Photometry of Solar Flares.

Dodson, Helen W.; Hedeman, E. Ruth; McMath, Robert R.

doi:10.1086/190027

Cited by 26 publications

(15 citation statements)

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“…Photometric measurements show at least three frequently observed rates of rise in Ha brightness (Dodson et al, 1956) (Figure 5). Increased X-ray emission appears to accompany the slow as well as the rapidly increasing Ha radiation.…”

Section: The Double Flarementioning

confidence: 97%

Some comments on flares after many years of observation

Dodson

Hedeman

1976

Sol Phys

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Ground based observations of flares are reviewed to seek implications for a flare build-up on either a long or a short time scale. Plots of flare frequency and importance for certain individual centers of activity suggest a possible crescendo in flare occurrence days and hours before the development of large and significant flares. The X-ray records follow the same; pattern of apparent build-up. A possible dependence between successive major flares, as phases one and two of a single complex flare event, suggests that the time scale in which the total flare event takes place may show extreme variation.Since all flares start as small features, there is a short term build-up in the optical records. The characteristics of this build up are not dear. The initial brightenings in a flare may or may not show a flash phase, and the rise to maximum may or may not be accompanied by filament activity. Flares rise to maximum Ha intensity at markedly different rates. Although most flares occur in centers of activity with well defined and often complex magnetic fields, certain large and relatively energetic flares have developed in centers of activity with apparently very simple circumstances.

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Section: The Double Flarementioning

confidence: 97%

Some comments on flares after many years of observation

Dodson

Hedeman

1976

Sol Phys

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“…Dodson (1953) and Dodson et al (1956) studied the light curves of chosen points in flares measured with a densitometer on Ha spectroheliograms. The flare intensity was measured relative to the quiet sun and was then converted into units of continuous spectrum at 6590 A.…”

Section: A Quantitative Measure Of Flare Developmentmentioning

confidence: 99%

“…Several studies of the temporal relation of the start of the explosive phase and flare related phenomena have demonstrated the importance of the explosive phase in flare development; e.g., X-rays (Moreton, 1964), centimeter-wavelength radio bursts (Covington and Harvey, 1961 ;Angle, 1968), flare waves (Athay and Moreton, 1961 ;Smith and Angle, 1968) and some ionospheric disturbances (Hansen and Kleczek, 1962;Donnelly, 1967Donnelly, , 1968Davies and Donnelly, 1966). For these studies, the existence and onset of the explosive phase was determined by visually scanning a sequence of Ha filtergrams and subjectively evaluating whether the flare exhibits explosive development.…”

Section: Introductionmentioning

confidence: 99%

The explosive phase of solar flares

Harvey

1971

Sol Phys

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The explosive phase of a flare can be defined by a simple photometric measurement of Ha film records of the flare development. Using the quantitative definition, improved correlations are found between the start of the explosive phase and the start of 10.7 cm radio bursts and Sudden Frequency Deviations compared to earlier correlations of the same data using visual estimates of the start of the explosive phase. Explosive development may be confined to only part of a flare.

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“…A 12-mm receiver was constructed for Mopra in 1996, primarily to support space VLBI observations with the HALCA satellite as part of the VLBI Space Observatory Programme (Hirabayashi et al 2000). The compromised performance of the HALCA 12-mm receiver (Kobayashi et al 2000) resulted in Mopra support for the VSOP mission being at 1.6 and 4.9 GHz (e.g., Scott et al 2004;Dodson et al 2008), however the 'VSOP' 12-mm receiver was used in a number of other Long Baseline Array VLBI observations (e.g., Greenhill et al 2003) until it was replaced with an MMIC-based receiver (Gough et al 2004(Gough et al ) in 2006 Under an agreement between ATNF and the University of New South Wales (UNSW), UNSW funded the replacement of the outer perforated panels of the dish in 1999 with solid panels, and the receiver optics were modified to illuminate the full 22 m. Several rounds of holography using a 30-GHz satellite beacon were used to reduce the surface RMS error from 270 μm in 1999 to 180 μm in 2004. In 2004, observing capabilities were enhanced with the addition of an on-the-fly mapping mode, enabling efficient mapping of larger regions of interest.…”

Section: Introductionmentioning

confidence: 99%

Characterisation of the Mopra Radio Telescope at 16–50 GHz

Urquhart

Hoare

Purcell

et al. 2010

Publ. – Astron. Soc. Aust

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Abstract:We present the results of a programme of scanning and mapping observations of astronomical masers and Jupiter designed to characterise the performance of the Mopra Radio Telescope at frequencies between 16 and 50 GHz using the 12-mm and 7-mm receivers. We use these observations to determine the telescope beam size, beam shape, and overall telescope beam efficiency as a function of frequency. We find that the beam size is well fit by λ/D over the frequency range with a correlation coefficient of ∼90%. We determine the telescope main beam efficiencies are between ∼48 and 64% for the 12-mm receiver and reasonably flat at ∼50% for the 7-mm receiver. Beam maps of strong H 2 O (22 GHz) and SiO masers (43 GHz) provide a means to examine the radial beam pattern of the telescope. At both frequencies, the radial beam pattern reveals the presence of three components: a central 'core', which is well fit by a Gaussian and constitutes the telescopes main beam; and inner and outer error beams. At both frequencies, the inner and outer error beams extend out to ∼2 and ∼3.4 times the full-width half maximum of the main beam, respectively. Sources with angular sizes of a factor of two or more larger than the telescope main beam will couple to the main and error beams, and therefore the power contributed by the error beams needs to be considered. From measurements of the radial beam power pattern we estimate the amount of power contained in the inner and outer error beams is of order one-fifth at 22 GHz, rising slightly to one-third at 43 GHz.

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Photometry of Solar Flares.

Cited by 26 publications

References 0 publications

Some comments on flares after many years of observation

Some comments on flares after many years of observation

The explosive phase of solar flares

Characterisation of the Mopra Radio Telescope at 16–50 GHz

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