sumspec: Combine multiple spectra into an assigned-velocity spectrum

Package: rvsao

Usage

sumspec spectra compfile

Parameters

spectra = "": List of file names of spectra to analyze. @<filename> indicates list should come from file <filename>. <filename>[<range>] indicates that a range of apertures in a multispec file should be processed, where <range> is a comma- and/or hyphen-separated list of numbers.

specnum = 0: If this is nonzero and spectra contains a single file name, this is a range of spectrum numbers in a multispec file which will be added. Wavelength dispersion information is read from APNUMn or the WCS keywords. Velocity information is read from APVELn and saved in APVELn and APVXCn. In a non-multispec file, radial velocity is read from the VELOCITY header parameter.

specband = 0: If this is nonzero, it is the band in the multispec file(s) specified by spectra which will be summed. Wavelength dispersion information is read from APNUMn, where n is the aperture specified by specnum or the WCS keywords. Velocity information is read from APVELn and saved in APVELn and APVXCn. (New in version 2.0)

specdir = "./": Directory containing spectra to analyze. This part of the pathname is not printed at the top of the page, and is assumed to be the same for all spectra listed in the spectra parameter.

compfile = "": File name for output spectrum.

compname = "": Title for output spectrum.

compdir = "": Directory for output spectrum

nspec = 1: Number of spectra in output file

save_names = yes: Save names of input files in output file header (yes or no)

copy_header = yes: Copy output header from first input spectrum (yes or no)

normin = no: If yes, the data spectrum is divided by its mean value before being processed. Use this on spectra which have unusual data values such as those produced by flux calibration.

fixbad = no: If "yes", remove wavelength-delimited regions listed in the file specfied by badlines. (added in version 2.0)

badlines = badlines.dat: File containing list of starting and stopping wavelengths in Angstroms for removal of portions of all object spectra if fixbad is yes. All information after the second wavelength is a comment field. This file is assumed to be in the directory linedir unless a complete pathname starting with "/" is specified. (added in version 2.0)

linedir = "rvsao$lib/": Directory containing line list file named by badlines. This parameter is ignored if: that filename contains a "/" in the first column, as it is assumed to be a full pathname, if there is a "/" anywhere else in the filename, as it is assumed to be a path relative to the current working directory, or if there is a "$" in the filename, as the part preceding the "$" is assumed to be an IRAF environment parameter (ending in "/") defining a directory.

cont_remove = no: Remove continuum from input spectra if not "no". If "subtract", subtract continuum. If "divide", divide by continuum. If "zerodiv", divide by continuum and subtract 1. This last should be used instead of "divide" if the file is to be cross-correlated. In version 2.0, "divide" subtracted 1; in version 2.1b15 and later, it doesn't, and the "zerodiv" option was added. Parameters used in the fit are mostly set in the contsum pset.

cont_split = 1: Number of regions into which to split the spectrum for separate continuum fits

reject = "no": Chop out emission lines from object spectra before adding them to the composite spectrum if "yes". If "specfile", emission lines are removed if the value of the CHOPEM keyword in the object spectrum image header is T. If the keyword is not present or is F, emission lines are not removed. If "no", emission lines are never removed. If EMCHOP in the input spectrum file is 1, emission lines are not removed.

abs_reject = 100.0: Input spectrum absorption line rejection in sigma of fit

em_reject = 2.0: Input spectrum emission line rejection in sigma of fit

contout = no: Remove continuum from output spectrum/spectra if not "no". If "subtract", subtract continuum. If "divide", divide by continuum. If "zerodiv", divide by continuum and subtract 1. This last should be used instead of "divide" if the file is to be cross-correlated. In version 2.0, "divide" subtracted 1; in version 2.1b15 and later, it doesn't, and the "zerodiv" option was added. Parameters used in the fit are mostly set in the contsum pset.

cont_plot = yes: If yes, plots of the continuum-subtracted input spectra are displayed. This is most useful for determining the appropriateness of the continuum fitting parameters.

cont_add = 0: Continuum level added to output spectrum to keep all flux above zero, for example

spec_smooth = 0: If >0, the spectra are smoothed smooth times before graphing them. The spectrum is NEVER smoothedvefore adding

st_lambda = INDEF: Starting wavelength in angstroms of output spectrum. If INDEF, use beginning of wavelength overlap between input spectra.

end_lambda = INDEF: Ending wavelength in angstroms of output spectrum. If INDEF, use end of wavelength overlap between input spectra.

pix_lambda = INDEF: Wavelength per pixel in angstroms of output spectrum. If INDEF, compute from wavelength range and number of pixels in output spectra.

ncol = 2048: Number of pixels into which to rebin data.

