D. Definition of the Coordinate System used for Suzaku

D.1 Definition of the Coordinates

The following coordinates are defined to describe event locations in the telemetry, on the detector, or on the sky. All the coordinates are written in the Suzaku event files.

• RAW coordinates:
  Original digitized values in the telemetry to identify pixels of the events. May not reflect physical locations of the pixels on the sensor. For example, XIS RAW X and Y coordinates will have values from 0 to 255 on each Segment^D.1.

• PPU coordinates:
  Coordinates system used for the Dark Frame mode of the XISs. The PPU coordinates add copied pixels (2 pixels) at the front and back of the RAW X coordinate.

• ACT coordinates:
  ACT is defined only for XIS. The ACT X and Y values are defined to represent actual pixel locations in the CCD chips. ACT XY will take 0 to 1023 to denote the 1024 $\times$ 1024 pixels in the chip. The XIS RAW to ACT conversion depends on the observation modes (such as Window Options) and will require housekeeping information. The XIS ACT coordinates is defined by looking-down the sensors.

• DET coordinates:
  Physical positions of the pixels within each sensor. Misalignments between the sensors are not taken into account. The DETX/Y coordinates are defined by looking up the sensor, such that the satellite +Y direction^D.2becomes the $-$DETY direction (the same as the ASCA convention). The DET X and Y values take 1 to 1024 for XIS.

• FOC coordinates:
  Focal plane coordinate common to all the sensors in unit of arcmin. Misalignments between the sensors as well as the difference of the focal length are taken into account so that the FOC images of different sensors can be superposed. FOC is calculated from DET by linear transformation to represent the instrumental misalignment, i.e., the offset and the rotation angle, and the focal length of the XRT. Information of these misalignment and the focal length are written in the teldef files.

• SKY coordinates:
  Positions of the events on the sky. The conversion from FOC to SKY is made using the satellite attitude in the attitude file and the alignment matrix (3$\times$3) written in the teldef file. For each XIS event, the equatorial coordinates of the pixel center projected on a tangential plane are given^D.3.

In this scheme, it is important that the conversion from RAW to DET does not depend on the misalignments between the sensors. Therefore, DET XY, as well as RAW XY, can be written in the event FITS files without having the calibration information. The DET to FOC conversion requires information of the focal length and the misalignment between the sensors. The same routines/functions can be used for FOC to SKY conversions for different sensors not depending on the individual characteristics.

D.2 Implementation to the FITS Event Files

D.2.1 Names of the Columns

	XIS	HXD
SENSOR	SENSOR	SENSOR
RAW	SEGMENT, RAWX, RAWY	-
PPU	SEGMENT, PPUX, PPUY	-
ACT	ACTX, ACTY	-
DET	DETX, DETY	-
FOC	FOCX, FOCY	-
SKY	X, Y	-

D.2.2 Type and Range of the Columns

D.2.2.1 XIS

	Type	Minimum	Maximum	Origin	Size of the Pixel
SENSOR	Integer	0	3	-	-
SEGMENT	Integer	0	3	-	-
RAWX/Y	Integer	0	255/1023	-	0.024 mm
PPUX/Y	Integer	0	259/1023	-	0.024 mm
ACTX/Y	Integer	0	1023	-	0.024 mm
DETX/Y	Integer	1	1024	512.5	0.024 mm
FOCX/Y	Integer	(1	1536)$^a$	768.5	0.0174 arcmin
X/Y	Integer	(1	1536)$^a$	768.5	0.0174 arcmin
$^a$: Default image region.

The DETXY pixel sizes correspond to the physical pixel size of the XIS CCD. The XY pixel size corresponds to the angular size of a single XIS CCD pixel. To allow rotation of the image and some shift of the pointing direction during the observation, the XY range is taken slightly bigger than $\sqrt{2} \times 1024$.

D.2.2.2 HXD

	Type	Minimum	Maximum	Origin	Size of the Pixel
SENSOR	Integer	0	15	-	-

HXD is not an imaging instrument and will not have coordinate columns. The average pointing direction may be written in the event FITS file header.