Slewing Problem Resolved

I rang Grant Christie today to let him know about the unhealthy noise the mount has been making when slewing, he let me know that the problem was probably due to me having to home the scope during the T - Point calibration run, apparently doing so changes two of the parameters of the pointing model and can cause problems, so I went out to Kumeu tonight to clear the pointing model to see if this would fix the slewing problem and I'm very happy to report that the slewing of the mount is now back to sounding healthy again, I also finally figured out how to connect the CCD to the Sky X, the reason I was getting error messages was that you can't have the camera connected to Maxim DL and the Sky X at the same time, up until now the first thing I used to do when I arrived at the observatory was to connect the camera to Maxim DL so I can turn on the camera's coolers as it takes a while for the camera to cool down, I know now this was the reason why I was getting no response from the camera when attempting to connect to it through the Sky X, I'm feeling a little bit sheepish that it took me so long to figure this out but I guess it's all part of the learning process to have a bit of trial and error.

Unfortunately the sky was pretty cloudy out at Kumeu tonight, I did take a few images using the Sky X to control the CCD but I failed to astrometrically solve the images, this was probably due to the images being affected by clouds, hopefully the next time it's clear I will be able to do a new pointing model using an automated calibration run, I plan to take two to three hundred samples of the sky so we will end up with a very robust pointing model, I stayed out at Kumeu until 10:30 but the sky seemed to be getting worse and with the internet not working ( another problem that needs to be addressed soon ) I had no way to know if it was worth waiting around to see if it would clear up, so heading home a bit frustrated that I couldn't get more done tonight I had to console myself that at least when the next opportunity presents itself the telescope and mount are ready for action again.

Posted by Jonathan Green

New T - Point and Slewing Problem with the Paramount

On Friday night I spent the entire night working on making a new pointing model, I scrapped the last one after reading the T - Point user manual and finding out that it was not advisable to take samples down near the horizon due to atmospheric refraction that causes offsets between the actual position of an object and it's observed position, I started collecting samples around 9:30 and only stopped collecting samples early in the morning due to the mount making an inexplicably unhealthy noise when it was slewing, I couldn't see any obvious reason why the mount was suddenly making the noise ( sounds like a rattle with clicking or cracking type noises ) so I just put the mount back in the home position and called it a night, by the time this had happened I had collected 82 sample points, the new model showed that we are only off by 2 arc-minutes in azimuth while the altitude was still excellent and we don't need any more adjustments in that area.

After attending the Auckland Astronomical Society council meeting at Andrew's house on Saturday, I thought I'd head out to Kumeu and see if the Slewing was still making that same noise and to also test the new pointing model, The first ten or so slews sounded healthy but then again inexplicably the unhealthy noise started up again, so again I just put the mount back into the home position and called it a night, I've talked to Steve about the problem and he is at a loss to explain it as well so we might need Grant Christie or Tim Natusch to come out and take a look at it, hopefully it's nothing too serious, before this happened I was quite happy with the accuracy of the new pointing model, objects were always just a few arc-seconds from the center of the frame although I didn't get a chance to slew all over the sky so some areas may be worse than others, I still had the same problem with the mount in the area of sky to the South East that I had the first time I attempted a pointing model so I couldn't take samples around Centaurus, Crux or Carina, below is an example image of the Galaxy NGC 1532, the image was a 100 sec long exposure and I was quite happy with how close the galaxy was to the center of the frame, the image exhibits some pretty bad vignetting but I think this was due to the Moon being almost full and very bright.

Posted by Jonathan Green

T - Point

Last night the waxing gibbous Moon was up and more than a few clouds were about as well but seeing that there were plenty of large gaps in the clouds I thought it would be a perfect night to get the new pointing model done using T - Point, when I arrived at the observatory I noticed that the computer was off and the temperature compensating focuser was flashing, I'm guessing that there was a power cut during the storm we had earlier on in the week, I booted up the computer and connected to both the telescope and camera without issue but when I tried to connect to the focuser it would not connect and came back with an error message from both Maxim DL and the Sky X, after ringing steve for help I switched the focuser back to manual mode and manually set the focuser back to the last known good focus, this worked well enough for me to be able to do the pointing model, the next issue was aligning the finder scope again which must have been knocked fairly far out of alignment at some point, this took me a while to get right but once I was happy that the finder scope and the field of view of the CCD were aligned again I got started on the pointing model, at first I had wanted to do an automatic calibration run but unfortunately the Sky X would not connect to the camera and I got error messages, I also noticed that it will be quite hard to keep up with an automated calibration due to the dome being fairly slow, not wanting to waste a good opportunity to get a pointing model done, I set about doing a manual pointing model using stars that I knew and that I could confirm through the finder scope, by the time the clouds really rolled in at 2:30 am, I had captured 57 samples, one problem I noticed when I was capturing the samples was that I couldn't take any samples from around Carina and Crux any attempt to jog the telescope in this area of the sky caused the mount to become confused and try to point the telescope at the floor, each time this happened I had to re-home the telescope before it would accurately point and track again.

