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Friday 28th Dec 2018 44F: An unexpected hour of sunshine in the late morning had me back up in my observatory. The Sun was blank in white light but had two prominences in H-alpha at my 10 o'clock. [Western limb.]
The [new] Simple Handset paddle was excellent for centering the sun at the eyepiece. I adjusted it to hang with enough cable drop to avoid pulling directly on the OTAs. I have finally adjusted the 6" to match the field of view of the 7." This will save constant adjustment between the two to check for matching features on the Sun.
I tried various filters to bring out any surface detail and then with the binoviewers viewed 'straight through.' [No 45 elbow or star diagonal.]
Now I need a pair of 20mm eyepieces for a larger image. The pair of 26mm Meade 4000 offer a slightly smaller image than I would like. Adding GPC elements boosts the power far too much. A second Meade 4000 in 20mm makes slightly more sense than a new budget pair.
The image on the laptop screen was far too large in the Celestron Neximage5 so I soon gave up on that. It needs a proper spring clean to get rid of all the dust on the optics and "naked" camera sensor.
The AWR drives are working well on my big mounting now. I can just leave them to run for hours after Syncing on the sun in C-Du-C. No heat is detected on any of the components except the power supply warms a little after several hours. Slews and Gotos still need watching due to the large pier. The telescope could easily collide with the pier if I don't constantly monitor the clearance.
The dome slit is very easily advanced at intervals, via the crank, to keep the view clear for the telescopes. This is quickly becoming almost routine. Anticlockwise on the crank moves the dome anticlockwise.
Much heavier cloud has arrived from the northwest so I busied myself making minor improvements. The thermometer is now on the southern wall fixed to the SW 4x4 to avoid direct sunshine through the slit. The 'outdoor' sensor is located in deep shadow, year round, where the sun's heat cannot affect the readings. The idea is to compare the two readings to show the difference in temperature and whether that affects "dome seeing" or not. If warm air flows constantly out of the observing slit then it will spoil the view through the telescopes.
This is not the same thing as poor atmospheric "seeing" but is much more localized. My observatory is well ventilated and enjoys quite a chimney effect through the open doors down on the ground floor. That said, it is midwinter, so the sun has little heat to warm the dome so far. I need a solar screen to stop myself being blinded by the sun while looking through the telescopes.
I can't remember having seen more than a 2°F difference between inside the dome and outside, in the shadows under the veranda. The entire structure is thermally light so I am hoping for almost no solar gain. Buildings of blocks or bricks tend to soak up heat and let it out slowly over time. A wooden structure should not gain remotely as much heat and should dump it quite quickly using ventilation. I could have improved matters with white paint on the dome but wanted something much less visible from a distance.
Click on any image for an enlargement.
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