rotation curve
dicostanzo84 wrote on Feb 13, 2009
I would want to know the procedure, step-step, in order to determine the rotation curve of a galaxy through the software iraf. thanks
Francisco Valdes wrote on Feb 13, 2009
Hello,
There is no step-by-step procedure. This is a somewhat complex analysis involving data reduction and analysis. First it depends on the type of data you have. Most likely this would be CCD long slit spectra. The CCDRED and TWODSPEC packages would do the data reductions (calibrating the fluxes, measuring and removing instrument distortions, calibrating the wavelength scale). Then you would have to measure the positions of one or more lines as a function of position along the slit (probably using IDENTIFY, REIDENTIFY, or RVIDENTIFY) in some wavelength unit. Finally you would convert this to velocities using standard doppler formulae.
Yours,
Frank Valdes
Consult the documents area for help with CCDRED and TWODSPEC reductions.
There is no step-by-step procedure. This is a somewhat complex analysis involving data reduction and analysis. First it depends on the type of data you have. Most likely this would be CCD long slit spectra. The CCDRED and TWODSPEC packages would do the data reductions (calibrating the fluxes, measuring and removing instrument distortions, calibrating the wavelength scale). Then you would have to measure the positions of one or more lines as a function of position along the slit (probably using IDENTIFY, REIDENTIFY, or RVIDENTIFY) in some wavelength unit. Finally you would convert this to velocities using standard doppler formulae.
Yours,
Frank Valdes
Consult the documents area for help with CCDRED and TWODSPEC reductions.
Last post on Feb 13, 2009