Search Publications
Update of the Photometric Calibration of the LASCO-C2 Coronagraph Using Stars
Howard, R. A.; Colaninno, R. C.
We present an update to the photometric calibration of the LASCO-C2 coronagraph onboard the SOHO spacecraft. We obtained the new calibration using data from the beginning of the mission in 1996 until 2013. We re-examined the LASCO-C2 photometric calibration by comparing the past three calibrations and the present calibration with the goal of valid…
Calibration of Hinode/XRT for Coalignment
McKenzie, David E.; Yoshimura, Keiji
We present coalignment calibration procedures for the X-ray Telescope (XRT) onboard the Hinode satellite. We performed not only an XRT stand-alone calibration, but also cross calibration using data from the Helioseismic and Magnetic Imager (HMI) and the Atmospheric Imaging Assembly (AIA) onboard the Solar Dynamics Observatory (SDO). Several new me…
Empirical Relationship Between CME Parameters and Geo-effectiveness of Halo CMEs in the Rising Phase of Solar Cycle 24 (2011 - 2013)
Moon, Y. -J.; Shanmugaraju, A.; Umapathy, S. +2 more
We analyzed the physical characteristics of 40 halo coronal mass ejections (CMEs) and their geo-effective parameters observed during the period 2011 to 2013 in the rising phase of Solar Cycle 24. Out of all halo CMEs observed by SOHO/LASCO, we selected 40 halo CMEs and investigated their geomagnetic effects. In particular, we estimated the CME dir…
Investigation on Radio-Quiet and Radio-Loud Fast CMEs and Their Associated Flares During Solar Cycles 23 and 24
Shanmugaraju, A.; Suresh, K.
We present the results of a detailed analysis on the differences between radio-loud (RL) and radio-quiet (RQ) fast coronal mass ejections (CMEs) (V≥900 km s−1) observed during the period 1996 - 2012. The analysis consists of three different steps in which we examined the properties of (i) RL and RQ CMEs, (ii) accelerating (class-A) and …
Investigation of the Geoeffectiveness of CMEs Associated with IP Type II Radio Bursts
Chen, Y.; Kong, X. L.; Wang, B. +1 more
We perform a statistical analysis of the geoeffectiveness of coronal mass ejections (CMEs) that are associated with interplanetary (IP) type II bursts in Solar Cycle 23 during the period 1997 - 2008. About 47 % (109 out of 232) of IP type II bursts are found to be associated with geomagnetic storms. Of these 47 %, 27 % are associated with moderate…
Active-Region Twist Derived from Magnetic Tongues and Linear Force-Free Extrapolations
Démoulin, Pascal; Mandrini, Cristina H.; López Fuentes, Marcelo +1 more
The main aim of this study is to compare the amount of twist present in emerging active regions (ARs) from photospheric and coronal data. We use linear force-free field models of the observed coronal structure of ARs to determine the global twist. The coronal twist is derived, on one hand, from the force-free parameter [α ] of the model and, on th…
Identifying and Tracking of Peripheral and Central Umbral Dots
Yang, Yunfei; Ji, Kaifan; Feng, Song +3 more
Umbral dots (UDs) are small isolated brightening observed in sunspot umbrae. They are usually classified into peripheral UDs (PUDs) and central UDs (CUDs) according to their positions inside an umbra. To accurately investigate the similarities and the distinctions between PUDs and CUDs and better understand their formation mechanisms, we propose a…
Dynamics of CMEs in the LASCO Field of View
Gopalswamy, N.; Bronarska, K.; Michalek, G. +1 more
A large set (16 000) of coronal mass ejections (CMEs) observed during 1996 - 2011 was selected to study their dynamics in the LASCO field of view (LFOV). These events were selected based on the criterion that at least three height-time measurements were available for each CME. The height-time measurements included in the SOHO/LASCO catalog were us…
Decameter U-burst Harmonic Pair from a High Loop
Rucker, H. O.; Panchenko, M.; Poedts, S. +6 more
The results of the first observations of solar sporadic radio emission within 10 - 70 MHz by the Giant Ukrainian Radio Telescope (GURT) are presented and discussed. Observations in such a wide range of frequencies considerably facilitate the registration of harmonic pairs. The solar U-burst harmonic pair observed on 8 August 2012 is analyzed. The …
Evolution and Flare Activity of δ -Sunspots in Cycle 23
Takizawa, K.; Kitai, R.
The emergence and magnetic evolution of solar active regions (ARs) of β γ δ -type, which are known to be highly flare-productive, were studied with SOHO/MDI data in Cycle 23. We selected 31 ARs that can be observed from their birth phase as unbiased samples for our study. From the analysis of the magnetic topology (twist and writhe), we obtained t…