Above us only sky: 2021

Thursday, September 16, 2021

Report at the Scientific conference "Astronomy in Lviv University" (September 14-17, 2021)

My report at the Scientific conference "Astronomy in Lviv University" (September 14-17, 2021)

Period Variation of the Close Binary System V405 Dra

Thursday, August 19, 2021

PMAK V106: a New Bright Eclipsing Binary with Deep and Short Minimum

Looking through the TESS QLP data, I've found another bright eclipsing binary with a rather deep primary minimum that, I think, can be observed even visually (with the aid of a small telescope). It is BD+47 3904 star of the Lacerta constellation, it is registered in the AAVSO's International Variable Star Index as PMAK V106 (https://www.aavso.org/vsx/index.php?view=detail.top&oid=2224389)

In the maximum, the star has a visual magnitude of 9.4, the primary minimum reaches a magnitude of 10.1, the period is 3.17082 d and the duration of the primary eclipse is 3.8 h hours.

Here is a phase plot of the star:

Components of the system obviously have different colors (temperature): there is a noticeable difference in depths of eclipses in V (and clear) filters compared to the TESS passband.

The star also shows a rotational variability with a period of 3.1308 d, an amplitude of about 0.03 TESS, see https://www.aavso.org/vsx/index.php?view=detail.top&oid=2224389 for details.

Thanks to Sebastian Otero for his advice and helpful criticism.

Friday, April 30, 2021

Observations of KP Lyn in the night 27-28th of March 2021

I'm continuing to investigate my new monochrome CMOS camera, ASI183MM-Pro, making test observations. Now it was a HADS star KP Lyn. The light curve was obtained with the mentioned camera, a photometric V-filter from Baader Planetarium, and a 150mm Newtonian telescope. The night was clear, however, with almost full Moon.

The data looks quite satisfactory.

I tried to compare my data with KP Lyn observations available via the AAVSO International Database; it turned out that the period and the epoch of maxima from the International Variable Star Index (VSX), in turn, originated from the GCVS, are not accurate enough. Double-checking the star's parameters with ASAS-SN data proved this: a phase plot with VSX period was very fuzzy. So I made a precise determination of times of maxima available in the AAVSO International Database (from December 2008 to present) using an approach previously used in my recent paper "Refining Ephemeris and Estimating Period Change Rate for V965 Cephei" ( https://app.aavso.org/jaavso/article/3707/ ) and built an O-C diagram to check if the period constant. It appeared to be constant with very good stability (data from one observer were definitely discrepant, so I removed them). I determined improved values of the period and the epoch; the corresponding phase plot with ASAS-SN and my data is shown in the attached figure. Thinking about sending a revision to the VSX...

The variable, a comparison, and a check star:

Tuesday, April 13, 2021

ASI183MM Pro Test: AE UMa revisited

Тест моєї нової камери: ZWO ASI183MM Pro. І знову AE UMa, змінна, на якій я вже третій раз перевіряю обладнання. Попередні тести (ASI120MM та Canon EOS 600D тут).

AE UMa -- швидкий пульсатор типу SXPHE (VSX), період близько двох годин.

Обладнання: ASI183MM Pro (температура сенсору -15*C, unity gain); фотометричний фільтр V від Baader Planetarium; телескоп: Sky Watcher Newtonian 150mm f/5.