KOA Tables Documentation ( as of January 2008 )
------------------------
These output files will be created only if the '-koa' option is used
with MAKEE.
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File format for tables is 'KOA-fff_c-oo_type.tbl'. Where 'fff' is the
frame number, 'c' is the CCD number (1, 2, or 3), 'oo' is the index
order number, and 'type' is either 'flux', 'trace', 'profile', or
'arcids'.
The header cards for each order is given by 'KOA-fff_c-oo_hdr.txt' and
'KOA-fff_c-oo_hdr.fits'.
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Flux table ( KOA-fff_c-oo_flux.tbl ) :
col : Column number, where '0' is the first column in the internal
image. (In the MAKEE program, the raw HIRES CCD image is
clipped and rotated so that orders run blue-to-red and
left-to-right withe bluest order closest to row=0).
row : Row number in the clipped, rotated image.
raw_col : Column number in the raw image (first column is defined as zero).
raw_row : Row number in the raw image (first row is defined as zero).
wave : Wavelength in Angstroms (vacuum, heliocentric, and possibly
shifted to the night sky lines).
Flux : Relative flux in counts after division by (normalized) flat
field image.
Error : One sigma error on relative flux.
Background : Background level in counts scaled to match total background in
region of object extraction.
Sig_to_Noise: Signal-to-noise ratio per column (one sigma).
Flat : Level of flat field (not normalized). (The normalization
scale factor is given by 'FLATSCAL' header card.)
Arc_Lamp : Arc lamp spectrum in counts per pixel.
Sum_Flux : Same as 'Flux' but using a simple summation, rather than
an optimal extraction.
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Trace table ( KOA-fff_c-oo_trace.tbl ) :
col : Column number in the clipped, rotated image.
(Only every fifth column is shown in this table.)
row : Row number in the clipped, rotated image.
raw_col : Column number in the raw image (first column is defined as zero).
raw_row : Row number in the raw image (first row is defined as zero).
centroid : Centroided row value.
fit : Polynomial fit to centroided row value.
cent_fit : Centroid minus fit (residual).
cent_linear : Centroid minus a straight line passing through end points of fit.
fit_linear : Fit minus a straight line passing through end points of fit.
(These last two columns are plotted in the 'profiles-fff_c.ps'.)
weight : Weight of this point (usually either 1.0 or 0.0).
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Profile table ( KOA-fff_c-oo_profile.tbl ) :
relative_pixel : Spatial-direction pixel value relative to the trace.
The centroid of the profile will be zero only if the
object profile falls at the same point of the detector
as the trace object.
median_flux : Median flux per pixel in approximate counts (for the entire
exposure). This value is a median of all data values at a
given pixel position relative to the trace position, There
is no background subtraction and the values are corrected
by the mean of the flat field in this order to yield counts.
Notice the profile is sampled at about 10 points per pixel.
smooth_flux : This is the smoothed version of the profile which is
used for the spectral extraction, and is shown in the
'profiles-###.ps' plot. The size of the smoothing box
varies depending on the S/N of the object.
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Arclamp Identifications table ( KOA-fff_c-oo_arcids.tbl ) :
col_cen : Column centroid of arclamp emission line.
row : Row number in the clipped, rotated image (center of order).
raw_col : Column number in the raw image (first column is defined as zero).
raw_row : Row number in the raw image (first row is defined as zero).
wave_exp : Expected wavelength position of arc line (in Angstrons and in
air (15deg/76cm)).
wave_fit : Wavelength of the centroid of this line in polynomial fit (in
Angstroms and in air (15deg/76cm)).
wave_obj : Wavelength position of this line in the object wavelength
scale (which is vacuum, heliocentric and possibly shifted to
night sky emission lines).
wave_res : Difference between 'wave_fit' and 'wave_exp'.
col_res : Difference between 'col_cen' and polynomial fit.
weight : Weight used in polynomial fit.
peak : Peak counts of this arc line.
disp : Dispersion (Angstroms/pixel) at this position.
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Header cards added for KOA (per order) tables:
REJ_FRAC= 0.50527 / rejection fraction (actual/expected)
(Ratio of actual masked pixels to those expected based on exposure
time and size of background region.)
REJ_ADJ = 1.00000 / adjustment to rejection threshold
(Adjustment applied to rejection threshold to avoid excessive pixel
masking sometimes caused by unusual object profiles. If this number
is larger than 1.0, it could indicate problems with the extraction.)
REJ_SKY = 411 / masked pixels in sky region
(Total number of rejected pixels in sky, usually between 300-600 for
a one hour exposure.)
REJ_OBJ = 196 / masked pixels in object region
(Total number of rejected pixels in the object region.)
INDX_ORD= 16 / index of echelle order (internal)
(Internal order number, where '1' is the bluest order.)
ECHL_ORD= 72 / true echelle order number
(Actual cross-disperser order number, based on HIRES simulator.)
