MOIRCS field of view

Imaging mode

MOIRCS imaging field of view (4' x 7') is sampled by two detectors, each of which has 4' x 3.5' area. The beam from the telescope is divided by the beam spliter at the focal plane and send to the independent optical system (lenses and filters).

There is an area which are not used for observation at a side of the detector with the width of ~30 arcseconds, as shown in Figure 2a. And also, there is a slight gap (a few arcseconds) between the area sampled by each channel. The telescope pointing center just falls into the gap, so make sure to move the target to one of the channels if your target is single compact object

We note that the Hawaii-2 RG detector has a 4-pixel-wide "reference pixels" on each side. The sensitive pixel region is 2040 x 2040.

Figure 1: (left)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). Channels 1 and 2 each refers to the area covered by detector 1 and 2, respectively. (Middle) Vignetted and unused areas in the detectors of MOIRCS for imaging. The vignetted area at the bottom left (channel 1) has been removed since July 2010. The crosses indicates the pointing position (center of the F.O.V.) of MOIRCS.
(Right) The definition of the PA in OPE file.


(1) There is a vignetted region at the upper-right corner of the channel 2 (see the middle panel of Figure 1). Vignetting source is Cal Probe Box in the Cs frange unit.

(2) 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.

(3) 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 the right panel of Fig.1).

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 2: Spectra in the detectors of MOIRCS for spectroscopy.
The crosses are the center of the F.O.V. of MOIRCS. The raw image format is rotated clockwise from the figure.

Please note that all data on these pages are subject to change as the evaluation of the performance of MOIRCS progresses.

Updated 2016-07-07

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