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--- vatt:dome_flats [2022/02/13 21:27]
paul
+++ vatt:dome_flats [2022/05/07 04:52] (current)
paul
@@ Line 9: / Line 9: @@
     * Suppose you want to obtain dome flats after observing. You will need to close the dome shutters, which should only be done with the mirror cover on. Therefore, stow the telescope, disable drives, close mirror cover, and close dome shutters. Then, open mirror cover, and enable drives.
     * The telescope is still in the stowed position, i.e., nominally at Az=180°. With Dome tracking enabled, right click on the Dome azimuth field in TCSglue and introduce an offset of +190°. Wait until the dome stops rotating to its offset position, bringing the screen to the South meridian.
-    * Slew to RA = LST + 2'  (Local Sidereal Time + 2 min, i.e., round LST up and add a minute), Dec = -27°17'55"((This corresponds to 30° above the horizon: -[(90°-φ)-30°]= φ-60°, where φ = 32°42'05" is the local latitude.)) ((Alternative way, using XEPHEM: find a star close to Alt=29.5°, and Az=179°, and slew to its position ("Telescope Go To" in XEPHEM).)) As a result, the telescope will be tracking (through the closed dome) an object which is about to pass through the south meridian at Alt=30°. Wait until the telescope reaches Az=180°, and Disable Drives. Disable Dome Tracking (otherwise the dome keeps oscillating slightly around the required position).
+    * Slew to RA = LST + 2'  (Local Sidereal Time + 2 min, i.e., round LST up and add a minute), Dec = -27°30'00"((-27°17'55" corresponds to 30° above the horizon: -[(90°-φ)-30°]= φ-60°, where φ = 32°42'05" is the local latitude but the telescope pointing compensates for atmospheric refraction.)) ((Alternative way, using XEPHEM: find a star close to Alt=29.5°, and Az=179°, and slew to its position ("Telescope Go To" in XEPHEM).)) As a result, the telescope will be tracking (through the closed dome) an object which is about to pass through the south meridian at Alt=30°. Wait until the telescope reaches Az=180°, and Disable Drives. Disable Dome Tracking (otherwise the dome keeps oscillating slightly around the required position).
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@@ Line 18: / Line 18: @@
     * After finishing your flats, return dome to home Az=180°: Turn on Dome Tracking, right click on the Dome azimuth field, and eliminate the dome tracking offset. Keep Dome tracking on (you will need it later when you go to the dome).
-    * Return to the Control room and release breaks in TCSglue. (The mirror cover being still open, the telescope is well balanced and will not move of its own accord. Better make sure this is the case, though: In TCSglue, release breaks, and observe the behavior of the Altitude value. The Azimuth axis will not budge because the hydrostatic bearing is off.)
+    * Release breaks in TCSglue. The mirror cover being still open, the telescope is well balanced and will not move of its own accord. Better make sure this is the case, though: In TCSglue, release breaks, and observe the behavior of the Altitude value. Better, the observer and co-observer should split the task, one releasing the breaks in the control room while the other is in the dome ready to move the telescope to zenith manually. (The Azimuth axis will not budge because the hydrostatic bearing is off.)
+      * Solo observers may have to prevent the telescope from slumping towards the horizon, using the small ''A'' ladder with some rubber foam, wedging it against the South counterweight cylinder.
     * In the dome, power up the stow pin system. Then move the telescope manually to the stow position, and insert the stow pins.
     * Use your presence in the dome also to home the dome position in the usual manner (manually tweaking the dome's encoder wheel).

MOON

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