Photometric Observations of Recent Supernovae

Regular photometric observations of sufficiently bright northern supernovae are carried out at Sternberg Astronomical Institute’s observatories. Since 1998 the observations of more than 60 supernovae were obtained on about 150 nights with different telescopes and detectors. We present the data of the observation program, the parameters of light curves for 18 SNe and the light curves for SNe 1999aa, 2001B, 2002bo.

Photometric observations of the variable star ASASSN-13cx acquired in the course of a program of studies of cataclysmic variables and their parameters recently carried out at the Sternberg Astronomical Institute (SAI) are presented. The star was observed with the 50-cm and 60-cm telescopes of the SAI Crimean Astronomical Station and a CCD photometer (similar to 1800 images in the V and Rc filters) during the variable's outburst of August-September 2014 and in a period of quiescence in October-November 2016. The ASASSN-13cx system is confirmed to be a SU UMa variable. Parameters of the system are derived from eight light curves using a "composite" model that takes into account the presence of a hot spot on the lateral surface of the geometrically thick disk and of a region of enhanced energy release near the disk edge, at the base of the gas flow (the so-called "hot line"). Parameters of the system for three light curves during the outburst were obtained in the framework of a "spiral" model that additionally takes into account the presence of geometric perturbations on the accretion-disk surface. The parameters of ASASSN-13cx determined using these models provide good accuracy in reproducing the system's light curves in both states. The basic parameters of the system have been determined for the first time: the component mass ratio q = M (1)/M (2) = 7.0 +/- 0.2, the orbital inclination i = 79.9A degrees-80.1A degrees, the distance between the components' centers of mass a (0) = 0.821(1) R (Ey), and the sizes and temperatures of the stars: R (1) = 0.0124(5)a (0) = 0.0102(4) R (Ey), T (1) = 12 500 +/- 280 K, aEuroR (2)aEuroe = 0.236(4)a (0) = 0.194(3) R (Ey), T (2) = 2550 +/- 400 K, corresponding to M4-9V for the spectral type of the secondary. Parameters of the accretion disk have been derived for both activity states. The mass of matter in the accretion disk increased by almost a factor of two during similar to 400 orbital periods in quiescence.

<p>Catalogs of impact craters – not only a layers of objects in GIS but complete databases containing the morphometric and geomorphological characteristics – can help to solve such fundamental problems as the estimation of parameters of populations of impactors that collided with the surface of the planet throughout its history, as well as to clarify the processes of crater formation in the Solar System.</p><p>Currently, there are few global catalogues of Mercury that includes big craters only. For example: 1) global digital GIS-catalogue of Mercury’s craters created by the Braun University, USA. It is based on modern data gathered by MESSENGER and, along with approximately 9000 objects; it includes coordinates and diameters of large craters (> 20 km), exclusively. At the same time, it doesn’t contain any geomorphological information; 2) the other source is a geomorphological catalogue that was composed by Sternberg Astronomical Institute (SAI), which, while containing geomorphological information, was created in accordance to data of Mariner 10 and was presented as a text in a table. The SAI’s catalogue includes craters with a size of 10 km and larger. </p><p>Creation of a new global catalog of Mercury’s craters based on the latest MESSENGER data is a comprehensive work. The catalog will consist of two subdirectories: 1) the geomorphological catalog of craters with a size of 10 km and larger; 2) the morphometric catalog of craters with a size less than 10 km. We use MESSENGER MDIS global mosaic of Mercury with resolution ~166 m/pixel and several MESSENGER DEMs – the first global Mercury DEM with resolution 665 m/pixel and four DEMs on Mercury quadrants with resolution ~222 m/pixel (which will be used for formation of a database of craters with diameters less than 10 km).</p><p>In addition to the required elements of any catalog (coordinates of craters and their diameters), we will be able to add full geomorphological description of craters, reduced to code designations (to simplify the implementation of the catalog in the GIS) and morphometric characteristics. For instance: 1) the diameter of the interior feature (flat floor, central peak, or inner ring); 2) depth and relative depth of each crater; 3) max and min slopes; 4) the average level of inclination of the external; 5) internal slopes of crater; 6) the ratio of volume of the crater rim to the volume of the bowl. The most of listed parameters can be calculated both for craters and for the surrounding surface.</p><p>By using this catalog, we will be able to quickly get statistics and create thematic maps, for example, maps of crater density on regions of interest.</p><p>This research was supported by Russian Foundation for Basic Research (RFBR), project No 20-35-70019.</p>

During the 2014-2015 mutual events season, the Institut de Mecanique Celeste et de Calcul desEphemerides (IMCCE), Paris, France, and the Sternberg Astronomical Institute (SAI), Moscow, Russia, led an international observation campaign to record ground-based photomet-ric observations of Galilean moon mutual occultations and eclipses. We focused on processing the complete photometric observations data base to compute new accurate astrometric positions. We used our method to derive astrometric positions from the light curves of the events.

