Monday, May 16, 2016

Day and Night at Kumeu Observatory.

On Saturday the 14th of May myself,Tony Burns and Steve Hennerley met up at Kumeu Observatory to see if the dome slave issues could be resolved, I'm happy to report that with Tony's expertise the dome now stops at home and can be parked again, so now it should just be a matter of refining the parameters to get the dome slaved to the telescope properly, Tony did mention that he wasn't really that happy with the setup and is already making plans on how to best improve the dome slave situation, Steve also managed to find the problem with the dew strap it was just a wire that was loose so that's all fixed now so dew shouldn't be a problem anymore, while we were testing the dome rotation a new problem with the dome motor became apparent it was really making some jerking movements that none of us had seen before, after some inspection Steve discovered that one of the bolts had worked it's way loose, so he jacked the dome up a bit so we could take the motor out and repair it which Steve did without much issue, this was really lucky that this had happened while Steve and Tony were there as no doubt if it had happened at night when I was there by myself it would have sent me home early and been a waste of a good night.

Tony Burns working on the dome control board. ^

Steve Hennerley fixing the loose bolt on the dome motor. ^

One thing that happened while we were trying to refine the parameters of the dome was that when Steve was driving the telescope around with the Sky X it kept on trying to point at the ground, we couldn't figure out why it was doing this at the time, at this stage it was getting late in the day and Steve's daughters who had been very well behaved all day were starting to become a little bit restless so we called it a day and all headed home, after making myself something to eat I headed back out to Kumeu by 7 pm, after setting up I discovered that the Sky X no longer knew where it was pointing in the sky, when the mount was in the home position the Sky X thought it was pointing up near the zenith, so no doubt this was the reason why the telescope had been trying to point at the ground earlier, after ringing Steve to discuss the problem I set about doing a resynchcronisation, the 1st problem I ran into was the finder scope was not even closely aligned anymore as we had taken it off the OTA a while back, trying to center a star without the finder scope aligned is like trying to find a needle in a haystack! So after further discussion with Steve he suggested I align the finder scope on the Moon, but even with the lowest exposure I couldn't see any detail on the Moon, I was a little bit exasperated as I was thinking that I might have to go home and grab my diagonal and eyepiece and have to take off the CCD to just get the finder scope aligned, thankfully I got lucky as some thick clouds rolled in, they acted like a Moon filter and allowed me to see detail on the Moon so I found a large crater and managed to align the finder scope on it, I think this must be the very first time that I was actually happy to see the clouds come rolling in.

Moon image captured with heavy clouds acting as a filter that allowed me to see surface detail and align the finder scope. ^

Now that the finder scope was aligned I set about synchronising the Sky X on some bright stars, through gaps in the clouds I managed to synch to nine bright stars before the rain arrived, this seemed to do the trick as now the Sky X knew where it was, I have left the finder scope on the OTA just in case Grant or Steve thinks we might need to do more star synchronisation than the nine I managed to get, in fact I was thinking that perhaps the problem with our slewing in the zone of death may be due to never having done any synchronisation in that part of the sky before, the rain was quite heavy at this stage ( 10 pm ) so after packing up I headed home to relax, by midnight things had cleared up again, after consulting some satellite images I figured I had maybe a 3-4 hour window of clear skies to work with so I headed back to Kumeu and got back to work, the sky was fairly clear when I arrived so I set about capturing a new pointing model, I managed to capture 230 samples before I ran into the zone of death as sample points must have drifted into this area, so I finished and saved the pointing model before re-homing the telescope, I then turned the pointing model into a super model and found that it just dropped the last sample just like last time so I had 229 good samples to work with, I noticed that the RMS wasn't quite as good as the last model I captured but I think this may have been due to the sky conditions not being as good as last time, the astronomical "seeing" wasn't as good and I did have to image through thin passing clouds from time to time, even though the Sky X had no trouble solving all the images I suspect this may still have had an adverse effect.

After converting my pointing model into a super model and turning on the Pro-Track function so the model could make adjustments to the Paramount's tracking, I set about testing the accuracy of the new pointing model, again I was very impressed with the accuracy of the model with objects either directly on the crosshairs or just a couple of arc seconds off from it, I'm going to have to monitor the tightness of the shipping bolts on the C14 as any movement in the primary mirror will of course cause the pointing accuracy to deteriorate over time, if this is the case and we do discover that the primary mirror is indeed displaying signs of movement then I'm hopeful that adding locking nuts should resolve the issue, after doing quite a few pointing tests I noticed that the clouds had rolled back in, so I closed up the dome just in time before another heavy rain shower came rolling in, it was 3:40 am by this stage so I just packed up and headed home to catch up on some sleep.

Pointing test of Comet 116/P Wild with a 100 second exposure at 2x2 binning. ^

Pointing test of NGC 5643 the image is a median stack of 4 x 200 second exposures at 2x2 binning. ^

Posted by Jonathan Green

No comments:

Post a Comment

Feel free to add comments - all comments are moderated, so please allow some time for them to show up.

Abusive, commercial, or junk comments are never shown!

Time Zone

All times on this page are in New Zealand Daylight Time in winter GMT +12 or summer GMT +13.