TRAC_OFF= 2.33737 / centroid relative to trace (pixels)
(Centroid of primary object relative to position of fit to the
trace 'star'.)
TRAC_RMS= 0.01279 / trace RMS (pixels)
TRC_FIT1= ' 2.027382562e+03 5.000000000e+00 9.346586692e+02 2.370441452e-0'
TRC_FIT2= ' 1.173676048e-06 1.970342744e-11 -7.192673190e-15 0.000000000e+0'
(Trace fit parameters. The first number is an 'x offset value'. The second
number is the polynomial order. The third through eigth number are the
polynomial coffecients. The row value at a given column position for this
echelle order is given by:
(row value) = coef(0) + ( coef(1)*(column - x offset) ) +
( coef(2)*(column - x offset)^2 ) + ...
)
OBJ_FIT1= ' 2.027382562e+03 5.000000000e+00 9.369960353e+02 2.370441452e-0'
OBJ_FIT2= ' 1.173676048e-06 1.970342744e-11 -7.192673190e-15 0.000000000e+0'
(Trace fit parameters shifted to position of primary object.)
BK1O_OFF= -11.20737 / backgrnd limit 1 (outside) rel. to trace (px)
BK1I_OFF= -3.60941 / backgrnd limit 1 (inside) rel. to trace (px)
BK2I_OFF= 8.28415 / backgrnd limit 2 (inside) rel. to trace (px)
BK2O_OFF= 15.11612 / backgrnd limit 2 (outside) rel. to trace (px)
(The four values above show the background window on either side of the
object relative to the position of the trace 'star'.)
HOBJW_PX= 4.94677 / half object width (pixels)
OBJW_PX = 9.89354 / object width (pixels)
(Size of extraction window for primary object in pixels.)
OBJW_AS = 2.35466 / object width (arcseconds)
(Size of extraction window for primary object in arcseconds.)
WAVEFIT1= ' 4.909384192E+03 2.312743750E-02 -2.196307411E-07 -6.408911426E-1'
WAVEFIT2= ' 1.267038720E-14 -2.684015663E-18 2.238792894E-22 0.000000000E+0'
(Polynomial wavelength scale fit coeffecients for the object spectrum,
the first value is coef(0), etc. The wavelength scale is given by:
wavelength(Ang) = coef(0) + (coef(1) * column) + (coef(2) * column^2) + ...
)
PFWHM_PX= 3.71222 / profile FWHM in pixels
PFWHM_AS= 0.88351 / profile FWHM in arcsec
(Rough estimate of the object full-width-half-maximum based on the
peak and area of the object profile.)
PSKEW = -0.39550 / profile Skew
(Defined: Sum of{ y_i * ((x_i - x_mean)/x_rms)^3 } / Sum of{ y_i }.)
BCKGND_1= 1.93545 / background 1 in counts per pixel
BCKGND_2= 1.76999 / background 2 in counts per pixel
(Background level on either side of object.)
FRACFLUX= 0.99041 / fractional flux extracted from profile
(Rough estimate of fraction of object extracted, usually about 98%.)
MDN_S2N = 26.86371 / median signal-to-noise per column
MIN_WAVE= 4909.38419 / minimum wavelength (usable data)
MAX_WAVE= 4996.75971 / maximum wavelength (usable data)
MIN_COL = 0 / minimum column (usable data)
MAX_COL = 4055 / maximum column (usable data)
(Range of usable spectrum for this order in Angstroms and column numbers.)
AVE_DSP = 0.02155 / average dispersion (Angstroms/pixel)
CEN_COL = 2027.50000 / central column for this order
CEN_ROW = 936.99882 / image row at central column for this order
(Center of usable range of spectrum.)
MID_COL = 2027.50000 / image middle column for this order
MID_ROW = 936.99882 / image row at middle column for this order
(Middle of spectrum based on the middle of the original full image.
'MID_COL' is the same for all orders of a given CCD.)
WFIT_RMS= 0.06630 / wavelength fit RMS
WFIT_HI = 0.17220 / wavelength fit high residual
WFIT_NUM= 33 / number of arclines used in wavelength fit
WFIT_NRJ= 0 / number of arclines rejected in wavelength fit
(Wavelength fit quality values for this order.)
ARC_FIT1= ' 4.908466241E+03 2.312340571E-02 -2.195937110E-07 -6.407760192E-1'
ARC_FIT2= ' 1.266803167E-14 -2.683514698E-18 2.238374908E-22 0.000000000E+0'
(Polynomial wavelength scale fit coeffecients for the arclamp spectrum. This
is similar to the 'WAVEFIT1,2' cards, except the wavelengths are in air
(15deg/76cm) and not heliocentric or nightsky corrected.)
MK_GAIN = 0.45455 / MAKEE gain used (inverse of e-/DN)
(The inverse of electrons per digital number card 'EPERDN'.)