Sun
First Result from Digital Vector Magnetograph at BBSO
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Determination of Bias and Cross-talk in Stokes Components
The plot in the left gives the background bias level in Stokes Q, U and V components
over the observing period (212 series over 5 hours). The bias is determined by taking the mean value
of the Q (U, V) map of the whole active region as the percentage of the
maximum value of the Q (U, V) component.
The plot in the right gives the V->Q and V->U cross-talk level over the observing
period (altogether 212 series over 5 hours). The cross-talk is determined by the
linear fitting of the Q (U) and V intensities in the weak field regions. The plot
shows the Q intensity as the percentage of V intensity.
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Study of the Change of the Calibration in the Line-of-sight Field
The calibration of the line of sight magnetic field data counts changes in 3 hours
time with the sunrise. The following plots demonstrate such change: a constant increase
of the line of sight component in most of the regions (sunspots or plages) by about 30%
in 3 hours time. In Figure 1, the sub-regions in which the integration we made for
Figure 2 are illustrated. Figure 2a demonstrates the change of the line intensity
(white light) of the sub-regions throughout the observing time on Oct26. Figure 2b
demonstrates the integrated positive flux from each sub-regions (in arbitrary unit)
and Figure 2c demonstrates the negative flux. The exact reason of such significant change
remains unknown. (Possible reason can be: improvement of seeing during 3 hrs??).
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M2.3 Flare on October 26, 1999
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On September 13, 1999
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On September 15, 1999
Comments: qiuj@bbso.njit.edu