C3 polarizers Post SOHO Recovery - Oct 18, 1998

The C3 polarized light images clearly showed a problem in the central parts of the image when the first post-SOHO recovery images came down on Oct 15, 1998. This is the first look at the post-SOHO calibration lamp images that were taken on Oct 18, 1998.

The cal lamp images were compared with those from launch (Jan 4, 1996) and the last set of cal lamp images (April 18,1998) prior to the loss of SOHO. The Jan 4, 1996 images are not rectified and require a right-left flip to match them to the latest set. The April set and the Jan 1996 set match very well. The polarization characteristics of the cal lamp are not well known. However we can use it to look for changes in the polarizer transmissions.

The major result is that the C3 +00 polarizer has become more opaque in the central area when compared to the -60 and +60 polarizers. This is most clearly seen in the 981018 Post +00/ 980418 Pre +00 Cal Lamp Image. Other polarizers do not show significant changes. All ratios which involve the +00 degree polarizer also show the change in the same direction. The +00/+60 ratio image shows a central darkening and the -60/+00 image shows a central brightening. The effect is slightly off-center (column 440) and tapers off toward the edge of the field on the left and an equal distance to the right. The -60/+60 images look almost the same as at launch.

Post Recovery SOHO Cal Lamp Ratios

-60/+60 Polarizers , Orange Filter (830k)

+00/+60 Polarizers, Orange Filter

-60/+00 Polarizers, Orange Filter

Pre-Recovery Cal Lamp Plots

-60/+60 Polarizers , Orange Filter, Row 512 Plot

+00/+60 Polarizers, Orange Filter, Row 512 Plot

-60/+00 Polarizers, Orange Filter, Row 512 Plot

Post Recovery(981018)/Pre-Recovery (980418) Cal Lamp Ratio Images

981018 cl/980418 cl Polarizers, Clear Filter

981018 +60/980418 +60 Polarizers, Clear Filter

981018 +00/980418 +00 Polarizers, Clear Filter

981018 -60/980418 -60 Polarizers, Clear Filter

981018 +60/980418 +60 Polarizers, Orange Filter

981018 +00/980418 +00 Polarizers, Orange Filter

981018 -60/980418 -60 Polarizers, Orange Filter

SOHO Cal Lamp Ratios - April 18,1998

-60/+60 Polarizers , Orange Filter

+00/+60 Polarizers, Orange Filter

-60/+00 Polarizers, Orange Filter

-60/+60 Polarizers , Orange Filter, Row 512 Plot

+00/+60 Polarizers, Orange Filter, Row 512 Plot

-60/+00 Polarizers, Orange Filter, Row 512 Plot

Launch SOHO Cal Lamp Ratios - Jan 4, 1996

-60/+60 Polarizers , Orange Filter

+00/+60 Polarizers, Orange Filter

-60/+00 Polarizers, Orange Filter


Updated: 23 Oct 1998 - DW