INT_spectra_manual

How to deal with slit spectra - the quick way

- locate package noao -> imred -> kpnoslit

- imartih to remove bias from observed spectra

- look at cosmetics.cl for functions and steps

Master bias:
- median combine bias frames

Master flat:
- substract master bias values from all flat exposures
- median combine all de-biased flat and scale them properly -> master flat
- normalize master flat to a range 0..1

Spectra tracing and extraction:
- substract master bias values from all science exposures
- flatten (divide by master flat) all science exposures
- apall procedure
- run it on every exposure (and trace) individuatlly
- determine traces and background ranges
- background fitting function and order
- use apall with reference trace to extract arc spectra without background substraction
- mean combine spectra from different exposures (assuming wavelength sollution is the same for all exposures allong the dispersion axis)

Wavelength callibration:
- use identify
- supply the list of possible emission lines to the identify function
- on the arc spectra mark few (3-6) lines, then do the automatic identification of others
- remove ouliers, modify function to be fitted
- save results

Applying wvl solution to the spectra:
- use dispcor on the arc image
- modify header of the final combined spectra (hedit function of fv-tool)
- using fv-tool add REFSPEC1 parameter that points to the indentified arc spectra

Spectra normalization:
- use continuum function

Meassurement of fluxes and EW:
- using the splot plotting tool in iraf
- press d, then g/v, a, a, n, q, q or something very simillar

SDSS spectra in iraf:
- export the spectra from fits to dat using sdss_to_csv.py
- run rspectext (with dtype='nonlinear') to create corresponding fits file
- meassure fluxes from the spectra