We present the review of the main results of more than two decades of the Moscow program of Cepheid studies, carried out at the Institute of Astronomy (INASAN) and Sternberg Astronomical Institute (SAI). This program consists of extensive photometry and radial velocity measurements (the contribution from our team being the largest among observations of comparable precision), studies of period variations (permitting identification of the number of a particular star’s current instability-strip crossing), detection of spectroscopic binaries among Cepheids, determinations of Cepheid radii, discoveries of double-mode Cepheids, studies of galactic structure, kinematics, and dynamics, etc.

Replenishment of the database of observations of distant satellites of planets is always useful, since the accuracy of the motion models and ephemeris depends not only on the accuracy of observations. Accuracy improves with increasing observation time. Therefore, observations made even with the same accuracy are in demand. Astrometric observations of two distant satellites of Jupiter were carried out at the Caucasian Mountain Observatory (CMO) of the Sternberg State Astronomical Institute, Moscow State University, on a new telescope with a mirror diameter of 2.5 m in 2017. As a result, six positions of the J6 satellite (Himalia) and 27 positions of the J8 satellite (Pasiphae) are obtained. The root-mean-square deviations from the ephemeris for all 33 observations of these two satellites were 0.085″ in right ascension and 0.064″ in declination. This accuracy corresponds to the current level of ground-based observations. Our refinements of the orbits for the MULTI-SAT ephemeris server based on all available observations showed that the weighted root-mean-square values of the angular deviations of the measured positions from those calculated for satellites J6 (Himalia) and J8 (Pasiphae) are 0.22″ . At the same time, the accuracy of the ephemeris is estimated with the MULTI-SAT server for 2017 at 0.008″ for J6 (Himalia) and 0.05″ for J8 (Pasiphae). New observational data will be useful for refining the motion models of distant satellites of Jupiter.

Beginning in 1975 Sternberg Astronomical Institute of Moscow University (SAI) developed a search of places with the best astroclimate in Middle Asia. Mount Maidanak (150 km to south from Samarkand) was chosen after investigation of the meteorological conditions, temperature fluctuations and seeing quality by astroclimatical expeditions in a different city testing for Moscow University Observatory. Having an isolated summit Maidanak has good astroclimatical parameters: 2000 clean observational hours/year, median seeing about 0.7 arcsec (Artamonov et al. 1987, Bugaenko et al. 1992). At the end of 1992 SAI mainly finished the construction of Maidanak Observatory with a 1.5 meter RC telescope, but in 1993 the development of the observatory was stopped after nationalization by Uzbekistan. At present Sternberg Astronomical Institute and Tashkent Astronomical Institute (new owner of the observatory) continue to work in joint observations and try to create International Maidanak Observatory.

Search for and study of hot circumstellar dust envelopes

We present ultravioliet (UV) observations of supernovae (SNe) obtained with the UltraViolet/Optical Telescope (UVOT) on board the Swift spacecraft. This is the largest sample of UV light curves from any single instrument and covers all major SN types and most subtypes. The UV light curves of SNe Ia are fairly homogenous while SNe Ib/c and IIP show more variety in their light curve shapes. The UV-optical colors clearly differentiate SNe Ia and IIP, particularly at early times. The color evolution of SNe IIP, however, makes their colors similar to SNe Ia at about 20 days after explosion. SNe Ib/c are shown to have varied UV-optical colors. The use of UV colors to help type SNe will be important for high redshift SNe discovered in optical observations. These data can be added to ground based optical and near infrared data to create bolometric light curves of individual objects and as checks on generic bolometric corrections used in the absence of UV data. This sample can also be compared with rest-frame UV observations of high redshift SNe observed at optical wavelengths.

In April 1995 an international scientific memorial conference dedicated to the 50th anniversary of the victory over Nazi Germany took place in Pulkovo. The conference was convened and organized by the Euro-Asian Astronomical Society jointly with the main astronomical observatory of the Russian Academy of Sciences in Pulkovo, supported also by the Sternberg Astronomical Institute and the Institute of theoretical astronomy. It was a great patriotic war for our country. The war had tragic repercussions for all aspects of life in this country, for science on the whole and perhaps, for astronomy above all.

