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diff --git a/noao/imred/echelle/doc/doecslit.hlp b/noao/imred/echelle/doc/doecslit.hlp new file mode 100644 index 00000000..7bf69f00 --- /dev/null +++ b/noao/imred/echelle/doc/doecslit.hlp @@ -0,0 +1,1230 @@ +.help doecslit Feb93 noao.imred.echelle +.ih +NAME +doecslit -- Echelle slit spectra reduction task +.ih +USAGE +doecslit objects +.ih +SUMMARY +\fBDoecslit\fR subtracts background sky or scattered light, extracts, +wavelength calibrates, and flux calibrates multiorder echelle slit spectra +which have been processed to remove the detector characteristics; i.e. CCD +images have been bias, dark count, and flat field corrected. The spectra +should be oriented such that pixels of constant wavelength are aligned with +the image columns or lines. Small departures from this alignment are not +critical resulting in only a small loss of resolution. Single order +observations should be reduced with \fBdoslit\fR. +.ih +PARAMETERS +.ls objects +List of object images to be processed. Previously processed spectra are +ignored unless the \fIredo\fR flag is set or the \fIupdate\fR flag is set +and dependent calibration data has changed. If the images contain the +keyword IMAGETYP then only those with a value of "object" or "OBJECT" +are used and those with a value of "comp" or "COMPARISON" are added +to the list of arcs. Extracted spectra are ignored. +.le +.ls apref = "" +Aperture reference spectrum. This spectrum is used to define the basic +extraction apertures and is typically a bright star spectrum. +.le +.ls arcs = "" (at least one if dispersion correcting) +List of arc calibration spectra. These spectra are used to define +the dispersion functions. The first spectrum is used to mark lines +and set the dispersion function interactively and dispersion functions +for all other arc spectra are derived from it. If the images contain +the keyword IMAGETYP then only those with a value of "comp" or +"COMPARISON" are used. All others are ignored as are extracted spectra. +.le +.ls arctable = "" (optional) (refspectra) +Table defining which arc spectra are to be assigned to which object +spectra (see \fBrefspectra\fR). If not specified an assignment based +on a header parameter, \fIsparams.sort\fR, such as the Julian date +is made. +.le +.ls standards = "" (at least one if flux calibrating) +List of standard star spectra. The standard stars must have entries in +the calibration database (package parameter \fIechelle.caldir\fR). +.le + +.ls readnoise = 0., gain = 1. (apsum) +Read out noise in photons and detector gain in photons per data value. +This parameter defines the minimum noise sigma and the conversion between +photon Poisson statistics and the data number statistics. Image header +keywords (case insensitive) may be specified to obtain the values from the +image header. +.le +.ls datamax = INDEF (apsum.saturation) +The maximum data value which is not a cosmic ray. +When cleaning cosmic rays and/or using variance weighted extraction +very strong cosmic rays (pixel values much larger than the data) can +cause these operations to behave poorly. If a value other than INDEF +is specified then all data pixels in excess of this value will be +excluded and the algorithms will yield improved results. +This applies only to the object spectra and not the standard star or +arc spectra. For more +on this see the discussion of the saturation parameter in the +\fBapextract\fR package. +.le +.ls norders = 10 (apfind) +Number of orders to be found automatically. +.le +.ls width = 5. (apedit) +Approximate full width of the spectrum profiles. This parameter is used +to define a width and error radius for the profile centering algorithm, +and defaults for the aperture limits and background regions. +.le + +.ls dispcor = yes +Dispersion correct spectra? This may involve either defining a nonlinear +dispersion coordinate system in the image header or resampling the +spectra to uniform linear wavelength coordinates as selected by +the parameter \fIsparams.linearize\fR. +.le +.ls extcor = no +Extinction correct the spectra? +.le +.ls fluxcal = no +Flux calibrate the spectra using standard star observations? +.le +.ls resize = no (apresize) +Resize the defaults apertures for each object based on the spectrum profile? +.le +.ls clean = no (apsum) +Detect and correct for bad pixels during extraction? This is the same +as the clean option in the \fBapextract\fR package. If yes this also +implies variance weighted extraction. In addition the datamax parameters +can be useful. +.le +.ls trace = yes (non-quicklook mode only) (aptrace) +Allow tracing each object spectrum separately? If not set then the trace +from the aperture reference is used, with recentering to allow for shifts +across the dispersion. If set then each object and standard star +image is retraced. Retracing is NOT done in quicklook mode. +.le +.ls background = "none" (apsum, apscatter) +Type of background light subtraction. The choices are "none" for no +background subtraction, "scattered" for a global scattered light +subtraction, "average" to average the background within background regions, +"median" to use the median in background regions, "minimum" to use the +minimum in background regions, or "fit" to fit across the dispersion using +the background within background regions. The scattered light option fits +and subtracts a smooth global background and modifies the input images. +This is a slow operation and so is NOT performed in quicklook mode. The +other background options are local to each aperture. The "fit" option uses +additional fitting parameters from \fBsparams\fR and the "scattered" option +uses parameters from \fBapscat1\fR and \fBapscat2\fR. +.le +.ls splot = no +Plot the final spectra? In quicklook mode a noninteractive, stacked plot +is automatically produced using the task \fBspecplot\fR while in +non-quicklook mode a query is given and the task \fBsplot\fR is used for +interactive plotting. +.le +.ls redo = no +Redo operations previously done? If no then previously processed spectra +in the objects list will not be processed unless required by the +update option. +.le +.ls update = no +Update processing of previously processed spectra if the aperture +reference image, the dispersion reference image, or standard star +calibration data are changed? +.le +.ls quicklook = no +Extract and calibrate spectra with minimal interaction? In quicklook mode +only aperture reference definitions, the initial dispersion function +solution, and the standard star setup are done interactively. Scattered +light subtraction and individual object tracing are not performed. +Normally the \fIsplot\fR option is set in this mode to produce an automatic +final spectrum plot for each object. It is recommended that this mode not be +used for final reductions. +.le +.ls batch = no +Process spectra as a background or batch job provided there are no interactive +steps remaining. +.le +.ls listonly = no +List processing steps but don't process? +.le + +.ls sparams = "" (pset) +Name of parameter set containing additional processing parameters. This +parameter is only for indicating the link to the parameter set +\fBsparams\fR and should not be given a value. The parameter set may be +examined and modified in the usual ways (typically with "epar +sparams" or ":e sparams" from the parameter editor). The parameters are +described below. +.le + +.ce +-- GENERAL PARAMETERS -- +.ls line = INDEF, nsum = 10 +The dispersion line (line or column perpendicular to the dispersion +axis) and number of adjacent lines (half before and half after unless +at the end of the image) used in finding, recentering, resizing, +editing, and tracing operations. A line of INDEF selects the middle of the +image