174 lines
5.5 KiB
Python
174 lines
5.5 KiB
Python
#!/usr/bin/env python
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import numpy as np
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from astropy.io import fits
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from astropy.time import Time
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class observation:
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"""Satellite observation"""
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def __init__(self,ff,x,y,t,sig):
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"""Fit a satellite track"""
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# Get times
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self.tmin=np.min(t)
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self.tmid=np.mean(t)
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self.tmax=np.max(t)
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self.mjd=ff.mjd+self.tmid/86400.0
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self.nfd=Time(self.mjd,format='mjd',scale='utc').isot
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# Very simple polynomial fit; no weighting, no cleaning
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px=np.polyfit(t-self.tmid,x,1)
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py=np.polyfit(t-self.tmid,y,1)
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# Store
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self.x0=px[1]
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self.y0=py[1]
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self.dxdt=px[0]
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self.dydt=py[0]
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self.xmin=self.x0+self.dxdt*(self.tmin-self.tmid)
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self.ymin=self.y0+self.dydt*(self.tmin-self.tmid)
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self.xmax=self.x0+self.dxdt*(self.tmax-self.tmid)
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self.ymax=self.y0+self.dydt*(self.tmax-self.tmid)
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class satid:
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"""Satellite identifications"""
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def __init__(self,line):
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s=line.split()
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self.nfd=s[0]
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self.x0=float(s[1])
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self.y0=float(s[2])
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self.t0=0.0
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self.x1=float(s[3])
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self.y1=float(s[4])
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self.t1=float(s[5])
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self.norad=int(s[6])
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self.catalog=s[7]
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self.state=s[8]
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self.dxdt=(self.x1-self.x0)/(self.t1-self.t0)
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self.dydt=(self.y1-self.y0)/(self.t1-self.t0)
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def __repr__(self):
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return "%s %f %f %f -> %f %f %f %d %s %s"%(self.nfd,self.x0,self.y0,self.t0,self.x1,self.y1,self.t1,self.norad,self.catalog,self.state)
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class fourframe:
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"""Four frame class"""
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def __init__(self,fname=None):
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if fname==None:
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# Initialize empty fourframe
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self.nx=0
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self.ny=0
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self.nz=0
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self.mjd=-1
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self.nfd=None
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self.zavg=None
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self.zstd=None
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self.zmax=None
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self.znum=None
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self.dt=None
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self.site_id=0
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self.observer=None
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self.texp=0.0
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self.fname=None
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self.crpix=np.array([0.0,0.0])
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self.crval=np.array([0.0,0.0])
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self.cd=np.array([[1.0,0.0],[0.0,1.0]])
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self.ctype=["RA---TAN","DEC--TAN"]
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self.cunit=np.array(["deg","deg"])
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self.crres=np.array([0.0,0.0])
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else:
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# Read FITS file
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hdu=fits.open(fname)
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# Read image planes
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self.zavg,self.zstd,self.zmax,self.znum=hdu[0].data
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# Frame properties
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self.ny,self.nx=self.zavg.shape
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self.nz=hdu[0].header['NFRAMES']
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# Read frame time oselfsets
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self.dt=np.array([hdu[0].header['DT%04d'%i] for i in range(self.nz)])
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# Read header
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self.mjd=hdu[0].header['MJD-OBS']
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self.nfd=hdu[0].header['DATE-OBS']
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self.site_id=hdu[0].header['COSPAR']
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self.observer=hdu[0].header['OBSERVER']
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self.texp=hdu[0].header['EXPTIME']
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self.fname=fname
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# Astrometry keywords
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self.crpix=np.array([hdu[0].header['CRPIX1'],hdu[0].header['CRPIX2']])
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self.crval=np.array([hdu[0].header['CRVAL1'],hdu[0].header['CRVAL2']])
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self.cd=np.array([[hdu[0].header['CD1_1'],hdu[0].header['CD1_2']],
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[hdu[0].header['CD2_1'],hdu[0].header['CD2_2']]])
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self.ctype=[hdu[0].header['CTYPE1'],hdu[0].header['CTYPE2']]
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self.cunit=[hdu[0].header['CUNIT1'],hdu[0].header['CUNIT2']]
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self.crres=np.array([hdu[0].header['CRRES1'],hdu[0].header['CRRES2']])
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self.sx=np.sqrt(self.cd[0,0]**2+self.cd[1,0]**2)
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self.sy=np.sqrt(self.cd[0,1]**2+self.cd[1,1]**2)
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self.wx=self.nx*self.sx
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self.wy=self.ny*self.sy
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self.vmin=np.mean(self.zmax)-2.0*np.std(self.zmax)
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self.vmax=np.mean(self.zmax)+6.0*np.std(self.zmax)
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def significant(self,sigma,x0,y0,dxdt,dydt,rmin=10.0):
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"""Extract significant points"""
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# Generate sigma frame
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zsig=(self.zmax-self.zavg)/(self.zstd+1e-9)
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# Select
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c=(zsig>sigma)
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# Positions
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xm,ym=np.meshgrid(np.arange(self.nx),np.arange(self.ny))
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x,y=np.ravel(xm[c]),np.ravel(ym[c])
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inum=np.ravel(self.znum[c]).astype('int')
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sig=np.ravel(zsig[c])
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t=np.array([self.dt[i] for i in inum])
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# Predicted positions
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xr=x0+dxdt*t
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yr=y0+dydt*t
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r=np.sqrt((x-xr)**2+(y-yr)**2)
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c=r<rmin
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return x[c],y[c],t[c],sig[c]
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def track(self,dxdt,dydt,tref):
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"""Track and stack"""
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# Empty frame
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ztrk=np.zeros_like(self.zavg)
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# Loop over frames
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for i in range(self.nz):
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dx=int(np.round(dxdt*(self.dt[i]-tref)))
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dy=int(np.round(dydt*(self.dt[i]-tref)))
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if dx>=0:
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i1min,i1max=dx,self.nx-1
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i2min,i2max=0,self.nx-dx-1
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else:
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i1min,i1max=0,self.nx+dx-1
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i2min,i2max=-dx,self.nx-1
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if dy>=0:
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j1min,j1max=dy,self.ny-1
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j2min,j2max=0,self.ny-dy-1
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else:
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j1min,j1max=0,self.ny+dy-1
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j2min,j2max=-dy,self.ny-1
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zsel=np.where(self.znum==i,self.zmax,0.0)
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ztrk[j2min:j2max,i2min:i2max]+=zsel[j1min:j1max,i1min:i1max]
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return ztrk
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def __repr__(self):
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return "%s %dx%dx%d %s %.3f %d %s"%(self.fname,self.nx,self.ny,self.nz,self.nfd,self.texp,self.site_id,self.observer)
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