Photometry of mutual eclipses and occultations of planetary satellites is a powerful technique to explore these bodies. Observations of these rare events are a source of much precise information. In 1995 the Celestial Mechanics Department of the Sternberg Astronomical Institute (SAI) has organized the observations of mutual eclipses and occultations of Saturnian satellites on a num- ber of observatories of the Commonwealth of Independent States (CIS) | the former Soviet Union (FSU). The ephemerides of satellites and their observing conditions have been computed beforehand and mailed these data to many observatories of CIS. The Crimean laboratory (CL) of the Sternberg Astronomical Institute, two observatories of the Fesenkov Astrophysical Institute of the Academy of Sciences of the Republic of Kazakhstan (FAI AS RK) in Almaty, and the Main Astronomical Observatory of Russian Academy of Sciences (MAO RAS) in Pulkovo took part in observations. A photoelectric photometer was used in CL of SAI, a CCD was employed to secure satellite images in FAI AS RK, and both CCD and pho- tographic plates were used in MAO RAS. As a result of this observing campaign, photometric data and light curves were obtained for three mutual eclipses and oc- cultations of Saturnian satellites. A number of position observations made allowed us to measure relative coor- dinates of satellites. Astrometric information has already been derived from photometric data. The mutual appar- ent positions of satellites were calculated with an accuracy

SS Cyg is the brightest and therefore well-studied classical dwarf nova with the orbital period ≈ 6h.6. The photometric investigation of SS Cygni in quiescence was fulfilled in frames of large observational program “The investigation of close binary system on late evolutionary stages” that is performing during several years in Sternberg Astronomical Institute. On the base of numerous observations during period 1982–1990 the narrow eclipse minimum with ΔV = 0m.05 ΔB = 0m.07 and ΔU = 0m.09 at the φ = 0.54 was detected on the light curve of this star at the moment of the white dwarf superior conjunction (Voloshina, 1986).

The extended observational program for study of cataclysmic variables is realized in Sternberg Astronomical Institute during the last years. A few telescopes of Crimean Observational Station equipped with a different devices, — UBV photometer and two CCD camera, are used for observations. Among the close binary systems (CBS), cataclysmic variables are the most interesting objects because of the outburst activity and variety of their observational features. They could serve a good laboratory for study of physical processes in CBS. GAIA provides astronomers with a new ample opportunity for investigation of cataclysmic variables. Though the relative faintness of detected objects it is still possible to carry out a high accuracy ground-based observations with our equipment. Obtained ground-based data permit us to confirm classification of detected CV-candidates, to determine the physical characteristics with a sample of new cods and improve the current understanding of their nature.

There is wide interest in the results of studies of the dynamics of satellites of planets. Such data are needed to determine the physical properties of celestial bodies, and they may be able to provide information about the origins and evolution of the solar system. The general approach to studying the dynamics of satellites involves developing models for the motion and ephemerides based on observational data. Ephemerides are required to prepare and launch space missions to other planets and help discover new celestial bodies. High-precision astrometric coordinates of the principal satellites of Jupiter, Saturn, and Uranus are derived from photometric observations of occultations and eclipses of these satellites. To this end, worldwide observing campaigns have been organized. Enhancement in the precision of ephemerides can be obtained not only by increasing the accuracy of observations, but also by expanding the time interval covered by the observations. Many new, distant satellites of the major planets were discovered in the early 21st century. However, observations of these satellites are scarce and were obtained over short time intervals; as a result, some of these satellites were lost. To date, 179 natural satellites are known. This paper is based on a presentation made at the conference “Modern Astrometry 2017,” dedicated to the memory of K.V. Kuimov (Sternberg Astronomical Institute, Moscow State University, October 23–25, 2017).

Type IIP (plateau) supernovae are thought to come from stars with initial mass ~8-25 M☉ that end their lives as red supergiants. The expected stellar endpoints can be found from evolutionary calculations, and the corresponding mass-loss properties at these points can be estimated from typical values for Galactic stars. The mass-loss densities of observed supernovae can be estimated from observations of the thermal X-ray and radio synchrotron emission that result from the interaction of the supernova with the surrounding wind. Type IIP supernovae are expected to have energy-conserving interaction during typical times of observation. Because Type IIP supernovae have an extended period of high optical luminosity, Compton cooling could affect the radio-emitting electrons, giving rise to a relatively flat radio light curve in the optically thin regime. Alternatively, a high efficiency of magnetic field production results in synchrotron cooling of the radio-emitting electrons. Both the X-ray and radio luminosities are sensitive to the mass loss and initial masses of the progenitor stars, although the turn-on of radio emission is probably the best estimator of circumstellar density. Both the mass-loss density and the variation of density with stellar mass are consistent with expectations for the progenitor stars deduced from direct observations of recent supernovae. Current observations are consistent with mass being the only parameter; observations of supernovae in metal-poor regions could show how the mass loss depends on metallicity.