Phase-ratio and phase dependence of albedo of irregular mare patch maskelyne obtained from lroc nac data

Introduction: One of the interesting geological formations on the Moon is Irregular Mare Patches (IMPs). At the moment there are dozens of similar features in the lunar maria[1], describing them as IMPs. Because of the unusual and complex characteristics of IMPs, their specific mechanism of formation is being discussed. Maskelyne is one of unusual and large IMPs, a ~3×3 km depression composed of bleb‐like mounds surrounded by hummocky and blocky terrains. The phase-ratio technique [2] is a powerful tool to investigate the lunar surface, especially, being applied to LROC NAC data with resolution on order of 1 m [3-6]. A new approach to photometric corrections based on photoclinometry technique proposed in [7] allows one to obtain phase-ratio of higher-quality for the subsequent analysis. Also, the corrected albedo images obtained using the proposed method [7] allow to carry out more accurate analysis of the phase dependence of albedo for selected areas on the image. New photometric studies provide additional information for understanding the mechanisms of formation of Maskelyne and other IMPs. Phase-ratio: We demonstrate results of photometric analysis of IMP Maskelyne (4.33°N, 33.75°E) (Fig. 1). Figure 2 shows the phase ratio Aeq(62°)/Aeq(44°) of the area (approximately 5.0 × 5.0 km). The structure anomalies of Maskelyne are very well expressed and effectively discriminated on phase-ratio image.