    AZEL(VI)                      6/3/74                     AZEL(VI)

    NAME
         azel - satellite predictions

    SYNOPSIS
         azel [ -d ] [ -l ] satellite1 [ -d ] [ -l ] satellite2 ...

    DESCRIPTION
         Azel predicts, in convenient form, the apparent trajectories
         of Earth satellites whose orbital elements are given in  the
         argument  files.   If a given satellite name cannot be read,
         an attempt is made to find it in a directory  of  satellites
         maintained  by  the programs's author.  The -d option causes
         azel to ask for a date and read line 1 data (see below) from
         the  standard  input.   The -l option causes azel to ask for
         the observer's latitude, west-longitude,  and  height  above
         sea level.

         For  each  satellite  given the program types its full name,
         the date, and a sequence of lines each containing a time, an
         azimuth,  an  elevation, a distance, and a visual magnitude.
         Each such line indicates that: at the  indicated  time,  the
         satellite  may  be  seen from Murray Hill (or provided loca-
         tion) at the indicated azimuth and elevation, and  that  its
         distance  and  apparent magnitude are as given.  Predictions
         are printed only when the sky is dark (sun more than  5  de-
         grees  below  the  horizon)  and  when  the satellite is not
         eclipsed by the earth's shadow.  Satellites which  have  not
         been seen and verified will not have had their visual magni-
         tude level set correctly.

         All times input and output by azel are GMT (Universal Time).

         The satellites for which elements are maintained are:

         sla,b,e,f,kSkylab A through Skylab K.  Skylab A is the labo-
                   ratory; B was the rocket but it  has  crashed.   A
                   and probably K have been verified.

         cop       Copernicus I. Never verified.

         oao       Orbiting Astronomical Observatory.  Seen and veri-
                   fied.

         pag       Pageos I.  Seen and verified; fairly dim (typical-
                   ly  2nd-3rd magnitude), but elements are extremely
                   accurate.

         exp19     Explorer 19; seen  and  verified,  but  quite  dim
                   (4th-5th magnitude) and fast-moving.

         c103b, c156b, c184b, c206b, c220b, c461b, c500b
                   Various of the USSR Cosmos series; none seen.

         7276a     Unnamed (satellite # 72-76A); not seen.

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    AZEL(VI)                      6/3/74                     AZEL(VI)

         The  element  files  used  by  azel contain five lines.  The
         first line gives a year, month number, day, hour, and minute
         at  which the program begins its consideration of the satel-
         lite, followed by a number of minutes  and  an  interval  in
         minutes.   If the year, month, and day are 0, they are taken
         to be the current date (taken to  change  at  6  A.M.  local
         time).   The output report starts at the indicated epoch and
         prints the position of the satellite for the indicated  num-
         ber of minutes at times separated by the indicated interval.
         This line is ended by two numbers which specify  options  to
         the  program  governing the completeness of the report; they
         are ordinarily both ``1''.  The first option flag suppresses
         output when the sky is not dark; the second supresses output
         when the satellite is eclipsed by the earth's  shadow.   The
         next  line of an element file is the full name of the satel-
         lite.  The next three are the elements themselves (including
         certain derivatives of the elements).

    FILES
         /usr/jfo/el/* - orbital element files

    SEE ALSO
         sky(VI)

    AUTHOR
         J. F. Ossanna

    BUGS

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