Search Publications
Interplanetary scintillation (IPS) analyses during LOFAR campaign mode periods that include the first three Parker Solar Probe close passes of the Sun
Barnes, D.; Jackson, B. V.; Buffington, A. +9 more
The University of California, San Diego (UCSD) time-dependent three-dimensional (3-D) reconstruction technique provides volumetric maps of density, velocity, and solar surface extrapolated magnetic fields by iteratively fitting our kinematic 3-D model to interplanetary scintillation (IPS) observations. While we currently use data from the Institut…
Relationships between energetic storm particle events and interplanetary shocks driven by full and partial halo coronal mass ejections
Vainio, Rami; Valtonen, Eino; Al-Sawad, Amjad +1 more
We have analysed energetic storm particle (ESP) events in 116 interplanetary (IP) shocks driven by front-side full and partial halo coronal mass ejections (CMEs) with speeds > 400 km s-1during the years 1996-2015. We investigated the occurrence and relationships of ESP events with several parameters describing the IP shocks, and the …
The north-south asymmetry of active regions of different magneto-morphological types in solar cycles 23 and 24
Zhukova, Anastasiya; Sokoloff, Dmitry; Abramenko, Valentina +1 more
We used the elaborated earlier catalog of the magneto-morphological classes (MMC) of active regions (ARs) to study 2046 ARs of the solar cycle (SC) 23 and 1507 ARs of the SC24. According to empiric rules for sunspot groups (Hale's polarity law, Joy's law, etc.) and MMC, all ARs (except for unipolar spots) were sorted out between two categories: A-…
CCD UBV and Gaia DR3 based analysis of NGC 189, NGC 1758 and NGC 7762 open clusters
Bilir, Selçuk; Yontan, Talar; Canbay, Remziye +5 more
This paper presents photometric, astrometric, and kinematic analyses of the open clusters NGC 189, NGC 1758 and NGC 7762 based on CCD UBV photometric and Gaia Data Release 3 (DR3) data. According to membership analyses, we identified 32, 57 and 106 most probable member stars with membership probabilities P ⩾ 0.5 in NGC 189, NGC 1758 and NGC 7762, …
Assessing the spectral characteristics of band splitting type II radio bursts observed by CALLISTO spectrometers
Kozarev, Kamen; Minta, Felix N.; Nozawa, Satoshi I. +2 more
Metric type II radio bursts are usually early indicators of CME-driven shocks and other space weather phenomena in the solar corona. This paper presents a detailed investigation of the spectral properties of band splitting type II radio bursts and their association with sunspot number. Using type II radio bursts in a frequency range [20 MHz-200 MH…
Artificial neural network for star tracker centroid computation
Zapevalin, P. R.; Novoselov, A.; Zharov, V. E.
We propose a unique dataset with star images, their centroids, and a new centroid algorithm based on machine learning, that significantly improves star image centroid performance. The centroid of the star image is the subpixel coordinates on the image plane corresponding to the assumed point source of the light (a star). We have compiled and open-…
Analysis of NASA's DSN Venus Express radio occultation data for year 2014
Gramigna, Edoardo; Tortora, Paolo; Zannoni, Marco +5 more
The Venus Express Radio Science Experiment (VeRa) was part of the scientific payload of the Venus Express (VEX) spacecraft and was targeted at the investigation of Venus' atmosphere, surface, and gravity field as well as the interplanetary medium. This paper describes the methods and the required calibrations applied to VEX-VeRa raw radio occultat…
Trigonometric parallax discrepancies in space telescopes measurements I: The case of the stellar binary system Hip 84976
Al-Wardat, Mashhoor A.; Hussein, Abdallah M.; Widyan, Hatem +1 more
In addition to the complete set of fundamental parameters of its individual components, we present the solution for the discrepancy between the two main astrometric space telescopes Gaia and Hipparcos, in their measurements of the trigonometric parallax for the stellar binary system Hip 84976. In our analysis of the system, we followed Al-Wardat's…
Characteristics of X-class flares of solar cycles 23 and 24 in X-ray and EUV bands
Bhardwaj, Anil; Kumar, A.; Chakrabarty, D. +4 more
The characteristics of X-class flares of solar cycles 23 and 24 are examined based on the soft X-ray (0.1-0.8 nm) and EUV (26-34 nm) light curves. First, the commonly used correction factors for the center-to-limb variation of EUV flux are compared. Subsequently, enhancements in X-ray and EUV levels are used to calculate the relative apportionment…
New insights from cross-correlation studies between solar activity indices and cosmic-ray flux during Forbush decrease events
Savić, Mihailo; Veselinović, Nikola; Dragić, Aleksandar +5 more
Observed galactic cosmic ray intensity can be subjected to a transient decrease. These so-called Forbush decreases are driven by coronal mass ejection induced shockwaves in the heliosphere. By combining in situ measurements by space borne instruments with ground-based cosmic ray observations, we investigate the relationship between solar energetic…