C+
C NAME:
C	sidereal_t.f
C PURPOSE:
C	Calculate the true sidereal time at ASHI from the true sidereal time at the beginning of the ASHI nighttime observations.
C CATEGORY:
C	Abnalysis
C CALLING SEQUENCE:
C	call sidereal_t(JDX,JDbeg,stbeg,alonx,st)
C
C INPUTS:
C	JDX         real*8            Julian date of the observation (UT time)
C	JDbeg       real*8            Julian date at the beginning of the ASHI observations (UT time)
C     stbeg       real*8            Sidereal time at the beginning of the ASHI observations (in degrees)
C     alonx       real              longitude of the observation (ASHI)
C
C OUTPUTS:
C	st		real		      sidereal time at ASHI in degrees since the beginning of the day
C
C FUNCTIONS/SUBROUTINES:
C     julian8
C
C MODIFICATION HISTORY:
C	April-2022, Bernard Jackson (UCSD)
C-
	subroutine sidereal_t(JDX,JDbeg,stbeg,alonx,alonb,st)
        real      alonx             ! Longitude of the ASHI observation (in degrees and fraction)
        real*8    JDX               ! Input time of the ASHI observation in Day of Year in UTC
        real*8    JDbeg             ! Input time of the beginning ASHI observation in Day of Year in UTC
        real*8    stbeg             ! True sidereal time at the beginning of the ASHI observation (in degrees)
C        (from http://neoprogrammics.com/sidereal_time_calculator/index.php) 
	  real*8    caobsdoy,         ! UT calendar days plus longitude offset since the beginning ASHI observation 
     &            daytidif,         ! difference in sidereal days from calendar days
     &            sideg             ! sidereal time in degrees and fraction at the time of the ASHI observation

C          print*, ' Into sidereal',JDX,JDbeg,stbeg,alonx,alonb

          caobsdoy = (JDX-JDbeg)     ! calendar days since the beginning ASHI obs. in UT plus the longitude offset difference
          daytidif = 0.00273042407d0*caobsdoy
          sideg    = stbeg + (caobsdoy + daytidif)*360.0d0 + (alonb-alonx)
          if(sideg.gt.360.0d0) sideg = sideg - 360.0d0
          st       = sideg           ! Sidereal time at ASHI in degrees in single precision

C          write(*,'(5F14.8)') daytidif, caobsdoy, sideg, alonb-alonx,st

	  return
	end