XMM-Newton
Data Files Handbook
Next: 4.1.8 OM diagnostics files
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Previous: 4.1.6 RGS science files
4.1.7 OM science files
The following OM Science Files are defined:
- Imaging Mode Data Image Files (*OM*IMI.FIT)
- Imaging Mode (full frame high resolution) Data Image Files (*OM*E4I.FIT)
- Fast Mode Event List Files (*OM*FAE.FIT)
- Tracking History Data Auxiliary File (*OM*THX.FIT)
- Reference Frame Data Auxiliary File (*OM*RFX.FIT)
- Priority Field Acquisition Auxiliary Files (*OM*PFX.FIT)
- Priority Window Data Auxiliary Files (*OM*WDX.FIT)
- Priority Fast Auxiliary File (*OM*PAX.FIT)
- Periodic Housekeeping file (*OM*PEH.FIT)
- Non-periodic Housekeeping file (*OM*NPH.FIT)
These files are all
binary table files, except the imaging data, which are written
in a single IMAGE extension.
Type 9 are engineering type data, which are not available for general
users.
The reader may refer to [6] for a detailed
description of its structure and content.
The first two modes above
map one-to-one the corresponding instrumental modes, as specified
in [16]: the Imaging and the Fast mode, respectively.
The above files can be recognised by the value of the keyword DATATYPE in their binary/image table header, as indicated in
Tab. 16.
Table 16:
Values of the DATATYPE keywords for the OM science data
file types
| Data mode |
value of DATATYPE |
| Imaging Mode |
IMG.EL |
| Full-frame low resolution |
IMG.EM |
| Full-frame high resolution |
ENG.IM |
| Fast Mode |
FST.EL |
| Reference frame Auxiliary file |
REF.EL |
| Tracking history Auxiliary File |
TRH.EL |
|
OM Imaging Mode Data Image File
An OM image file (*OM*IMI.FIT) is produced for each imaging mode science
window. It is an image file, with a single image extension containing
a single image. For images taken in full frame high resolution mode, the
image files are stored as *OM*E4I.FIT (see also Sect. 4.1.8).
The binning information is provided by the header keywords BINAX1 and BINAX2.
The header keywords WINDOWX0, WINDOWY0, WINDOWDX, WINDOWDY
give the lower left corner and the size of the readout window in pixel units. For
example, in "High-resolution" Full Frame Mode:
WINDOWX0=0, WINDOWY0=0, WINDOWDX=2048, WINDOWDY=2048.
OM Fast Mode Event List File
OM fast event files (*OM*FAE.FIT) are created for each fast mode science
window. Each file contains data from one exposure only and is constituted
by one binary table.
The binary table consists of the columns listed in
Tab. 17. A more detailed description can be found in
[14].
Table 17:
OM Fast Mode Event List file (*OM*FAE.FIT) binary table columns
| Name |
Type |
Units |
Description |
| FRAME |
1J |
COUNTER |
Time slice number |
| FTCOARSE |
1J |
SECOND |
Coarse Time Stamp |
| FTFINE |
1I |
SECONDS |
Fine Time Stamp |
| RAWX |
1I |
PIXEL |
Event X position |
| RAWY |
1I |
PIXEL |
Event Y position |
See Sect. 8 for convention
|
OM Tracking History Data Auxiliary File
One OM tracking history file (*OM*THX.FIT) is created for each exposure of
an observation if tracking occurred (lack of suitable tracking stars can in principle
prevent this from happening). Each file consists of a single binary table,
with each row representing one frame. It contains the coordinates, in
detector pixels, of the guide stars found in the FOV as well as the
offsets found in different tracking frames due to small jitters in the
spacecraft pointing. These
offsets are corrected by the shift-and-add algorithm on board.
The binary table consists of the columns listed in
Tab. 18. A more detailed description can be found
in [14].
Table 18:
OM Tracking History Data Auxiliary file (*OM*THX.FIT) binary table columns
| Name |
Type |
Units |
Description |
| FRAME |
1J |
COUNTER |
Tracking number |
| NGGS |
1J |
COUNTS |
No. of good guide stars found |
| DX |
1J |
1/1000th PIXELS |
Drift in x direction |
| DY |
1J |
1/1000th PIXELS |
Drift in y direction |
| ROLL |
1J |
|
Roll drift (in units
sin(θ)) |
| QUALITY |
1J |
|
Quadratic sum of the x and y residuals |
| GSX |
10J |
PIXEL |
Guide Star x coordinate |
| GSY |
10J |
PIXEL |
Guide Star y coordinate |
| GSCTS |
10J |
COUNTS |
Guide Star counts integrated over PSF |
See Sect. 8 for convention
|
OM Reference Frame Data Auxiliary File
An OM reference frame file (*OM*RFX.FIT) is created for each exposure of
an observation. Each file consists of a single binary table, with
each row representing one frame.
