I'm not sure what you accept a priori as "well". For instance, do you accept manual extraction, but not necessarily anything automated (until proven reliable)? In that case, have you compared your automated results to a manual extraction -SMBH said:I've been doing some spectrum extractions in IRAF, stellar and galactic, and I was wondering if anyone here had any ideas on how to tell if the extraction/calibration/etc went well? I have a bunch of finished projects but I'm not sure about how to tell if they're any good or not. Let me know if anyone has any ideas. I could also post some images of the spectra themselves if that might help.
The quality of a stellar spectrum extraction can be determined by examining several key parameters. These include the signal-to-noise ratio, the spectral resolution, the presence of telluric lines, and the overall shape and smoothness of the spectrum. A high signal-to-noise ratio, high spectral resolution, minimal telluric lines, and a smooth spectrum with no obvious artifacts or irregularities indicate a successful extraction.
The signal-to-noise ratio (SNR) is a measure of the strength of the signal compared to the level of background noise. In spectrum extraction, a higher SNR is desirable as it indicates a stronger and clearer signal from the target object. This allows for more accurate measurements and analyses of the spectrum.
Telluric lines are caused by absorption of light from the Earth's atmosphere and can be present in stellar spectra if not properly corrected for. To check for their presence, a comparison of the extracted spectrum to a telluric-free spectrum can be made. This can be done by observing a standard star with known telluric features or by utilizing telluric correction software.
The spectral resolution refers to the ability to distinguish between small changes in wavelength in a spectrum. A higher spectral resolution means that more fine details in the spectrum can be resolved. This is important for accurately identifying and analyzing spectral features, especially in complex spectra with multiple lines and features.
To ensure a smooth and artifact-free spectrum extraction, it is important to properly calibrate and reduce the data before extraction. This includes correcting for instrumental effects, such as bias and dark frames, and removing cosmic ray hits. Additionally, careful selection of extraction parameters and visual inspection of the resulting spectrum can help identify and correct any remaining artifacts or irregularities.