AIPS HELP file for XBASL in 31DEC24
As of Thu Apr 25 9:45:28 2024
XBASL: Fits n'th order polynomials to rows of images
INPUTS
INNAME Input image name (name)
INCLASS Input image name (class)
INSEQ 0.0 9999.0 Input image name (seq. #)
INDISK 0.0 9.0 Input image disk unit #
OUTNAME Output image name (name)
OUTCLASS Output image name (class)
OUTSEQ -1.0 9999.0 Output image name (seq. #)
OUTDISK 0.0 9.0 Output image disk unit #.
BLC Bottom left corner of input
TRC Top right corner of input
YINC 0.0 128.0 Do every YINCth row
ZINC 0.0 128.0 Do every ZINCth plane
FLUX 0.0 Flux cutoff (see HELP)
DOOUTPUT -1.0 1.0 Write images of parms
DOCONT -1.0 1.0 > => retain continuum
DOSLICE -1.0 2.0 Plot data on TEK/TV
DOMODEL -1.0 1.0 Plot model on TEK/TV
DORESID -1.0 1.0 Plot residuals on TEK/TV
PIXRANGE Min,Max of image intensity
Max <= Min => entire range
LTYPE -410.0 410.0 Type of labeling: 1 border,
2 no ticks, 3 standard, 4 rel
to center, 5 rel to subim cen
6 map pixels
PIXVAL 0.0 Display if peak < PIXVAL
ORDER 0.0 4.0 Max order of polynomial
NBOXES 1.0 40.0 Max number of baseline
windows
BOX 0.0 4096.0 Begin/end channel numbers for
windows 1 - NBOXES
DOTV -1.0 1.0 > 0 use TV instead of TEK
GRCHAN 0.0 7.0 TV graphics channel to use
BADDISK Disk(s) to avoid for scratch
HELP SECTION
XBASL
Task: Fits n'th order polynomials to each row of an image. (Normally
XBASL will be used on images with frequency or velocity as the
first axis, but it will procede with others as well.) The task
fits up to 4'th order plus a constant baseline to each row and,
optionally, writes up to 4 + 2*ORDER n-1 dimensional images
containing the fit parameters and their uncertainties. It will
always write the image corrected for the baseline (i.e. with the
baseline function, optionally minus its average, subtracted).
With a careful choice of input parameters, the task is capable of
running in a batch-like mode. However, an interactive mode
(using the TEK or TV graphics terminal) is recommended. Note
that, since the TEK and TV are not allowed in AIPS batch jobs,
XBASL turns off all interactive options and TV/TEK displays when
it is run in batch.
Adverbs:
INNAME.....Input image name (name). Standard defaults.
INCLASS....Input image name (class). Standard defaults.
INSEQ......Input image name (seq. #). 0 => highest.
INDISK.....Disk drive # of input image. 0 => any.
OUTNAME....Output image name (name). Standard defaults.
OUTCLASS...Output image name (class). Standard defaults.
Used only for the corrected image. The OUTCLASSes
for the fit parameters are CONST and DERIVn and for the
uncertainties are DCONST and DDERVn. The "flux" (average)
of the baseline function is written with OUTCLASSes of FLUX
and DFLUX.
OUTSEQ.....Output image name (seq. #). 0 => highest unique.
OUTDISK....Disk drive # of output image. 0 => highest number with
sufficient space.
BLC........Bottom right corner in input image of desired subimage.
Default is entire image.
TRC........Top right corner in input image of desired subimage.
Default is entire image.
YINC.......Do only every YINC'th row (beginning at BLC(2)).
ZINC.......Do only every ZINC'th plane (beginning at BLC(3)).
FLUX.......A flux cutoff in the same units as the input image (i.e.
Jy/beam). If a row does not have three consecutive points
above this level - or below minus this level, no baseline
is fit to the row. Note that the row values are tested
after subtracting a linear baseline for this test.
0 => 0.00005.
DOOUTPUT...True (> 0) requests that the parameter and uncertainty
images be catalogued (see OUTCLASS).
DOCONT.....True (> 0) implies subtract the baseline and add the
average of the baseline from the output. This attempts to
retain the continuum (if any). False (<= 0) is used when
the continuum is zero, or already removed.
