Long-Slit Spectra Reduction with IRAF

l Arp 63 Fig.1: Galaxy + slit Fig.2: Galaxy spectrum Fig.3: Star spectrum

Bias subtraction noao.imred.ccdred zerocombine ccdproc / imarith Frame - <bias> Fig.4: Bias image imstat # IMAGE NPIX MEAN MIDPT STDDEV MIN MAX Zero 1036324 197.6 197.7 0.7823 193.7 201.5

Flat-field correction noao.imred.ccdred flatcombine ccdproc / imarith Frame - <bias> ----------------- <flat> - <bias> Fig.5: Flat image imstat # IMAGE NPIX MEAN MIDPT STDDEV MIN MAX Flat 1036324 10913. 12410. 5605. 912.1 19706.

Flat-field normalization noao.twodspec.longslit response Fig.6: Flat-field fitting along dispersion Fig.7: Normalized flat imstat # IMAGE NPIX MEAN MIDPT STDDEV MIN MAX nFlat 1036324 1. 0.996 0.03019 0.1302 1.135

Cosmic-rays removal noao.imred.ccdred cosmicrays crutils crmedian Fig.8: Spectrum after bias and flat correction

L.A. Cosmics (Van Dokkum, 2001) Fig.10: Cosmic-rays mask Fig.9: Spectrum with cosmic-rays Fig.11: Cleaned image

Wavelength calibration noao.twodspec.longslit identify reidentify fitcoords transform Fig.12: Helium-Argon lamp spectrum

li = 4458.3 Å dl = 2.6 Å/px Fig.13: Spectral lines identification Fig.15: Bidimensional fit li = 4458.3 Å dl = 2.6 Å/px Fig.14: Fit residuals

Checking calibration Fig.17: After calibration Fig.16: Before calibration Fig.17: After calibration Fig.18: Night-sky [OI] lines

Flux calibration noao.twodspec.apextract apall noao.onedspec standard sensfunc noao.twodspec.longslit calibrate Feige 56 Fig.19: Standard star spectrum

Fig.20: Star profile across dispersion Fig.21: Tracing along dispersion Fig.22: Extracted 1-D spectrum

counts erg cm-2 sec-1 Å-1 Fig.23: Star fluxes measurement Fig.24: Calibration curve (upper) erg cm-2 sec-1 Å-1

Frame ------------- calib. func. Fig.25/26: Before and after flux calibration Frame ------------- calib. func. Fig.27: Calibrated spectrum (red)

Night-sky subtraction noao.twodspec.longslit background Fig.28: Fit of the sky across dispersion Fig.29: Spectrum after sky subtraction