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Analysis of photometric data of the active giant PZ Mon is presented. Using ASAS-3 project data and new more accurate photometry we establish that during 15 years of PZ Mon CCD observations the light curve remains stable, and consequently a longitude of the active spotted area is stable. The small deviations may be explained by differential rotation or inhomogeneous distribution of spots on the active hemisphere of PZ Mon. The stability of the active longitude and its location on the PZ Mon surface indicates on the secondary component as reason of stellar activity.
Based on our photometric observations in 2015-2016 and archival photometric data for the active red giant PZ Mon, we have found the main characteristics of the stellar surface: the unspotted surface temperature Teff=4730K, the spot temperature Tspot=
Based on the multiband (BVRIJHKL) photometric observations of the active red giant PZ Mon performed for the first time in the winter season of 2017-2018, we have determined the main characteristics of the spotted stellar surface in a parametric three
Two sets of multiple-color ($B, V, R_c, I_c$) light curves of PZ UMa were observed in dependently with the 2.4 meter telescope at the Thai National Observatory and the 1 meter telescope at Yunnan Observatories. The light curves were analyzed with the
This paper describes a multiwavelengh optical study of chromospheres in two X-ray/EUV selected active binary stars with strong H_alpha emission, V789 Mon (2RE J0725-002) and GZ Leo (2RE J1101+223). The goal of the study is to determine radial velocit
Despite frequent references in modern reviews to a seventeenth-century Venetian longitude prize, only a single, circumstantial reference to the alleged prize is known from contemporary sources. Edward Harrisons scathing assessment of the conditions g