Do I need the laser?

When Do I need LGS-AO?

In general, NGS-AO produces better results than LGS-AO for on-axis observations of bright targets. As the guide star becomes fainter or moves off axis, it might be advisable to switch to LGS-AO. The following plot and tables show the best regimes for both observing modes.

On-axis K-band Strehl vs. Magnitude

NGS: Green line; LGS: Orange line
Reference: AO System Performance - KAON 489
Use NGS-AO Use LGS-AO
Guide Star is:
  1. R brighter than 14th mag
  2. separation under 10"
Guide Star is:
  1. R dimmer than 14th mag
  2. separation over 10"
Absolute Performance Limits (with excellent seeing)

NGS-AO LGS-AO
NIRC2:
  1. R brighter than mag 15.5
  2. separation under 30"
NIRC2:
  1. R brighter than mag 18.5
  2. separation under 60"
NIRSPAO:
  1. R brighter than mag 15.5
  2. separation under 30"
NIRSPAO:
  1. R brighter than mag 18.5
  2. separation under 60"
OSIRIS:
  1. R brighter than mag 15.5
  2. separation under 35"
OSIRIS:
  1. R brighter than mag 18.5
  2. separation under 65"

Last modified: 09/27/2014 01:47
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