ar X iv : a st ro - p h / 03 06 01 1 v 1 3 1 M ay 2 00 3 Is the Pre - WMAP CMB Data Self - consistent ?

Although individual observational groups vigorously test their data sets for systematic errors, the pre-WMAP CMB observational data set has not yet been collectively tested. Under the assumption that the concordance model is the correct model, we have explored residuals of the observational data with respect to this model to see if any patterns emerge that can be identified with systematic errors. We found no significant trends associated with frequency, frequency channels, calibration source, pointing uncertainty, instrument type, platform and altitude. We did find some evidence at the ∼ 1 to ∼ 2σ level for trends associated with angular scale (l range) and absolute galactic latitude. The slope of the trend in galactic latitude is consistent with low level galactic contamination. The residuals with respect to l may indicate that the concordance model used here needs slight modification. See Griffiths & Lineweaver (2003) for more detail. 1. Motivation and Method The ever-tightening network of constraints from CMB and non-CMB observations favors a concordant Λ cold dark matter (CDM) model that is commonly accepted as the standard cosmological model. As long as the systematic errors associated with CMB observations are small, the CMB power spectrum can play an increasingly large role in establishing and refining this model. Thus, it is crucial to check the CMB data for possible systematic errors in as many ways as possible. Systematic errors and selection effects are notoriously difficult to identify and quantify. Calibration and/or beam uncertainties dominate CMB measurements and there may be lower level systematic errors of which we are not aware. Individual experimental groups have developed various ways to check their CMB observations for systematic effects (e.g. Kogut et al. 1996; Miller et al. 2002), including the use of multiple calibration sources, multiple frequency channels and extensive beam calibrating observations. Internal consistency is the primary concern of these checks.