User's Guide to the Prime Focus Camera

Table of Contents

Hardware Overview
Software Overview
Detector Characteristics
Plate Scale and FOV
Count Rates
PFCam User Interfaces
Motor Control GUI
CCD Interface
Observing with PFCam
Starting the Software
Observing Hints
3-D representation
2-D representation
CCD diagrams
PFCam layout

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Hardware Overview

PFCam is essentially a CCD, filter wheel, and guide camera, mounted on-axis above a prime-focus corrector and atmospheric dispersion compensator (ADC). The arrangement of the instrument's hardware components is shown in the 3-D representation below, left, and in simplified form in the schematic representation below, right.

3-D representation of PFCam
click for full-size image
Schematic representation of PFCam
click for full-size image

It can be seen that PFCam hardware consists of three distinct parts:

1. The prime-focus (top-end) optics

The ADC and prime-focus corrector comprise the top-end optics. The ADC consists of two independently rotating prisms which automatically adjust to the telescope's altitude and azimuth, correcting the elongating effect of atmospheric dispersion. The prime focus corrector compensates for spherical aberration and coma, providing a well-corrected, one-degree field, only a portion of which is used by PFCam. PFCam has a field of view 12.6 x 12.6 arcminutes, but may be somewhat less if using filters other than the 4 inch square broad-band filters.

2. The science camera

The science camera includes filters, shutter, and science CCD. The filter wheel has six positions, each of which can accommodate a filter up to 4 inches square (enabling the full 12.6' field to be imaged). 4 inch square photometry filters are provided by the observatory. Any of Lick's collection of 2" x 2" narrow-band filters can also be used with PFCam, but they reduce the useful field of view to about six arcminutes.

The science camera assembly moves up and down along the optical axis to put the CCD at the telescope focus (see "Focusing PFCam" under Observing Hints).

3. The guide camera

The guide camera views an approximately 1.5 x 2.0 arcminute field, about thirty arcminutes north of the center of the science field. The guider assembly can be moved E-W through approximately 12 arcminutes to help find suitable guide stars. The relationship of the guider and science fields is illustrated in the following diagram:

click for full-size image

Note: To observe the science target on the guide camera, move the telescope 30 arcminutes south of the target coordinates and position the guider X stage at -140 arcsecond position.

The guide camera is controlled by the telescope operator. The observer may choose to display a copy of the guide camera image with the program "guidercopy," but guiding control remains with the operator. An Rs filter (Spinrad-R night sky filter, see filters). is available from the Motor Control GUI.

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Last modified: Tue Apr 10 15:41:08 PDT 2012