Monday, June 19, 2017

Sharp Focus on a Marginal Night!

Saturday the 17th of June was a fantastic Winters day with lovely blue skies, unfortunately as the Sun began to set thin clouds started to roll in, thinking that I may as well head out to Kumeu anyway in the hope that the clouds would clear up I arrived at the observatory at 7:30 pm, the Sky was certainly not clear on arrival, so I just opened up the dome and hoped that things would improve, while waiting for the sky to clear I noticed that the cloud sensor was no longer logging data, I'm not sure what the problem is, after giving Steve a call, I tried a few things but failed to get it working again, so that will be something we will need to have a look at, as having a working cloud sensor is very useful indeed.


<- The Sharpest Focus ever recorded at Kumeu Observatory so far!


I noticed that the one part of the Sky that seemed not to have many clouds, was looking in the direction of the constellation of Carina, so knowing that there is an interesting target in that part of the sky, I set about gaining focus, It was a bit strange that on a night when the conditions were so marginal I managed to get the sharpest focus ever obtained from Kumeu Observatory! With a FWHM of 1.25 arc seconds per pixel on a Mag 8.6 star! We have discovered evidence that we have mirror flop issues so maybe the mirror just flopped into perfect collimation or something?


After gaining a sharp focus I started to image the Star Cluster Westerlund 2, the cluster contains some of the most massive stars known in our galaxy as well as many interesting "Wolf–Rayet stars", even though that part of the sky was the clearest, I think there was still enough clouds around to end up effecting the images so I'm not sure if the data will be useful or not but Grant Christie and Tim Natusch at Stardome Observatory have been studying the cluster for a while now so they might find the data useful.



^ A stack of an hours worth of one minute exposures of the Star Cluster Westerlund 2 in the constellation of Carina.

By the time I finished the hour long run on Westerlund 2 I set about attempting to gain some data on our current microlensing targets but needing to get five minute exposures I found I couldn't autoguide for long before losing the guide star due to clouds, so after a few attempts I went outside and found that the sky conditions had deteriorated, so I packing down and headed home just after midnight.


<- The Sky Conditions when I arrived at Kumeu Observatory.



Posted by Jonathan Green

Saturday, June 10, 2017

8th-9th of June, A new T-Point Model and Data Acquisition Begins.

On Wednesday night I headed out to Kumeu Observatory around midnight, clouds and rain stopped me from heading out earlier, after arriving I had to then wait for another hour for the sky to clear up enough to bother opening up the dome, after gaining focus I imaged a microlensing target "OGLE_2017_BLG_0896" this time I tried to keep the dew strap turned off in the hopes I could gain better image quality but after just 20 minutes the corrector plate had fogged up, so I turned the dew strap back on and waited for the corrector to clear, unfortunately by the time the corrector had cleared the clouds came rolling back in and I only barely managed to close the dome before another rain shower hit, I waited for a while after this but with no end in sight for the clouds and rain I decided to pack down and head home around 3 am.


^ Dew on the inside of the corrector plate, it's looking like we will have to just work with the dew strap on or else risk not getting much done on clear nights.

Thursday was a lovely clear day so seeing my opportunity I headed out to Kumeu in the afternoon before sundown to grab sky flat's for calibration, while I was waiting for twilight I was visited by Steve Calveley and his wife, Steve owns the land that Kumeu Observatory is located on and he is also a past president of the Auckland Astronomical Society, I showed him all the new equipment in the dome and talked about our research projects, he was very happy to see Kumeu Observatory back in operation and shared some interesting stories about the observatory and the society from back when he was involved, he also expressed an interest in helping out with the current projects.

After Steve and his wife left I got on with capturing Sky flats, now that I have the flats for the "wratten filter" we can now reduce our image data correctly for submission, being there so early and with all our current targets very low in the sky I decided to have a go at doing a new pointing model using the T-Point add on for the Sky X, after a few failed attempts I figured out how to do it properly again and managed to get a decent pointing model, although I did have a few failed pointing samples near the almost full Moon, we could definitely see that there is an east / west bias that is indicative of mirror flop but at least we won't have to do star synchronization and solve images each night to be able to point the telescope accurately, hopefully it will stay reasonably accurate until we decide to change things again, while I was finishing my T-Point model Steve Hennerley showed up, so after looking at the results and having a chat we decided to get on with some image acquisition of the microlensing target "OGLE-2017-BLG-0019", we managed to grab 2 hours worth of data on this target as well as some new images of "OGLE_2017_BLG_0896", one of the best moments of the night came when me and Steve managed to identify the target star using the OGLE finder Chart.