The new pointing model confirmed that the altitude of the mount is correct but that the azimuth still needed to be adjusted ( by about 3 arc minutes ), I then enabled the Pro Track so that the new pointing model can make minor adjustments to improve the sidereal tracking rate of the Paramount GT - 1100S, at this stage the clouds had become so thick that trying to test the new pointing model's accuracy was pointless, so at 3:30 am I closed up the dome and called it a night, I'm looking forward to the next clear night when we can test out the adjusted tracking rate and also the accuracy of the new pointing model.

Posted by Jonathan Green

Polar Alignment Refined & Observations of Arp 123 & Arp 279

Last week we had a one good clear night and few nights with sporadic clouds, Thuesday night was the one clear night and on that night I took images of two pairs of galaxies that are in the catalog of interacting galaxies of Dr. Halton C Arp, one pair was NGC 1253 & NGC 1253A, collectively known as ARP 279 they are located in the constellation Eridanus and are thought to be lie around 75 million light years away, the other pair is NGC 1888 & NGC 1889 which are collectively known as Arp 123, they can be found in the constellation Lepus, after doing some research I've found that NGC 1888 is thought to lie 33.5 megaparsecs away which is over 109 million light years! for now this is the most distant object I have ever imaged, I'm looking forward to breaking that record soon hopefully, the image below is of Arp 123, image data was captured by Jonathan Green and then processed by Amit Kamble.

On the Thursday I also collected more image data on Arp 279 but not long after the Moon set clouds started to roll in, there were still gaps in the clouds so I attempted to image a couple of comets, I imaged both 81P/Wild and 203P/Linear but finding them took some effort, I realised after finding the 1st comet that our pointing model was off by about 13 arc minutes, this was due to our refinement of the polar alignment on a previous night.

On the Friday night the sky looked nice and clear and the satellite image data also looked promising so I rang Steve to see if he was free to head out to Kumeu to work on the Polar alignment and to create a new pointing model with T-Point, we also had a couple of Auckland Astronomical Society members show up with their Dobsonian telescopes looking to take advantage of the clear skies, unfortunately the clear skies did not last long so the nights observing was a bit of a bust, fortunately we could still detect stars through the cloud so we ended up spending the night until 2 am in the morning refining the polar alignment again, now all we need is some clear skies to do a new pointing model.

Posted by Jonathan Green

Rain, rain and more rain....

After some wonderful days and nights between Christmas and New Year, (when, of course I was away from Auckland!), the rain has been falling pretty much non-stop - not to great for observing, but a perfect opportunity to get a few things done that have been on the list for a while. First order of business was getting the USB interface board for the dome rotation system. This has up to now been screwed to the wall inside the dome, but with the issue being unprotcted and that its location was right below the dome home position.  Whilst we've been working, a number of times we've opened the dome and has mosture drip perilously close to the board.  Installing the plastic enclosure took a little longer than expected, but the board should now be protected from and water or moisture from above and be a little more immune to spiders and dust. 

 With that complete, next step was to install the new red LED strip lighting around the dome.  The old dome lighting was too dim with the red bulbs in when working in the dome, and inconvenient to adjust brightness or turn on/off (as the switch is downstairs).  We switched out the bulbs for white bulbs making it easier when we are working (not imaging!) but also bought some red LED lighting with an RF remote to adjust brightness and/or turn on and off. The new lighting is much more controllable and convenient, and hopefully makes life much easier whilst imaging in the dome.  

The final job for the day was re-wiring the dew heater to the new power supply.  At the same time, i added in a PWM controller to control the temperature, ironically one actually designed to dim LED lighting strips.    A good productive day, even though the rain continued relentlessly. The only challenge at this point seems to be that Azimuth sensor for the dome rotation doesn't seem to be functional  (before and after the board was remounted, so not the loose wire I was hoping for) this could be a configuration issue rather than a hardware fault (the dome home sensor is working fine proving the interface inputs are working) but this will need more work

 

 

