MOIRCS field of view
Imaging mode
The field of view of MOIRCS is about 4' x 7'.
To achieve this wide field of view, while keeping the high resolution,
the field of the Cassegrain focus is divided into two areas by a roof mirror
and then re-focused onto two HAWAII-2 arrays through
two channels of identical optics, each of which covers a 4' x 3'.5
field. There is an unused area in 30 arcseconds height in each detector
for the imaging mode as shown in Figure 2a. We note that there is almost no
gap between FOVs of each channel, although we do not recommend to use the ~2-arcsecond-width rows around the pointing center (Figure 1).
Note:
(2) Each quadrant boundary has no data region with the width of 1 pixel for both chips. See the Detector Information page.
(3) The raw data is stored in the fits file with the rotated rayout by 90 degrees clockwise from the rayout shown in Figure 1. Therefore the y axis on the raw fits data will be the 4'-length side on Figure1.
(4) The image position angle (PA) is defined as counter-clockwise direction of the MOIRCS FOV on the sky, with PA=0 when 7'-long side is to the North (see Figure 2a Right).
Figure 1: The field of view of MOIRCS at the Subaru Cassegrain focus. The cross symbol with the label "1" is the pointing center position.
(Tokoku et al. 2002)
(1) Since the nominal field of view of the Subaru Cassegrain focus is 6.0 arcminutes in diameter, a corner of each channel is a bit vignetted. The areas are located in the northeast and the southeast edges. In Figure 2a the areas are marked in gray.
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Figure 2a: (Left) Vignetted and unused areas in the detectors of MOIRCS for imaging.
The crosses are the center of the F.O.V. of MOIRCS. (Right) The definition of the PA in OPE file.
Spectroscopy mode
In spectroscpic mode the spatial direction of slits will be in y-axis direction in raw image coordinates. Spectra are imaged also onto the areas which are not used for imaging mode. Please refer to the MOS page.
Figure 2b: Spectra in the detectors of MOIRCS for spectroscopy.
The crosses are the center of the F.O.V. of MOIRCS.
Please note that all data on these pages are subject to change as the evaluation of the performance of MOIRCS progresses.
Created by Yuka Katsuno Uchimoto (Mar 2006)
Revised by Ichi Tanaka 2008-02-06