WCS issue in sector 1, camera 2, ccd 1 #20
Description
The SPOC-derived WCS for sector 1, camera 2, CCD 1 uses a ninth order polynomial for the distortion correction. This is unlike other sector/camera/CCDs, which use lower order polynomials.
In the corners of the FFI from sector 1/camera 2/CCD 1, the WCS solution from the ninth order polynomial is not accurate. However, by taking only the first five components (i.e. a fourth order polynomial), the fit is much better. This can be seen in the attached image. This FFI cutout is centered on TIC 403154032 (RA = 336.713 deg, dec = -56.636 deg). Using the WCS derived from a ninth-order polynomial, the predicted position of the star is off by ~20 pixels. Using the WCS derived from a fourth-order polynomial, the predicted position of the star is more accurate. tesswcs also uses a WCS with a fourth-order polynomial, and you can see the predicted position is in good agreement.
tesscube should be updated to only use the first five components from the polynomial for sector 1, camera 2, CCD 1.
