Check if platescale varies over the mission using measured occulter diameter

[jburkepile]

For each K-Cor camera (there are 2 cameras), plot the measured occulter diameter for each of the four K-Cor occulters to see if there are any changes in the measured diameter over the K-Cor mission. Such changes suggest a change in the instrument platescale. Information needed to create the plots can be read from the K-Cor fits headers.

Method:

1. Find the 2nd K-Cor level 2 image for each day of the mission. [ On occasion the first image of the day may still have the dome slot or calibration hardware in the beam that causes a blurred structure in the images. These can be avoided by selecting the 2nd K-Cor image of the day. ] Use a 15 second image - do not use an average image.
   Images should have filenames: yyyymmdd_hhmmss_kcor_l2.fts.gz

2. Read the image FITS header keywords listed below for one K-Cor image per day over the K-Cor mission: Jan 1 2014 through Nov 25, 2022 and store the information in a file for plotting, for computing the platescale, and for future reference:

• DATE-OBS - date and time of image
• RCAM_DCR - camera 0 distortion corrected occulter radius
• TCAM_DCR - camera 1 distortion corrected occulter radius
• RSUN_OBS - radius of the Sun in arcsec
• OCCULTRID - ID of occulter in telescope

3. Make a separate plot for each of the 4 K-Cor occulters that shows the occulter radius in camera 0 and camera 1 over the K-Cor mission using a different line style to differentiate the the two cameras.

4. Ben has pointed out that early in mission the observers could focus the cameras (toward/away) from the Sun. This would change the platescale. The focus value is in the headers. This would have occurred from start of mission until ~June 19, 2015 when old camera stages were replaced. We need to record the focus keywords from the headers to assess the impact of the focus changes on the platescale. The keywords to read and record are:

• RCAMFOCS
• TCAMFOCS

[bberkeyU]

I pulled the camera focus values from the DB. It seems interesting. I have a CSV file of the data, but it is ~26Mb, so I can't attach it to the GitHub posts. But it is in /home/berkey/kcor-cam-focus-time.csv on the unix hosts; happy to copy it somewhere else if you cant read this location.

I've attached two plots for the focus from the start of the mission until the focus motors were removed in June 2015. The second plot zooms the z-scale to ignore the Rcam=10.02mm 2014-06-07 17:06:58 -> 2014-06-11 22:52:57.

[jburkepile]

I have asked Mike to create level 1 cam0 and cam1 images with circles in the gifs in ticket #359 in order to study changes in the measured radii for the winter occulter. I used Samaiyah's plots and IDL save file to identify dates with changes in the measured occulter radius.