STRONG CHANGES OF THE PHOTOMETRIC BEHAVIOUR OF CARBON MIRAS

Analysis of variations of the light curves parameters of 16 Miras of spectral classes C and S has been made. A number of the peculiarities of these variations has been found. One of the most interesting results is the detection of the mean brightness variations: they are cyclic (with a superperiod of about 10 Х P0 and not stable cycle length) or secularly decreasing

T CEP, U UMI, Z SCO – MIRA-TYPE VARIABLES WITH CYCLIC PERIOD CHANGES

Period and amplitude changes of three Mira-type variables have been analyzed. Characteristics of  long-term cyclicity were obtainedPeriod and amplitude changes of three Mira-type variables have been analyzed. Characteristics of  long-term cyclicity were obtaine

Long-term color variations of the peculiar X-ray binary V Sagittae

We present an analysis of the color variations of the X-ray binary V Sge during high, medium and low state of its activity over the years 1995-1997, using UBV data. We resolved the track of V Sge in the color diagrams ($B-V$ and $U-B$ versus mag(V)) during transitions between the states and show that the color variations on the orbital time scale are significantly smaller than the changes caused by the long-term activity. The mean $B-V$ decreases by 0.15 mag during the upper part of the transition (brightness higher than 11.5 mag(V)) from the low to the high state but stays almost constant below this level. On the contrary, $U-B$ does not change significantly during the whole transition. Comparison of our data with those of Herbig et al. ([CITE]) shows that although the character of the long-term activity in V Sge changed significantly during the last decades (Šimon & Mattei [CITE]) the colors and their variations with the brightness level remained similar

LOCAL FITS OF SIGNALS WITH ASYMPTOTIC BRANCHES

The method of "asymptotic parabola" fit is described, its analytical properties are discussed in comparison with other types of fits. The method is effective for the (possibly highly asymmetric) signals with practically linear ascending and descending branches connected by relatively short transitions at maximum or minimum, e.g. for the brightness variations of pulsating or eclipsing variables or for the phase variations in stars with abrupt period changes. The method is illustrated by an application to the Mira-type star U Her.The method of "asymptotic parabola" fit is described, its analytical properties are discussed in comparison with other types of fits. The method is effective for the (possibly highly asymmetric) signals with practically linear ascending and descending branches connected by relatively short transitions at maximum or minimum, e.g. for the brightness variations of pulsating or eclipsing variables or for the phase variations in stars with abrupt period changes. The method is illustrated by an application to the Mira-type star U Her

The orbital modulation of the X-ray binary V Sagittae in the high and low states

Our analysis of the orbital modulation of V Sge, carried out in the intensity scale instead of the previously used magnitude scale, revealed that the full amplitude of the modulation remains almost constant as the intensity of the system rises from the low to the high state. The primary minimum remains very similar, as regards both its depth and width. The secondary minimum tends to slightly lag behind phase 0.5. The depth of the secondary minimum is subjected to the largest changes; it becomes almost as deep as the primary minimum during the high state while it is significantly more shallow than the primary one in the low state

THE QUANTITY AND QUALITY OF OBSERVATIONAL NIGHTS MONITORED WITH USING THE ASTRONOMICAL INSTRUMENTS AT THE SUBURBAN OBSERVATION STATIONS OF ASTRONOMICAL OBSERVATORY OF ODESSA NATIONAL UNIVERSITY

The Astronomical Observatory of Odessa National University named after I.I. Mechnikov is one of the four astronomical observatories which exist in classical universities.The Observatory has a main office in the T.G. Shevchenko Park that located near historical center of Odessa. The Observatory also has several observation stations: in the Odessa suburb Mayaki and Kryzhanovka villages

