We present an analysis of a deep , 172 ks Chandra observation of the Large Area Lyman Alpha Survey ( LALA ) Boötes field , obtained with the Advanced CCD Imaging Spectrometer ( ACIS-I ) on the Chandra X-ray Observatory .
This is one of the deepest Chandra 
images of the extragalactic sky ; only the 2 Ms CDF-N and 1 Ms CDF-S are substantially deeper .
In this paper we present the X-ray source catalog obtained from this image , along with an analysis of source counts , and optical identifications .
The X-ray image is composed of two individual observations obtained in 2002 , and reaches 0.5 – 2.0 and 2.0 – 10.0 keV flux limits of 1.5 \times 10 ^ { -16 } and 1.0 \times 10 ^ { -15 } ergs cm ^ { -2 } s ^ { -1 } , respectively , for point sources near the aim point .
A total of 168 X-ray sources were detected : 160 in the 0.5 – 7.0 keV band , 132 in the 0.5 – 2.0 keV band , and 111 in the 2.0 – 7.0 keV band .
The X-ray source counts were derived and compared with those from other Chandra deep surveys ; the hard X-ray source density of the LALA Boötes field is 33 % higher than that of CDF-S at the flux level of 2.0 \times 10 ^ { -15 } 
ergs cm ^ { -2 } s ^ { -1 } , confirming the field-to-field variances of the hard band source counts reported by previous studies .
The deep exposure resolves \gtrsim 72 % of the 2.0 – 10.0 keV X-ray background .

Our primary optical data are R -band imaging from NOAO Deep Wide-Field Survey ( NDWFS ) , with limiting magnitude of R = 25.7 ( Vega , 3 \sigma , 4″ diameter aperture ) .
We have found optical counterparts for 152 of the 168 Chandra sources ( 90 % ) ; 144 of these are detected on the R -band image , and 8 have optical counterparts in other bands ( either B _ { W } , V , I , z ^ { \prime } ) .
Among the R -band non-detected sources , not more than 11 of them can possibly be at z > 5 , based on the hardness ratios of their X-ray emission and nondetections in bluer bands ( B _ { W } , V ) .
The majority ( \sim 76 % ) of the X-ray sources are found to have log ( f _ { X } / f _ { R } ) within 0.0 \pm 1 , which are believed to be AGNs .
Most of the X-ray faint/optically bright sources ( log ( f _ { X } / f _ { R } ) < 
-1.0 ) are optically extended , which are low-z normal galaxies or low luminosity AGNs .
There is also a population of sources which are X-ray overluminous for their optical magnitudes ( log ( f _ { X } / f _ { R } ) > 1.0 ) , which are harder in X-ray and are probably obscured AGNs .