The Large Angle Spectroscopic Coronagraph (LASCO)

Brueckner, G. E.; Howard, R. A.; Koomen, M. J.; Korendyke, C. M.; Michels, D. J.; Moses, J. D.; Socker, D. G.; Dere, K. P.; Lamy, Philippe; Llebaria, A.; Bout, M. V.; Schwenn, R.; Simnett, G. M.; Bedford, D. K.; Eyles, C. J.

doi:10.1007/978-94-009-0191-9_10

Cited by 605 publications

(480 citation statements)

References 5 publications

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“…The active region 7981 was previously observed during its transit on the visible solar disc at solar latitudes 0ø-20øS. A direct signature of the solar eruption was the CME observation by the LASCO instrument [Brueckner et al, 1995]. The CME was seen at the southwest limb as a bright structured loop with a bright core.…”

Section: Observationsmentioning

confidence: 83%

Energetic (∼10–65 MeV) protons observed by ERNE on August 13–14, 1996: Eruption on the solar back side as a possible source of the event

Torsti¹,

Kocharov²,

Teittinen³

et al. 1999

J. Geophys. Res.

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Abstract. The onset of the >10-MeV proton event of August 13-14, 1996, revealed a velocity dispersion, which is a signature of its solar origin, but no associated soft X ray flare was observed. The LASCO CME observations, the presence of AR 7981 beyond the west limb, and type II and IV radio burst timing with respect to the proton event onset indicate that the parent solar eruption may be centered on the back side of the Sun, at ---150øW. In such a case, expanding CME-associated wave can reach the Earth-connected interplanetary magnetic field line in ---1 hour and so give rise to the > 10-MeV proton event observed with the Energetic and Relativistic Nuclei and Electron (ERNE) instrument onboard SOHO. We verify this hypothesis against observational data and conclude that a solar back side eruption is the most plausible explanation of the August 13, 1996, event. We compare the August 13, 1996, event with events associated with Earth directed CMEs and show that the August 13, 1996, event reveals many properties common to >10-MeV proton events originating from solar eruptions centered ---90 ø away from the root of the Earth-connected interplanetary magnetic field line. In such events, the first detected protons are released ---1 hour after the start time of type II and IV radio bursts. The first injection spectrum is essentially harder than the spectrum at the intensity maximum; that is, the hard but less intensive proton production is followed by the major soft-spectrum production when CME expands farther from the Sun. sion that the interplanetary CME-driven shocks mainly accelerate seed particles originating from the solar corona. This may imply, when studying the efficiency of proton production, that more attention must be paid to the beginning of the event when the CME expands near the Sun.A careful study of the commencement of the August 13, 1996, particle event is important also because there were no signatures of a parent eruption in the GOES soft X ray data.

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Section: Observationsmentioning

confidence: 83%

Energetic (∼10–65 MeV) protons observed by ERNE on August 13–14, 1996: Eruption on the solar back side as a possible source of the event

Torsti¹,

Kocharov²,

Teittinen³

et al. 1999

J. Geophys. Res.

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“…Global imaging of the outer corona with white-light measurements of unprecedented sensitivity and dynamic range such as those available from the SOHO coronagraphs (LASCO for Large Angle Spectrometric Coronagaph) [Brueckner et al, 1995] not only confirms the radial preservation of density profiles revealed by radio Copyright 1999 by the American Geophysical Union.…”

Section: Introductionmentioning

confidence: 81%

Radial evolution of density structure in the solar corona

Woo

Habbal

1999

Geophysical Research Letters

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Abstract. White-light measurements made by the SOHO coronagraphs (LASCO for Large Angle Spectrometric Coronagraph) and the HAO Mauna Loa Mk III K-coronameter are combined to follow the evolution of path-integrated density structure in the solar corona overlying both coronal hole and quiet Sun regions from 1.15 to 5.5 Ro. The global imaging provided by these two instruments confirms and strengthens earlier results discovered by spacecraft radio ranging measurements [Woo and Habbal, 1999], that the imprint of density structure at the Sun-as manifested in the background latitudinal density profile closest to the Sun at 1.15 Ro --is carried essentially radially into interplanetary space with the same density gradient. The only exceptions are coronal streamers that evolve into the heliospheric current sheet within a few solar radii of the Sun.

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“…SOHO LASCO C3 [Brueckner et al, 1995] white light coronagraph images from April 9 to May 12, 1998, were analyzed to determine the 3-D location in solar coordinates of relatively stable bright raylike coronal streamers using the multiple viewpoints provided by solar rotation; the technique is illustrated in Figures 2-5. Throughout, we assume that the streamers are magnetic field aligned and, in the outer corona, (R > 3 Rs) radial.…”

Section: Technique For Determination Of Streamer Locationmentioning

confidence: 99%

Determination of three‐dimensional structure of coronal streamers and relationship to the solar magnetic field

Liewer¹,

Hall²,

Jong³

et al. 2001

J. Geophys. Res.

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Abstract. We have determined the location, in three dimensions, of eight quasi-stable coronal "streamers" from an analysis of Solar and Heliospheric Observatory (SOHO) Large-Angle and Spectrometric Coronagraph images acquired over approximately one solar rotation. We use the locations to attempt to determine the solar origin of the streamers. Comparison of the streamers' locations (longitude and latitude at the R = 2.5 Rs source surface) with that of the current sheet computed from a potential source surface model show that all of the streamers lie in or near the heliospheric current sheet. We assume that the streamers coincide with magnetic field lines and use a potential source surface magnetic model to map the location of the streamers from the source surface (R = 2.5 Rs) to the photosphere. We find that many of the streamers are associated with strong magnetic field active regions. When a streamer and its associated active region are visible simultaneously, the active region is seen to be bright in the SOHO extreme ultraviolet imaging telescope (EIT) EUV full disk images. This, and other evidence, leads us to conclude that many of the bright streamers are the result of scattering from regions of enhanced density associated with active region outflow, and not a result of line-of-sight viewing through folds in a warped current sheet with uniform density.

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The Large Angle Spectroscopic Coronagraph (LASCO)

Cited by 605 publications

References 5 publications

Energetic (∼10–65 MeV) protons observed by ERNE on August 13–14, 1996: Eruption on the solar back side as a possible source of the event

Energetic (∼10–65 MeV) protons observed by ERNE on August 13–14, 1996: Eruption on the solar back side as a possible source of the event

Radial evolution of density structure in the solar corona

Determination of three‐dimensional structure of coronal streamers and relationship to the solar magnetic field

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