along the dispersion axis. +.le +.ls extras = no (apsum) +Include raw unweighted and uncleaned spectra, the background spectra, and +the estimated sigma spectra in a three dimensional output image format. +See the discussion in the \fBapextract\fR package for further information. +.le + +.ce +-- AUTOMATIC APERTURE RESIZING PARAMETERS -- +.ls ylevel = 0.05 (apresize) +Fraction of the peak to set aperture limits during automatic resizing. +.le + +.ce +-- TRACE PARAMETERS -- +.ls t_step = 10 (aptrace) +Step along the dispersion axis between determination of the spectrum +positions. Note the \fInsum\fR parameter is also used to enhance the +signal-to-noise at each step. +.le +.ls t_function = "spline3", t_order = 2 (aptrace) +Default trace fitting function and order. The fitting function types are +"chebyshev" polynomial, "legendre" polynomial, "spline1" linear spline, and +"spline3" cubic spline. The order refers to the number of +terms in the polynomial functions or the number of spline pieces in the spline +functions. +.le +.ls t_niterate = 1, t_low = 3., t_high = 3. (aptrace) +Default number of rejection iterations and rejection sigma thresholds. +.le + +.ce +-- BACKGROUND AND SCATTERED LIGHT PARAMETERS -- +.ls b_function = "legendre", b_order = 1 (apsum) +Default background fitting function and order. The fitting function types are +"chebyshev" polynomial, "legendre" polynomial, "spline1" linear spline, and +"spline3" cubic spline. The order refers to the number of +terms in the polynomial functions or the number of spline pieces in the spline +functions. +.le +.ls b_naverage = -100 (apsum) +Default number of points to average or median. Positive numbers +average that number of sequential points to form a fitting point. +Negative numbers median that number, in absolute value, of sequential +points. A value of 1 does no averaging and each data point is used in the +fit. +.le +.ls b_niterate = 0 (apsum) +Default number of rejection iterations. If greater than zero the fit is +used to detect deviant fitting points and reject them before repeating the +fit. The number of iterations of this process is given by this parameter. +.le +.ls b_low_reject = 3., b_high_reject = 3. (apsum) +Default background lower and upper rejection sigmas. If greater than zero +points deviating from the fit below and above the fit by more than this +number of times the sigma of the residuals are rejected before refitting. +.le +.ls buffer = 1. (apscatter) +Buffer distance from the edge of any aperture for data to be included +in the scattered light determination. This parameter may be modified +interactively. +.le +.ls apscat1 = "", apscat2 = "" (apscatter) +Parameter sets for the fitting functions across and along the dispersion. +These parameters are those used by \fBicfit\fR. These parameters are +usually set interactively. +.le + +.ce +-- APERTURE EXTRACTION PARAMETERS -- +.ls weights = "none" (apsum) (none|variance) +Type of extraction weighting. Note that if the \fIclean\fR parameter is +set then the weights used are "variance" regardless of the weights +specified by this parameter. The choices are: +.ls "none" +The pixels are summed without weights except for partial pixels at the +ends. +.le +.ls "variance" +The extraction is weighted by the variance based on the data values +and a poisson/ccd model using the \fIgain\fR and \fIreadnoise\fR +parameters. +.le +.le +.ls pfit = "fit1d" (apsum and approfile) (fit1d|fit2d) +Type of profile fitting algorithm to use. The "fit1d" algorithm is +preferred except in cases of extreme tilt. +.le +.ls lsigma = 3., usigma = 3. (apsum) +Lower and upper rejection thresholds, given as a number of times the +estimated sigma of a pixel, for cleaning. +.le + +.ce +-- ARC DISPERSION FUNCTION PARAMETERS -- +.ls threshold = 10. (identify/reidentify) +In order for a feature center to be determined the range of pixel intensities +around the feature must exceed this threshold. +.le +.ls coordlist = "linelist$thar.dat" (ecidentify) +Arc line list consisting of an ordered list of wavelengths. +Some standard line lists are available in the directory "linelist$". +.le +.ls match = 1. (ecidentify) +The maximum difference for a match between the dispersion function computed +value and a wavelength in the coordinate list. +.le +.ls fwidth = 4. (ecidentify) +Approximate full base width (in pixels) of arc lines. +.le +.ls cradius = 10. (reidentify) +Radius from previous position to reidentify arc line. +.le +.ls i_function = "legendre", i_xorder = 3, i_yorder = 3 (ecidentify) +The default function, function order for the pixel position dependence, and +function order for the aperture number dependence to be fit to the arc +wavelengths. The functions choices are "chebyshev" or "legendre". +.le +.ls i_niterate = 3, i_low = 3.0, i_high = 3.0 (ecidentify) +Number of rejection iterations and sigma thresholds for rejecting arc +lines from the dispersion function fits. +.le +.ls refit = yes (ecreidentify) +Refit the dispersion function? If yes and there is more than 1 line +and a dispersion function was defined in the arc reference then a new +dispersion function of the same type as in the reference image is fit +using the new pixel positions. Otherwise only a zero point shift is +determined for the revised fitted coordinates without changing the +form of the dispersion function. +.le + +.ce +-- AUTOMATIC ARC ASSIGNMENT PARAMETERS -- +.ls select = "interp" (refspectra) +Selection method for assigning wavelength calibration spectra. +Note that an arc assignment table may be used to override the selection +method and explicitly assign arc spectra to object spectra. +The automatic selection methods are: +.ls average +Average two reference spectra without regard to any sort parameter. +If only one reference spectrum is specified then it is assigned with a +warning. If more than two reference spectra are specified then only the +first two are used and a warning is given. +This option is used to assign two reference spectra, with equal weights, +independent of any sorting parameter. +.le +.ls following +Select the nearest following spectrum in the reference list based on the +sorting parameter. If there is no following spectrum use the nearest preceding +spectrum. +.le +.ls interp +Interpolate between the preceding and following spectra in the reference +list based on the sorting parameter. If there is no preceding and following +spectrum use the nearest spectrum. The interpolation is weighted by the +relative distances of the sorting parameter. +.le +.ls match +Match each input spectrum with the reference spectrum list in order. +This overrides the reference aperture check. +.le +.ls nearest +Select the nearest spectrum in the reference list based on the sorting +parameter. +.le +.ls preceding +Select the nearest preceding spectrum in the reference list based on the +sorting parameter. If there is no preceding spectrum use the nearest following +spectrum. +.le +.le +.ls sort = "jd" (setjd and refspectra) +Image header keyword to be used as the sorting parameter for selection +based on order. The header parameter must be numeric but otherwise may +be anything. Common sorting parameters are times or positions. +.le +.ls group = "ljd" (setjd and refspectra) +Image header keyword to be used to group spectra. For those selection +methods which use the group parameter the reference and object +spectra must have identical values for this keyword. This can +be anything but it must be constant within a group. Common grouping +parameters are the date of observation "date-obs" (provided it does not +change over a night) or the local Julian day number. +.le +.ls time = no, timewrap = 17. (refspectra) +Is the sorting parameter a 24 hour time? If so then the time origin +for the