Abstract
We present here $UBVI$ and H${\alpha}$ photometric results of stellar sources in the bubble nebula NGC 7635. The early type members are selected from the photometric membership criteria. H${\alpha}$ photometry allows us to detect 11 pre-main sequence candidates with H${\alpha}$emission. In addition, we performed PSF photometry for the Spitzer IRAC and MIPS 24${\mu}m$ images from archive (program ID 20726, PI: J. Hester) in order to search for the young stellar objects (YSOs). Total 19 sources are classified as YSOs (7 class I, 11 class II, and 1 transitional disk candidates) in the color-color diagrams according to the classification scheme of Gutermuth et al.. Among them, 7 YSOs have counterparts in optical photometric data. These stars can be divided into two groups at given color indices. It implies that there occurred the star formation events more than twice. We would like to discuss the star formation history in the bubble nebula using the results from SED fitter (Robitaille et al.), color composite image from IRAC bands, and spatial distribution of early type stars and YSOs.