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We have made a multiwavelength study of the overlapping error boxes of theunidentified gamma-ray sources TeV J2032+4130 and 3EG J2033+4118 in thedirection of the Cygnus OB2 association (d = 1.7 kpc) in order to search for apoint-source counterpart of the first unidentified TeV source. Opticalidentifications and spectroscopic classifications for the brighter X-raysources in ROSAT PSPC and Chandra ACIS images are obtained, without finding acompelling counterpart. The classified X-ray sources are a mix of early andlate-type stars, with one exception. The brightest source in the Chandraobservation is a new, hard absorbed source that is both transient and rapidlyvariable. It lies 7' from the centroid of the TeV emission, which places itoutside of the claimed 2 sigma location (r = 4.8'). A possible eclipse or "dip"transition is seen in its light curve. With a peak 1-10 keV luminosity of 7 x10^(32) (d/1.7 kpc})^2 ergs s^(-1), this source could be a quiescent low-massX-ray binary that lies beyond the Cyg OB2 association. A coincident, reddenedoptical object of R = 20.4, J = 15.4, H = 14.2, and K = 13.4 is observed, butnot yet classified due to the lack of obvious emission or absorption featuresin its spectrum. Alternatively, this Chandra} and optical source might be aconsidered a candidate for a proton blazar, a long hypothesized type ofradio-weak gamma-ray source. More detailed observations will be needed todetermine the nature of this variable X-ray source, and to assess thepossibility of its connection with TeV J2032+4130.Comment: 24 pages, 8 figures, accepted by Ap

Search for a Point‐Source Counterpart of the Unidentified Gamma‐Ray Source TeV J2032+4130 in Cygnus