DOSLICE....True (> 0) implies plot the data on the TEK or TV. > 1
also requests a TEK/TV plot of the initial guess. It
must be set > 1. if you wish the option to correct
initial guesses with the TEK cross hairs or TV cursor.
If DOSLICE > 1 and NGAUSS > 1, the program pauses after
plotting its initial guess and
requests user input from the terminal. Hit RETURN to
procede with the program's initial guess. Enter BAD to
have the solution for the row blanked and E to have the
program request your guidance as to an altered set of
baseline windows.
DOMODEL....True (> 0) requests a plot of the final model for each row
on the TEK or TV.
DORESID....True (> 0) requests a plot of the final residual values in
each row. If any one or more of DOSLICE, DOMODEL, or
DORESID is true, then the program will pause after each row
and request input from the terminal. At that point, you
may enter BAD to have the solution blanked or simply a
RETURN to keep the answer. One may also enter RETR to loop
back and try again with a new set of baseline windows.
PIXRANGE...Min,Max of Image intensity. 0,0 => min,max of EACH row
(separately). Note that this will mean some plots are at
too fine a scale and that the residuals will appear only if
the slice contains a sufficient range about 0.0.
LTYPE.......Labelling type, see HELP LTYPE for details:
1 = border, 2 = no ticks, 3 or 7 = standard, 4 or 8 =
relative to ref. pixel, 5 or 9 = relative to subimage
(BLC, TRC) center, 6 or 10 = pixels. 7-10 all labels
other than tick numbers and axis type are omitted.
Less than 0 is the same except that the plot file
version number and create time are omitted.
Add n * 100 to alter the metric scaling.
PIXVAL.....Plot row only if the peak value < PIXVAL. Limits the plots
to those of uncertain intensities.
ORDER......The maximum allowed order for the polynomial. 0 is a
constant, 1 is linear, 4 is a bit much and is the maximum
allowed.
NBOXES.....The number of windows in each row (maximum) to be used in
fitting the baseline up to 20. This may be changed
interactively, reducing it or raising it. The adverb
value is really used only to select how much of BOX is
used initially and what is done in non-interactive
modes. If NBOXES=0, the outer 1/10th's of BLC to TRC are
set as the initial pixels to examine for valid data.
BOX........NBOXES pairs of channel numbers specifying the beginning
and end channel numbers of each of the baseline windows.
These numbers may be entered with the TEK/TV cursor in
interactive modes. If NBOXES>0 and BOX=0, the initial
boxes are all pixels from BLC(1) to TRC(1).
DOTV.......> 0 => use TV, otherwise the TEK emulator is used. This
emulator sometimes does not work well on Linux systems.
GRCHAN.....TV graphics channel to use. 0 -> use more than one to
allow color to contain extra meaning.
BADDISK....Disk drives to avoid for scratch files.
EXPLAIN SECTION
In interactive modes, the task selects a row to be fit and plots it on
the display (REK or TV) screen. The windows are plotted as boxes with
the left and right sides as vertical lines centered on the flux value
at the end pixels and the top and bottom lines connect these lines
together. The slope of the plotted boxes is not related to the order
of the fit.
1. It then asks you what order of fit to use, any order up to and
including the value of ORDER is allowed. The answer is in a fixed
format: the first character must be c or C and the second character
must be a number.
2. It then asks you what to do with this row. Answer:
B or b to skip this fit and copy the row to the output
Q or q to abort the task now
E or e to enter new fitting windows interactively
else to continue with current windows
3. If entering new fitting windows, it asks you to position the
cursor at the start of window 1 and the the stop of window 1, then
the start of window 2, the stop of window 2, etc. The loop exits
when you select an X value outside the plot. Note that you do not
have to set the points working from left to right - if the point
marked as the start of window n is at a higher X pixel then the
point marked as the stop of window N, they will be reversed by the
code. The windows can also occur in any order. If you are using
the TV, the task will also leave the loop if you hit button D.
Note, that the window is not entered in the list until the stop
point is set.
4. After doing a fit and plotting the requested parameters, it then
asks you if you want
R or r to retry this row (you should enter a new set of windows)
Q or q to abort the task now
B or b to mark this solution as bad
else to subtract the solution, write the output and go on