Possible Origin of a Newly Discovered GeV Gamma-Ray Source Fermi J1242.5+3236

Based on the first 13.4 yr of Fermi science data in energy range from 300 MeV to 500 GeV, we discovered a bright GeV gamma-ray source with $\sim$5.64 $\sigma$ detection, named J1242.5+3236, which has an offset about 0fdg0996 nearby star-forming galaxy NGC 4631. When using 12-yr data, detection significance J1242.5+3236 is 4.72 $\sigma$. steady point without significant temporal variability and hard photon index -1.60 $\pm$0.24. The spatial spectrum disfavor this as diffuse emission galaxy. This new might have possible origin unidentified background blazar, more likely high-synchrotron-peaked blazar for its index. A follow-up optical observation would help distinguish J1242.5+3236.