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Tunable Beacons

Tunable blue laser beacons have been installed on all telescopes . The S2 blue beacon is currently running on the red channel. So for now use the red buttons on S2 for controlling the bluebeacon.

You can start the control GUI from a terminal on a CHARA computer by:

  • Navigate to directory: cd /chara/rainer/tunable_beacon
  • start GUI: ./tubea_gtk &

Instructions for starting the server can be found in the README file in the same directory as the GUI program.

Findings with the tunable blue beacons during SPICA observing run in October 2022:

At a setting of 10, the beacon is just visible on the labao at 100 fps. 13-14 gives better contrast., still without the star. Turning it to 13-17 after locking a star of mag V2.4 worked well to just suppress the starlight while not shining through to the TWFS. A star of mag V1.8 required settings from 20-30 and mag V4 required 13-16. Mag V5.2 was 11-14. I think these are at 40 fps on the labao. Mag V6 used settings of 10-13, about 2 clicks above where the starlight was seen. Mag V7.1 used the same 10-13.

Turning the setting down until the starlight is just being seen and then back up by 2-3 seems to work well. Since the labao display has an auto gain, it will not look brighter as you turn the setting up, but will add light to the TWFS which is not taken out by the ZDARK. ​

chara/tunable_beacons.txt · Last modified: 2023/02/06 23:24 by charaobs