Formatting AO Target Lists

Note the new formatting requirement for NGS targets!

Target lists for both NGS AO and LGS AO observations must follow the standard Keck starlist format. In adddition, they must include the guide stars (NGS) or tip-tilt reference stars (LGS) chosen for each target.

We have therefore decided on the following format, in which LGS AO targets are identified by the flag lgs=1 after the standard required fields, and the tip-tilt reference stars follow each target on successive lines. For NGS AO targets, the targets are identified by the flag lgs=0 and the guide stars follow the target on successive lines. If you wish to observe the target using both NGS and LGS, you must flag the target as lgs=1.

Software has been developed to help observers find tip-tilt stars for a list of targets, and automatically compile a target list in the proper format. See the LGS AO software page for more information. Once you have created a list, please verify it with the target list checker

General Rules
  • One object per line.
  • No blank lines or comment lines allowed.
  • Maximum line length 130 characters.
  • All fields are separated by spaces (not tabs), except for Target Name which has a fixed length and within which spaces are allowed.
  • All fields with decimal numbers may have an arbitrary number of decimal places.
  • All keyword=value fields may be in any order.
  • The pmra/pmdec keywords normally allowed in Keck starlists, are not allowed in laser starlists.
  • Maximum 378 laser targets per night. If you have a half night, you are allotted 188 targets.
LGS AO targets, required fields
  1. Target Name: Columns 1-16 (Maximum 15 characters, spaces allowed).
  2. RA: hh mm ss.sss
  3. Dec: +dd mm ss.ss
  4. Equinox: yyyy.yy or APP meaning apparent.
  5. LGS AO flag: lgs=1
Tip-Tilt reference stars, required fields
Must follow on line(s) immediately after target
  1. Star Name: Columns 1-16 (Maximum 15 characters, spaces allowed).
  2. RA: hh mm ss.sss
  3. Dec: +dd mm ss.ss
  4. Equinox: yyyy.yy or APP meaning apparent.
  5. TT ref R magnitude: rmag=mm.m in magnitudes.
  6. B-V or B-R color for DAR compensation: b-v=m.m or b-r=m.m in magnitudes.
If an LGS AO target is its own tip-tilt reference, then just add lgs=1 after the above fields.
Optional fields
  • vmag=m.m (V magnitude).
  • lgs=0 Identifies an NGS AO target.
  • pmra=+s.ssss (Not yet allowed in laser starlists, see above)
  • pmdec=+a.aaa (Not yet allowed in laser starlists, see above)
  • ttdra=s.ssss (RA differential tracking rate, in arcsec/hr divided by 15).
  • ttddec=a.aaa (Dec differential tracking rate, in arcsec/hr).
  • comments=priority any other information you desire, after the required fields
Example
You may download a sample LGS AO target list here.
NGS AO targets, required fields
  1. Target Name: Columns 1-16 (Maximum 15 characters, spaces allowed).
  2. RA: hh mm ss.sss
  3. Dec: +dd mm ss.ss
  4. Equinox: yyyy.yy or APP meaning apparent.
  5. LGS AO flag: lgs=0 or lgs=1 (if also an LGS AO target)
NGS guide stars, required fields
Must follow on line(s) immediately after target
  1. Star Name: Columns 1-16 (Maximum 15 characters, spaces allowed).
  2. RA: hh mm ss.sss
  3. Dec: +dd mm ss.ss
  4. Equinox: yyyy.yy or APP meaning apparent.
  5. TT ref R magnitude: rmag=mm.m or vmag=mm.m in magnitudes.
If the target is an extended object, the AO system needs to be configured differently. This is accomplished by including the exact name of the science object in the target name field, followed by a space. For example, Uranus or Titan 16UT. The objects automatically supported by the AO operating software are Uranus, Neptune, Titan, Io and AGN (where the guide star is assumed to be 1.0'' across).

Target name Uranus Neptune AGN Titan Io
Extent (FWHM in arcsec) 2.80 1.68 1.0 0.7 0.7

Notes:
  • The actual extent of the planetary object is larger than the FWHM
  • The AGN was arbitrarily designated to be 1.0 arcsec so that an option for an object larger than Titan but smaller than Neptune is available.
  • Be careful NOT to include the name of one of the planetary objects in the target name field for an object other than the planetary object (e.g., do NOT use Uranus PSF star as a target name).
    • Optional fields
    • B-V or B-R color for DAR compensation: b-v=m.m or b-r=m.m in magnitudes.
    • comments=priority any other information you desire, after the required fields
    Example
    You may download a sample NGS AO target list here. Note that the targets that are both NGS and LGS targets are submitted with lgs=1.

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    For more information, please contact .