Bolotin Yu.L., Zazunov L.G., Konchatnyi M.I., Lemets O.A. «The ABC of cosmography» Публикации Одесской астрономической обсерватории (Odessa Astronomical Publications, Украина), 30, с. 13-15 (2017)

DOI: https://doi.org/10.18524/1810-4215.2017.30.114129

Oknyansky V.L., Gaskell C.M., Huseynov N.A., Mikailov Kh.M., Lipunov V.M., Malanchev N.I., Tsygankov S.S., Gorbovskov E.S., Tatarnikov A.M., Metlov V.G., Shatsky K.L., Brotherton M.B., Kasper D., Du P., Chen X., Burlak M.A., Buckley D.A.H., Rebolo R., Serra-Ricart M., Podesta R., Levato H. «Ulti-wavelength monitoring of the changing-look AGN NGC 2617 during state changes» Публикации Одесской астрономической обсерватории (Odessa Astronomical Publications, Украина), 30, с. 117-120 (2017)

DOI: https://doi.org/10.18524/1810-4215.2017.30.114366 Optical and near-infrared photometry, optical spectroscopy, and soft X-ray and UV monitoring of the changing-look active galactic nucleus NGC 2617 show that it continues to have the appearance of a type-1 Seyfert galaxy. An optical light curve for 2010–2017 indicates that the change of type probably occurred between 2010 October and 2012 February and was not related to the brightening in 2013. In 2016 and 2017 NGC 2617 brightened again to a level of activity close to that in 2013 April. However, in 2017 from the end of the March to end of July 2017 it was in very low level and starting to change back to a Seyfert 1.8. We find variations in all passbands and in both the intensities and profiles of the broad Balmer lines. A new displaced emission peak has appeared in H_β. X-ray variations are well correlated with UV–optical variability and possibly lead by ∼2–3^d. The K band lags the J band by about 21.5±2.5^d and lags the combined B+J bands by ∼25^d. J lags B by about 3 d. This could be because J-band variability arises predominantly from the outer part of the accretion disc, while K-band variability is dominated by thermal re-emission by dust. We propose that spectral-type changes are a result of increasing central luminosity causing sublimation of the innermost dust in the hollow bi-conical outflow. We briefly discuss various other possible reasons that might explain the dramatic changes in NGC 2617.

Oknyansky V.L., Gaskell C.M., Huseynov N.A., Mikailov Kh.M., Lipunov V.M., Malanchev N.I., Tsygankov S.S., Gorbovskov E.S., Tatarnikov A.M., Metlov V.G., Shatsky K.L., Brotherton M.B., Kasper D., Du P., Chen X., Burlak M.A., Buckley D.A.H., Rebolo R., Serra-Ricart M., Podesta R., Levato H. «Ulti-wavelength monitoring of the changing-look AGN NGC 2617 during state changes» Публикации Одесской астрономической обсерватории (Odessa Astronomical Publications, Украина), 30, с. 117-120 (2017)

DOI: https://doi.org/10.18524/1810-4215.2017.30.114366 Optical and near-infrared photometry, optical spectroscopy, and soft X-ray and UV monitoring of the changing-look active galactic nucleus NGC 2617 show that it continues to have the appearance of a type-1 Seyfert galaxy. An optical light curve for 2010–2017 indicates that the change of type probably occurred between 2010 October and 2012 February and was not related to the brightening in 2013. In 2016 and 2017 NGC 2617 brightened again to a level of activity close to that in 2013 April. However, in 2017 from the end of the March to end of July 2017 it was in very low level and starting to change back to a Seyfert 1.8. We find variations in all passbands and in both the intensities and profiles of the broad Balmer lines. A new displaced emission peak has appeared in H_β. X-ray variations are well correlated with UV–optical variability and possibly lead by ∼2–3^d. The K band lags the J band by about 21.5±2.5^d and lags the combined B+J bands by ∼25^d. J lags B by about 3 d. This could be because J-band variability arises predominantly from the outer part of the accretion disc, while K-band variability is dominated by thermal re-emission by dust. We propose that spectral-type changes are a result of increasing central luminosity causing sublimation of the innermost dust in the hollow bi-conical outflow. We briefly discuss various other possible reasons that might explain the dramatic changes in NGC 2617.

