Spectroscopic Data Reduction in Pyraf ASTR 3010 Textbook N/A

Steps of Spectral Data Reduction 1.Copy data files 1.cp –a../SpectralData/*. 2.overscan and trim 3.zerocombine 4.darkcombine 5.flatcombine 6.ccdproc *.fits  both objects and arcs … 12.splot and specplot…

Spectroscopic Data Reduction Final-exam Project --> ccdlist dbs* dbs0300r.fits[1798,50][ushort][flat][]:flatdbs0301r.fits[1798,50][ushort][flat][]:flatdbs0302r.fits[1798,50][ushort][flat][]:flatdbs0303r.fits[1798,50][ushort][flat][]:flatdbs0304r.fits[1798,50][ushort][flat][]:flatdbs0305r.fits[1798,50][ushort][flat][]:flatdbs0306r.fits[1798,50][ushort][flat][]:flatdbs0307r.fits[1798,50][ushort][zero][]:biasdbs0308r.fits[1798,50][ushort][zero][]:biasdbs0309r.fits[1798,50][ushort][zero][]:biasdbs0310r.fits[1798,50][ushort][zero][]:biasdbs0311r.fits[1798,50][ushort][dark][]:darkdbs0312r.fits[1798,50][ushort][dark][]:darkdbs0313r.fits[1798,50][ushort][dark][]:darkdbs0314r.fits[1798,50][ushort][dark][]:darkdbs0315r.fits[1798,50][ushort][dark][]:dark dbs0344r.fits[1798,50][ushort][object][]:HD dbs0345r.fits[1798,50][ushort][object][]:arc HD dbs0346r.fits[1798,50][ushort][object][]:GJ 773 dbs0347r.fits[1798,50][ushort][object][]:arc GJ 773 dbs0348r.fits[1798,50][ushort][object][]:GJ 716 dbs0349r.fits[1798,50][ushort][object][]:arc GJ 716 dbs0350r.fits[1798,50][ushort][object][]:GJ 722 dbs0351r.fits[1798,50][ushort][object][]:arc GJ > 1.Reduce data (pre-processing + spec. red) 2.produce a plot of final reduced spectrum of HD165196,GJ 773, GJ 716, GJ Measure equivalent widths of Hα (6563Å) and Ca I (6717Å) lines and report them. Due date is Dec 2

Line Identification of the Arc images

refspec and dispcor In pyraf, dispcor takes 1D spectra as input and adds wavelength calibration into the FITS header dispcor takes 1D spectra as input and adds wavelength calibration into the FITS header refspec “assign” wavelength reference spectra (i.e., arcs) to object spectra. This will create two FITS header keyword (refspec1, refspec2) and weighting factors can be given immediately following the ref specname (e.g., REFSPEC1=“dbs0345r.ms 0.7”, REFSPEC2=“dbs0347r.ms 0.3”) refspec “assign” wavelength reference spectra (i.e., arcs) to object spectra. This will create two FITS header keyword (refspec1, refspec2) and weighting factors can be given immediately following the ref specname (e.g., REFSPEC1=“dbs0345r.ms 0.7”, REFSPEC2=“dbs0347r.ms 0.3”)

SPLOT Use splot to display spectra on the screen. But, it can do much more than simple plotting of a spectrum. Some useful splot command keys are Use splot to display spectra on the screen. But, it can do much more than simple plotting of a spectrum. Some useful splot command keys are o continuum fitting: ‘t’ followed by ‘/’ o save a current spectrum (in the display buffer) to a file: ‘i’ and give a filename o zoom in: ‘a’ to define a zooming window (e.g., press ‘a’ at one wavelength and press ‘a’ again at different wavelength to zoom). o zoom out: press ‘a’ twice without moving the mouse pointer. o equivalent width measurement: ‘h’ followed by ‘c’ or ‘k’ o etc… type ‘?’ for a full list of command keys or type “help splot’ at the pyraf prompt.

Filelist handling in Pyraf Special symbol and ‘//’ Special symbol and ‘//’ is used as a prefix to denote a filelist. The filelist contains image file names one per line. When was given as input to a command, the command will be executed repeatedly for each entry in the filelist. is used as a prefix to denote a filelist. The filelist contains image file names one per line. When was given as input to a command, the command will be executed repeatedly for each entry in the filelist. ‘//’ is a string concatenation operator. When used in conjunction with one can easily customize the input and output files. ‘//’ is a string concatenation operator. When used in conjunction with one can easily customize the input and output files.

Example of using and ‘//’ dispcor is equivalent to dispcor input=myimage1 output=OUT_myimage1 dispcor input=myimage1 output=OUT_myimage2 … dispcor input=myimage1 output=OUT_myimage10 sample.list myimage1 myimage2 … myimage10 is equivalent to splot myimage1 splot myimage2 … splot myimage10

In summary… Important Concepts You should be able to run the entire spectroscopic data reduction by yourself in Pyraf! Important Terms Chapter/sections covered in this lecture : N/A