Use Case:  Preset Telescope to Astronomical Coordinates

Description:  The Astronomical Preset takes care of requests to move the telescope to a new object, specified by its celestial coordinates (right ascension and declination), and to configure all the sub-systems for observation. Tracking will start automatically just after the preset procedure has completed. A preset request can be delivered either by specifying in a command the value of the required presetting parameters or by passing a pointer to a setup file, which holds the complete information to configure and position the telescope.

Role(s)/Actor(s): 
Primary: Operator, Maintenance
Secondary: Tracking Axes, FAS

Priority: Critical

Performance: 

• Less than 4 minutes for 360 deg preset (including 3 minutes for telescope motion)
• Less than 10 seconds for 10 deg offset
• Less than 2 seconds for 10 arcmin offset (without object recentering)

Frequency: At any time

Package Assignment:  Presetting.

Preconditions: 

• Telescope is ONLINE

Basic Course:  Send command to preset the telescope to astronomical coordinates (Astronomical Preset)

• Send preset command PRSCOOR with presetting parameters
  Alternate Course:
  
  • Send a (partial) setup file (command) with presetting parameters
    
  • ATCS Handles Setup File
  Exception Course: Command failed
  
• ATCS sends command ACT/STPWAIT to Stop any Active Optics action
• ATCS sends command CHP/STOPCHP to Stop Chopping
• ATCS sends command AG/STOPAG to Stop Autoguiding
• ATCS sends command TRK/OBJSTAR to Preset to Star object
  Exception Course: Command failed
  Postcondition: Telescope is tracking on Object
• ATCS sends command AG/SETUP to forward Setup
• ATCS sends command TRK/SETLAM to Set Tracking Wavelength
• ATCS sends command AG/PRTOGS to Probe To Next Guide Star
• ATCS sends command CHP/SETUP to forward Setup
• ATCS sends command TRK/SETAV to Set Tracking Additional Velocity
• ATCS sends command ACT/ONECAL to Calculate calibrated M2 position and set M2
• ATCS sends command AG/DETGS to Center Object, if requested
  Postcondition: Object is centered.
• ATCS sends command FS/OPTCGS to Optimize Field Stabilisation, if requested
• ATCS sends command TRK/OFFSAD to Telescope Offset, if requested
• ATCS performs Start Autoguiding via command AG/STARTAG
  or Start Field Stabilization via command FS/STARTAG as requested
  Postcondition: Auto-Guiding or Field Stabilization started.
• ATCS sends final OK reply

Exception Course:  Command failed

• Return ERROR reply

Postconditions: 

• Telescope is preset and tracking on astronomical target
• ATCS state ONLINE, substate TRACKING

Issues to be Determined or Resolved: 

Notes:

Last modified: Mon Feb 25 13:35:00 UTC 2002