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J/A+A/613/A20    r' magnitudes and sizes of Oph cluster galaxies (Durret+, 2018)

The optical properties of galaxies in the Ophiuchus cluster. Durret F., Wakamatsu K., Adami C., Nagayama T., Omega Muleka Mwewa Mwaba J.M. <Astron. Astrophys. 613, A20 (2018)> =2018A&A...613A..20D (SIMBAD/NED BibCode)
ADC_Keywords: Clusters, galaxy ; Galaxies, photometry ; Morphology Keywords: clusters: individual: Ophiuchus - large-scale structure of Universe Abstract: Ophiuchus is one of the most massive clusters known, but due to its low Galactic latitude its optical properties remain poorly known. We investigate the optical properties of Ophiuchus to obtain clues on the formation epoch of this cluster, and compare them to those of the Coma cluster, which is comparable in mass to Ophiuchus but much more dynamically disturbed. Based on a deep image of the Ophiuchus cluster in the r' band obtained at the Canada France Hawaii Telescope with the MegaCam camera, we have applied an iterative process to subtract the contribution of the numerous stars that, due to the low Galactic latitude of the cluster, pollute the image, and have obtained a photometric catalogue of 2818 galaxies fully complete at r'=20.5mag and still 91% complete at r'=21.5mag. We use this catalogue to derive the cluster Galaxy Luminosity Function (GLF) for the overall image and for a region (hereafter the "rectangle" region) covering exactly the same physical size as the region in which the GLF of the Coma cluster was previously studied. We then compute density maps based on an adaptive kernel technique, for different magnitude limits, and define three circular regions covering 0.08, 0.08, and 0.06 deg2, respectively, centred on the cluster (C), on northwest (NW) of the cluster, and southeast (SE) of the cluster, in which we compute the GLFs. The GLF fits are much better when a Gaussian is added to the usual Schechter function, to account for the excess of very bright galaxies. Compared to Coma, Ophiuchus shows a strong excess of bright galaxies. The properties of the two nearby very massive clusters Ophiuchus and Coma are quite comparable, though they seem embedded in different large-scale environments. Our interpretation is that Ophiuchus was built up long ago, as confirmed by its relaxed state (see paper I, Durret et al., 2015, Cat. J/A+A/583/A124) while Coma is still in the process of forming. Description: The study presented here is based on the full exploitation of the CFHT/MegaCam image that we obtained in the r' band. Magnitudes have been measured in the AB photometric system. At the redshift of Ophiuchus, the 1x1 deg2 MegaCam field corresponds to a region of about 2.1x2.1 Mpc2. File Summary:
FileName Lrecl Records Explanations
ReadMe 80 . This file tableb1.dat 86 2818 A photometric catalogue of galaxies in the Ophiuchus cluster
See also: J/A+A/583/A124 : Ophiuchus r'g'z' photometry and redshifts (Durret+, 2015) Byte-by-byte Description of file: tableb1.dat
Bytes Format Units Label Explanations
1- 20 A20 --- Name Galaxy name (OPHJHHMMSS.ss+DDMMSS) 23- 31 F9.5 deg RAdeg Right ascension (J2000.0) 33- 41 F9.5 deg DEdeg Declination (J2000.0) 43- 48 F6.3 mag r'mag Measured r' band magnitude with no extinction correction (1) 50- 55 F6.3 mag r'magc1 r' band magnitude corrected for a constant extinction value of 1.357mag (1) 57- 62 F6.3 mag r'magc2 r' band magnitude corrected for its individual extinction correction (1) 64- 68 F5.1 arcsec aaxis Major axis (2) 71- 74 F4.1 arcsec baxis Minor axis (2) 76- 80 F5.1 deg PA Position angle of the major axis 83- 86 F4.1 deg e_PA Error on the position angle
Note (1): We do not give individual errors on the observed magnitudes, but their typical values are given in Table A.1. of the paper. Note (2): the error bars on these two quantities are typically 0.1 arcsec, so they are not given for every galaxy.
Acknowledgements: Florence Durret, durret(at)iap.fr References: Durret et al., Paper I, 2015A&A...583A.124D, Cat. J/A+A/583/A124
(End) Patricia Vannier [CDS] 25-Jan-2018
The document above follows the rules of the Standard Description for Astronomical Catalogues.From this documentation it is possible to generate f77 program to load files into arrays or line by line

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