The CNOC1 Cluster Survey targeted 16 rich X-ray selected galaxy clusters at 0.17 < z < 0.55. Observations were made from Jan 1993 to Mar 1995 using the CFHT Multi-Object-Spectrograph (MOS). Gunn g and r images to r>24 and spectroscopy to r=21.5-23, depending on the cluster redshift, were obtained. A total of ~1200 cluster redshifts to cluster-centric radii of up to 3 Mpc and ~1000 field redshifts were identified. The raw data are now available publicly and can be accessed via the CFHT Archive at the Canadian Astronomical Data Center (CADC).
Flowchart for Finding Omega_M Using the CNOC1 Survey
Observational Details on CNOC1 Clusters
|Cluster||z||N cluster members*||Velocity dispersion (km/sec)*||Number of masks **|
|MS0440+02||0.20||36||606||CA, CB, E1A, E1B, W1A, W1B|
|MS0451+02||0.20||113||988||CA0, CA, CB, CC, E1A, e1Aa, E1B, W1A, W1B,E2A, E2 (image only)|
|MS1008-12||0.26||67||1054||CA,CB, N (image only), S(image only)|
*From Carlberg et al. 1996 (ApJ 462, 32)
**Each slightly overlapping field covers a region 8x9 arcminutes. Field positions are designated C=central, E1=first east field, etc., and multiple masks per field are designated A,B,C. A total of 71 masks were observed over 24 nights, with ~3 nights lost to weather.
The published CNOC data (on clusters A2390, MS0015, MS0302, MS0451S, MS1008, MS1224, MS1358, MS1512, and MS1621) is available as a gzipped tar file.
If you are interested in using our database, please read the relevant technique and data papers to see completeness rates and selection effects. Within the cluster, there is very little selection effect due to galaxy color, but a mganitude and geometric weighting scheme is necessary to construct a representative sample of objects. CNOC1 field samples are strongly affected by selection effects from the limited bandpass used; CNOC2 should provide a much more robust sample.