High Humidity and More Frosting Issues.

Last night I went out to Kumeu Observatory around 7 pm, Steve wasn't free so I set about testing out the camera in the hopes that by cooking the desiccant I would have solved our frosting problems, unfortunately as I cooled down the camera I saw halos start to develop around the stars and after just ten or so minutes I started to see the tell tale signs of frost starting to form, while I was working in the observatory I had set up my DSLR outside to capture a startrail and after going over the images today I noticed quite a bit of thin cloud that was invisible to the naked eye but was clearly captured by the camera, so maybe some of the halos I was seeing may have been caused by the clouds although the tell tale signs of frosting are really quite distinctive and can't really be mistaken for anything else.

Halos around the stars after cooling down the CCD ^

The problem with the halos must have been in camera though because when I warmed up the camera the halos all went away and when I cooled down the camera they quickly came back, I had read online that after cooking the desiccant it may take a day or two for the desiccant to absorb all the moisture from the camera so maybe there just hasn't been enough time for the desiccant to do it's job or perhaps it's time to buy a new desiccant, we can't really do anything below zero degrees Celsius at the moment as you start to develop the halos below that temperature and once you have the halos they tend to effect being able to obtain good focus, I noticed that the weather station was reporting that the humidity was at 90% so I think this may have been a factor also, when I shut down the dome later on in the night the shutter was literally dripping wet! I also did some tests of running the camera at zero degrees Celsius for an hour or so and then cooling it down as me and Steve had read that in an online forum as being a possible solution to the problem but to no avail as soon as the camera was set to -20 you would see the halos start to form followed by frost in the 5-10 minutes after cool down, we will have to find a solution to our frosting issues quickly as the microlensing season is fast approaching.

Startrail looking south over the Wasp Observatory that I took while working in Kumeu Observatory. ^

I stuck it out until 2 am doing some pointing tests by astrometricaly solving images with the Image Link function in the Sky X, using this technique I could easily find variable stars such as AR Sco, so we will probably just use this method until we can get a really robust pointing model done, by 2 am the clouds had inevitably rolled in and put an end to the nights observations.

Posted by Jonathan Green.

Ice and Clean

After the adventures in collimation of the night before, another clear night saw Jonathan and I again off to Kumeu (missing out on the AAS film night).  Jonathan was out there first and was quickly frustrated once again by frosting on the CCD sensor.  After a couple of "warm up" and "cool down" cycles still hadn't fixed it, it was clear this problem was going to start getting annoying rather fast.

Cleaning the corrector plate on the C14

After I arrived, we decided to leave the camera with the coolers off for a while and tackle another little job that's been on the list for far too long - the C14 corrector plate.  We haven't cleaned the corrector at all since we started (a long long time ago....) so you can imagine the quantity of dust, water spots, insect gunk and all manner of things on there. (Actually you don't need to imagine - we've got quite a few pics of the corrector on the blog!)

I'll get you....dust particles... 

Using the old faithful technique of a bulb blower,  soft white tissue and 30% alcohol solution in demineralised water, the outside surface of the corrector was slowly and carefully de-gunked  - which had the predictable effect of showing just how much gunk was on the inside of the corrector - this will have to be addressed in the short term.  A medium term project might also be to get the primary cleaned (I know people have had fantastic results using the novel cleaning kit from https://www.photoniccleaning.com/)  or potentially re-aluminized - as there is an appreciable quantity of dust and a small mould/fungal spot.

Dismantling the filter wheel on the SBIG ST10XME

We also checked out the filters, as we know the new RGB we were testing needed to be tightened up - but also noticed the L and the #12 Wratten filter were looking past their best too...  after pulling the flter wheel out it was clear that the L and #12 filters would definitely be causing issues with our images.  Even though we are planning to replace these filters, these too had a very careful cleaning and came out looking much better than they were originally.

Carefully cleaning the L filter

We reattached the camera and cooled it down, only to be instantly frustrated by frosting again almost immediately.  We are definitely going to "cook" the dessicant pack again, as it's clear there is obviously moisture in the system that's not being removed.  We jumped on the internet (via Steve's phone as we've not get this sorted yet still) and learned a couple of interesting things about this problem:

1. you can buy a replacement dessicant plug that takes disposable gel packs - this is fantastic as it would allow us to replace the dessicant quickly without the "cooking" process
2. A technique described on a forum for cooling down in stages to avoid the frost. 

