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Note Concerning Subroutine SOLUN

This subroutine, which derives the solar and lunar vectors (for use in correcting event times) was recently distributed on the "AO-2 History Tape" The subroutine contains two common blocks, CBASC and CSOLR, for which the contents are not defined internally. For this reason, the values of the relevant variables are listed here.




       COMMON /CBASC/ PI, TWOPI, PIH, DEG, RAD
       COMMON /CSOLR/ SOLPR, ECL, CECL, SECL, XLSUNA, XLSUNB, ECLECC, ECLOM 
       PI -3.14159265358979324DO
       TWOPI = PI+PI
       PIH = PI*.5D0
       DES = 180.D0/PI
       RAD = PI/180.DO
C ECL, CECL, SECI = INCLINATION OF THE ECLIPTIC AND ITS COS AND SIN
C XLSUNA, XLSUNB, ECLECC, ECLOM GIVE WITH A PRECISION OF 0.01 DEG
C A VALUE FOR THE LONGITUDE OF THE SUN (LS(RAD)) IN THE ECLIPTIC
C FROM: LM=XLSUNA+XLSUNB*DAY; LS=LM+ECLECC*DSIN(LM-ECLOM)
C REF: THE ASTRONOMICAL EPHEMERIS 1978, CALCULATED FOR MID 1980. 
       ECL = RAD*0.234418185380D+02
       CECL = DCOS(ECL)
       SECL = DSIN(ECL)

In addition, please note that the routine, as written, returns coordinates in the 1950.0 system, despite a comment statement suggesting otherwise. To obtain coordinates in the mean geocentric system of date, delete the references to PR50 and PREC.

J R. Sternberg


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