complog = no: Rebin into log wavelength (yes or no)

interp_mode = "spline3": Interpolation mode to use when rebinning spectra, must be "nearest" or "linear" or "spline3" or "poly3" or "poly5" or "sinc" or "lsinc" or "drizzle" or "sums".

normout = no: If true, the output spectrum is divided by its mean value before being transformed. This is used on spectra which may have unusual values due to their having already been flux-calibrated.

spec_plot = yes: If yes, plots of the individual spectra are displayed. During this time the normal IRAF cursor commands are active as well as several more that are itemized below. If emission lines are chopped, before and after plots are displayed, as well as the chopped line(s).

spec_int = no: If yes, pause in cursor mode after each input spectrum has been plotted.

comp_plot = yes: If yes, a plot of the output spectrum is displayed after each input spectrum is added. Cursor commands are activated for zooming in on a portion of the spectrum and hard copies may be made to stdplot using the @ command.

comp_int = no: If yes, pause in cursor mode after the composite spectrum has been plotted.

ymin = INDEF: Minimum y value to plot. Autoscale if INDEF

ymax = INDEF: Maximum y value to plot. Autoscale if INDEF

velcomp = INDEF: Velocity in km/sec to which to shift individual spectra. If INDEF, do not shift spectra at all.

zcomp = INDEF: Velocity of output spectrum as delta lambda / lambda; overrides velcomp if not INDEF.

svel_corr = "barycentric": Spectrum velocity correction to the solar system barycenter. Set to "none" if spectrum has already been shifted or if this correction is unnecessary. If "file", BCV is used if present in the file header, or else HCV. If "hfile", the header parameter HCV is always used. If neither is found, no correction is made. If svel_corr is not set to "none", but velcomp and zcomp are INDEF, data is shifted to the barycentric velocity correction of the first spectrum, if it has one. If "heliocentric" or "barycentric" corrections are chosen, position and time parameters are read from the spectrum data file header. DATE-OBS (date in format 'dd-mm-yy') UT (U.T. at end of exposure as 'hh:mm:ss') and UTOPEN (U.T. at start of exposure as 'hh:mm:ss') or EXPOSURE (length of exposure in seconds) are used to compute the midtime of the exposure. RA (right ascension as 'hh:mm:ss.ss'), DEC (declination as 'dd:mm:ss.ss'), and EPOCH (epoch of coordinates defaults to 1950.0) give the position of the object whose spectrum this is. SITELONG (observatory longitude as 'dd:mm:ss.ss' or degrees), SITELAT (observatory latitude as 'dd:mm:ss.ss' or degrees), and SITEELEV (observatory altitude in meters) give the observatory position. Use bcvcorr task to set BCV in header and use "file" here if header parameters are different.

nsmooth = 0: Number of times to 1-2-1 smooth displayed spectrum

device = "stdgraph": Interactive device on which to graphicallly

plotter = "stdplot": Second, non-interactive device on which to plot the graphic summary of results.

logfiles = "STDOUT,sumtemp.log": All results from SUMTEMP are recorded in these files.

nsum = 1: Number of pixels to sum across dispersion

debug = no: If yes, values of the parameters fit to the selected peak are recorded in the log files. This is most useful for debugging.

Description

SUMSPEC combines spectra, shifting them to a common redshift, if either the vel_comp or the z_comp parameter is not INDEF. The VELOCITY header parameter of each of these spectra is assumed to be a solar-system-barycenter-corrected velocity, and a barycentric correction (computed by SUMSPEC or extracted from the BCV or HCV header parameter) is subracted to get the redshift of the spectrum. Each spectrum is shifted and rebinned to log or linear wavelength, then added to the composite spectrum. Input may be multispec or twodspec format, but output is always a one-dimensional file.

Cursor

The following keystrokes are active for graphs of input and output spectra in addition to the normal IRAF cursor facilities (a list of those is available with the command ":.help"):

@: Make a hard copy on the device designated by plotter.

c: Prints cursor position in x and y. This is the default. All other undefined keys perform this same function.

d: Replaces a region between the marked vertical cursors with interpolated values from the edges of the marked region. This is typically used to eliminate poorly subtracted night sky lines or emission lines.

n: Smooth spectrum n times before plotting. This only affects to current spectrum display and the final spectrum graph, not the spectrum data.

q: Quit and exit.

r: Forces a replot of the current spectrum at the original scale.

u: Redisplay the entire plot after zooming.

z: Zoom in on the region marked by two successive <z>'s

Example

To make a galaxy template by combining a list of galaxy spectra:

rvsao> sumspec @galaxies template=galtemp tempvel=1000.0