Lozitsky V.G., Baranovsky E.A., Lozitska N.I., Tarashchuk V.P. «Estimations of local magnetic fields in solar flares: basic methods and some results» Публикации Одесской астрономической обсерватории (Odessa Astronomical Publications, Украина), 30, с. 232-235 (2017)

DOI: https://doi.org/10.18524/1810-4215.2017.30.114690 We consider three methods for estimations of local magnetic fields in solar flares: (1) analysis of bisectors of I±V profiles (Lozitsky, 2015); (2) search for Zeeman-like effects in cores of spectral lines with very low Lande factors, g_eff≈0.01 (Lozitsky, 1993, 1998); (3) semi-empirical modeling using many spectral lines and two-component models (see, e.g., Lozitsky et al., 2000). We illustrate the application of named methods to different observational data and to different spectral lines. Our main conclusions are following: (a) upper limit of local magnetic fields in solar flares is, at least, ∼10⁴G, (b) such extremely strong fields can occur in very small, spatially unresolved scales, (c) lifetime of such fields is, at least, a few minutes.

Lozitsky V.G., Baranovsky E.A., Lozitska N.I., Tarashchuk V.P. «Estimations of local magnetic fields in solar flares: basic methods and some results» Публикации Одесской астрономической обсерватории (Odessa Astronomical Publications, Украина), 30, с. 232-235 (2017)

DOI: https://doi.org/10.18524/1810-4215.2017.30.114690 We consider three methods for estimations of local magnetic fields in solar flares: (1) analysis of bisectors of I±V profiles (Lozitsky, 2015); (2) search for Zeeman-like effects in cores of spectral lines with very low Lande factors, g_eff≈0.01 (Lozitsky, 1993, 1998); (3) semi-empirical modeling using many spectral lines and two-component models (see, e.g., Lozitsky et al., 2000). We illustrate the application of named methods to different observational data and to different spectral lines. Our main conclusions are following: (a) upper limit of local magnetic fields in solar flares is, at least, ∼10⁴G, (b) such extremely strong fields can occur in very small, spatially unresolved scales, (c) lifetime of such fields is, at least, a few minutes.

Isaeva E.A., Lytvynenko O.A., Shepelev V.A. «Software for adapting DSPZ receivers to the URAN interferometer network» Публикации Одесской астрономической обсерватории (Odessa Astronomical Publications, Украина), 30, с. 219-221 (2017)

DOI: https://doi.org/10.18524/1810-4215.2017.30.115456 More than 10 years ago, URAN interferometer network (Megn A.V.,1997; Konovalenko A.A., 2014) had been equipped with newly designed receivers with a pass band extended up to 250 kHz and software rejection of interferences (Rashkovskii, 2012). The broadening of bandwidth of received signal increase the sensitivity of the receivers significantly and let us to investigate the angular structure about one hundred radio sources. A software package had been developed that allows: preparing a program of observations, carrying out observations automatically, making data cross-correlation, calculating visibility functions for all pairs of antennae, and fitting models of an angular structure of the sources. Data storage formats were elaborated for each stage of recording or processing. At present, new digital radio astronomy receiver DSPZ have been developed by IRA NASU (Zakharenko, 2016). The receiver allows recording an entire bandwidth of signals of a decameter range from 8 to 32 MHz. It is used at UTR-2 and URAN radio telescopes operated in a single dish mode. Application of the receivers for interferometer observation with the URAN network provides additional advantages in accuracy and sensitivity of studies. In this report we consider the data formats and synchronization methods used in URAN equipment and DSPZ receivers, and discuss algorithms of their transformation. Newly elaborated software is described, that allows selecting a set of frequency bands of signals recorded with DSPZ and converting them to the form used by the URAN software. This approach allows us to carry out the interferometer observations in an the extended frequency range provided by DSPZ and to use as much as possible the software package developed for the URAN network for data reduction.