Multi-wavelength observations of the impulsive C2.8 class flare producing photospheric impact at the penumbra region of the leading sunspot in NOAA 13256

We present the results of a study of the non-eruptive C2.8 class flare in the active region (AR) NOAA 13256, which occurred on March 19,2023 from 02:12 to 02:19 UTC. This event was chosen on the basis of the test launches of the Irkutsk Solar Radio Spectropolarimeter (SOLARSPEL), Badary (ISTP RAS). Despite the low X-ray class and short duration, according to SOLARSPEL data, this impulsive flare had a complex multi-peak fine time structure, recorded at different frequencies in the microwave range. The presence of a photospheric disturbance in the vicinity of the sunspot penumbra, recorded using HMI/SDO, was of great interest for physics and motivated this study. There are few detailed multi-wavelength studies in the literature of low-power flares accompanied by a response at the photosphere level. Notably, this event was observed simultaneously by four X-ray instruments: SoLO/STIX, ASO-S/HXI, FERMI/GBM, and Konus-Wind. As a result, the unique observation conditions of this flare, from the point of view of the available instruments and various recorded physical high-energy processes, motivated us to carry out detailed research. We found that the photospheric perturbations are mostly associated with the stronger magnetic field in the penumbra rather than with the distribution of the HXR sources. The observed flare ribbons were located in the penumbral PIL region, which revealed the complexity of the larger events in terms of the spatial and temporal structure of the energy release. We also briefly discuss the observed quasi-periodic pulsations.