sorting is specified by the timewrap parameter. This time +should precede the first observation and follow the last observation +in a 24 hour cycle. +.le + +.ce +-- DISPERSION CORRECTION PARAMETERS -- +.ls linearize = yes (dispcor) +Interpolate the spectra to a linear dispersion sampling? If yes the +spectra will be interpolated to a linear or log linear sampling using +the linear dispersion parameters specified by other parameters. If +no the nonlinear dispersion function(s) from the dispersion function +database are assigned to the input image world coordinate system +and the spectral data is not interpolated. Note the interpolation +function type is set by the package parameter \fIinterp\fR. +.le +.ls log = no (ecdispcor) +Use linear logarithmic wavelength coordinates? Linear logarithmic +wavelength coordinates have wavelength intervals which are constant +in the logarithm of the wavelength. +.le +.ls flux = yes (ecdispcor) +Conserve the total flux during interpolation? If \fIno\fR the output +spectrum is interpolated from the input spectrum at each output +wavelength coordinate. If \fIyes\fR the input spectrum is integrated +over the extent of each output pixel. This is slower than +simple interpolation. +.le + +.ce +-- SENSITIVITY CALIBRATION PARAMETERS -- +.ls bandwidth = 10., bandsep = 10. (standard) +Interpolated bandpass grid. If INDEF then the same bandpasses as in the +calibration files are used otherwise the calibration data is interpolated +to the specified set of bandpasses. +.le +.ls s_interact = yes (standard) +Display the bandpasses on the standard star data and allow interactive +addition and deletion of bandpasses. +.le +.ls s_function = "spline3", s_order = 1 (sensfunc) +Function and order used to fit the sensitivity data. The function types are +"chebyshev" polynomial, "legendre" polynomial, "spline3" cubic spline, +and "spline1" linear spline. +Order of the sensitivity fitting function. The value corresponds to the +number of polynomial terms or the number of spline pieces. The default +values may be changed interactively. +.le +.ls fnu = no (calibrate) +The default calibration is into units of F-lambda. If \fIfnu\fR = yes then +the calibrated spectrum will be in units of F-nu. +.le + +.ce +PACKAGE PARAMETERS +.ls dispaxis = 2 +Default dispersion axis. The dispersion axis is 1 for dispersion +running along image lines and 2 for dispersion running along image +columns. If the image header parameter DISPAXIS is defined it has +precedence over this parameter. The default value defers to the +package parameter of the same name. +.le +.ls extinction = "onedstds$kpnoextinct.dat" (standard, sensfunc, calibrate) +Extinction file for a site. There are two extinction files in the +NOAO standards library, onedstds$, for KPNO and CTIO. These extinction +files are used for extinction and flux calibration. +.le +.ls caldir (standard) +Standard star calibration directory. A directory containing standard +star data files. Note that the directory name must end with '/'. +There are a number of standard star calibrations directories in the NOAO +standards library, onedstds$. +.le +.ls observatory = "observatory" (observatory) +The default observatory to use for latitude dependent computations. +If the OBSERVAT keyword in the image header it takes precedence over +this parameter. +.le +.ls interp = "poly5" (nearest|linear|poly3|poly5|spline3|sinc) (dispcor) +Spectrum interpolation type used when spectra are resampled. The choices are: + +.nf + nearest - nearest neighbor + linear - linear + poly3 - 3rd order polynomial + poly5 - 5th order polynomial + spline3 - cubic spline + sinc - sinc function +.fi +.le +.ls database = "database" +Database name used by various tasks. This is a directory which is created +if necessary. +.le +.ls verbose = no +Verbose output? If set then almost all the information written to the +logfile is also written to the terminal except when the task is a +background or batch process. +.le +.ls logfile = "logfile" +If specified detailed text log information is written to this file. +.le +.ls plotfile = "" +If specified metacode plots are recorded in this file for later review. +Since plot information can become large this should be used only if +really desired. +.le +.ih +ENVIRONMENT PARAMETERS +The environment parameter \fIimtype\fR is used to determine the extension +of the images to be processed and created. This allows use with any +supported image extension. For STF images the extension has to be exact; +for example "d1h". +.ih +DESCRIPTION +\fBDoecslit\fR subtracts background sky or scattered light, extracts, +wavelength calibrates, and flux calibrates multiorder echelle slit spectra +which have been processed to remove the detector characteristics; i.e. CCD +images have been bias, dark count, and flat field corrected. The spectra +should be oriented such that pixels of constant wavelength are aligned with +the image columns or lines. Small departures from this alignment are not +critical resulting in only a small loss of resolution. Single order +observations should be reduced with \fBdoslit\fR. + +The task is a command language script which collects and combines the +functions and parameters of many general purpose tasks to provide a single, +complete data reduction path and a degree of guidance, automation, and +record keeping. In the following description and in the parameter section +the various general tasks used are identified. Further +information about those tasks and their parameters may be found in their +documentation. \fBDoecslit\fR also simplifies and consolidates parameters +from those tasks and keeps track of previous processing to avoid +duplications. + +The general organization of the task is to do the interactive setup steps, +such as the aperture definitions and reference dispersion function +determination, first using representative calibration data and then perform +the majority of the reductions automatically, possibly as a background +process, with reference to the setup data. In addition, the task +determines which setup and processing operations have been completed in +previous executions of the task and, contingent on the \fIredo\fR and +\fIupdate\fR options, skip or repeat some or all the steps. + +The description is divided into a quick usage outline followed by details +of the parameters and algorithms. The usage outline is provided as a +checklist and a refresher for those familiar with this task and the +component tasks. It presents only the default or recommended usage +since there are many variations possible. + +\fBUsage Outline\fR + +.ls 6 [1] +The images are first processed with \fBccdproc\fR for overscan, +zero level, dark count, and flat field corrections. +.le +.ls [2] +Set the \fBdoecslit\fR parameters with \fBeparam\fR. Specify the object +images to be processed, an aperture reference image (usually a bright +star spectrum) to use in finding the orders and defining the +aperture parameters, one or more arc images, and one or more standard +star images. If there are many object, arc, or standard star images +you might prepare "@ files". Set the detector and data +specific parameters. Select the processing options desired. +Finally you might wish to review the \fBsparams\fR algorithm parameters +though the defaults are probably adequate. +.le +.ls [3] +Run the task. This may be repeated multiple times with different +observations and the task will generally only do the setup steps +once and only process new images. Queries presented during the +execution for various interactive operations may be answered with +"yes", "no", "YES", or "NO". The lower case responses apply just +to that query while the upper case responses apply to all further +such queries during the current execution