<- The Ogle finder Chart image



And our image of the target, which is a crop from one of the original Fit's files ->

After Steve left to catch some sleep before work, I stayed behind and kept on imaging but I noticed that the auto-guider started losing it's guide star, I managed to resolve the problem eventually by disconnecting the camera and then restarting MaxIm DL, I then re-enabled the auto-guider in the telescope setup section and this seemed to fix the problem, although when your taking 5 minute exposures and run into problems like this you can end up wasting a lot of time and when your tired from being up late a couple of nights you tend to make mistakes, so after finishing off the two hours worth of images of the "OGLE-2017-BLG-0019" target and creating copies of the images that I then calibrated, I ended up closing up the dome and copied all the images onto my USB stick and headed home around 5:30 am.

I'm really looking forward to the next clear night and hopefully we will soon be able to complete our next goal which is to start submitting our data for analysis.

Posted by Jonathan Green


Tuesday, June 6, 2017

1st attempt at a Microlens Star Field.

Last night after attending the Auckland Astronomical Society meeting at Stardome Jonathan & Steve headed out to Kumeu Observatory at Grant Christie's suggestion to attempt to image a microlensing event in the galactic bulge, Steve arrived first and opened up the dome but quickly found he could not astrometrically solve any images, the reason why this was the case is because while Steve had been working on the dome rotation automation over the long weekend he noticed that the time on the dome computer was not correct, he fixed the time but that of course caused all our pointing data to become out of wack so essentially the Mount didn't know where in the sky it was pointing anymore, after trying a few different failed attempts to resolve the problem Jonathan suggested to Steve that we just start from scratch and clear all pointing data and go find a known star to synch to, we eventually ended up on Alpha Centauri and managed to get synchronization by this stage it was fairly late (1:30 am ) so Steve headed home because he needed to get up early for work.



After Steve left I solved a few images and then focused a mag 8.5 star to a FWHM of 1.499 arc seconds per pixel, I then went to the microlens field and astrometrically solved the field to confirm the position, I managed to get 17 five minute exposures before the sky crapped out with fog and clouds, I left the observatory around 5:30 am as there was pretty much no chance to get dawn flats due to the bad conditions so we still can't reduce our data until we get new flats.

<- Focus Star



The above image is of the target microlens star field, please note that the image is not calibrated and was taken while the waxing gibbous Moon was still well above the horizon, even though I managed to get a decent focus I was forced to run the dew strap at full to keep dew off the corrector plate which would have no doubt affected the images, also something else I noticed was that the aberrations all look worse on the left hand side of the image but I'm not really sure if that's our collimation or the focal reducer causing that.


^ The current observing conditions have been very sporadic out at Kumeu, as you can see from this cloud sensor graph above, the blue parts are rain, the red parts are heavy clouds, the yellow parts are light clouds and or fog and the white parts are clear skies, so you really need to be on your toes to be able to get anything done, hopefully we will have more stable conditions soon.


^ The very picturesque scene looking at the valley across the road from Kumeu observatory, you can see that the fog and mist fills up the low lands but it's like the fog is like water in a bath and eventually it fills up the valley until it spills over and ends up over the trees and dome of Kumeu Observatory, it seems like this phenomenon might be quite a common occurrence at this time of year out at Kumeu.

Posted by Jonathan Green

Thursday, June 1, 2017

A Foggy Start to Winter

Last night I didn't manage to get out to Kumeu until around 9 pm, not long after I arrived Auckland Astronomical Society member Alan Kane turned up and set up his big Dobsonian telescope to continue his current visual observing challenge of ticking off all the Catalogue of Principal Galaxies (PGC) objects that he can see through his telescope, he's already ticked off all the NGC objects! so he's onto fainter more challenging targets now.


Before Alan had turned up I had opened up the dome, pointed the telescope to near the zenith and started to attempt to gain a good focus using the auto-focus function in MaxIm DL but I couldn't manage to get anything better than a FWHM of 2.3 arc seconds per pixel, I had already wasted around half an hour trying to get a better focus but I was kind of in a rush because I really wanted to go after a Star Cluster that Grant Christie and Tim Natusch have been currently studying over at Stardome Observatory, the time constraint was because the Star Cluster is in the Constellation of Carina and at this time of the year Carina quickly goes behind the trees so it's hidden from our view for most of the night as seen from the Kumeu Observatory dome.

So in the end I had to just settle for a less than perfect focus, finding the Star Cluster which is named "Westerlund 2" was fairly uncomplicated because all I had to do was enter the RA and DEC coordinates into the My Chart Elements feature of the Sky X, then centered the target and slewed to the object and it almost dead center on the first try, I then proceeded to image the cluster until it went behind the trees I managed to grab around 58 images, unfortunately these images couldn't be correctly reduced as we still haven't taken any sky flats for the "Wratten filter" which is the filter we should be using for all our scientific work from now on, I did fire off a couple of the images for Grant to take a look at for comparison purposes, I can now really appreciate how much work is needed to try get the "Nustrini" C14 as optimised as the 16' Meade LX200ACF that Grant and Tim use over at Stardome.


