def in_FOR(self,date,ngc_1,ngc_2): #ngc_1 & ngc_2 are ra & dec in radians
(sun_1,sun_2) = self.sun_pos(date)
d = astro_func.dist(ngc_1,ngc_2,sun_1,sun_2)
#sun pitch is always equal or greater than sun angle (V1 to sun)
if (d<MIN_SUN_ANGLE or d>MAX_SUN_ANGLE):
return False
return True
def bisect_by_FOR(self,in_date,out_date,ngc_1,ngc_2):#in and out of FOR, assumes only one "root" in interval
delta_days = 200.
mid_date = (in_date+out_date)/2.
while delta_days > 0.000001:
(sun_1,sun_2) = self.sun_pos(mid_date)
d = astro_func.dist(ngc_1,ngc_2,sun_1,sun_2)
if (d>MAX_SUN_ANGLE or d<MIN_SUN_ANGLE):
out_date = mid_date
else:
in_date = mid_date
mid_date = (in_date+out_date)/2.
delta_days = abs(in_date-out_date)/2.
#print "UU", mid_date
if in_date>out_date:# ensure returned date always in FOR
mid_date = mid_date + 0.000001
else:
mid_date = mid_date - 0.000001
return mid_date
def is_valid(self, date, ngc_1, ngc_2, V3pa):
"""Indicates whether an attitude is valid at a given date."""
#First check that the date is within the time interval of the ephemeris.
if ((date < self.amin) or (date > self.amax)):
return False
(sun_1, sun_2) = self.sun_pos(date)
d = astro_func.dist(ngc_1, ngc_2, sun_1, sun_2)
vehicle_pitch = pi / 2 - d #see JI memo from May 2006
#sun pitch is always equal or greater than sun angle (V1 to sun)
if (d < MIN_SUN_ANGLE or d > MAX_SUN_ANGLE):
return False
# now checking the roll and pitch angle combination
pa = astro_func.pa(ngc_1, ngc_2, sun_1, sun_2) + pi
roll = acos(cos(V3pa - pa))
sun_roll = asin(sin(roll) * cos(vehicle_pitch))
if (abs(sun_roll) <= 5.2 * D2R):
sun_pitch = atan2(tan(vehicle_pitch), cos(roll))
if (sun_pitch <= 5.2 * D2R and sun_pitch >= -45. * D2R):
return True
return False