and no further queries of that +type will be made. +.le +.ls [4] +The specified number of orders (ranked by peak strength) in the aperture +reference image are located and default fixed width apertures are +assigned. If the resize option is set the apertures are resized by finding +the level which is 5% (the default) of the peak above local background. +You then have the option of entering the aperture editing loop to check the +aperture positions, sizes, and background fitting parameters. This is +highly recommended. Note that it is important that the aperture numbers be +sequential with the orders and if any orders are skipped the aperture +numbers should also skip. It is also important to verify the background +regions with the 'b' key. Usually you want any changes made to the +background definitions to apply to all apertures so use the 'a' key to +select all apertures before modifying the background parameters. To exit +the background mode and then to exit the review mode use 'q'. +.le +.ls [5] +The order positions at a series of points along the dispersion are measured +and a function is fit to these positions. This may be done interactively +to examine the traced positions and adjust the fitting parameters. To exit +the interactive fitting type 'q'. Not all orders need be examined and the +"NO" response will quit the interactive fitting using the last defined +fitting parameters on the remaining traces. +.le +.ls [6] +Apertures are now defined for all standard and object images. This is only +done if there are no previous aperture definitions for the image. The +aperture references previously defined are used as the initial set of +apertures for each image. The apertures are then recentered by an average +shift over all orders and resized if that option is selected. +The apertures may also be retraced and interactively examined +for each image if the tracing option is selected and quicklook mode is not. +.le +.ls [7] +If scattered light subtraction is selected the scattered light parameters +are set using the aperture reference image and the task \fBapscatter\fR. +The purpose of this is to interactively define the aperture buffer distance +for the scattered light and the cross and parallel dispersion fitting +parameters. The fitting parameters are taken from and recorded in the +parameter sets \fBapscat1\fR and \fBapscat2\fR. All other scattered light +subtractions are done noninteractively with these parameters. Note that +the scattered light correction modifies the input images. Scattered light +subtraction is not done in quicklook mode. +.le +.ls [8] +If dispersion correction is selected the first arc in the arc list is +extracted. The dispersion function is defined using the task +\fBecidentify\fR. Identify a few arc lines in a few orders with 'm' and +'o' and use the 'l' line list identification command to automatically add +additional lines and fit the dispersion function. Check the quality of the +dispersion function fit with 'f'. When satisfied exit with 'q'. +.le +.ls [9] +If the flux calibration option is selected the standard star spectra are +processed (if not done previously). The images are background subtracted, +extracted, and wavelength calibrated. The appropriate arc +calibration spectra are extracted and the dispersion function refit +using the arc reference spectrum as a starting point. The standard star +fluxes through the calibration bandpasses are compiled. You are queried +for the name of the standard star calibration data file. Because echelle +spectra are often at much higher dispersion than the calibration data, +interpolated bandpasses may be defined with the bandpass parameters in +\fBsparams\fR and checked or modified interactively. + +After all the standard stars are processed a sensitivity function is +determined using the interactive task \fBsensfunc\fR. Finally, the +standard star spectra are extinction corrected and flux calibrated +using the derived sensitivity function. +.le +.ls [10] +The object spectra are now automatically background subtracted +(an alternative to scattered light subtraction), +extracted, wavelength calibrated, and flux calibrated. +.le +.ls [11] +The option to examine the final spectra with \fBsplot\fR may be given. +To exit type 'q'. In quicklook mode the spectra are plotted +noninteractively with \fBspecplot\fR. +.le +.ls [12] +The final spectra will have the same name as the original 2D images +with a ".ec" extension added. +.le + +\fBSpectra and Data Files\fR + +The basic input consists of echelle slit object, standard star, and arc +calibration spectra stored as IRAF images. +The type of image format is defined by the +environment parameter \fIimtype\fR. Only images with that extension will +be processed and created. +The raw CCD images must be +processed to remove overscan, bias, dark count, and flat field effects. +This is generally done using the \fBccdred\fR package. Flat fields which +are not contaminated by low counts between the apertures may be prepared +with the task \fBapflatten\fR (recommended) or \fBapnormalize\fR. Lines of +constant wavelength across the orders should be closely aligned with one of +the image axes. Sometimes the orders are aligned rather than the spectral +features. This will result in a small amount of resolution loss but is +often acceptable. In some cases one may correct for misalignment with the +\fBrotate\fR task. More complex geometric problems and observations of +extended objects should be handled by the \fBlongslit\fR package and single +order observations should be processed by \fBdoslit\fR. + +The aperture reference spectrum is generally a bright star. The arc +spectra are comparison arc lamp observations (they must all be of the same +type). The assignment of arc calibration exposures to object exposures is +generally done by selecting the nearest in time and interpolating. +However, the optional \fIarc assignment table\fR may be used to explicitly +assign arc images to specific objects. The format of this file is +described in task \fBrefspectra\fR. + +The final reduced spectra are recorded in two or three dimensional IRAF +images. The images have the same name as the original images with an added +".ec" extension. Each line in the reduced image is a one dimensional +spectrum with associated aperture, order, and wavelength +information. When the \fIextras\fR parameter is set the lines in the +third dimension contain additional information (see +\fBapsum\fR for further details). These spectral formats are accepted by the +one dimensional spectroscopy tasks such as the plotting tasks \fBsplot\fR +and \fBspecplot\fR. The special task \fBscopy\fR may be used to extract +specific apertures or to change format to individual one dimensional +images. The task \fBscombine\fR is used to combine or merge orders into +a single spectrum. + +\fBPackage Parameters\fR + +The \fBechelle\fR package parameters set parameters which change +infrequently and define the standard I/O functions. The extinction file +is used for making extinction corrections and the standard star +calibration directory is used for determining flux calibrations from +standard star observations. The calibration directories contain data files +with standard star fluxes and band passes. The available extinction +files and flux calibration directories may be listed using the command: +.nf + + cl> page onedstds$README + +.fi +The extinction correction requires computation of an air mass using the +task \fBsetairmass\fR. The air mass computation needs information +about the observation and, in particular, the latitude of the observatory. +This is determined using the OBSERVAT image header keyword. If this +keyword is not present the observatory parameter is used. See the +task \fBobservatory\fR