1. HI 1A - Raw Image

2. HI 1A – Shutterless/Flatfield Corrected Image (secchi_prep)

3. HI 1A – Bloom removed image

4. HI 1A – Background subtracted image

10. Starfield fitting for alignment

11. HI Calibration Parameters HI 1AHI 2A Pre-flight StarsPre-flightStars HI x offset (°) -13.98 -13.9789±0.0001-53.68-53.51±0.02 HI y offset (°) 0.00 0.075±0.0020.000.23±0.02 HI roll (°) 0.00 1.0241±0.00010.000.130±0.001 Distortion parameter (μ) 0.16677 0.146±0.0060.833290.820±0.002 Fparaxial (mm) - 77.4263-21.4311 Platescale (degrees/pixel) 0.009977 0.009990060.0360470.0360921 CCD x offset (bins) 0.00 -0.068±0.0070.00-1.9±0.2 CCD y offset (bins) 0.00 -1.31±0.080.001.9±0.3

12. HI Calibration Parameters HI 1BHI 2B Pre-flightStarsPre-flightStars HI x offset (°)13.9814.185±0.00653.6853.2±0.2 HI y offset (°)0.000.022±0.0020.000.7±0.2 HI roll (°)0.000.30141±8x10 -5 0.00-0.6±0.4 Distortion parameter (μ) 0.100010.1581±0.00060.65062-0.820±0.001 Fparaxial (mm)-77.6297-- Platescale (degrees per pixel) 0.00996254080.009963880.0359479- CCD x offset (bins) 0.00-0.5±0.30.00-6.5±0.8 CCD y offset (bins) 0.00-0.9±0.10.00-3±2

13. HI 1A – Star removal image

14. HI 2A – Milky Way

15. HI 2A – Magellanic Clouds

16. HI 1A – small-scale flatfield 1.Take series of images (at least 3) 2.Find the minimum value per pixel 3.Low-pass filter this background 4.Pixel-to-pixel variations are the difference between the two over small areas of the CCD 5.Do this many times to build up statistics for each pixel

17. HI 1A – small-scale flatfield

19. HI 1A – small-scale flatfield uncertainties

20. HI 1A – large-scale flatfield 1.Identify stars in image 2.Wait for them to drift through the field of view 3.Measure the variation in their intensities as they do so. 4.Do this for many stars.

21. HI 1A – large-scale flatfield