A Dark Night

Last night was cloudy so I took the opportunity to spend a night taking dark frames for image calibration, when I arrived at the observatory at 9 pm I noticed that the computer had crashed since the last time me and Steve were there, we had left the computer updating the Sky X with a star catalogue that Grant Christie had advised us to use, the computer fan seemed to be really labouring so I restarted the computer which seemed to resolve this problem. I then connected the camera and set the coolers on to reach -20 but after waiting until 10 pm the coolers still couldn't cool down the camera past -15, seeing as it was a pretty hot night I figured this might just be as cool as the camera would get, so I then set about taking the dark frames, I collected 5 hours worth of 600 second exposures which was about as exciting as that sounds, after that was finished I took 30 bias frames to go with my 30 Dark frames, it was well past 3 am by this point, so I decided to call it a night, I closed up the observatory but when I came to clamp the observatory dome I noticed the big clamp was stuck it couldn't be tightened or loosened so unable to secure that clamp I had to just leave it with only one clamp holding down the dome, hopefully the clamp just needs some CRC lubricant or something, In the meantime I will look to buy a replacement clamp as we can't really afford to have the dome unsecured. Posted By Jonathan Green

Galaxy Hunt

On the 7th of November I went out to Kumeu Observatory, I had loads of fun taking images of galaxies in Sculptor, Fornax and Aquarius, although unfortunately I couldn't get lucky enough with clear skies to grab enough data to make an RGB image of any one galaxy, by midnight the clouds really started to roll in, so while I waited around to see if it would clear I went outside and took a few nightscape images with my 6d, the clouds didn't end up clearing and by 1am I decided to call it a night.   Posted by: Jonathan Green

Impromptu Star Party!

After such a long period of there being few visitors up to the Kumeu site, a clear, dark night brought quite a few visitors out to the site tonight - with the end result being a great night of viewing both in the dome, and outside.

In the dome, Jonathan tested out auto-saved exposures through MaximDL, capturing a whole series of exposures and (and changing the filter wheel - though Jonathan did this manually on Friday) using an automated routine.

We found that the residual polar alignment error (we still were not guiding at this point) whilst causing no noticeable trailing on the 80s or so subframes, certainly did show up in a gradual shift over time between the images - this shows up in a slight framing mismatch on the stacked images that I deliberately haven't "fixed" in the image (blue and green band at the bottom)

Target for tonight was the Helix Nebula NGC7293, a planetery nebula located in Aquarius a little under 700ly away.

Outside the dome Alastair had his 16" Binoscope up and running - and the views through it were simply magnificent.  The detail and immersive nature of seeing familiar objects such as 74Tuc, Tarantuala and the Orion Nebula in "stereo" was really something else and was frankly mindblowing!

Another member had an 18" dob out hunting for faint galaxies and a pair of keen new members came along with their 8" Astronz dobsonian enjoying the dark skies and good company.

Go the All Blacks!

Even though an early morning had been had (watching the All Blacks win the 2015 Rugby World Cup at 5am), the night too was looking "all black" so it was time for Jonathan and I to head out to Kumeu and continue the process.

The original intention of the next visit was to get the dome rotation "slaved" to the mount using Pierre de Ponthiere's excellent "LesveDome" software.  We were upgrading from the old version and so using a trial license until we were up and running.  A little planning snafu though was that I found the trial had expired the day before - so that was not really an option for tonight.   (Many thanks to Pierre though for now extending our trial whilst we get up and running  - if you are interested in dome automation, do check out his website http://www.dppobservatory.net/)

Instead we decided to do a short pointing model run, which would help our ability to "goto" objects accurately, but would also give us a sense of our residual polar alignment error (after only drift testing to there being no noticeable drift after 5 minutes or so).

After opening up the some and starting everything up though it appeared we had a strange problem. Even though the last visit the scope had been "synced" and would "goto" reasonably accurately, and the scope had been correctly "homed", the home point appeared to be a long way off.  We re-synced it using Canopus and this proved to be a mistake - the next slew commend sent the scope into pointing in completely the wrong direction (and manual joysticking to the target resulted in TheSky telling us we were pointing below the horizon).

Once we synced again though on a star much further away from the SCP everything went back to normal.  We eventually traced the home problem to not having set up the "home position offset" - and once we'd done this the mount worked fine even after a power cycle.

We set about doing a short pointing model run, and opted to do this "manually" using the CCD and the jog controls to centre stars across the sky  in the centre of the CCD chip.  The results quickly converged reasonably well, with us ending up with the stars being much less than 1 arcminute off dead centre in every case.

The pointing model also gave us an indication of what error we might have in our polar alignment - and indicated about 4.7 arcminutes out in altitude, and 6.6 on azimuth.  In terms of the adjustment to correct this, this is just over a third of a turn of the azimuth adjustment screw West, and just under a third of a turn on the altitude screw high.

