NGC 6823 is a young open cluster that lies at a distance of \sim 2 kpc in the Vulpecula OB1 association .
Previous studies using CCD photometry and spectroscopy have identified a Trapezium system of bright O- and B-type stars at its center , along with several massive O- B- and A-type stars in the cluster .
We present optical VRI and near-infrared JHK photometric observations , complemented with Spitzer /IRAC archival data , with an aim to identify the young low-mass population and the disk candidates in this region .
Our survey reaches down to I \sim 22 mag and K _ { s } \sim 18 mag .
There is significant differential reddening within the cluster .
We find a bimodal distribution for A _ { V } , with a peak at \sim 3 mag and a broader peak at \sim 10 mag .
We have classified the sources based on the [ 4.5 ] - [ 8 ] color , which is least affected by extinction .
We find a \sim 20 % fraction of Class I/Class II young stellar objects ( YSOs ) in the cluster , while a large 80 % fraction of the sources have a Class III classification .
We have made use of the INT Photometric H \alpha Survey ( IPHAS ) in order to probe the strength in H \alpha emission for this large population of Class III sources .
Nearly all of the Class III objects have photospheric ( r ^ { \prime } -H \alpha ) colors , implying an absence of H \alpha in emission .
This large population of Class III sources is thus likely the extincted field star population rather than the diskless YSOs in the cluster .
There is a higher concentration of the Class I/II systems in the eastern region of the cluster and close to the central Trapezium .
The western part of the cluster mostly contains Class III/field stars and seems devoid of disk sources .
We find evidence of a pre-main sequence population in NGC 6823 , in addition to an upper main-sequence population .
The pre-main sequence population mainly consists of young disk sources with ages between \sim 1-5 Myr , and at lower masses of \sim 0.1-0.4 M _ { \sun } .
There may be a possible mass dependent age spread in the cluster , with the older stars being more massive than the younger ones .
The presence of young disk sources in NGC 6823 indicates similar star formation properties in the outer regions of the Galaxy as observed for young clusters in the solar neighborhood .