Wednesday, April 26, 2017

Back In Action!

After almost a year of the observatory being on hiatus, we finally got the observatory up and running again, the Paramount GT-1100S unfortunately could only be repaired by upgrading it's internal motherboard and chip sets to that of the Paramount ME-II, thankfully Software Bisque provided us with an upgrade kit for a reasonable price, the upgrade required us to modify the mount itself to accommodate for the larger chipsets and motherboard, the work was mainly carried out by Steve Hennerley and Tony Burns, after many setbacks and delays the mount is now operational ( expect a much more detailed account of the upgrade from Steve in the future ), Jonathan Green and Grant Christie then installed the newly upgraded mount back on the pier after cyclone cook bypassed Auckland the other week.

The upgraded Paramount GT-1100S
Last night Jonathan Green and Steve Hennerley met out at Kumeu to cable up the mount and give it a test run, we quickly ran into problems after connecting the mount to the Sky X as we found that it was tracking in the wrong direction in the right ascension drive, getting a bit frustrated with not being able to fix the problem in the Sky X we decided to install the latest version of the "Sky" from the Software Bisque website as our old version was well out of date, this completely fixed our problem with the right ascension drive, so once that was sorted we moved onto drift aligning the telescope after re-setting the altitude graduation of the mount to the latitude of our location we were pleased to see we weren't really that far off polar alignment, we spent maybe around two hours or so drift aligning but plan to do a much more thorough job once we refine the balance of the optical tube, camera and counterweights.

After getting a rough polar alignment we set about focusing the telescope, we quickly became frustrated with the auto-focus failing, so after re-setting the temperature compensating focuser to the halfway position, Steve manually focused the telescope and then locked the primary mirror using the shipping bolts, we still couldn't get an auto focus after doing that but we decided the focus was probably good enough to move forward, so we then set about finding a star to synchronize onto so that way the "Sky X" would know where the telescope was pointing, obviously the new version of the Sky X is a bit different than the old version that we were used to using, so it took us a while to figure out how to do it, what we actually ended up doing was loading up an old pointing model I captured before all the troubles began and then re-calibrated the model by syncing to the star Spica, this seemed to work well with targets being only slightly off center, we didn't worry about that too much as the camera will need to come off the mount to have the filters looked at and we will also need to re-balance and re-collimate the "Nustrini" optical tube, so once that's all done we will no doubt attempt a really robust pointing model that should increase our accuracy exponentially.
Steve Hennerley cabling up the upgraded mount at Kumeu Observatory last night

By this time it was starting to get late and Steve had to work in the morning so we got onto doing what more we could before Steve had to go, so we ended up getting Pin Point in MaxIm DL to successfully plate solve an image and we also got Image Link in the Sky X to successfully plate solve an image which will be very helpful once we get back to starting a new pointing model, Steve also wanted to capture a "first light" image and did so by capturing the Sombrero galaxy, after Steve left I couldn't help myself and set about capturing ten one minute images of Messier 83 (Southern Pinwheel Galaxy) I then calibrated them using my old calibration files ( so they probably didn't work that effectively, although visually you could see a big improvement in the images once they were calibrated ) then stacked the images to produce the best "first light" image I could, the result is below, although please note the focus was still only manually done at this point.

Messier 83 (Southern Pinwheel Galaxy)

After completing the "first light" image, I set about trying to figure out why the auto focus wasn't working, I must admit to being a little rusty after being out of action for so long but after many frustrating auto-focus fails I managed to find the correct settings in the options to make it work and managed to focus a star at a FWHM of 2.5 arcseconds per pixel, which isn't fantastic but is probably more indicative of our collimation rather than the local "seeing" conditions, Steve had fixed the temperature probe at the start of the night and after setting the focuser to track the temperature I can confirm that the TCF was successfully tracking the temperature changes for the rest of the night, I did then attempt a small pointing model but that ended up failing as the sample points were not solving in Image Link, it must have been another setting that needs adjustment or maybe the focus wasn't good enough, I'm not sure, at this stage it was getting pretty late ( 3:45 am ) so I packed down and closed up the dome and headed home around ( 4 am ).

All in all it was a good start, we still have loads of work ahead of us but hopefully we can now move forward confident that the upgraded mount will be dependable, I'm also looking forward to getting back out there tonight if the sky stays clear as well.

Posted by Jonathan Green

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