86 lines
3.0 KiB
Plaintext
86 lines
3.0 KiB
Plaintext
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subroutine ephem(mjd0,dut,east_long,geodetic_lat,height,nspecial, &
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RA,Dec,Az,El,techo,dop,fspread_1GHz,vr)
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implicit real*8 (a-h,o-z)
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real*8 jd !Time of observationa as a Julian Date
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real*8 mjd,mjd0 !Modified Julian Date
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real*8 prec(3,3) !Precession matrix, J2000 to Date
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real*8 rmatn(3,3) !Nutation matrix
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real*8 rme2000(6) !Vector from Earth center to Moon, JD2000
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real*8 rmeDate(6) !Vector from Earth center to Moon at Date
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real*8 rmeTrue(6) !Include nutation
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real*8 raeTrue(6) !Vector from Earth center to Obs at Date
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real*8 rmaTrue(6) !Vector from Obs to Moon at Date
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logical km,bary !Set km=.true. to get km, km/s from ephemeris
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common/stcomx/km,bary,pvsun(6) !Common used in JPL subroutines
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common/librcom/xl(2),b(2)
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twopi=8.d0*atan(1.d0) !Define some constants
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rad=360.d0/twopi
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clight=2.99792458d5
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au2km=0.1495978706910000d9
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pi=0.5d0*twopi
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pio2=0.5d0*pi
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km=.true.
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freq=1000.0d6
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do jj=1,2
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mjd=mjd0
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if(jj.eq.1) mjd=mjd - 1.d0/1440.d0
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djutc=mjd
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jd=2400000.5d0 + mjd
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djtt=mjd + sla_DTT(jd)/86400.d0
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ttjd=jd + sla_DTT(jd)/86400.d0
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if(nspecial.ne.8) then
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call pleph(ttjd,10,3,rme2000) !RME (J2000) from JPL ephemeris
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year=2000.d0 + (jd-2451545.d0)/365.25d0
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call sla_PREC (2000.0d0, year, prec) !Get precession matrix
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rmeDate(1:3)=matmul(prec,rme2000(1:3)) !Moon geocentric xyz at Date
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rmeDate(4:6)=matmul(prec,rme2000(4:6)) !Moon geocentric vel at Date
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else
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call sla_DMOON(djtt,rmeDate) !No JPL ephemeris, use DMOON
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rmeDate=rmeDate*au2km
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endif
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if(nspecial.eq.7) then
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rmeTrue=rmeDate
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else
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!Nutation to true equinox of Date
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call sla_NUT(djtt,rmatn)
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call sla_DMXV(rmatn,rmeDate,rmeTrue)
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call sla_DMXV(rmatn,rmeDate(4),rmeTrue(4))
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endif
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! Local Apparent Sidereal Time:
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djut1=djutc + dut/86400.d0
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if(nspecial.eq.6) djut1=djutc
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xlast=sla_DRANRM(sla_GMST(djut1) + sla_EQEQX(djtt) + east_long)
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call sla_PVOBS(geodetic_lat,height,xlast,raeTrue)
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rmaTrue=rmeTrue - raeTrue*au2km
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if(nspecial.ne.2) then
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! Allow for planetary aberration
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tl=499.004782D0*SQRT(rmaTrue(1)**2 + rmaTrue(2)**2 + rmaTrue(3)**2)
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rmaTrue(1:3)=rmaTrue(1:3)-tl*rmaTrue(4:6)/au2km
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endif
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!Topocentric RA, Dec, dist, velocity
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call sla_DC62S(rmaTrue,RA,Dec,dist,RAdot,DECdot,vr)
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dop=-2.d0 * freq * vr/clight !EME doppler shift
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techo=2.d0*dist/clight !Echo delay time (s)
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call libration(jd,RA,Dec,xl(jj),b(jj))
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enddo
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fspread_1GHz=0.0d0
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dldt=57.2957795131*(xl(2)-xl(1))
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dbdt=57.2957795131*(b(2)-b(1))
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rate=sqrt((2*dldt)**2 + (2*dbdt)**2)
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fspread_1GHz=0.5*6741*rate
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call sla_DE2H(xlast-RA,Dec,geodetic_lat,Az,El)
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return
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end subroutine ephem
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