Using autofocus_auto_star.py

Introduction

The script autofocus_auto_star.py handles finding a focus star, slewing to the star, autofocusing and then returning to the original position. It does this by calling other python utilities which handle most of the actual work.

Invocation

The invocation of autofocus_auto_star.py is:

usage: autofocus_auto_star.py [-h] [--profile PROFILE] [--lst LST]
                              [--onlyside ONLYSIDE] [--lon LON]
                              [--meridianthres MERIDIANTHRES]
                              [--maxtries MAXTRIES]
                              dist mag
positional arguments:
  dist                  Max distance in degrees
  mag                   Desired mag focus star

optional arguments:
  -h, --help            show this help message and exit
  --profile PROFILE     Name of astro profile
  --lst LST             Local sidereal time
  --onlyside ONLYSIDE   EAST or WEST side only
  --lon LON             Location longitude
  --meridianthres MERIDIANTHRES
                        How close to meridian is allowed (hh:mm:ss)
  --maxtries MAXTRIES   Number of stars to try before giving up

Explanation of specifying side of pier

The “–lon” argument allows the specification of the observing latitude. Then script can then compute the local sidereal time. Optionally the local sidereal time can be given with the “–lst” argument.

Once the local sidereal time has been determined then the “–onlyside” parameter can be used to retrict the star to one side of the meridian or the other. It can take a value of “EAST” or “WEST” (capitalized!).

The “–meridianthres” argument can be used to create a “keep out” area near the meridian that excludes choosing a focus star in that area.

Using an astro profile

There are no specific settings covered by an astro profile for the autofocus_auto_star.py script, but several scripts it relies on do.