Display contemporary information about a source.

Mandatory Arguments:

Source source

The source to describe.

Optional Arguments:

Date utc

The date/time to use when calculating the displayed statistics. When this argument is omitted the date and time at which the command is executed are used instead.

Elevation horizon

The elevation of the local horizon to be used when calculating the rise and set times. When this argument is omitted the value that was last set via the horizon command, is used.

Example:

The following example shows contemporary details about the moon.

  show moon

An example of the possible output is:

  Source: moon  (31-JAN-1999 23:57:19 UTC)
   AZ:  55:14:50.329  EL: -19:30:22.728  PA: -44:43:35.743
   RA:   9:14:47.196 DEC:  14:54:40.407
   Currently below the 43 degree horizon (rising).
   Next rises in 5.5 hours, and sets in 11.9 hours.

Note that the 43 degree horizon that is shown here implies that prior to this command, eg. in the initialization file, the following command was invoked.

  horizon 43

To override this temporarily, for example to see when the sun is going to set, you could use the optional horizon argument of the show command, as follows:

  show sun, horizon=0

Similarly, to show the position and almanac of a source at a different time, one can use the optional utc argument, as follows:

  show moon, utc=$date+1

where in this example the expression $date+1 has been used to ask for the position of the moon in 24 hours. See the documentation of the Date datatype for details on date specifications. For the above case I could also have specified the time explicitly, like:

  show moon, utc=1-FEB-1999:23:57:19

to achieve the same effect.

Context:

The show command displays the location of the source after correcting for precession and nutation. The reported horizon coordinates do not take atmospheric refraction or telescope tilts into account, so they will differ slightly from the actual locations used by the control system.