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Matwey Kornilov

Publications and source records attributed to Matwey Kornilov.

4 recordsLinked to original sources

SNAD: enabling discovery in the era of big data

In the era of wide-field surveys and big data in astronomy, the SNAD team is exploiting the potential of modern datasets for discovering new, unforeseen, or rare astrophysical objects and phenomena with machine learning (ML). The SNAD pipeline was built under the hypothesis that, although automatic ML algorithms have a crucial role to play in this task, the scientific discovery is only completely realized when such systems are designed to boost the impact of domain knowledge experts. Our key contributions include the development of the Coniferest Python library, which offers implementations of two active learning algorithms with an ``expert in loop'', and the creation of the SNAD Transient Miner, facilitating the search for specific types of transients. We have also developed the SNAD Viewer, a web portal that provides a centralized view of individual objects from the Zwicky Transient Facility's (ZTF) data releases, making the analysis of potential anomalies more efficient. Finally, when applied to ZTF data, our approach has resulted in more than a hundred new supernova (SN) candidates, along with a few other non-catalogued objects, such as red dwarf flares, superluminous SNe, RS CVn type variables, and young stellar objects.

astro-ph.HE

Useful relations for the analysis of stellar scintillation at the entrance pupil of a telescope

The development of new techniques for characterizing atmospheric optical turbulence (OT) has become an active topic of research again in recent years. In order to facilitate these studies, we reconsidered known theoretical results and obtained some new practically useful conclusions. We introduce a dimensionless Fresnel filter, which allows us to approximate a polychromatic weighting function (WF) by a monochromatic one with a typical precision of several percent. A so-called dimensionless WF can be easily scaled for a receiving aperture of any size. For the case of a circular aperture and monochromatic radiation, an analytical expression for the WF was found. The WFs for a square aperture and for a circular aperture match with relative difference less than 0.01 if the circular aperture diameter is 1.15 times larger than the square aperture side. A linear digital filter can be applied to the scintillation signal from an image detector. As an example of digital filtering, we considered the power law filter $\propto f^{5/3}$ with the WF being constant in a wide range of altitudes. We discuss the main limitations of this approach for measuring OT integral: finite pixel size, aliasing, and finite image detector size.

astro-ph.IM

Fips: an OpenGL based FITS viewer

FITS (Flexible Image Transport System) is a common format for astronomical data storage. It was first standardised in the early 1980s. Even though astronomical data is now processed mostly using software, visual data inspection by a human is still important during equipment or software commissioning and while observing. We present Fips, a cross-platform FITS file viewer open source software. To the best of our knowledge, it is for the first time that the image rendering algorithms are implemented mostly on GPU (graphics processing unit). We show that it is possible to implement a fully-capable FITS viewer using OpenGL interface. We also emphasise the advantages of using GPUs for efficient image handling.

astro-ph.IM

Study on atmospheric optical turbulence above Mt. Shatdzhatmaz in 2007--2013

We present the results of the atmospheric optical turbulence (OT) measurements performed atop Mt. Shatdzhatmaz at the installation site of new 2.5-m telescope of Sternberg Astronomical Institute. Nearly 300 000 vertical OT profiles from the ground up to an altitude of 23 km were obtained in the period November 2007 - June 2013 with the combined multi-aperture scintillation sensor (MASS) and differential image motion monitor (DIMM) instrument. The medians of the main OT characteristics computed over the whole dataset are as follows: the integral seeing $β_0 = 0.96$ arcsec, the free-atmosphere seeing $β_{free} = 0.43$ arcsec, and the isoplanatic angle $θ_0 = 2.07$ arcsec. The median atmospheric time constant is $τ_0 = 6.57 \mbox{ ms}$. The revealed long-term variability of these parameters on scales of months and years implies the need to take it into account in astroclimatic campaign planning. For example, the annual variation in the monthly $θ_0$ estimate amounts up to 30% while the time constant $τ_0$ changes by a factor of 2.5. Evaluation of the potential of Mt. Shatdzhatmaz in terms of high angular resolution observations indicates that in October--November, this site is as good as the best of studied summits in the world.

astro-ph.IM