Changing photospheric vector magnetic fields associated with a B4.2-class solar flare

Recent observations have provided evidence that the solar photospheric magnetic fields could have rapid and permanent changes in both longitudinal and transverse components associated with large (Xor M-class) solar flares. However, little work on small ones has been reported on this field. In this paper we find the observational evidence of changing photospheric vector magnetic fields associated with a B4.2-class flare obtained with the Solar Magnetic Field Telescope (SMFT) installed at Huairou Solar Observing Station(HSOS) of Nation Astronomical Observatories of Chinese Academy of Sciences.