Search Publications
Photometric Calibration of the Lasco-C3 Coronagraph Using Stars
Thernisien, A. F.; Howard, R. A.; Wang, D. +1 more
The LASCO-C3 coronagraph on SOHO, launched in December 1995, has been collecting images of the corona and background star fields in a regular manner since 1996. This instrument contains a number of broadband filters with various passbands in the range between 400 and 1100 nm. The filter used most often has been the Clear filter (400-900 nm) but th…
On the Propagation and Dissipation of Alfvén Waves in Coronal Holes
Srivastava, A. K.; Dwivedi, B. N.
We underline the importance of Alfvén wave dissipation in the magnetic funnels through the viscous and resistive plasma. Our results show that Alfvén waves are one of the primary energy sources in the innermost part of coronal holes where the solar wind outflow starts.
Active Region Detection and Verification With the Solar Feature Catalogue
Zharkova, V. V.; Ipson, S.; Zharkov, S. +1 more
We describe the automated extraction of active regions (ARs) or plages from the European Grid of Solar Observations (EGSO) Solar Feature Catalogue using a region-growing technique. In this work, Hα and Ca II K3 solar images from the Meudon Observatory and EUV solar images from the SOHO/EIT instrument were used. For better detection accuracy, the s…
Evidence for Tether-Cutting Reconnection in a Quadrupole Magnetic Configuration in the April 9, 2001, M7.9 Flare
Yurchyshyn, V.; Wang, H.; Karlický, M. +1 more
We studied the M7.9 flare on April 9, 2001 that occurred within a δ-sunspot of active region NOAA 9415. We used a multi-wavelength data set, which includes Yohkoh, TRACE, SOHO, and ACE spacecraft observations, Potsdam and Ondřejov radio data and Big Bear Solar Observatory (BBSO) images in order to study the large-scale structure of this two-ribbon…
A Radio Burst and Its Associated CME on March 17, 2002
Pick, M.; Krucker, S.; Vourlidas, A. +2 more
In this study, we present a detailed analysis, based on multiwavelength observations and magnetic field extrapolation, of a radio and X-ray event observed on March 17, 2002. This event was accompanied by a Coronal Mass Ejection (CME) observed by the Large-Angle Spectrometric Coronagraph (LASCO) aboard SOHO. During the main event, the Reuven Ramaty…
The Automatic Predictability of Super Geomagnetic Storms from halo CMEs associated with Large Solar Flares
Yang, Guo; Wang, Haimin; Yurchyshyn, Vasyl +3 more
We investigate the relationship between magnetic structures of coronal mass ejection (CME) source regions and geomagnetic storms, in particular, the super storms when the Dst index decreases below −200 nT. By examining all full halo CMEs that erupted between 1996 and 2004, we selected 73 events associated with M-class and X-class solar …
Multi-Site Spectrographic and Heliographic Observations of Radio Fine Structure on April 10, 2001
Tan, Chengming; Yan, Yihua; Huang, Guangli +5 more
We present results of the first simultaneous observations of zebra patterns (ZPs) with super-fine spiky structure in the microwave range made at two observatories ∼1000 km apart (Beijing and Nanjing, China). The fine structure was recorded by a spectra polarimeter in the 5.2 - 7.6 and 2.8 - 3.6 GHz ranges at the Huairou station and by the spectrom…
Evolution of Electric Currents Associated with Two M-Class Flares
Tan, Baolin; Ji, Haisheng; Huang, Guangli +3 more
Using one-minute cadence vector magnetograms from Big Bear Solar Observatory (BBSO), we analyze the temporal behavior of derived longitudinal electric currents associated with two flares on July 26, 2002. One of the events is an M1.0 flare which occurred in active region NOAA 10044, while the other is an M8.7 flare in the adjacent region 10039. Ra…
Is Pre-Eruptive Null Point Reconnection Required for Triggering Eruptions?
Li, Hui; Aulanier, Guillaume; Schmieder, Brigitte +1 more
We study the magnetic field evolution and topology of the active region NOAA 10486 before the 3B/X1.2 flare of October 26, 2003, using observational data from the French-Italian THEMIS telescope, the Michelson Doppler Imager (MDI) onboard Solar and Heliospheric Observatory (SOHO), the Solar Magnetic Field Telescope (SMFT) at Huairou Solar Observat…
The Gradual Phase of the X17 Flare on October 28, 2003
Schmieder, B.; Berlicki, A.; del Zanna, G. +2 more
We present SOHO/CDS observations taken during the gradual phase of the X17 flare that occurred on October 28, 2003. The CDS data are supplemented with TRACE and ground-based observations. The spectral observations allow us to determine velocities from the Doppler shifts measured in the flare loops and in the two ribbon kernels, one hour and a half…