”ASYMPTOTIC PARABOLA” FITS FOR SMOOTHING GENERALLY ASYMMETRIC LIGHT CURVES

A computer program is introduced, which allows to determine statistically optimal approximation using the "Asymptotic Parabola" fit, or, in other words, the spline consisting of polynomials of order 1,2,1, or two lines ("asymptotes") connected with a parabola. The function itself and its derivative is continuous. There are 5 parameters: two points, where a line switches to a parabola and vice versa, the slopes of the line and the curvature of the parabola. Extreme cases are either the parabola without lines (i.e.the parabola of width of the whole interval), or lines without a parabola (zero width of the parabola), or "line+parabola" without a second line. Such an approximation is especially effective for pulsating variables, for which the slopes of the ascending and descending branches are generally different, so the maxima and minima have asymmetric shapes. The method was initially introduced by Marsakova and Andronov (1996OAP.....9...127M) and realized as a computer program written in QBasic under DOS. It was used for dozens of variable stars, particularly, for the catalogs of the individual characteristics of pulsations of the Mira (1998OAP....11...79M) and semi-regular (200OAP....13..116C) pulsating variables. For the eclipsing variables with nearly symmetric shapes of the minima, we use a "symmetric" version of the "Asymptotic parabola". Here we introduce a Windows-based program, which does not have DOS limitation for the memory (number of observations) and screen resolution. The program has an user-friendly interface and is illustrated by an application to the test signal and to the pulsating variable AC Her.A computer program is introduced, which allows to determine statistically optimal approximation using the "Asymptotic Parabola" fit, or, in other words, the spline consisting of polynomials of order 1,2,1, or two lines ("asymptotes") connected with a parabola. The function itself and its derivative is continuous. There are 5 parameters: two points, where a line switches to a parabola and vice versa, the slopes of the line and the curvature of the parabola. Extreme cases are either the parabola without lines (i.e.the parabola of width of the whole interval), or lines without a parabola (zero width of the parabola), or "line+parabola" without a second line. Such an approximation is especially effective for pulsating variables, for which the slopes of the ascending and descending branches are generally different, so the maxima and minima have asymmetric shapes. The method was initially introduced by Marsakova and Andronov (1996OAP.....9...127M) and realized as a computer program written in QBasic under DOS. It was used for dozens of variable stars, particularly, for the catalogs of the individual characteristics of pulsations of the Mira (1998OAP....11...79M) and semi-regular (200OAP....13..116C) pulsating variables. For the eclipsing variables with nearly symmetric shapes of the minima, we use a "symmetric" version of the "Asymptotic parabola". Here we introduce a Windows-based program, which does not have DOS limitation for the memory (number of observations) and screen resolution. The program has an user-friendly interface and is illustrated by an application to the test signal and to the pulsating variable AC Her.A computer program is introduced, which allows to determine statistically optimal approximation using the "Asymptotic Parabola" fit, or, in other words, the spline consisting of polynomials of order 1,2,1, or two lines ("asymptotes") connected with a parabola. The function itself and its derivative is continuous. There are 5 parameters: two points, where a line switches to a parabola and vice versa, the slopes of the line and the curvature of the parabola. Extreme cases are either the parabola without lines (i.e.the parabola of width of the whole interval), or lines without a parabola (zero width of the parabola), or "line+parabola" without a second line. Such an approximation is especially effective for pulsating variables, for which the slopes of the ascending and descending branches are generally different, so the maxima and minima have asymmetric shapes. The method was initially introduced by Marsakova and Andronov (1996OAP.....9...127M) and realized as a computer program written in QBasic under DOS. It was used for dozens of variable stars, particularly, for the catalogs of the individual characteristics of pulsations of the Mira (1998OAP....11...79M) and semi-regular (200OAP....13..116C) pulsating variables. For the eclipsing variables with nearly symmetric shapes of the minima, we use a "symmetric" version of the "Asymptotic parabola". Here we introduce a Windows-based program, which does not have DOS limitation for the memory (number of observations) and screen resolution. The program has an user-friendly interface and is illustrated by an application to the test signal and to the pulsating variable AC Her