Produces a dark or pre-flash calibration image
"
master"
, giving an output image whose data represent one unit of the given exposure
time per pixel. Thus the calibration frame should be multiplied by the appropriate factor before
subtracting from other frames (i.e. by the dark time or the flash-exposure time). This can
be performed by CALCOR and should be done prior to the production of a flatfield and
flatfield correction. The data combination methods give a mixture of very robust (median) to
very efficient (mean) methods to suit the data. "
TRIMMED"
[0.2] Or: A single value which applies to all the input images.
Indirection through an ASCII file may be used to specify these values. If more than one line is required
at prompt time then a continuation line may be requested by adding "
-"
to the end of the
line.
This parameter will not be used if USEEXT is set TRUE.
NOTE the use of wildcards with this program is not recommended unless the input images all have the same calibration exposure factors. The order of processing of any wildcarded images cannot be guaranteed.
The default for this parameter is TRUE and this cannot be overridden except by assignment on the command line or in response to a forced prompt. [TRUE]
If the logging system has been initialised using CCDSETUP then the value specified there will be
used. Otherwise, the default is "
CCDPACK.LOG"
. [CCDPACK.LOG]
TERMINAL – Send output to the terminal only
LOGFILE – Send output to the logfile only (see the LOGFILE parameter)
BOTH – Send output to both the terminal and the logfile
NEITHER – Produce no output at all
If the logging system has been initialised using CCDSETUP then the value specified there will be
used. Otherwise, the default is "
BOTH"
. [BOTH]
"
THRESH"
then this value defines the upper limit for values which can be used when combining the data. This
limit applies to the range of the output data (i.e. the values after the exposure factors have been
divided into the input data). MEAN – Mean of the input data values
MEDIAN – Weighted median of the input data values
TRIMMED – An "
alpha trimmed mean"
in which a fraction alpha/2 of the values are removed from
each extreme
MODE – An iteratively "
sigma clipped"
mean which approximates to the modal value
SIGMA – A sigma clipped mean
THRESHOLD – Mean with values above and below given limits removed
MINMAX – Mean with the highest and lowest values removed
BROADENED – A broadened median (the mean of a small number of central values)
CLIPMED – A sigma clipped median
FASTMED – Unweighted median of the input data values
[MEDIAN]
"
THRESH"
then this value defines the lower limit
for values which can be used when combining the data. This limit applies to the range of the output
data (i.e. the values after the exposure factors have been divided into the input data). "
MODE"
. [7] "
MODE"
, "
SIGMA"
and "
CLIPMED"
methods. For
METHOD = "
MODE"
the standard deviation is estimated from the population of values, for
METHOD = "
SIGMA"
and "
CLIPMED"
the variances are used. If no variances exist then
the variation of the population is used to estimate one. [4.0] "
FLASH"
, "
DARK"
or
"
NONE"
. The value of this parameter affects the output image frame type which will be
set to "
MASTER_FLASH"
or "
MASTER_DARK"
or "
MASTER_?"
. [NONE] If a global value for this parameter has been set using CCDSETUP then that value will be used. [FALSE]
"
imported"
using the programs
PRESENT or IMPORT. Typically it is used when processing using CCDPACK’s "
automated"
methods.
Values obtained from the CCDPACK extension are identified in the output log by the presence of a trailing asterisk (∗). [FALSE]
’
"
f1,f2,f3,f4"
’
expose=’
"
100,200,300,400"
’
method=median
out=master_flash ’
"
d1,d2,d3,d4"
’
1 master_dark trimmed alpha=0.2 ^
flash_frames
^
flash_exposures
flash_master "
current"
value is the value
assigned on the last run of the application. If the application has not been run then the
"
intrinsic"
defaults, as shown in the parameter help, apply. The exceptions to this rule are:
TITLE – always "
Output from MAKECAL"
KEEPIN – always TRUE
Retaining parameter values has the advantage of allowing you to define the default behaviour of the application but does mean that additional care needs to be taken when using the application on new datasets/different devices, or after a break of sometime. The intrinsic default behaviour of the application may be restored by using the RESET keyword on the command line.
Certain parameters (LOGTO, LOGFILE and USESET) have global values. These global values will always take precedence, except when an assignment is made on the command line. Global values may be set and reset using the CCDSETUP and CCDCLEAR commands.
The parameter EXPOSE will not be used if the USEEXT parameter is set TRUE. In this case the necessary values will be extracted from the CCDPACK extensions of the input images.
The routine supports BAD pixels and all data types except COMPLEX. All combinational arithmetic is performed in floating point. The AXIS and TITLE components are correctly propagated. The variances are propagated through the combination processing, assuming that the input data have a normal distribution.