Friday, December 4, 2015

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

Saturday, November 7, 2015

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

Friday, November 6, 2015

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.

Sunday, November 1, 2015

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

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.

Monday, October 26, 2015

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.


Friday, October 23, 2015

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.


Tuesday, October 20, 2015

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

Thursday, October 8, 2015

Putting it back together

Fun with serial cables
Jonathan and I had a productive (if occasionally frustrating) evening out at Kumeu.  Although the weather was awful (so we didnt actually open the dome) Jonathan installed the finder and the shipping/lock and safety bolts, we have had the computer controlling the mount using (I need to make up a more permanent connector), confirmed the dome rotates under power, and also confirmed the Velleman board (used for the dome rotation system) works by using the test program and i can slew and reverse the dome fro the PC
Still do do: (not exhaustive)
  • Permanent wiring for serial connection PC to Paramount
  • Connect and Set up TCF
  • Route 12v power cables for dome rotation and dew heater
  • Tidy all cables box for Velleman board
  • Connect camera
  • Set up Lesvedome 
  • Polar alignment
  • TPoint Mapping

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