for more on defining the observatory parameters. + +The spectrum interpolation type is used whenever a spectrum needs to be +resampled for linearization or performing operations between spectra +with different sampling. The "sinc" interpolation may be of interest +as an alternative but see the cautions given in \fBonedspec.package\fR. + +The verbose parameter selects whether to print everything which goes +into the log file on the terminal. It is useful for monitoring +what the \fBdoecslit\fR task does. The log and plot files are useful for +keeping a record of the processing. A log file is highly recommended. +A plot file provides a record of the apertures, traces, and extracted +spectra but can become quite large. +The plotfile is most conveniently viewed and printed with \fBgkimosaic\fR. + +\fBProcessing Parameters\fR + +The input images are specified by image lists. The lists may be +a list of explicit comma separate image names, @ files, or image +templates using pattern matching against file names in the directory. +To allow wildcard image lists to be used safely and conveniently the +image lists are checked to remove extracted images (the .ec images) +and to automatically identify object and arc spectra. Object and arc +images are identified by the keyword IMAGETYP with values of "object", +"OBJECT", "comp", or "COMPARISON" (the current practice at NOAO). +If arc images are found in the object list they are transferred to the +arc list while if object images are found in the arc list they are ignored. +All other image types, such as biases, darks, or flat fields, are +ignored. This behavior allows simply specifying all images with a wildcard +in the object list with automatic selections of arc spectra or a +wildcard in the arc list to automatically find the arc spectra. +If the data lack the identifying information it is up to the user +to explicitly set the proper lists. + +As mentioned earlier, all the arc images must be of the same type; +that is taken with the same arc lamp. The aperture reference parameter +is a single image name which is usually a bright star. + +The next set of parameters describe the noise characteristics and the +general layout of the orders. The read out noise and gain are used when +"cleaning" cosmic rays and when using variance or optimal weighting. These +parameters must be fairly accurate. Note that these are the effective +parameters and must be adjusted if previous processing has modified the +pixel values; such as with an unnormalized flat field. + +The general direction in which the orders run is specified by the +dispersion axis parameter. Recall that ideally it is the direction +of constant wavelength which should be aligned with an image axis and +the dispersion direction will not be aligned because of the cross-dispersion. +The \fInorders\fR parameter is used to automatically find the orders. The +specified number of the brightest peaks are found. Generally after finding the +orders the aperture definitions are reviewed and adjusted interactively. +The profile width should be approximately the full width at the profile +base. The default aperture limits and background regions are all +derived from this width parameter. + +The next set of parameters select the processing steps and options. The +various calibration steps may be done simultaneously, that is at the same +time as the basic extractions, or in separate executions of the task. +Typically, all the desired operations are done at the same time. +Dispersion correction requires at least one arc spectrum and flux +calibration requires dispersion correction and at least one standard star +observation. + +The \fIresize\fR option resets the edges of the extraction apertures based +on the profile for each object and standard star order. The default +resizing is to the 5% point relative to the peak measured above the +background. This allows following changes in the seeing. However, one +should consider the consequences of this if attempting to flux calibrate +the observations. Except in quicklook mode, the apertures for each object +and standard star observation may be reviewed graphically and further +adjustments made to the aperture width and background regions. + +The apertures for each observation are adjusted for small shifts relative +to the reference aperture definitions. If you think this is not sufficient, +say to account for rotation of the detector or for differing atmospheric +dispersion, the \fItrace\fR option allows redefining the aperture trace +functions for each observation. Note this is only allowed in non-quicklook +mode. + +The \fIclean\fR option invokes a profile +fitting and deviant point rejection algorithm as well as a variance weighting +of points in the aperture. See the next section for more about +requirements to use this option. + +The \fIbackground\fR option selects a type of correction for background +or scattered light. If the type is "scattered" a global scattered light +is fit to the data between the apertures and subtracted from the images. +\fINote that the input images are modified by this operation\fR. +This option is slow and is not allowed in quicklook +mode. Alternatively, a local background may be subtracted using +background regions defined for each aperture. The background may be +within the slit for a sky subtraction or outside of the slit for a +local scattered light subtraction. The data in the regions +may be averaged, medianed, or the minimum value used. Another choice +is to fit the data in the background regions by a function and interpolate +to the object aperture. + +Generally once a spectrum has been processed it will not be reprocessed if +specified as an input spectrum. However, changes to the underlying +calibration data can cause such spectra to be reprocessed if the +\fIupdate\fR flag is set. The changes which will cause an update are a new +reference image, adding the scattered light subtraction option, a new arc +reference image, and new standard stars. If all input spectra are to be +processed regardless of previous processing the \fIredo\fR flag may be +used. Note that reprocessing clobbers the previously processed output +spectra. + +The final step is to plot the spectra if the \fIsplot\fR option is +selected. In non-quicklook mode there is a query which may be +answered either in lower or upper case. The plotting uses the interactive +task \fBsplot\fR. In quicklook mode the plot appears noninteractively +using the task \fBspecplot\fR. + +The \fIquicklook\fR option provides a simpler, less interactive, mode. +The quicklook mode automatically assigns the reference apertures to +the object and standard star observations without interactive review +or tracing, does not do the time consuming scattered light correction, +and the \fIsplot\fR option selects a noninteractive plot to be +shown at the end of processing of each object and standard star +spectrum. While the algorithms used in quicklook mode are nearly the same +as in non-quicklook mode and the final results may be the same it is +recommended that the greater degree of monitoring and review in +non-quicklook mode be used for careful final reductions. + +The batch processing option allows object spectra to be processed as a +background or batch job. This will occur only if the interactive +\fIsplot\fR option is not active; either not set, turned off during +processing with "NO", or in quicklook mode. In batch processing the +terminal output is suppressed. + +The \fIlistonly\fR option prints a summary of the processing steps +which will be performed on the input spectra without actually doing +anything. This is useful for verifying which spectra will be affected +if the input list contains previously processed spectra. The listing +does