We gave #2 a go and cooled the chip to zero for half an hour before taking it any colder - this seemed to do the trick (though it might have just been luck this time) as we managed to cool further without seeing any frosting.  We'll certainly add this to our process for the future to see if this will avoid this situation.  

One final challenge for the night is that the focal reducer we have is also in dire need of replacement/professional cleaning or removal - though at this point we noted that we don't have the original 2" nosepiece- something else for our shopping list.

After I left around 12:30, all Jonathan did  was try image for a while but soon got hit with more frosting issues so frustrated, packed down and cleaned up the observatory including removing a dead mouse from under the dome ( gross but at least we know the rat bait is effective ), Jonathan ended up taking the desiccant home and cooked it (it goes in the oven for 4 hours to dry out the dessicant material) the next day. He then took it back out to Kumeu and reinstalled into the CCD camera, hopefully that should resolve our frosting issues for a while.

Steve and Jonathan

Collimation

Dew on the inside of the corrector plate

Last night Jonathan & Steve met up at Kumeu Observatory to take advantage of the clear skies and get to work on collimating the "Nustrini" C14, Jonathan arrived first and while waiting for Steve set about focusing the camera and doing some pointing tests, from the outset he was hit with frosting on the CCD, this happened 4 times before we decided to run the camera at -15 instead of -20, this seemed to resolve our frosting issues on the night but what is certain is that we either need to cook the desiccant again or replace it with a new one, also had an issue with dew on the inside of the corrector plate again and found this was due to the dew strap not being warm all the way around, it looks like we are using a dew strap that is not designed for a C14, so after adjusting the dew strap so it was providing heat to the affected area and taking off some of the masking tape over the vents so that we could air out the optical tube, thankfully this seemed to to do the trick as the dew eventually disappeared. Grant at Stardome has experience a similar problem with dew on the inside of the corrector - whilst sealing any small holes is great to prevent dust setting into the system it is also preventing adequate ventilation, and any humid air in the tube is unable to be circulated out.

CCD Inspectors's Single Star Collimation 

.After Steve arrived we set about collimating the telescope, we used CCD inspector and defocused a single star into an annulus.  It appears we don't have enough "travel" on the TCF focuser to defocus the star enough, so we needed to manually defocus to get the start image big enough for the CCDInspector process.

Starting off by identifying where on the image the collimation screws were in relation to the image (by making a shadow with my hand) it was easy to see which screw to adjust - basically the one which "moves" the image in the direction of the line on screen.

After making the corrections that CCD inspector gave us we improved the collimation then moved onto using the multi star collimation feature of CCD inspector, we used an open star cluster near the zenith but after a few attempts we ended up making the collimation worse so ended up having to star over !

Steve Hennerley collimating the "Nustrini" C14.

When we did start over though, and had to manually refocus and start again with the single star, we learned that our "shipping bolts" we installed to combat "mirror flop" may be causing us more problems than they are solving.  If we leave them loose enough so they don't interfere with the mirror, they are probably ineffective, and we've noticed they loosen up as we slew around (as the mirror cell is moving we guess).  If we tighten them however (or more correctly, tighten the focus against them) then there is a significant deflection of the mirror affecting collimation.  The shipping bolts are not opposite each other - rather they are 120degrees apart and opposite the focuser (if you imagine the CCD inspector picture of the collimation screws above as being the back of the scope, the focuser is at "A" and the two bolts are at "B" and "C").  This has the end result that the mirror is pivoted along the A to "B-C midpoint" axis.   This may need revisiting - but for now we left the bolts "just" touching the mirror cell.

We ended up collimating the telescope until about almost 3 am in the morning, we could definitely see a huge improvement in the images and the shape of the stars, after Steve left Jonathan managed to focus a star near the zenith at a FWHM of 1.7 arc seconds per pixel, after taking a few test shots he could really see how improved the images were but we will need to monitor the situation because if the primary mirror is flopping we can expect the collimation to degrade fairly quickly, with another clear night tonight Jonathan and Steve plan to catch up again and see what else can be done in preparation for the forthcoming microlensing season.




