Notes on Keck AO for PSF Recovery Project

AO Parameters

AO Sign Conventions

Keck DM to WFS geometry: Square subaperture Hartmann sensor lenslets. Actuators are located at the corners. This geometry is sometimes referred to as a "actuator centered Fried Geometry" see picture (not posted yet) . Detail on numbering and orientation can be found here KAON 368 . The actuator spacing is 7 mm at the DM corresponding to 0.200 mm at the lenslet array. 562.5 mm at the telescope primary mirror and 74.8 mm on the virtual pupil image formed by the telescope pupil secondary. The secondary obscuration (including mirror support and baffling) is circular with a diameter of 2.65 m on the center of the primary mirror.

The following IDL code disp2d.pro and associated text files sub_ap_map.txt and act_map.txt are useful for plotting and displaying AO data queried from the telemetry systems (TRS) with the IDL tv command.

WFS

Telemetry TRS

The basic method of querying the TRS system using our IDL library is described here Keck Telemetry Webpage the most important thing on that web page is the description of the SQL tables and the field names. An example of using the IDL library is gettrs.pro. This code queries both the full frame rate table (ffb) and the configuration table (configuration). We have been using variations of this tool to save AO telemetry data in the IDL save file format (*.sav). These files can be read into IDL with the restore command. The IDL help and help,/structure command are useful to see what has been saved. SQL tables names are generally preserved as field names (i.e.offsetcentroids, dmcommand, etc.) of the relevant data structure.

NIRC2 Parameters

NIRC2 is the main imagining camera used with the Keck 2 AO system. It is positioned behind the AO bench on the Left Nasmyth Platform of Keck II telescope. The instrument operates from 1 to 5 µm, providing three selectable cameras to cover the expected range in image sizes. Two filter wheels with 18 positions each provide a variety of filters and/or grisms, while a focal plane mechanism provides slits and occulting spots for coronography. A dedicated slide carries larger grisms for spectroscopy. Six selectable pupil masks are available to reduce background noise sources; four of these rotate in concert with the telescope pupil and one is specific to spectroscopy.The detector is a 1024x1024 Aladdin-3 InSb array with four-quadrant readout into 32 channels.The main public NIRC2 web page is here: NIRC2 Home Page and much useful information is here NIRC2 Observers Manual

Field of view	10x10 arcsec (narrow camera)
	20x20 arcsec (medium camera)
	40x40 arcsec (wide camera)
Pixel scale	0.009942 arcsec/pixel (+/- 0.00005)
	0.019829 arcsec/pixel
	0.039686 arcsec/pixel
Filters	J, H, K, Ks, Kp, Lp, Ms, H2, Fe II, Br Gam, plus others
Pupil mask	1 circular fixed, circumscribes the telescope pupil
	1 circular rotating, inscribes the telescope pupil and masks the spiders
	3 hexagonal, rotating

A number of telescope, AO system, and instrument "keywords" that are useful for observers are added to the NIRC2 FITS files as additional header fields. The ones used by the Flicker PSF estimation code include the following:

OBJECT	Object name
UTC	Coor. UT (h:m:s)
DATE-OBS	UT date of obs Year-Month-Day
NAXIS1	Number of pixels in axis 1
NAXIS2	Number of pixels in axis 2
COADDS	number of coadds
SAMPMODE	Sample mode 1=Single; 2=CDS; 3=MCDS
NREADS	Number of reads per integration, if SAMPMODE = 3
ITIME	Integration time per coadd
FILTER	Composite filter names (both wheels)
EFFWAVE	effective wavelength of passband (microns)
MINWAVE	minimum wavelength of passband (microns)
MAXWAVE	maximum wavelength of passband (microns)
WSFRRT	Frame rate for WFS camera (Hz)
CAMNAME	camera slider's named position, one of: narrow, medium wide
PMSNAM	pupil wheel's named position, one of: INCIRCLE, LARGEHEX, MEDIUMHEX, SMALLHEX, OPEN, ...
PMRANGL	Pupil mask drive angular position (deg)
WSFRRT	Frame rate for WFS camera (Hz)
ROTMODE	Mode of AO system K-mirror one of, position angle, vertical angle, or stationary
DTCLP	OPEN/CLOSE Tip Tilt Closed Loop Mirror Positioning
AODTSTAT	AO deformable mirror loop state
AODMSTAT	AO deformable mirror loop state