RESULTS FROM HI IMAGE SCRUBBING
Section 5.3.6 of the Software Operations Manual briefly describes two capabilities of the SECCHI flight software to remove cosmic rays from HI images. The first is a two image scrub where the current image is compared with the previous image on a pixel by pixel basis. If the current image pixel is greater than previous pixel plus N times the photon noise of the pixel, the pixel is replaced with the previous pixel. The three image scrub takes the median value of the current, previous and oldest image. The original two 2048 x 2048 pixel images are then saved to compare with the next current image.
We have plotted the scrub data for each HI telescope (1/2 and A/B) first by month and then by 6 day intervals. The plots contain the following information:
Plotted as a line is average value of the number of pixels in each image in the sum that are scrubbed
Plotted as individual points (+) is the scrubbed value of the first image in the sum. This is always higher because it is comparing the first image in the current sequence with the last image of the previous sequence. This might be a difference of 10s of minutes.
Plotted as error bars are the maximum and minimum of the individual image scrubbings (other than the first)
Following is a table with links to the various file types:
IDL save sets contain the scrubbing information for all the images in a month. IDL software is available in SOLARSOFT to read the files and to generate the plots.
Monthly plots and