Posted by Jonathan Green & Steve Hennerley.

Cables....Be Gone !!!

Even though the skies weren't particularly clear this evening, Jonathan and I headed out to the observatory to tackle a few jobs that were on the list. A critical job that needed doing was to reconnect the dew strap to 12v power.  Since we'd replaced the mount electronics, the dew strap power couldn't actually be hooked up as the power had been routed through the original mount wiring (pretty much the only thing that was).

I wasn't keen on a temporary fix (we all know how these have a habit of becoming permanent) - and a "dream" of mine since we installed the paramount was to get as much of the cabling as we could to use "through mount" cabling to eliminate the risky "cable snake" that carried signal and power to the scope equipment.

Indeed when we rebuilt the mount, we were already supplied with the standard SoftwareBisque connector panel -  this was prewired with USB, a multipole pass thorugh power connector 5v and 12v outputs (though low current - we weren't too comfortable trying to drive the heater with the 12v).  We worked out this was almost enough for us to connect everything we needed bar a couple of items - one of which was the dew heater.

Custom wiring box on the mount dovetail plate

In the end we added to this two "network" sockets (connected with Cat5E cable) and two DC power sockets (locking 2 pin connectors) neatly mounted to the dovetail plate in a 3D printed enclosure. This provided all the connectivity we needed now, plus a little room for changes and expansion as we broaden our astronomical horizons.

in theory therefore, all that was required was making up a few cable connectors and we'd be to enjoy a cable-snake-less future....   Step one though is that we hadn't quite worked out the best (ie tidiest) way to get power into our extra power cables.  There were a number of spare "keystone" type connectors in the mount side panel we could have used - but unfortunately the locking connectors we used at the scope side were too big to fit.  We were originally planning to use "Anderson Power Pole" connectors but they didn't have an elegant panel mount solution.

The mount control panel showing our
newly installed Anderson PowerPole
connectors (top centre)

In the end the 3D modelling software and 3d printer again came to the rescue and we manufactured a custom "keystone" style mounting bracket for a pair of "PP30" connectors.  After adding further PP30 connectors to the lead from our 12V power supply (which would have been easier with the correct crimping tool for the job!) , and the appropriate 2 pin connector to the lead to the dew heater we were finally ready to test.  The dew strap (controlled by a PWM controller designed to handle LED lights) heated up properly and we were back in business to fight the dew. (if only it had been powerful enough to evaporate the clouds that had started gathering thickly!)

How many parts?

Of course one win doesn't make a successful evening - and with one device fully cabled up through our new mount wiring, sights were set on the rest of them!  Next in line was the biggest chunkiest cable - the power supply to our SBIG ST10XME camera.  From research this unit couldn't be driven from just 12v - the power supply has +12v -12v and +5v all supplied though a "DIN" style connector.

Making the cable connectors

The plan for this was to route through the small "Kycon" 4 pin connector in the SoftwareBisque wiring loom (labelled "power in" on the pic above).  this meant making up two adapter leads with DIN connectors on one end and "Kycon" on the other.  The DIN connectors were straightforward enough (once I'd checked, diagrammed, double checked and tested the pin layout) - but the Kycon connectors must be the fiddliest, most over-engineered plug on the planet.  It is supplied in no less than 8 individual parts, all in separate plastic baggies and a set of instructions.  The first one took some time to carefully assemble - though by the time I got to the second it was admittedly not quite as challenging.

Whilst it was a little nerve wracking to plug the new connector into the camera (even after double checking the polarity and voltage of the 3 voltage line pins), happily everything worked as it should have done and the camera spun up nicely.  The only remaining piece of equipment to handle was our Optec TCF Focuser.

As luck would have it, this one was probably the easiest.  The focuser connects to the controller by way of a 9 pin "D" plug cables to a modular RJ45 socket.  As a career geek, I've always got a handful of RJ-45s and a crimper at hand, so this was a 2 minute chop the wire smaller and connect on a new plug (which was even cabled as standard "T-568-B Spec").  Adding a small Cat5 patch cord at the control panel end and suddenly a long time dream was just about reality!