not include any arc spectra which may be extracted to dispersion +calibrate an object spectrum. + +The last parameter (excluding the task mode parameter) points to +another parameter set for the algorithm parameters. The default +parameter set is called \fBsparams\fR. The algorithm parameters are +discussed further in the next section. + +\fBAlgorithms and Algorithm Parameters\fR + +This section summarizes the various algorithms used by the +\fBdoecslit\fR task and the parameters which control and modify the +algorithms. The algorithm parameters available to you are +collected in the parameter set \fBsparams\fR. These parameters are +taken from the various general purpose tasks used by the \fBdoecslit\fR +processing task. Additional information about these parameters and +algorithms may be found in the help for the actual +task executed. These tasks are identified below. The aim of this +parameter set organization is to collect all the algorithm parameters +in one place separate from the processing parameters and include only +those which are relevant for echelle slit data. The parameter values +can be changed from the defaults by using the parameter editor, +.nf + +cl> epar sparams + +.fi +or simple typing \fIsparams\fR. +The parameter editor can also be entered when editing the \fBdoecslit\fR +parameters by typing \fI:e\fR when positioned at the \fIsparams\fR +parameter. + +\fBAperture Definitions\fR + +The first operation is to define the extraction apertures, which include the +aperture width, background regions, and position dependence with +wavelength, for the input echelle slit spectra and, if flux calibration is +selected, the standard star spectra. This is done only for spectra which +do not have previously defined apertures unless the \fIredo\fR option is +set to force all definitions to be redone. Thus, apertures may be +defined separately using the \fBapextract\fR tasks. This is particularly +useful if one needs to use reference images to define apertures for very +weak spectra which are not well centered or traced by themselves. + +Initially apertures are defined for a specified \fIaperture reference\fR +image. The selected number of orders are found automatically by selecting +the highest peaks in a cut across the dispersion. Apertures are assigned +with a width given by the \fIwidth\fR parameter and numbered sequentially. +The background regions are also defined in terms of the width parameter +starting at one width distance from the profile center and extending to two +widths on both sides of the profile. As an example, if the width parameter +is 5 pixels the default aperture limits are +/- 2.5 pixels and the +background sample regions will be "-10:-5,5:10". If the \fIresize\fR +parameter is set the aperture limits are adjusted to a specified point on +the spectrum profile (see \fBapresize\fR). + +A query is then given allowing the aperture definitions to be reviewed and +modified. Queries made by \fBdoecslit\fR generally may be answered with either +lower case "yes" or "no" or with upper case "YES" or "NO". The upper +case responses apply to all further queries and so are used to eliminate +further queries of that kind. + +Reviewing the aperture definitions is highly recommended to check the +aperture numbering, aperture limits, and background regions. The aperture +numbers must be linearly related, with a slope of +/- 1, to the true order +numbers though absolute order numbers need not be known. The key point is +that if an order is skipped the aperture numbers must also skip. The +background regions are checked with the 'b' key. Typically one adjusts all +the background regions at the same time by selecting all apertures with +the 'a' key first. To exit the background and aperture editing steps type +'q'. + +Next the positions of the orders at various points along the dispersion +are measured and "trace functions" are fit. The user is asked whether +to fit each trace function interactively. This is selected to adjust +the fitting parameters such as function type and order. When +interactively fitting a query is given for each aperture. After the +first aperture one may skip reviewing the other traces. + +After the aperture reference image is done all the object and standard star +images are checked for aperture definitions and those without definitions +are assigned apertures. The assignment consists of inheriting the aperture +from the reference aperture image, recentering the apertures based on an +average shift that best centers all the apertures, resizing the apertures +if the resize option is selected, and retracing the spectral orders if the +retracing option is selected. Retracing is only allowed in non-quicklook +mode (set by the \fIquicklook\fR parameter). Also interactive review of +the aperture definitions is only done in +non-quicklook mode. In quicklook mode the aperture definitions are all set +noninteractively without retracing. It is recommended that quicklook only +be used for initial quick extractions and calibration and that for final +reductions one at least review the aperture definitions and possibly +retrace each observation. + +The above steps are all performed using tasks from the \fBapextract\fR +package and parameters from the \fBsparams\fR parameters. As a quick +summary, the dispersion direction of the spectra are determined from the +package \fBdispaxis\fR parameter if not defined in the image header. The default +line or column for finding the object position on the slit and the number +of image lines or columns to sum are set by the \fIline\fR and \fInsum\fR +parameters. A line of INDEF (the default) selects the middle of the +image. The automatic finding algorithm is described for the task +\fBapfind\fR and basically finds the strongest peaks. The resizing is +described in the task \fBapresize\fR and the parameters used are also +described there. The tracing is +done as described in \fBaptrace\fR and consists of stepping along the image +using the specified \fIt_step\fR parameter. The function fitting uses the +\fBicfit\fR commands with the other parameters from the tracing section. + +\fBBackground or Scattered Light Subtraction\fR + +In addition to not subtracting any sky or scattered light there are two +approaches to subtracting background light. The first is to determine +a smooth global scattered light component. The second is to subtract +a locally determined background at each point along the dispersion and +for each aperture. This can be either for a sky subtraction if the +background regions are within the slit or scattered light if the +background regions are outside of the slit. Note that background +subtraction is only done for object and standard star images and not +for arc spectra. Also, the global scattered light option is not done +in quicklook mode. + +The global scattered light fitting and subtraction is done with the task +\fBapscatter\fR. The function fitting parameters are set interactively +using the aperture reference spectrum. All other subtractions are done +noninteractively with the same set of parameters. The scattered light is +subtracted from the input images, thus modifying them, and one might wish +to first make backups of the original images. + +The scattered light is measured between the apertures using a specified +buffer distance from the aperture edges. The scattered light pixels are +fit by a series of one dimensional functions across the dispersion. The +independent fits are then smoothed along the dispersion by again fitting +low order functions. These fits then define the smooth scattered light +surface to be subtracted from the image. The fitting parameters are +defined and recorded in the two parameter sets \fIapscat1\fR and +\fIapscat2\fR. The scattered