A Detection of Bright Features in the Microwave Background

We report the characterization of bright, compact features in the cosmic microwave background radiation (CMBR) detected during the 1992 June and 1994 June balloon flights of the Medium-Scale Anisotropy Measurement. Spectral flux density is determined at 5.7, 9.3, and 16.5 cm^-1. No viable counterparts are found in source catalogs at 5 GHz or at 100 μm. The measured spectrum is consistent with a temperature fluctuation in the CMBR. The existence of such features is consistent with adiabatic fluctuation models of anisotropy in the CMBR.