Open AccessOn the CCD calibration of Zwicky galaxy magnitudes and the properties of nearby field galaxies
Author(s) -
Gaztañaga E.,
Dalton G. B.
Publication year - 2000
Publication title -
monthly notices of the royal astronomical society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.058
H-Index - 383
eISSN - 1365-2966
pISSN - 0035-8711
DOI - 10.1046/j.1365-8711.2000.03139.x
Subject(s) - physics , astrophysics , photometry (optics) , galaxy , sky , astronomy , redshift , magnitude (astronomy) , position angle , stars
We present CCD (charge‐coupled device) photometry for galaxies around 204 bright ( m Z <15.5) Zwicky galaxies in the equatorial extension of the APM Galaxy Survey, sampling an area over 400 deg 2 , which extends 6 h in right ascension. We fit a best linear relation between the Zwicky magnitude system, m Z , and the CCD photometry, B CCD , by doing a likelihood analysis that corrects for Malmquist bias. This fit yields a mean scale error in Zwicky of 0.38 mag mag −1 : i.e. Δ m Z ≃(0.62±0.05)Δ B CCD and a mean zero‐point of 〈 B CCD − m Z 〉=−0.35±0.15 mag. The scatter around this fit is about 0.4 mag. Correcting the Zwicky magnitude system with the best‐fitting model results in a 60 per cent lower normalization and 0.35‐mag brighter M * in the luminosity function. This brings the CfA2 luminosity function closer to the other low‐redshift estimations (e.g. Stromlo‐APM or LCRS). We find a significant positive angular correlation of magnitudes and position in the sky at scales smaller than about 5 arcmin, which corresponds to a mean separation of 120 h −1 kpc. We also present colours, sizes and ellipticities for galaxies in our fields, which provides a good local reference for the studies of galaxy evolution.