MNRAS-2014-Baldry-2440-51.pdf (2.05 MB)
Galaxy And Mass Assembly (GAMA): AUTOZ spectral redshift measurements, confidence and errors
journal contribution
posted on 2023-06-08, 21:14 authored by I K Baldry, M Alpaslan, A E Bauer, J Bland-Hawthorn, S Brough, M E Cluver, S M Croom, L J M Davies, S P Driver, M L P Gunawardhana, B W Holwerda, A M Hopkins, L S Kelvin, J Liske, Á R López-Sánchez, Jonathan LovedayJonathan Loveday, P Norberg, J Peacock, A S G Robotham, E N TaylorThe Galaxy And Mass Assembly (GAMA) survey has obtained spectra of over 230 000 targets using the Anglo-Australian Telescope. To homogenize the redshift measurements and improve the reliability, a fully automatic redshift code was developed (AUTOZ). The measurements were made using a cross-correlation method for both the absorption- and the emission-line spectra. Large deviations in the high-pass-filtered spectra are partially clipped in order to be robust against uncorrected artefacts and to reduce the weight given to single-line matches. A single figure of merit (FOM) was developed that puts all template matches on to a similar confidence scale. The redshift confidence as a function of the FOM was fitted with a tanh function using a maximum likelihood method applied to repeat observations of targets. The method could be adapted to provide robust automatic redshifts for other large galaxy redshift surveys. For the GAMA survey, there was a substantial improvement in the reliability of assigned redshifts and in the lowering of redshift uncertainties with a median velocity uncertainty of 33?km?s-1.
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- Published
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- Published version
Journal
Monthly Notices of the Royal Astronomical SocietyISSN
0035-8711Publisher
Oxford University PressExternal DOI
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3Volume
441Page range
2440-2451Department affiliated with
- Physics and Astronomy Publications
Full text available
- Yes
Peer reviewed?
- Yes
Legacy Posted Date
2015-06-24First Open Access (FOA) Date
2015-06-24First Compliant Deposit (FCD) Date
2015-06-24Usage metrics
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