All raw data (except for BIAS and DARK frames) have two binary tables
in addition to HDU#1 hosting the pixels: HDU#2 is the ozpoz table, HDU#3
is the fibre table.
The OzPoz table relates objects on the sky and fibre buttons in Ozpoz.
It is partly defined by the user in the Target Setup File.
Click here
for an example of the OzPoz table (ASCII format; science exposure).
Column
Content
Comment
Col 1
OBJECT
Identification (from Target Setup File, col 1)
Col 2
RA
Right Ascension (from Target Setup File, col 2)
Col 3
DEC
Declination (from Target Setup File, col 3)
Col 4
R
Button R (polar coordinate) position (microns)
Col 5
R_ERROR
Error in R (microns)
Col 6
THETA
Button Theta position on plate (radians)
Col 7
THETA_ERROR
Error in Theta (radians)
Col 8
TYPE
Object type (Medusa, IFU, etc.)
Col 9
BUTTON
OzPoz button number
Col 10
PRIO
Object priority (from Target Setup File, col 5)
Col 11
ORIENT
Button orientation
Col 12
IN_TOL
T or F if positioned or not within tolerance (40 microns = 0.08")
Col 13
MAGNITUDE
Target Magnitude (from Target Setup File, col 6; SCIENCE only)
The second binary table is the Fibre Table. It relates the fibre buttons
on Ozpoz and the fibre positions in the slits, and also includes lab-measured
fibre transmission values. This table is static and is maintained by the
Observatory.
Click here
for the ASCII version of the present fibre table
Click here
for a plot of the relative fibre transmission per sequential fibre number
The columns have the following content:
Column
Content
Comment
Col 1
SLIT
slit name and plate (Medusa1, Medusa2, IFU1, IFU2, Argus)
Col 2
FPS
Progressive position number of fibre in the slit
Col 3
SSN
Subslit number
Col 4
PSSN
Fibre position in the subslit
Col 5
RETRACTOR
Serial number of the retractor
Col 6
BN
Serial number of the button used in the retractor
Col 7
FBN
Serial Number of the Fibre used for the button
Col 8
RP
Retractor position on the plate. This number corresponds to the
fibre number used e.g. in FPOSS (target setup file). All even numbers
are Medusa fibres.
Cols 9-17
wave
Fibre Transmission values as measured in the lab (as percentage).
Each column has a different wavelength.
Col 18
X
X position of the fibre in the reconstructed image matrix
Col 19
Y
Y position of the fibre in the reconstructed image matrix
Col 20
FPD
fibre position on the detector; for Medusa and IFU identical to
FPS, for Argus the order is reversed.
Note that the ARGUS image reconstruction using the X and Y columns for
the table gives the image in the standard NE orientation on the sky. If
the ARGUS position angle was 0 (ARGPOSAN = 0), N is along the X axis and
E along the Y axis. The position angle is counted in the standard sense,
i.e. N to E.
That table is attached to each pipeline product, as HDU#2. It
combines information from the ozpoz and the fibre tables, and includes
added information:
Column
Content
taken from
Comment
Col 1
INDEX
pipeline
index of the fibre signal as found by the pipeline
Col 2
FPS
fibre
Progressive position number of fibre in the slit
Col 3
SSN
fibre
Subslit number
Col 4
PSSN
fibre
Fibre position in the subslit
Col 5
RP
fibre
Retractor position on the plate. This number corresponds to the
fibre number used e.g. in FPOSS. All even numbers are Medusa fibres.
Col 6
X
fibre
X position of the fibre in the reconstructed image matrix
Col 7
Y
fibre
Y position of the fibre in the reconstructed image matrix
Col 8
RETRACTOR
fibre
Serial number of the retractor
Col 9
FPD
fibre
fibre position on the detector; for Medusa and IFU identical to
FPS, for Argus the order is reversed.
Col 10
OBJECT
ozpoz
Identification (from Target Setup File, col 1)
Col 11
R
ozpoz
Button R (polar coordinate) position (microns)
Col 12
THETA
ozpoz
Button Theta position on plate (radians)
Col 13
ORIENT
ozpoz
Button orientation
Col 14
RA
ozpoz
Right Ascension (from Target Setup File, col 2)
Col 15
DEC
ozpoz
Declination (from Target Setup File, col 3)
Col 16
MAGNITUDE
ozpoz
Target Magnitude (from Target Setup File, col 6; SCIENCE only)
Col 17
TRANSMISSION
pipeline
transmission values used to correct for fibre-to-fibre differences
Col 18
WLRES
pipeline
OBJECT,SimCal data only: differential wavelength shifts, applied
for differential correction and obtained by the pipeline from the SimCal fibres
Col 19
GCORR
pipeline
OBJECT,SimCal data only: geocentric correction to be applied (in
km/s)
Col 20
HCORR
pipeline
like above, heliocentric correction
Col 21
BCORR
pipeline
like above, barycentric correction
The INDEX counts the pipeline-detected fibres. It will always increment
by one. The FPS represents the physical index of the fibres. As long as
it increments along with INDEX, this means that all fibres (up to the
present INDEX have been allocated and extracted. An increment by more
than 1 means that at least one fibre has given no signal, either because
it could not be allocated (fibre broken), or has not been allocated by
the user, or had a signal too low for the pipeline to detect. The last
possibility will actually not happen since fibre signal localization is
always done on flat field data, and if there a fibre gives too low a signal,
it can be considered as not operational.
The number of columns in the product files corresponds to the maximum
INDEX. There are no columns for fibres with no signal.
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