All that remained was to tidy and tie up the wring to keep it need and free from snagging on anything and to double check all our connections, and - importantly - to make sure everything still worked..

The process of moving from externally cabled equipment to using a "through mount" approach has taken a lot of planning - even at the early stages when we were tearing out the old control gear from the mount.  We needed to have our dovetail plate machined to take extra cables, and even create custom connector boxes.  Even with everything in place there was a bit of research required for the final cabling and it took a good few hours just to get everything built and plugged in.

The end result though is that now, as well as a much neater set up, we are free from the worry of the cables dragging on the floor or snagging on something - or of course one of us tripping on it.  We've also reduced the risk of damage to the cables, or a connector.

Steve

The end result - notice that all the cabling to the OTA now goes to the dovetail palte connector boxes.

6th-7th of May, Clouds and CCD Frost.

On the 6th of May I headed out to the observatory after sundown to be pleasantly surprised to find that the Wasp Observatory was open, Nicola Gujer was there using the University of Auckland's Department of Physics Meade 12' Inch LX200 Schmidt–Cassegrain to capture data for her project to study the astronomical "seeing" in Auckland, after setting up I went to focused on a few stars only to find I was getting some pretty bad results, after realising that I wasn't pointing the telescope high enough I managed to focus a star with a FWHM of 1.8 arc seconds per pixel, after finding an interesting target to image I noticed some strange features on the images, I think some of the early ones could have been ice starting to form and I was sure of it later on when the familiar arcs appeared, knowing that the only way to fix this was to "warm up" the camera, I did so and confirmed that the aberrations on the images were indeed caused by CCD frosting, the thing was I had to "warm up" the camera about three times before the problem went away entirely so i think we may have to cook the desiccant again.

NGC 2997 with the 1st signs of frost starting to form.(note that the image is uncalibrated and was also affected by the gibbous Moon.) ^

The Star that Nicola was monitoring went behind the trees so she packed up and headed home around 11 pm, after she left I started imaging part of the Lobster Nebula (NGC 6357), I captured around half an hours worth of data before the clouds started to arrive, I tried to wait them out but they were very consistent, it was very frustrating as I could tell the rest of Auckland was in the clear, the clouds were coming in from the west and not getting much further in before thinning out and dispersing, while I waited I got the vacuum cleaner out and gave the observatory a good clean up, after packing down I left the observatory around 2 am.

Part of the Lobster Nebula (NGC 6357) ^

I also went out to the observatory on Sunday night (7th) but got clouded out before I could get much done, I looked at the cloud sensor downstairs and noticed I had made the right decision leaving the previous night as the sensor showed that the sky didn't clear until 6 am!

Posted by Jonathan Green

Documentation, Guiding, and "Point Telescope Here"

After a few rainy nights, the clouds cleared and another opportunity came up to knock off a few tasks. I arrived the site a little earlier than Jonathan and as I was starting things up, started to produce our "SOP" (Standard Operating Procedure) documentation.  By documenting our startup, operation and shutdown procedures we will ultimately make it easier to train others into using the site - and more importantly have a consistent way of doing things.  This also allows us to document little used procedures to save "head scratching" time when we need to use them again.

So we now have the bones of the Startup, Guiding and also "Point Telescope Here" documentation.

Cats Paw - 40 mins exposure (2 min subs)

The 'PTH' process is one that we were really happy to get working the last time we were set up - this allows us to centre an object in our field, if it's slightly off to one side say, just by clicking the point in the image that we are interested in.  The mount automatically tweaks it's alignment to get your desired target dead centre.

It's not a particularly hard process to get working - in fact when we first did it we were surprised we had taken so long to get it working.  It was so easy in fact that we didn't bother writing down what we'd done.   Needless to say, it wasn't working in the  new setup, and we couldn't quite remember the simple steps we needed to do!!

After requisite head scratching, it was indeed really easy to do - so I did it - but more importantly, I also wrote down how I did it so that next time it will be much faster!

