _i = 0, dimen($1)-1
	set _indx = _i if ($1>90.)
	if(dimen(_indx)>0) {
		set $1[_indx] = 180.-$1[_indx]
		set $2[_indx] = $2[_indx]+180.
	}
	atbound $1 -180. 180.
	atbound $2 0. 360.

eqsdss 4 # eqsdss ra dec eta lambda 
	# Convert from Equatorial to Survey coordinates
	define realRa0 275.
	define realDec0 0.
	define surveyRa0 57.5
	set _ra = $1
	set _dec = $2
	set _lambda = asind(sind($realDec0)*sind(_dec)+cosd($realDec0)*cosd(_dec)*cosd(_ra-$realRa0))
	set _eta = $surveyRa0+atan2d(cosd(_dec)*sind(_ra-$realRa0),cosd($realDec0)*sind(_dec)-sind($realDec0)*cosd(_dec)*cosd(_ra-$realRa0))
	atbound2 _eta _lambda 
	set $3 = _eta 
	set $4 = _lambda
  foreach i (_lambda _eta _ra _dec) {delete $i}

sdsseq 4 # sdsseq eta lambda ra dec
	# Convert from Survey to Equatorial coordinates
	define realRa0 275.
	define realDec0 0.
	define surveyRa0 57.5
	set _eta = $1
	set _lambda = $2	
	set _dec = asind(sind($realDec0)*sind(_lambda)+cosd($realDec0)*cosd(_lambda)*cosd(_eta-$surveyRa0))
	set _ra = $realRa0 + atan2d(cosd(_lambda)*sind(_eta-$surveyRa0),cosd($realDec0)*sind(_lambda)-sind($realDec0)*cosd(_lambda)*cosd(_eta-$surveyRa0))
	atbound2 _dec _ra 
	set $3 = _ra
	set $4 = _dec
  foreach i (_lambda _eta _ra _dec) {delete $i}

eqgc 6 # eqgc ra dec nu mu anode ainc
   # Convert from equatorial to Great Circle coordinates
   #
   # To convert to and from Great Circle coordinates, you must input the
   # node and inclination of the reference great circle.  For "normal" drift
   # scan great circles, use anode=95. and ainc=-25.+2.5*n
   #
	define _anode $5
	define _ainc $6
	set _ra = $1
	set _dec = $2
	set _x1 = cosd(_ra-$_anode)*cosd(_dec)
	set _y1 = sind(_ra-$_anode)*cosd(_dec)
	set _z1 = sind(_dec)
	set _x2 = _x1
	set _y2 = _y1*cosd($_ainc)+_z1*sind($_ainc)
	set _z2 = -_y1*sind($_ainc)+_z1*cosd($_ainc)
	set _mu = atan2d(_y2,_x2)+$_anode
	set _nu = asind(_z2)
	atbound2 _nu _mu
	set $3 = _nu
	set $4 = _mu
  foreach i (_x1 _x2 _y1 _y2 _z1 _z2 _mu _nu _ra _dec) {delete $i}

gceq 6 # gceq nu mu ra dec anode ainc
   # Convert from equatorial to Great Circle coordinates
   #
   # To convert to and from Great Circle coordinates, you must input the
   # node and inclination of the reference great circle.  For "normal" drift
   # scan great circles, use anode=95. and ainc=-25.+2.5*n
   #
	define _anode $5
	define _ainc $6
	set _nu = $1
	set _mu = $2
	set _x2 = cosd(_mu-$_anode)*cosd(_nu)
	set _y2 = sind(_mu-$_anode)*cosd(_nu)
	set _z2 = sind(_nu)
	set _x1 = _x2
	set _y1 = _y2*cosd($_ainc)-_z2*sind($_ainc)
	set _z1 = _y2*sind($_ainc)+_z2*cosd($_ainc)
	set _ra = atan2d(_y1,_x1)+$_anode
	set _dec = asind(_z1)
	atbound2 _dec _ra
	set $3 = _ra
	set $4 = _dec
  foreach i (_x1 _x2 _y1 _y2 _z1 _z2 _mu _nu _ra _dec) {delete $i}