def radec2fp(self, ra, dec):
x_tan, y_tan = radec2tan(ra,
dec,
self.ra,
self.dec,
mjd=self.mjd,
lst_deg=self.lst,
hexrot_deg=self.hexrot_deg,
precession=self.precession,
aberration=self.aberration,
polar_misalignment=self.polar_misalignment)
x_tan, y_tan = self.tancorr_sky2inst(x_tan, y_tan) # correction
x_fp, y_fp = tan2fp(x_tan, y_tan, self.adc1, self.adc2)
return x_fp, y_fp
def compute_fieldrot(self) :
# cross of side length 1 degree in tangent plane
phi = np.arange(4)*np.pi/2.
x1 = np.append(0.,np.pi/180.*np.cos(phi))
y1 = np.append(0.,np.pi/180.*np.sin(phi))
# convert to sky
xfp,yfp = tan2fp(x1,y1,self.adc1,self.adc2)
ra,dec = self.fp2radec(xfp,yfp)
# vanilla transformation from ha,dec to tangent plane
ha = self.lst - ra
x2,y2 = hadec2xy(ha,dec,ha[0],dec[0])
return 180./np.pi*np.mean((y1[1:]*x2[1:]-x1[1:]*y2[1:])/np.sqrt((x1[1:]**2+y1[1:]**2)*(x2[1:]**2+y2[1:]**2)))
def test_default_tan2fp(self):
ifilename = resource_filename("desimeter",
"data/raytrace-tan2fp-4957-v17.csv")
table = Table.read(ifilename, format="csv")
tmp = np.unique(table["ADC1"])
adc1 = float(tmp[tmp.size // 2]) # one random value of adc1 on grid
selection = (table["ADC1"] == adc1)
adc2 = float(table["ADC2"][selection][0])
selection = (table["ADC1"] == adc1) & (table["ADC2"] == adc2)
xtan = table["X_TAN"][selection]
ytan = table["Y_TAN"][selection]
xfp = table["X_FP"][selection]
yfp = table["Y_FP"][selection]
xfp2, yfp2 = tan2fp(xtan, ytan, adc1, adc2)
rms = np.sqrt(np.mean((xfp2 - xfp)**2 + (yfp2 - yfp)**2))
print("for ADC1={} ADC2={} rms(TAN->FP) = {:4.3f} microns".format(
adc1, adc2, rms * 1000.))
self.assertLess(rms, 3e-3) # less than 3 um