The binary table consists of the columns listed in
Tab. 19. A more detailed description can be
found in [14].
Table 19:
OM Reference Frame Auxiliary file (*OM*RFX.FIT)
binary table columns
| Name |
Type |
Units |
Description |
| XROLL |
1J |
PIXEL |
Roll centre x coordinate |
| YROLL |
1J |
PIXEL |
Roll centre y coordinate |
| GOODSTAR |
1J |
COUNTER |
No. of good guide stars |
| BADSTAR |
1J |
COUNTER |
No. of bad guide stars |
| GGSX |
16J |
PIXEL |
Good guide star x coordinate |
| GGSY |
16J |
PIXEL |
Good guide star y coordinate |
| GGSCNTS |
16J |
COUNTS |
Good guide star counts |
| GGSXMIN |
16J |
PIXEL |
Good guide star box minimum X |
| GGSXMAX |
16J |
PIXEL |
Good guide star box maximum X |
| GGSYMIN |
16J |
PIXEL |
Good guide star box minimum Y |
| GGSYMAX |
16J |
PIXEL |
Good guide star box maximum Y |
| GGSX2MNT |
16J |
PIXEL |
Good guide star X 2nd momentum |
| GGSY2MNT |
16J |
PIXEL |
Good guide star Y 2nd momentum |
| GGSXYMNT |
16J |
PIXEL |
Good guide star XY 2nd momentum |
| GGSPKCO |
16J |
PIXEL |
Good guide star peak coordinates |
| GGSPKCNT |
16J |
COUNTS |
Good guide star peak counts |
| GGSQUAL |
16J |
|
Good guide star quality |
| BGSX |
16J |
PIXEL |
Bad guide star x coordinate |
| BGSY |
16J |
PIXEL |
Bad guide star y coordinate |
| BGSCNTS |
16J |
COUNTS |
Bad guide star counts |
| BGSXMIN |
16J |
PIXEL |
Bad guide star box minimum X |
| BGSXMAX |
16J |
PIXEL |
Bad guide star box maximum X |
| BGSYMIN |
16J |
PIXEL |
Bad guide star box minimum Y |
| BGSYMAX |
16J |
PIXEL |
Bad guide star box maximum Y |
| BGSX2MNT |
16J |
PIXEL |
Bad guide star X 2nd momentum |
| BGSY2MNT |
16J |
PIXEL |
Bad guide star Y 2nd momentum |
| BGSXYMNT |
16J |
PIXEL |
Bad guide star XY 2nd momentum |
| BGSPKCO |
16J |
PIXEL |
Bad guide star peak coordinates |
| BGSPKCNT |
16J |
COUNTS |
Bad guide star peak counts |
| BGSQUAL |
16J |
|
Bad guide star quality |
See Sect. 8 for convention
|
``Priority files''
Three kinds of OM ``Priority'' data exist:
- Priority Field Acquisition Auxiliary (*OM*PFX.FIT) File (the so-called ``DP_FAQ''
data)
- Priority Window Data Auxiliary (*OM*WDX.FIT) File (the so-called ``DP_WDW'' data)
- Priority Fast Auxiliary (*OM*PAX.FIT) File (the so-called ``DP_BFAST'' data)
They are called ``priority'', because they are issued with a higher
priority by the Digital Processing Unit (DPU: 1024sec) than the
regular data. These files are created before the start of the actual
science exposure.
DP_FAQ data contain information on the OM field acquisition made at the
beginning of the observation. The purpose of the field acquisition exposure is
to recenter the window for more accurate coordinates, which is fundamentally
important for the fast mode. The coordinates of a set of uplinked
Guide Star (GS) positions are compared to the actual measured positions
in the field acquisition frame. From this comparison, the actual pointing
direction of OM is derived as offset from the nominal position. Each
instance of this file consists of a single binary table, whose columns
are described in Tab. 20.
Table 20:
OM Priority Field Acquisition Auxiliary file (*OM*PAX.FIT) binary table columns
| Name |
Type |
Units |
Description |
| ITERATN |
1J |
COUNTER |
No. of iterations to solution |
| XCOMMAND |
1J |
PIXEL |
Commanded X coordinate |
| YCOMMAND |
1J |
PIXEL |
Commanded Y coordinate |
| DX |
1J |
1/1000th PIXEL |
Pointing error in x |
| DY |
1J |
1/1000th PIXEL |
Pointing error in y |
| SINTHETA |
1J |
|
Absolute roll error [1/1000th
sin(θ)] |
| NGSUP |
1J |
COUNTER |
No. of uplinked guide stars |
| NGSFOUND |
1J |
|
No. of guide stars found |
| GSX |
16J |
PIXEL |
X coordinates of the guide stars |
| GSY |
16J |
PIXEL |
Y coordinates of the guide stars |
| RSX |
16J |
PIXEL |
X coordinates of the reference stars |
| RSY |
16J |
PIXEL |
X coordinates of the reference stars |
See Sect. 8 for convention
|
The main purpose of the DP_WDW (*OM*WDX.FIT) files
is to determine the effective exposure time by correcting for dead time
(time intervals during which no photons are recorded because of read out).