Whilst working on this we also discovered the cause of the guiding woes from earlier in the week - it looks like it was just an extra "calibrate" that might have been needed to fix the problems!  We had guiding working just fine in all the areas we tried.

Since Jonathan had enjoyed the remote operation experience so much, I also improved the monitor setup down in the bunkroom - there are now two bigger monitors to use which makes operation all that much easier.

The other major task completed tonight was another improvement on out polar alignment by doing a few more rounds of drift alignment.  We have got rid of almost all the drift but still see more East/West movement than we are expecting - this possibly needs more investigation (could be just PE) but it's so slow that the autoguider will take care of it fully for now.

There was a little light cloud around so our test imaging wasn't particularly great and we are desperately in need of collimation.  We have found out there is to be some microlensing work to complete next month so the race is now on to get these tasks - along with checking out the filters and focal reducer - knocked off before then.

2nd - 3rd of May, Cold Clear Skies!

I didn't get out to Kumeu as early as I would have liked last night as I helped to host a talk by the co-creator of the PhotoPills app Rafael Pons at Stardome Observatory on behalf of the Auckland Astronomical Society, after the talk was finished I gave Rafael a quick tour of the facilities and then dropped him off at the backpackers he was staying at and headed out to the observatory. On arrival I was pleasantly surprised to find Auckland Astronomical Society member Alan Kane on site observing with his big Dobsonian, after exchanging pleasantries I opened up the dome and got to work.

The first thing I did was obtain focus using the TCF's auto-focus procedure this worked very well with a focus star giving me a result of a FWHM of 1.6 arc seconds per pixel, I then set about slewing to different objects and taking some test images but after a while I noticed that the TCF wasn't tracking the temperature changes so the focus had shifted off a bit, the temperature had dropped by about two degrees so when I went to run another autofocus I found that I could no longer obtain focus as the TCF wanted to go past 7000 steps when looking for the autofocus start position, knowing that the solution was to put the TCF back to the 3500 half way point and then manually get the focus back to as tight as I could by eye, I finally got back into focus although the focus Star I was now measuring was only giving me a result of a FWHM of 2.3 arc seconds per pixel, I don't know if that was because the "seeing" had changed or because having re-set the focus manually I had somehow changed the collimation.

- A stack of ten one minute exposures of the spiral galaxy NGC 5247, I think in this image the focus was already starting to go "Pear" shaped.

Imaging targets around the sky using the auto-guider I noticed that objects in the east couldn't be autoguided as the target stars were drifting off fairly rapidly, on the western side of the sky their was no problem at all so I think we really do need to do a lot more drift alignment to make sure we can autoguide on both sides of the sky, at this stage of the night I noticed the star shapes looked a bit funny ( not quite round ) I wondered if maybe the collimation had slipped out, but after a bit of investigation I found that we had dew forming on the inside of the corrector plate! I had encountered this the night before when hanging out with Grant Christie at Stardome while sitting in on his observations of a binary Wolf-Rayet star system, I knew that the solution was to crank up the dew strap to heat up the corrector plate but unfortunately our dew strap is not currently powered, I remembered Steve saying he had to think about how we are going to power it moving forward, so not wanting more dew to form on the inside of the corrector plate I shut down and headed home around 2:30 am, I've got to say I'm very thankful that Steve had setup the computer downstairs to control the dome computer remotely, so that I could operate in comfort, as on the way home I noticed my car's outside temperature sensor was recording the outside temperature at a chilly 3 degrees!

- Dew on the inside of the corrector plate.

So moving forward I think we have a number of tasks to prioritize before we can start doing some research grade observations, we obviously really need to get the dew strap powered! With the cold / damp weather here now it won't take long for dew to form on the corrector plate, we also really need to take the CCD off the mount and make sure the new filters are not moving, if the filters move even slightly we won't be able to do the data reduction correctly and with the microlensing season about to start we really need to make sure our data is reduced correctly for scientific submission and of course we really need to spend a full night or two doing the tedious task of drift alignment so that our autoguider won't have to work as hard and that autoguiding will work across the entire sky, all in all though we have made some great progress over the last few weeks so it's just a matter of building upon these successes.

Posted by Jonathan Green