KIR A 1k x 1k IR camera for AOB/PUEO

The AOBIR cookbook is a short reference document, easily consulted during the observations. The AOB/KIR User's Manual is a full reference document.
 

KIR is a high resolution 1024 x 1024 near-infrared camera based on the Rockwell Science Center HAWAII (HgCdTe Astronomical Wide Area Infrared Imaging) focal plane array. This array is sensitive to radiation from 0.7 to 2.5 microns. KIR has been designed to be used at the F/20 output focus of PUEO, the CFHT Adaptive Optics Bonnette (AOB). It consists in an LN₂ cryostat which harbors the detector, the fixed 0.67:1.0 transfer optics, an F/20 cold stop and a filter wheel. The standard I, J, H, K and K' broad-band filters are available, as well as several narrow-band filters. A preamplifier and a shutter are mounted externally to the dewar. The system is driven by an SDSU/Leach CCD controller which is the controller commonly used at CFHT for all visible and infrared detectors. The system provides the observers with a user interface , called DetI, incorporated into the CFHT/Pegasus observing environment, through which they will configure the camera, control the data acquisition, monitor the data storage and do some pre-processing.

The Dewar has been constructed by the Universite de Montreal. The acquisition system and software were under the responsability of CFHT. The final integration of the science grade detector has been carried out at CFHT. The first light has been obtained during the first technical run in September 1997 and the final acceptance as well as the first astronomical observations were carried out in December 1997 and January 1998.

The following picture from KIR on PUEO was taken during the September 1997 technical run.

The following drawing gives the design of the cryostat as of August 1996 Dewar design
 

Characteristics:

Detector:

Different acquisition modes are available: one image per file, a cube of a given number of frames with the same integration time per file, the resulting image of a given number of coadds (power of 2).

For the time being, the readout noise is about 20e- but a multiple sampling readout mode (MSR) may be implemented in the near future, and would allow to reach a typical readout noise of less than 5e- for integration times longer than 1minute.

Here is a dark map and here is a flat field as received from Rockwell.

More information about the Rockwell HAWAII arrays in general can be found at at Rockwell's HAWAII array page

Other usefull references:

• Kozlowski et al. 1995, SPIE 2268, 353.
• Hodapp et al. 1994, SPIE 2198, 668.

 

Filters:

Broad-band filters:
 
 

Filter	CWL (microns)	FWHM (microns)	T (%)
I	0.834	0.194	80
J	1.250	0.160	80
H	1.635	0.290	80
K	2.200	0.340	80
K'	2.120	0.340	80

 

Narrow-band filters:
 
 

Filter	CWL (microns)	FWHM (microns)	T (%)
HeI_I	1.083	0.010	60
Pa Gamma	1.094	0.010	60
J continuum	1.207	0.015	65
[OII]	1.237	0.012	60
Pa Beta	1.282	0.012	60
H continuum	1.570	0.020	65
[FeII]	1.644	0.016	60
[FeII] continuum	1.690	0.018	65
H2 (1-0)	2.122	0.021	60
Br Gamma	2.166	0.022	60
H2 (2-1)	2.248	0.022	60
K continuum	2.260	0.060	65
CO (2-0)	2.296	0.023	60

 

Note: Visitor filters can also be installed on the KIR filter wheel by the CFHT technical staff, provided that they are made available in Waimea at least 3 weeks prior to the beginning of the corresponding observing run, and subject to the limitations of the 16 position filter wheel. Please note that the diameter and thickness of the visitor filters have to respectively be 12.7 mm (1/2 inch) and 5 mm (0.2 inch).
 

Performances:

• Flexures (to be added)

 
• Background

The following equivalent background magnitudes have been determined for KIR on the AOB, using the (slightly different) Redeye broad-band filters.
 
 

Filter	Background (mag/arcsec2)
J	16.3
H	14.6
K	11.6

 

• Photometry

The following photometric characteristics have been determined using the Redeye broad-band filters. Please note that these filters are sligthly different from the KIR filters which have been in use since semester 98II. The photometric parameters may have changed slightly but have not been systematically remeasured.
 
 

Filter	CWL (microns)	FWHM (microns)	Zero points (mag)	Throughput (%)
J	1.25	0.29	23.55	20.3+/-0.8
H	1.65	0.31	23.10	25.8+/-1.5
K	2.20	0.40	22.57	26.7+/-1.3

 
 

• Limiting Magnitudes

The following figures illustrate the limiting magnitudes (with S/N = 5 per pixel) reached with KIR as a function of the total integration time, for respectively broad-band and narrow-band imaging. These limiting magnitudes refer to one detector pixel (not one resolution element) and assume a perfectly corrected image. They need to be decreased by the Strehl ratio provided by KIR for the relevant combination of atmospheric conditions and reference star. For photometric or detection experiment they must be increased to account for integration over an apropriate aperture. For well corrected point sources these two corrections approximately compensate.

For each filter the image referred to here is the combination of several individual frames, with an elementary integration time (per frame) long enough that the detector readout noise is negligible. Typical such elementary integration times depend on the filter, and are are 3 mn for J, 2 mn for H, 1 mn for K and K', 30 mn for HeI, 20 mn for FeII and 5 mn for BrGamma.

KIR User's Manual:

The AOB/KIR User's Manual is available in postscript format.
 

AOBIR Cookbook:

The AOBIR cookbook is a short reference document, easily consulted during the observations.
 

AOBIR Filters:

Here is the list of filters currently installed in KIR.
 

For more information, contact:
Dr. Olivier Lai (lai@cfht.hawaii.edu) - support astronomer.
Dr. Thierry Forveille (forveill@cfht.hawaii.edu) - support astronomer