Calibration Access and Data Handbook


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Spatial coordinate systems

The CAL makes use of the following spatial coordinate systems

Please note: A pixel location in the CHIPCOORD system is given by two integer numbers. When converting any such CHIPCOORD pixel location to the CAMCOORD1 frame the corresponding physical location is that of the center of the pixel.

The following figures illustrate the alignment of the PIXCOORD1/CAMCOORD1/CAMCOORD2 and SACCOORD reference system with respect to each other for the six cameras. The last figure is a schematic overview of all available coordinate systems in the CAL and the provided paths of conversions between them.

Figure 1: Alignment of the CAMCOORD1/2 frames with respect to the PIXCOORD1 and SACCORD frames for the EMOS1 and EMOS2 cameras. Please note that the two CAMCOORD frames are identical because the telescopes' optical axes intersect the cameras in their centers.
\begin{figure}\begin{center}
\epsfig{file=emosgeo.eps,height=20cm}\\ [1cm]\end{center}\end{figure}

Figure 2: Alignment of the CAMCOORD1/2 frames with respect to the PIXCOORD1 and SACCORD frames for the EPN camera. Please note that the CAMCOORD2 frame is offset from the CAMCOORD1 frame by about (4mm/2mm) in the $-Z$ and $-Y$ SACCOORD direction respectively. The optical axis of mirror module 3 in front of EPN intersects the camera plane in the origin of CAMCOORD2.
\begin{figure}\begin{center}
\epsfig{file=epngeo.eps,height=20cm}\\ [1cm]\end{center}\end{figure}

Figure 3: Alignment of the CAMCOORD1 frame with respect to the PIXCOORD1 and SACCORD frames for the RGS camera units. Please note that strictly speaking CAMCOORD2 does not exists for RGS, however, it is formally equivalent to CAMCOORD1. The CAMCOORD1 $X/Y$ plane is rotated by $7.333^{\circ }$ with respect to the SACCOORD $Y/Z$ plane around the $+Y_{CC1}$ axis. Increasing values of the CAMCOORD1 $X$ coordinate correspond to decreasing dispersion, i.e., increasing energy (decreasing wavelength).
\begin{figure}\begin{center}
\epsfig{file=rgsgeo.eps,height=20cm}\\ [1cm]\end{center}\end{figure}

Figure 4: Alignment of the CAMCOORD1/2 frames with respect to the PIXCOORD1 and SACCORD frames for the OM camera.
\begin{figure}\begin{center}
\epsfig{file=omgeo.eps,width=15cm}\\ [1cm]\end{center}\end{figure}


next up previous contents
Next: Time coordinate system (TIMCOORD) Up: Coordinate Definitions used by Previous: Coordinate Definitions used by   Contents
Michael Smith 2011-09-20