The Star Cluster Westerlund 2 in the constellation of Carina, this cluster contains some very interesting Wolf–Rayet stars. ^

One piece of news that I'm really happy to announce is that our frosting issues seem to be over for now. I think the desiccant obviously just need more time to remove moisture out of the imaging system, last night was a really good test as well because the weather station was recording the humidity at 91%!

While I was imaging the Westerlund 2 Star Cluster I was thinking about why I couldn't gain as good a focus as the last time I was out at the observatory, one thought was that maybe the collimation may have slipped out but it then dawned on me that I had made a rookie mistake, last time I was out at the observatory I had the dew strap cranked up to full and I had forgotten to turn it off, a quick trip up to the dome confirmed my suspicions, so I turned off the dew strap and waited for a few minutes while it cooled off before I again pointed the telescope to near the zenith to try gain a good focus, this time I managed to measure a magnitude 8 star at a FWHM of 1.4 arc seconds per pixel, so I think it must have been the dew strap that was mucking up my focus attempts earlier on in the night, so it has to be part of our shut down procedure from now on that you turn off the dew strap when closing up for the night.

I should note that about twenty minutes after getting a good focus I had to turn the dew strap back on as the corrector plate was starting to fog up, I had to wait for five minutes or so for the corrector to clear again but thankfully the focuser was tracking the temperature correctly so I didn't lose my sharp focus.


<- Two frame mosaic of the Cats Paw Nebula in Scorpius.

With all that behind me I set about imaging the Cats Paw Nebula I wanted to try making a mosaic of the entire nebula but only managed to grab two fields of view using 25 x 1 exposures each with the Optolong Red filter before the stars all started to fade, thinking that corrector plate had fogged up again I raced up to the dome but no the corrector plate was clear, I then ventured outside to see some of the thickest fog I have ever seen! In fact the fog was so impressive it even made this evenings News report. It was so thick you could barely even see any stars with the naked eye anymore, seeing that this was going to end my nights activities I closed up the dome and headed home around 4:30 am.

Posted by Jonathan Green

Friday, May 26, 2017

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.

Monday, May 22, 2017

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

Sunday, May 21, 2017

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.

Monday, May 8, 2017

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

Saturday, May 6, 2017

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.

Wednesday, May 3, 2017

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

Friday, April 28, 2017

Autoguiding and Remote Control

After a beautifully clear day, and with the successes of the night before still fresh in our minds, Jonathan headed out to the observatory for sundown hoping to get an early start on some more work getting all the equipment set up.  Unfortunately the weather seemed to have other plans, and in not long at all, the sky was covered in cloud.

So after it started to look pretty hopeless, he closed up again and headed off.

After being busy with other things earlier in the evening, I became free at around 10pm and seeing the skies reasonably clear at home in Swanson, headed out - expecting Jonathan to perhaps still be around.  He wasn't of course after closing up earlier - but with only  a few clouds on the horizon, I set about a few tasks.

Whilst polar alignment still needs some refinement, I was also keen to get the autoguiding working again.  Even though we have guider relays on the ST-10XME camera,we are using "DirectGuide" (the SoftwareBisque implementation of pulse guiding) which is more accurate and required less cables.

Since we're using Maxim DL for the imaging, then Maxim needs to control the mount - this is done via TheSkyX's ASCOM driver.  This provides ASCOM with what looks like a telescope mount, with multiple autoguider options - including DirectGuide.  This was quickly set up and moving the manual controls in Maxim confirmed that the guider inputs weew working as expected.

NGC4038/NGC4039  20min (10x 120s) Stack
The guider calibrated correctly and seemed to be working, so I did a quick focus run and set up a short run of 120 second images of the NGC4038/NGC4039 Antennae galaxies (just in luminance) .  I did forget to turn temperature compensation back on though so my focus drifted a little between the images.

Whilst the image run was going on, I tool the opportunity to configure the PCs (the one in the dome and the one in the bunkroom) to be able to talk to each other - since we still have no internet connection at this point (we're working on that) - it was just a simple matter of assigning a fixed internal IP address on each machine.

NGC4945 28min (14x120s) Stack
This allowed us to use Remote Desktop to control the dome computer from the relative warmth and light of the bunkroom.  Jonathan arrived from being clouded out at an attempt at some photography further north to find that Kumeu was now perfectly clear.

Jonathan continued imaging for a while taking a (much better!!) set of images of NGC4945 - he of course noticed the focuser issue and came out with a very nice image!

Overall I'm really pleased with our progress this week getting things back into an operational state.  The polar alignment needs more work - though with Autoguiding working now we can still image whilst we refine that fully.  We have identified we need to work on collimation - so getting CCDInspector up and running for that is on the list.

The next big job is slaving the dome - we had some issues with the sensor wheel slipping resulting in us getting inconsistent counts.  This caused problems that the dome and the scope did not stay synced after a short run - we need to revisit this - perhaps install a rubber o ring or band "tyre" on the wheel - which may need a groove for it to sit in.

Steve


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