We pointed the scope at both the Tarantula Nebula (NGC2070) and the Sculptor Galaxy (NGC253) and ran a few images, partly to test the filter wheel and also to produce a pretty picture for the evening!  Here's the result - was only 10 frames (2 each RGB and 3 L) unguided getween 40 and 80 sec per exposure.  Stacked in DSS and processed in Photoshop.

Align Align Align

After being clouded out last night, and poor weather all night and all morning, I really didn't expect there to be an opportunity to come back to the observatory over the weekend.  However the weather cleared up in the afternoon and started to look quite clear.  A check of the satellite map showed the cloud moving away  and what looked like clear skies heading our way.

Jonathan wasn't available so  I headed out there myself to see whether I could make a start on the elusive (so far) polar alignment of the Paramount.  All the failed nights in here are certainly paying off because it takes very few minutes to be up and running with the scope.  Once we have a pointing model set up and the dome slaved to the scope (planned as soon as we have a somewhere close polar alignment) then it should be a breeze to get everything ready for an evenings observing.

First order of business was to see if I could get a rough align by clearing the previous sync and pointing model and telling the scope (through TheSkyX) to go to a star around the south celestial pole (I chose one of the three stars in a small triangle in Octans) .  Sounds simple - but no go - the scope ended up pointing somewhere near zenith.

Still encouraged by the low rate of drift, I decided to jump straight into the drift alignment process hoping that we were close enough for this to work.

Test image of 47 Tucanae (NGC104)

Part way through the clouds came in giving an opportunity to write up last nights blog, and threatening to shut down the operation again - fortunately tonight though they lightened off and then cleared completely. Backwards and forwards between the eastern horizon and the meridian I gradually tweaked the altitude and azimuth screws (only going the wrong way once thanks to my cheat notes i chalked on the pier ("star goes up, tighten this screw" and "up=higher") - until eventually after a few iterations there was no real noticeable movement for 5+ or so minutes  each side. Of course this can (and will be) improved and refined - but certainly a good starting point. 

It was getting late, and a little chilly in the dome but I decided I should at least take a picture of something before I locked up. The image of 47 tuc certainly isn't the best in the world, but  it representsthe completion of  another successful evening's work out at Kumeu, and another step on the journey to breath new life and bring new blood into the observatory so we can really start making use of this great facility.

Steve

Getting set up for a polar align (again)

With the mount now oriented on the pier close to the true north/south line in azimuth, Jonathan and I seized the opportunity of what looked like the first possible fine night in what seems like weeks.

Jonathan was opened up and powered on before I arrived, and it looked like we might be ok despite a few gathering clouds.  having had the OTA off the mount (and the mount of the pier!) it looked  like we'd managed to get the finder misaligned too.

Having spent far too long on previous sessions trying to align the finder with the OTA using the CCD (when the alignment was so far off it was just about impossible to work out where we were pointing,) the first order of business was to swap the CCD for a good old eyepiece.

Utilising a handy local house with it's lights on, we quickly got the finderscope aligned with the OTA and switched back to the CCD.  After cooling the CCD we soon confirmed that Jonathan had managed to get the finder spot on as we could get a star right in the centre of the CCD chip by moving the scope so that it was in the finder crosshairs.

All looking good, we noticed now that the drift of the stars was markedly reduced across the image - a good sign that we were now much closer to alignment.  We also noticed that the clouds had started to roll in ....

Whilst the clouds rolled over, we took the opportunity to tidy up a few of the cables more and also install a safety wire on the CCD - hoping that the weather would clear enough to have another crack at the polar alignment

Unfortunately, a look at the satellite image of the clouds confirmed there was more to come so we called it a night - warmed up the CCD, closed the dome and shut everything down...

Encouraged though by the discovery that the star drift was definitely smaller we were looking forward to coming back again at the next clear opportunity.

Steve

New lease of life

The Nustrini C14 on the Paramount GT-1100S

So after a short period of very little activity, there is now a serious push to get Kumeu back into being an active observing site.  With a new group of members from Auckland Astronomical Society looking to do some more research oriented projects, and a steadily growing enthusiastic group of astrophotographers, the time is certainly right to dust off the dome and get some activity going.

The other thing that has happened that is very exciting for the observatory is that the old (yet reliable) "push to" fork mount for the C14 "Nustrini" OTA has now had a fairly serious upgrade to a Software Bisque Paramount GT-1100S - that belongs to Stardome and became available due to the upgrade of the research dome equipment there earlier in the year.

Having a fully robotic mount means that the startup process is dramatically shortened, and also observing sessions should be much easier (and able to be fully controlled from outside the dome itself).

I will be posting updates regularly here as work progresses, and once we are back into the swing of observing regularly, there should be regular logs of the sessions and observations.

Steve Hennerley
Curator of Instruments, Auckland Astronomical Society