Continue - go to the next order to be fitted interactively. Repeat - return to working on the order just completed. Start - back to square one. Quit - quit prematurely.
Fit - Repeat the fit. O_fit - Change the order of the fit. Disp - Display the deviation of the fit from a linear fit. This shows the trend of the fit, and the errors in each line. Edit - Delete or change the wavelength of one or more of the selected lines, without returning to the cursor selection. Reselect - Return to selection using the cursor. Continue - Start to quit this order. Print - Prints a copy of the fit (what ARLINES.LIS would look like if you were to exit now). Auto - Starting from your current fit and arc line list, ECHARC looks for additional line in the arc at wavelengths given in the line list and adds any it finds to the identified line tables. Xauto - Deletes all the lines found by 'Auto'. Modify - Allows you some control over the Autofit parameters. Help - (or ?) Display this information.
The first letter of each command is sufficient.
It takes each pixel in turn. If that pixel is more than CHFACT times the current sigma value from any line already found, it uses that pixel as the starting point for a line search. If anything resembling a line can be found, it calculates its wavelength and looks in the line tables for a line close to that wavelength.
A line is accepted if the discrepancy between calculated and tabulated wavelength is less than SIGFACT times the current RMS value. This means that the criterion for accepting new lines is based on how their wavelength discrepancies compare with those for the lines that have already been accepted.
SIGFACT is the more important parameter.
It takes each pixel in turn. If that pixel is more than CHFACT times the current sigma value from any line already found, it uses that pixel as the starting point for a line search. If anything resembling a line can be found, it calculates its wavelength and looks in the line tables for a line close to that wavelength.
A line is accepted if the discrepancy between calculated and tabulated wavelength is less than SIGFACT times the current RMS value. This means that the criterion for accepting new lines is based on how their wavelength discrepancies compare with those for the lines that have already been accepted.
SIGFACT is the more important parameter.
E C H A R C (Version 1.0, 18-NOV-1987 ff.)
(Version 1.5, 08-DEC-1987 ff.)
This substantially revised version of ECHARC0 performs the 1-D
ARC process on 3-30 orders of a collapsed echelle image, and
then automatically detects lines and performs fits to all the
remaining orders. The output from the program is a complete
listing of all lines found (ARLINES.ECH) and an output image
with WAVES.Z.DATA containing the fitted wavelengths. One can
then use ICMULT and IADD to compute a weighted average of two
or more such output fits, and then ECHXREBIN to rebin the data
onto a constant "Meff * Lambda" .X.DATA scale.
Command parameters -
IMAGE The arc data. This should be a two-dimensional
image. ECHARC assumes there is a y axis giving
order numbers "m". If there is an x axis
component the information it contains will be
used during the program, although usually the
x data will simply be pixel number.
ARCTYPE The type of arc that was used - e.g. HELIUM,
NEON, etc. ARC will look for a file called
ARCTYPE.ARC which should hold the line list for
the arc.
INTERACTIVE The number of orders to be fit interactively.
ORDERS The array of INTERACTIVE order numbers to be fit.
ORDERFIT The initial order of the polynomial fit.
SIGMA The initial value for the line width.
ARFILE The name of the list file from which the previous
fit is to be read. Only used if PREVIOUS is
set. Note that the output is always written
to ARLINES.ECH. Default extension is .ECH
WAVES An output image containing the fitted wavelengths
from this ECHARC solution as image data (not as axis
data). This is created only if DOWAVES is set.
OUTPUT The name of the output file that combines the input
image data with the fitted wavelengths as axis
data. This is created only if DOWAVES is no.
CONTINUE Command after an order is done with.
ORDPPAG The number of sub-orders to be plotted per page in
the hard copy line atlas.
DISNCHAN Length of displayed sections.
MOVETOX New plot centre x value.
CMD Command in main menu.
LINENO Number of line to be edited.
WAVELEN Wavelength specification.
CHFACT
SIGFACT
Command keywords -
PREVIOUS If set, ARC will read in the line list from
the previous session as a starting point.
DOWAVES If set, the fitted wavelengths will be stored
as image data in a separate file. Otherwise the
fitted wavelengths will be stored as axis data along
with the input image.
HLINEMAP If set, a map of line locations is plotted as
a hard copy.
HATLAS If set, an atlas of lines is plotted as a
hard copy.
ANALYSIS If set, a detailed line-by-line analysis of the
arc fit is written to the file "echarc.lis".
HARDARC If set, the output spectrum is plotted in a
hard copy.
HARDISP If set, the dispersion curve is plotted in a
hard copy.
QUITSEL Used to confirm quitting line selection.
LINEOK Used to confirm a choice of line for deletion,
editing etc.
RESOLVE Used to decide what to do if a line is used twice.
User variables -
(>) SOFT (Char) The device/type to be used for graphics
soft plots. See the SOFT command for details.
The device must support a cursor.
(>) HARD (Char) The device/type for graphics hard plots.
Input -
As named May use the lines from a previous run. If so
by ARFILE these are read from the previous run's output
file. See below.
Output -
ARLINES.ECH File containing the lines used in the final fit.
Format is as follows -
Number of lines used in fit (I5)
1 blank record, then one header record.
Then one record for each line, giving order, channel
number, wavelength, calculated wavelength, wavelength
discrepancy, line number and auto flag (I3,4F13.4,I7,A4)
The auto flag is either " (A)" for a single order Auto
fit, " (E)" for complete echelle order auto fit, or is
a blank string for lines explicitly identified by user.
Then one blank record, then a record giving the RMS
error and the value of SIGMA used (12X,F10.2,19X,F5.2)
Then one blank record, then one record giving the
number of coefficients of the fit (15X,I3).
Functions / subroutines used -
ECH_ARINTR (FIGARO) Plots an order section by section and
allows user to identify lines, fit a
polynomial to those lines, and repeat.
When an order is finished, the lines
identified within it are written to
the file ARLINES.ECH in case of problems
during the fit to the next order.
ECH_ARGETL (FIGARO) Reads order, channel, wavelength, etc.,
information from an existing ARLINES.ECH
-format file to use as a starting point
for fits to the current order.
Originally ARC : KS / CIT 13 Jun 1984
Stolen & Modified --> ECHARC0: JKM / CIT 9 Dec 1986
Modified: --> ECHARC: v. 1.0 JKM / ESO 18 Nov 1987
Modified: --> ECHARC: v. 1.5 JKM / ESO 8 Dec 1987
FIGARO A general data reduction system