Monitoring of the Earth's atmosphere at the Terskol Observatory: current status and prospects

Continuous high-frequency (every minute) automatic measurements of surface ozone concentrations have been made at the high-altitude Terskol Observatory (on the slope of Elbrus mountain, the Northern Caucasus) since 2003. We present the main experimental results including seasonal variations and the main factors affecting ozone levels. Ozone concentrations in air at Terskol Peak (3100 m above sea level) show a distinct seasonal cycle with the highest concentrations during spring–summer period and a peak amplitude of about 85 ppbv. In autumn–winter period, the daily maximum ozone concentrations are typically around 40 ppbv

Long-period SUUMa dwarf nova V1006 Cygni: Outburst activity and variability at different brightness states in 2015 - 2017

© 2018, Astronomical Institute, Slovak Academy of Sciences. CCD photometric observations of the dwarf nova V1006 Cyg were carried out in 2015 { 2017 with 11 telescopes located at 7 observatories. They covered the 2015 superoutburst with rebrightening, five normal outbursts of ~ 4-day duration and one wide outburst that lasted at least seven days. The interval between normal outbursts was 16 and 22 days, and between superout- bursts is expected to be longer than 124 days. The positive superhumps with the mean period of 0d:10544(10) and 0d:10406(17) were detected during the 2015 superoutburst and during the short-term quiescence between rebrighten- ing and the start of the first normal outburst, respectively. During a wide 2017 outburst the orbital period 0d:09832(15) was found. The amplitude of this sig- nal was ~ 2:5 times larger at the outburst decline than at its end. During the quiescence stage between the first and the second normal outbursts in 2015 we possibly detected the negative superhumps with the period of 0d:09714(7). In all other cases of quiescence we found only the quasi-periodic brightness variations on a time scale of 20{30 minutes with a different degree of coherence and a variable amplitude reaching 0.5 mag in extremal cases

The astrometric Gaia-FUN-SSO observation campaign of 99 942 Apophis

Astrometric observations performed by the Gaia Follow-Up Network for Solar System Objects (Gaia-FUN-SSO) play a key role in ensuring that moving objects first detected by ESA's Gaia mission remain recoverable after their discovery. An observation campaign on the potentially hazardous asteroid (99 942) Apophis was conducted during the asteroid's latest period of visibility, from 12/21/2012 to 5/2/2013, to test the coordination and evaluate the overall performance of the Gaia-FUN-SSO . The 2732 high quality astrometric observations acquired during the Gaia-FUN-SSO campaign were reduced with the Platform for Reduction of Astronomical Images Automatically (PRAIA), using the USNO CCD Astrograph Catalogue 4 (UCAC4) as a reference. The astrometric reduction process and the precision of the newly obtained measurements are discussed. We compare the residuals of astrometric observations that we obtained using this reduction process to data sets that were individually reduced by observers and accepted by the Minor Planet Center. We obtained 2103 previously unpublished astrometric positions and provide these to the scientific community. Using these data we show that our reduction of this astrometric campaign with a reliable stellar catalog substantially improves the quality of the astrometric results. We present evidence that the new data will help to reduce the orbit uncertainty of Apophis during its close approach in 2029. We show that uncertainties due to geolocations of observing stations, as well as rounding of astrometric data can introduce an unnecessary degradation in the quality of the resulting astrometric positions. Finally, we discuss the impact of our campaign reduction on the recovery process of newly discovered asteroids.Comment: Accepted for publication in A&

Polarization and spectral energy distribution in OJ 287 during the 2016/17 outbursts

We report optical photometric and polarimetric observations of the blazar OJ 287 gathered during 2016/17. The high level of activity, noticed after the General Relativity Centenary flare, is argued to be part of the follow-up flares that exhibited high levels of polarization and originated in the primary black hole jet. We propose that the follow-up flares were induced as a result of accretion disk perturbations, travelling from the site of impact towards the primary SMBH. The timings inferred from our observations allowed us to estimate the propagation speed of these perturbations. Additionally, we make predictions for the future brightness of OJ 287. © 2017 by the authors

Authenticating the Presence of a Relativistic Massive Black Hole Binary in OJ 287 Using Its General Relativity Centenary Flare : Improved Orbital Parameters

Results from regular monitoring of relativistic compact binaries like PSR 1913+16 are consistent with the dominant (quadrupole) order emission of gravitational waves (GWs). We show that observations associated with the binary black hole (BBH) central engine of blazar OJ 287 demand the inclusion of gravitational radiation reaction effects beyond the quadrupolar order. It turns out that even the effects of certain hereditary contributions to GW emission are required to predict impact flare timings of OJ 287. We develop an approach that incorporates this effect into the BBH model for OJ 287. This allows us to demonstrate an excellent agreement between the observed impact flare timings and those predicted from ten orbital cycles of the BBH central engine model. The deduced rate of orbital period decay is nine orders of magnitude higher than the observed rate in PSR 1913+16, demonstrating again the relativistic nature of OJ 287's central engine. Finally, we argue that precise timing of the predicted 2019 impact flare should allow a test of the celebrated black hole "no-hair theorem" at the 10% level.Peer reviewe

Polarization and spectral energy distribution in OJ 287 during the 2016/17 outbursts

© 2017 by the authors. We report optical photometric and polarimetric observations of the blazar OJ 287 gathered during 2016/17. The high level of activity, noticed after the General Relativity Centenary flare, is argued to be part of the follow-up flares that exhibited high levels of polarization and originated in the primary black hole jet. We propose that the follow-up flares were induced as a result of accretion disk perturbations, travelling from the site of impact towards the primary SMBH. The timings inferred from our observations allowed us to estimate the propagation speed of these perturbations. Additionally, we make predictions for the future brightness of OJ 287