• Non-sidereal tracking in NGS-AO mode
• Non-sidereal tracking in LGS-AO mode

Non-sidereal tracking in NGS-AO mode

• Anecdotal evidence suggests that using non-sidereal tracking rates with NGS-AO on does not work.
• Instead, turn off non-sidereal tracking and simply allow the AO system to lock onto the moving target.

Non-sidereal tracking in LGS-AO mode

Note: If the non-sidereal target is its own tip-tilt star, then turn off non-sidereal tracking, allow the AO system to lock onto the moving target and ignore the instructions in this section.

1. Set rotator mode to position angle mode:
   • For NIRC2, run the command rotate 0 on a waikoko-new terminal.
   • Differential tracking only works with the rotator in PA mode. It does not work in stationary or vertical angle mode.
2. Ask the Staff Astronomer to start the differential tracking IDL code as follows:
   • Monitor keywords AOTSPROP, AOTSDX, and AOTSDY. On a waikoko-new terminal type:
     xshow -s ao aotsprop aotsdx aotsdy &
     
   • Start an xterm on k2aoserver-new as k2obsao. This can be done by selecting the following option in the VNC pulldown menu: NIRC2 Engineering → Xterm (k2obsao@k2oaserver-new)
   • In the xterm type cd arc/tss_track_1.0
   • Type the command enableTssTrack
   • Verify the keyword AOTSPROP is set to u2p.
   • Open a new k2aoserver-new terminal by typing xterm & in the existing k2aoserver-new terminal
   • Launch IDL in the new k2aoserver-new terminal by typing idl
3. Perform LGSAO acquisition, TT star and laser (do not offset to object).
4. Type tss_track, rate = [RAR, DECR]
   • where RAR and DECR units are arsec/sec (i.e., value from JPL horizons divided by 3600).
   • For most solar system objects (other than neo), the rates will be less than 36 arcsec/hour (So the units for this tool will be less than 36/3600 = 0.01).
   • The sign for RAR and DECR is the same as the rates provided from JPL Horizons.
   • Notes:
     1. tss_track runs in an infinite loop applying incremental changes to the tip-tilt stage position via the keywords AOTSDX and AOTSDY. You must stop it with CTRL-C.
     2. FACSUM will still say AO control (even though this is a new mode of differential tracking).
     3. For a fast moving target, step up to the high rate in increments of 0.05 (arsec/sec).
5. Manually offset to target.
   • e.g. en -4.0 -2.3
   • offset should be accurate for the current time
6. Complete Science observations.
7. To continue on the current target with different rates:
   • CTRL-C to stop the differential tracking.
   • tss_track, rate = [RAR, DECR] (at the IDL prompt).
8. To setup on a new target or re-acquire the same target:
   • CTRL-C to stop the differential tracking.
   • undoob at the IDL prompt.
   • slew to new target.
   • go to step 3.
9. At the end of night or end of diff track operations, it is important to turn off diff tracking completely. This step is of critical relevance in split nights, if differential tracking is used during the first half of the night but not during the second half.
   • undoob at the IDL prompt
   • disableTssTrack and verify the keyword AOTSPROP is set to 0 or false.