CCD MINIMA FOR SELECTED ECLIPSING BINARIES IN 2020

A total of 212 CCD determinations of times of minima for selected eclipsing binaries occurring in 2020 are presented. These were obtained at either Mountain Ash Observatory in Prince George, BC, Canada or Desert Blooms Observatory in Benson, AZ, USA

L199, A NEW VARIABLE STAR IN M13

During a routine study of the variable stars of Messier 13 (NGC 6205 = Cl 1639+365) we have discovered the variability of L199 (TYC 2588-1386-2), a red giant star member of the cluster: using the photometric data –in V band– obtained in the 2019 and 2020 campaigns we have verified its variability. Data from the Zwicky Transient Facility (ZTF) and Deras et al. (2019) were utilized to determine its type of variability and period estimation: our data suggest that it is a semiregular red giant, similar to the other variables of this type of the cluster, whose cycles of photometric variation are not identical; we derived a period of ~27 days (although without a regular periodicity) and an amplitude smaller: 0.08 ± 0.03 magnitudes in V band although they may be somewhat larger or smaller. With this discovery the cluster now has 63 variable stars.

CONFIRMATION OF SEVEN FAINT ATLAS VARIABLE STAR CANDIDATES

A pilot survey conducted at the Lookout Observatory has confirmed seven faint (V ~ 13 to 17) variables in the region of Kepler-76b that were recently discovered by the Asteroid Terrestrial-Impact Last Alert System (ATLAS). The ATLAS survey identified 315,000 probably variables within its wide-field survey in 2018. The faintness (down to r ~ 18) and small amplitudes (down to 0.02 mag) included in these candidates makes external validation difficult. Our confirmation of seven such variable stars gives credibility to the ATLAS list. Further, the agreement between various surveys and LO data validates the use of our new survey for variable star and exoplanet research.

NEW ECLIPSING BINARY TIMES OF MINIMA IN THE NORTHERN SKY MEASURED DURING THE YEAR 2020

We present 167 times of minima of 69 eclipsing binaries in the Northern Sky determined from differential, partly multicolor photometry, during the year 2020.

26 NEW MIRA VARIABLES FROM THE ZTF SURVEY

We have continued our search for hitherto unregistered Mira variables in publicly available sky survey data, using observations from the Zwicky Transient Facility and the information provided in the Zwicky Transient Facility Suspected Variables Catalog, which led to the discovery of 26 new Mira stars. Essential data as well as light curves and phase plots for all stars are presented.

PROPERTIES OF THE RECENTLY DISCOVERED ECLIPSING BINARY GSC 03421-01402

GSC 03421-01402 is a low-amplitude eclipsing binary with a period of 7.6800475(44) d. The eclipsing binary is one component of a close pair identified in the Gaia EDR3 data with ∆G = 0.m45. The light-curve suggests that the primary eclipse is total with an observed depth of 0.m13, but due to dilution the true depth could be ∼ 0.23 or 0.37 mag. A weak, 0.02 mag, secondary eclipse is seen displaced slightly to phase 0.491. The system is probably a detached Algol-type eclipsing binary dominated by a mid G-type primary, but until the uncertainties in the relative magnitudes and distance are resolved much remains in doubt.

VX HYA TIME KEEPING. STROBOSCOPIC ANALYSIS

Photometric observations of the double-mode pulsator VX Hya are presented. They are analyzed with a stroboscopic method, completed by Fourier analysis.

SEARCH FOR PERIOD CHANGES IN MIRA STARS

We reobserved in the RC and i(Sloan) bands, during the years 2020-2021, seven Mira variables in Cassiopeia, for which historical i(Sloan) light curves were available from Asiago Observatory plates taken in the years 1967-84. The aim was to check if any of

MINIMA AND MAXIMA TIMINGS OF SEVERAL VARIABLE STARS

We present 228 times of minima of 33 eclipsing binaries and nine maxima timings of two pulsating stars. The majority of the objects are newly discovered variables and they were observed as by product. The observations were employed five different telescop