Changes
/* Focusing the telescope */
* Click on the "continuous" button for an ongoing series of 2 second exposures
* Open the slit wide, to about 4"
* Adjust the slider bars at bar to the bottom right of the image (both most of the way to adjust the left) to set scaling, or hold down the brightness and contrastmouse button while mousing over the image, as in ds9 * Use Using GUIDE speed, use the handRA & Dec arrow buttons on the bottom-right of the TCS GUI (or the hand paddle if in the dome) to position the star near the centre of the slit (in both X and Y)* Adjust the telescope focus with on the TCS (or the hand-paddle if in the dome) in steps of 3-5 units and assess how the star image changes* The star will move around due to the translation of the secondary mirror, so adjust it back into view with the hand-paddle if necessary* Astigmatism in the system extends the star image diagonally and the orientation indicates whether the focus value is too high or too low: Star extended from upper-left to lower-right: focus number value is too high Star extended from lower-left to upper-right: focus number value is too low
* Best focus is where the star is as round and sharp as possible
* Optimum focus varies with temperature, typical summer values are ~2200 while cold winter nights may be closer to 2270 units