light algorithm is described more fully in +\fBapscatter\fR. This algorithm is relatively slow. + +Local background subtraction is done during extraction based on background +regions and parameters defined by the default background parameters or +changed during interactive review of the apertures. The background +subtraction options are to subtract the average, median, or minimum of the +pixels in the background regions, or to fit a function and subtract the +function from under the extracted object pixels. The background regions +are specified in pixels from the aperture center and follow changes in +center of the spectrum along the dispersion. The syntax is colon separated +ranges with multiple ranges separated by a comma or space. The background +fitting uses the \fBicfit\fR routines which include medians, iterative +rejection of deviant points, and a choice of function types and orders. +Note that it is important to use a method which rejects cosmic rays such as +using either medians over all the background regions (\fIbackground\fR = +"median") or median samples during fitting (\fIb_naverage\fR < -1). The +background subtraction algorithm and options are described in greater +detail in \fBapsum\fR and \fBapbackground\fR. + +\fBExtraction\fR + +The actual extraction of the spectra is done by summing across the +fixed width apertures at each point along the dispersion. +The default is to simply sum the pixels using +partial pixels at the ends. There is an option to weight the +sum based on a Poisson variance model using the \fIreadnoise\fR and +\fIgain\fR detector parameters. Note that if the \fIclean\fR +option is selected the variance weighted extraction is used regardless +of the \fIweights\fR parameter. The sigma thresholds for cleaning +are also set in the \fBsparams\fR parameters. + +The cleaning and variance weighting options require knowing the effective +(i.e. accounting for any image combining) read out noise and gain. +These numbers need to be adjusted if the image has been processed +such that the intensity scale has a different origin (such as +a scattered light subtraction) or scaling (such as caused by unnormalized +flat fielding). These options also require using background subtraction +if the profile does not go to zero. For optimal extraction and +cleaning to work it is recommended that any flat fielding be done +using flat fields produced by \fBapflatten\fR, no scattered light +correction, and using background subtraction if there is any +appreciable sky or to compensate for scattered light. +For further discussion of cleaning and variance weighted extraction see +\fBapvariance\fR and \fBapprofiles\fR as well as \fBapsum\fR. + +\fBDispersion Correction\fR + +If dispersion correction is not selected, \fIdispcor\fR=no, then the object +spectra are simply extracted. The extracted spectra may be plotted +by setting the \fIsplot\fR option. This produces a query and uses +the interactive \fBsplot\fR task in non-quicklook mode and uses +\fBspecplot\fR noninteractively in quicklook mode. + +Dispersion corrections are applied to the extracted spectra if the +\fIdispcor\fR processing parameter is set. There +are three basic steps involved; determining the dispersion functions +relating pixel position to wavelength, assigning the appropriate +dispersion function to a particular observation, and either storing +the nonlinear dispersion function in the image headers or resampling the +spectra to evenly spaced pixels in wavelength. + +The first arc spectrum in the arc list is used to define the reference +dispersion solution. It is extracted using the reference aperture definition. +Note extractions of arc spectra are not background or scattered light +subtracted. The interactive task \fBecidentify\fR is used to define the +dispersion function. The idea is to mark some lines in a few orders whose +wavelengths are known (with the line list used to supply additional lines after +the first few identifications define the approximate wavelengths) and to fit a +function giving the wavelength from the aperture number and pixel position. + +The arc dispersion function parameters are for \fBecidentify\fR and it's +related partner \fBecreidentify\fR. The parameters define a line list for +use in automatically assigning wavelengths to arc lines, a centering width +(which should match the line widths at the base of the lines), the +dispersion function type and orders, parameters to exclude bad lines from +function fits, and defining whether to refit the dispersion function as +opposed to simply determining a zero point shift. The defaults should +generally be adequate and the dispersion function fitting parameters may be +altered interactively. One should consult the help for the two tasks for +additional details of these parameters and the interactive operation of +\fBecidentify\fR. + +Once the reference dispersion function is defined other arc spectra are +extracted as required by the object spectra. The assignment of arcs is +done either explicitly with an arc assignment table (parameter +\fIarctable\fR) or based on a header parameter such as a time. +This assignments are made by the task +\fBrefspectra\fR. When two arcs are assigned to an object spectrum an +interpolation is done between the two dispersion functions. This makes an +approximate correction for steady drifts in the dispersion. + +The tasks \fBsetjd\fR and \fBsetairmass\fR are automatically run on all +spectra. This computes and adds the header parameters for the Julian date +(JD), the local Julian day number (LJD), the universal time (UTMIDDLE), and +the air mass at the middle of the exposure. The default arc assignment is +to use the Julian date grouped by the local Julian day number. The +grouping allows multiple nights of data to be correctly assigned at the +same time. + +In non-quicklook mode the arc spectra assigned to each object are +extracted using the same apertures as the object. This accounts for +changes in the recentering, aperture sizes, and tracing functions. +In quicklook mode the arc spectra are extracted using the reference +apertures. When the same arc is used for several object images this +allows the arc spectrum to only be extracted once. + +Defining the dispersion function for a new arc extraction is done with +the task \fBecreidentify\fR. This is done noninteractively with log +information recorded about the line reidentifications and the fit. + +The last step of dispersion correction is setting the dispersion +of the object image from the arc images. There are two choices here. +If the \fIlinearize\fR parameter is not set the nonlinear dispersion +function is stored in the image header. Other IRAF tasks interpret +this information when dispersion coordinates are needed for plotting +or analysis. This has the advantage of not requiring the spectra +to be interpolated and the disadvantage that the dispersion +information is only understood by IRAF tasks and cannot be readily +exported to other analysis software. + +If the \fIlinearize\fR parameter is set then the spectra are resampled to a +linear dispersion relation either in wavelength or the log of the +wavelength. For echelle spectra each order is linearized independently so +that the wavelength interval per pixel is different in different orders. +This preserves most of the resolution and avoids over or under sampling of +the highest or lowest dispersion orders. The wavelength limits are +taken from the limits determined from the arc reference spectrum and +the number of pixels is the same as the original images. The dispersion +per pixel is then derived from these constraints. + +The linearization algorithm parameters allow selecting the interpolation +function type, whether to conserve flux per pixel by