DP_WDW data contain the position of the science window (up to 5) during
an exposure and
the associated memory window and detector windows, together with the
position of the autonomously selected guide star windows (up to 16).
The dataset also lists the tracking window positions and the finally calculated
memory and detector window configurations. Each
instance of this file consists of a single binary table, whose columns
are described in Tab. 21.
Table 21:
OM Priority Field Window Data Auxiliary file (*OM*WDX.FIT) binary table columns
| Name |
Type |
Units |
Description |
| DETWINS |
1J |
|
No. of detector windows |
| SCIWIND |
1J |
|
No. of science windows |
| MEMWIND |
1J |
|
No. of memory windows |
| DWX0 |
16J |
PIXEL |
Bottom left X coordinate of detector window |
| DWY0 |
16J |
PIXEL |
Bottom left Y coordinate of detector window |
| DWXSIZE |
16J |
PIXEL |
X dimension of detector window |
| DWYSIZE |
16J |
PIXEL |
Y dimension of detector window |
| DWMMWID |
16J |
|
Identificator of corresponding memory window |
| DWKOMPX |
16J |
|
MIC data decoder parameter |
| DWBB |
16J |
|
MIC data decoder parameter |
| DWAA |
16J |
|
MIC data decoder parameter |
| DWKOMPY |
16J |
|
MIC data decoder parameter |
| SWX0 |
16J |
PIXEL |
Bottom left X coordinate of science window |
| SWY0 |
16J |
PIXEL |
Bottom left Y coordinate of science window |
| SWXSIZE |
16J |
PIXEL |
X dimension of memory window |
| SWYSIZE |
16J |
PIXEL |
Y dimension of memory window |
| SWMODE |
16J |
|
Science window operating mode (0=Imaging; 1=Fast) |
| |
|
|
15: placeholder for non-science windows |
| SWP1 |
16J |
|
Science window mode dependent parameter |
| SWP2 |
16J |
|
Science window mode dependent parameter |
| SWP3 |
16J |
|
Science window mode dependent parameter |
| SWP4 |
16J |
|
Science window mode dependent parameter |
| SWBASE |
16J |
|
Science window data storage address |
| SWMMWID |
16J |
|
Science window identificator of the corresponding memory window |
| MWX0 |
16J |
PIXEL |
Bottom left X coordinate of memory window |
| MWY0 |
16J |
PIXEL |
Bottom left Y coordinate of memory window |
| MWXSIZE |
16J |
PIXEL |
X dimension of memory window |
| MWYSIZE |
16J |
PIXEL |
Y dimension of memory window |
| MWBASE |
16J |
|
Memory window retrieval address |
See Sect. 8 for convention
If Imaging mode: Pixel binning factor in X (
);
If Fast mode: sampling time (in DPU units: 1024sec)
Only if imaging mode: Pixel binning factor in Y (
)
Not used
Starting address in DPU global memory to which the accumulated image is written
|
The DP_BFAST data contain information on the fast mode data.
A single file is produced for each exposure of the observation (excluding
the Field Acquisition Exposure) if there are windows configured in fast mode.
Conversely, this file is not present during exposures, where no fast windows
are active. The file consists of a single binary table, whose columns
are described in Tab. 22.
Table 22:
OM Priority Fast Auxiliary file (*OM*PFX.FIT)
binary table columns
| Name |
Type |
Units |
Description |
| BFASTID |
1J |
|
Blue DSP 1 or 2 |
| SAMPTIME |
1J |
|
Sample time |
| NFASTPIX |
1J |
|
No. of pixels for fast time slice |
| FASTDEST |
1J |
|
Memory address of fast mode data stream |
| FASTEND |
1J |
|
Termination address of fast mode data |
| NFASTEVT |
1J |
|
Total no. of events in mode data |
| FASTADDR |
503J |
|
Fast addresses |
See Sect. 8 for convention
|
There is one record per fast mode window.
Next: 4.1.8 OM diagnostics files
Up: 4.1 Observation/Slew data science, non-science, and spacecraft files
Previous: 4.1.6 RGS science files
European Space Agency - XMM-Newton Science Operations Centre