integrating across the +extent of the final pixel, and whether to linearize to equal linear or +logarithmic intervals. The latter may be appropriate for radial velocity +studies. The default is to use a fifth order polynomial for interpolation, +to conserve flux, and to not use logarithmic wavelength bins. These +parameters are described fully in the help for the task \fBdispcor\fR which +performs the correction. + +\fBFlux Calibration\fR + +Flux calibration consists of an extinction correction and an instrumental +sensitivity calibration. The extinction correction only depends on the +extinction function defined by the package parameter \fIextinct\fR and +determination of the airmass from the header parameters (the air mass is +computed by \fBsetairmass\fR as mentioned earlier). The sensitivity +calibration depends on a sensitivity calibration spectrum determined from +standard star observations for which there are tabulated absolute fluxes. +The task that applies both the extinction correction and sensitivity +calibration to each extracted object spectrum is \fBcalibrate\fR. Consult +the manual page for this task for more information. + +Generation of the sensitivity calibration spectrum is done before +processing any object spectra since it has two interactive steps and +requires all the standard star observations. The first step is tabulating +the observed fluxes over the same bandpasses as the calibrated absolute +fluxes. For very high resolution it may be the case that the measured +calibration bandpasses are too large or sparse. In this case one must +interpolate the calibration data to bandpasses appropriate for the data. +If the bandpass widths and separations are given as INDEF then the same +bandpasses as in the calibration file are used. Otherwise a uniform grid +of bandpasses is interpolated. Using interpolated bandpasses is not +rigorous but is sometimes the only choice for echelle spectra. + +The standard star tabulations are done after each standard star is +extracted and dispersion corrected. You are asked for the name of the +standard star as tabulated in the absolute flux data files in the directory +\fIcaldir\fR defined by the package parameters. If the \fIinteract\fR +parameter is yes the bandpasses can be displayed on the data and you can +interactively add or delete bandpasses. The tabulation of the standard star +observations over the standard bandpasses is done by the task +\fBstandard\fR. The tabulated data is stored in the file \fIstd\fR. Note +that if the \fIredo\fR flag is not set any new standard stars specified in +subsequent executions of \fBdoecslit\fR are added to the previous data in +the data file, otherwise the file is first deleted. Modification of the +tabulated standard star data, such as by adding new stars, will cause any +spectra in the input list which have been previously calibrated to be +reprocessed if the \fIupdate\fR flag is set. + +After the standard star calibration bandpass fluxes are tabulated the +information from all the standard stars is combined to produce a +sensitivity function for use by \fBcalibrate\fR. The sensitivity function +determination is interactive and uses the task \fBsensfunc\fR. This task +allows fitting a smooth sensitivity function to the ratio of the observed +to calibrated fluxes verses wavelength. The types of manipulations one +needs to do include deleting bad observations, possibly removing variable +extinction (for poor data), and possibly deriving a revised extinction +function. This is a complex operation and one should consult the manual +page for \fBsensfunc\fR. The sensitivity function is saved as one +dimensional spectra (one per order) with the root name \fIsens\fR. +Deletion of these images will also cause reprocessing to occur if the +\fIupdate\fR flag is set. +.ih +EXAMPLES +1. The following example uses artificial data and may be executed +at the terminal (with IRAF V2.10). This is similar to the sequence +performed by the test procedure "demos doecslit". + +.nf +ec> demos mkecslit +Creating example longslit in image demoobj ... +Creating example longslit in image demostd ... +Creating example longslit in image demoarc ... +ec> echelle.verbose=no +ec> echelle.caldir=onedstds$spechayescal/ +ec> doecslit Bdemoobj apref=Bdemostd arcs=Bdemoarc stand=Bdemostd \ +>>> norders=3 extcor+ fluxcal+ resize+ splot+ +Set reference aperture for Bdemostd +Edit apertures for Bdemostd? (yes): +<Check background with 'b', exit background and review with 'q'> +Fit traced positions for Bdemostd interactively? (yes): +Fit curve to aperture 1 of Bdemostd interactively (yes): +<Exit with 'q'> +Fit curve to aperture 2 of Bdemostd interactively (yes): N +Edit apertures for Bdemoobj? (yes): +<Check background with 'b', exit background and review with 'q'> +Fit traced positions for Bdemoobj interactively? (yes): N +Extract arc reference image Bdemoarc +Determine dispersion solution for Bdemoarc +<Type 'm' at first strong line (pixel 156) and identify it as 4965> +<Type 'k' to go to next order> +<Mark 52->5002, 74->5003.6, 155->5009.3> +<Type 'k' to go to next order and mark 18->5044.7, 231->5059.8> +<Type 'f' to see the fit residuals> +<Type 'q' to quit fit and then 'q' to exit> +Extract standard star spectrum Bdemostd +Assign arc spectra for Bdemostd +Extract and reidentify arc spectrum Bdemoarc +Dispersion correct Bdemostd +B...ec.imh: ap = 1, w1 = 4953.9, w2 = 4972.2, dw = 0.071, nw = 256 +B...ec.imh: ap = 2, w1 = 4998.3, w2 = 5016.5, dw = 0.071, nw = 256 +B...ec.imh: ap = 3, w1 = 5043.5, w2 = 5061.6, dw = 0.070, nw = 256 +Compile standard star fluxes for Bdemostd +Bdemostd.ec.imh[1]: Artificial Echelle Spectrum +Star name in calibration list: hz14 +Bdemostd.ec.imh[1]: Edit bandpasses? (no|yes|NO|YES|NO!|YES!) (no): y +<Exit with 'q'> +Bdemostd.ec.imh[2]: Artificial Echelle Spectrum +Bdemostd.ec.imh[2]: Edit bandpasses? (no|yes|NO|YES|NO!|YES!) (y): N +Bdemostd.ec.imh[3]: Artificial Echelle Spectrum +Bdemostd.ec.imh[3]: Edit bandpasses? (no|yes|NO|YES|NO!|YES!) (N): +Compute sensitivity function +Fit aperture 1 interactively? (no|yes|NO|YES) (no|yes|NO|YES) (yes): +<Exit with 'q'> +Sensitivity function for aperture 1 --> sens.0001 +Fit aperture 2 interactively? (no|yes|NO|YES) (no|yes|NO|YES) (yes): N +Sensitivity function for aperture 2 --> sens.0002 +Sensitivity function for aperture 3 --> sens.0003 +Flux and/or extinction calibrate standard stars +Standard stars: +Splot spectrum? (no|yes|NO|YES) (yes): +Image line/aperture to plot (0:) (1): +<Exit with 'q'> +Extract object spectrum Bdemoobj +Assign arc spectra for Bdemoobj +Extract and reidentify arc spectrum Bdemoarc +Dispersion correct Bdemoobj +B...ec.imh: ap = 1, w1 = 4953.9, w2 = 4972.2, dw = 0.071, nw = 256 +B...ec.imh: ap = 2, w1 = 4998.3, w2 = 5016.5, dw = 0.071, nw = 256 +B...ec.imh: ap = 3, w1 = 5043.5, w2 = 5061.6, dw = 0.070, nw = 256 +Extinction correct Bdemoobj +Flux calibrate Bdemoobj +Bdemoobj.ec.imh: +Splot spectrum? (no|yes|NO|YES) (yes): +Image line/aperture to plot (0:) (1): +<Exit with 'q'> +.fi +.ih +REVISIONS +.ls DOECSLIT V2.10.3 +The image format type to be +processed is selected with the \fIimtype\fR environment parameter. The +dispersion axis parameter is now a package parameter. Images will only +be processed if the have the CCDPROC keyword. A \fIdatamax\fR parameter +has been added to help improve cosmic ray rejection. A bug which +alphabetized the arc spectra was fixed. +.le +.ih +SEE ALSO +apbackground, apedit, apfind, approfiles, aprecenter, apresize, apsum, aptrace, +apvariance, calibrate, ccdred, center1d, ctioslit, dispcor, +echelle.doecslit, ecidentify, ecreidentify, icfit, kpnocoude, kpnoslit, +msred, observatory, onedspec.package, refspectra, sensfunc, setairmass, setjd, +splot, standard +.endhelp |