Friday, July 21, 2017

Crisis.....Averted... (but a lost night...)

On Tuesday 18th July, Jonathan headed out to the observatory to find beautifully clear skies perfect for some follow up imaging.  After getting set up and ready to grab some data, the remote connection to the dome PC from the bunkroom suddenly failed.  Checking upstairs the dome PC was no longer powered up - and - even worse, wouldn't actually power up.

Even the IT support favourite advice of "turn it off and turn it on again" (well unplug it completely) did not manage to solve the issue.  Unable to contact Steve initially, Jonathan headed out to make the most of the clear skies with some DSLR astrophotography.

The following night Jonathan and Steve managed to hurry along the Auckland Astronomical Society council meeting members with a view to getting out of the meeting and up to the observatory as quickly as possible - with a spare computer power supply in hand.

Almost as expected (remember Murphy?).. the PC powered up instantly...

The challenge was working out WHY the PC had failed because having unreliable equipment is certainly going to have a negative effect on our efforts.  Out came the power supply tester (Steve's a professional IT nerd so has these things lying around...) and everything looked good... fearing the worst... the "intermittent problem"... Steve reconnected everything and powered up again to start some additional diagnostics.

One common cause in the PC world when something goes off suddenly and won't power back up (even with a "power cycle") - but then does some time later (maybe many minutes later) - is that there has  been a short circuit, power surge or "overcurrent" problem somewhere on the motherboard or power supply.  Most IT techs have seen this most often when an errant screw accidentally makes its way (purely by itself you understand) onto the exposed boards of a PC.  The protection circuity (such as polyfuses) kick in and power is removed.  It is common not to instantly come back on when the fault is removed.

The hunt was on - for insects in the power supply, "errant screws", possibilities of electrical surge (though the surge protector was still functioning).  Nothing was obvious ... so case back on and stand the PC back up.

At that point the probably cause of the issue was suddenly staring us in the face... the bright blue power LED (which is normally covered loosely with black electrical tape) was off... whilst the PC was on.  Jonathan was certain the light was on the night before when he was setting up and checking inside again, it was still connected.

It seems likely that the blue LED had failed, which in turn had tripped protective circuitry on either the motherboard or the power supply.  The mystery solved, we could be a lot more confident it wasn't going to happen again, and we took the opportunity to do something that should have been done when Steve built the PC - disconnect the Hard Disk and  power lights completely to protect the darkness of the dome.

With that resolved, and the skies clearing, Jonathan and Steve set out to grab some images of a new high priority microlens target OB171186.  Joanathan managed to get 28 300 second images over the next couple of hours - though had a few problems - the strange and as yet undiagnosed mount disconnection (from an earlier blog post) and an issue plate solving a number of (most of) the images in PinPoint.

Light Curve from OB171186
Steve processed the images next day for upload and managed to get the astrometric solution by reducing the number of star used for the solve and also narrowing the intensity range used for matching in the PinPoint settings.  This seemed to do the trick.  Steve also ran the images through a tool called PySIS - which uses differential image analysis to generate a photometric light curve.

Posted by Steve Hennerley

Monday, July 17, 2017

Action Stations!

On Saturday the 15th of July Jonathan Green and Steve Hennerley were at Kumeu Observatory, after some advice from Grant Christie that the microlensing target OB170019 was still viable, we took just over an hour's worth of data on the target, Grant had advised that we didn't really need any more than an hour so we were kind of stuck for new projects as there had been now new microlensing alerts for a while, that day Jonathan Green had signed up for the Center for Backyard Astrophysics (CBA) in the hopes of finding some more projects to take on, he had copied down a few Cataclysmic Variable targets to attempt to image, so we attempted a few of the targets but found that each of them was only just above the noise level, so not knowing if that would be useful or not we decided to take more images of OB170019, unfortunately the clouds started rolling in about this time and we couldn't guide for 5 minutes anymore so we decided to pull the plug on the night and headed home with the idea of doing some research and finding some new projects to pursue when we don't have any more microlensing work to do.

On Sunday the 16th of July we finally had a new microlensing alert so it was action stations! Only one problem the forecast for that night was for increasing clouds! We decided to give it a go anyway and just hope for the best, Steve arrived 1st and found the sky was half clear and thankfully our target was on the clear side, so he opened up the dome and got to work, he captured 14 300 second exposures of our target OB171317 before Jonathan arrived, after a few cloudy patches we got back to work but it was slow going with passing clouds causing our guide star to fade more often than not, Steve headed home and Jonathan stayed on to keep imaging for as long as possible, we got to 27 300 second exposures of our target OB171317 although thin clouds may have affected a few of them.
Jonthan imaged the target when gaps allowed until 1:30 am when this cloud bank appeared in the West, it didn't take long after this photo was snapped for the cloud bank to move over our target and even though Jonathan stayed on at the observatory until around 3 am he never saw another opportunity to collect more data, so after calibrating the data we had collected he headed home and sent the files to Steve for submission to MicroFUN, hopefully we get a few more breaks in the clouds tonight to grab our normalizing data as apparently our target has already faded considerably.

Posted by Jonathan Green

Tuesday, July 11, 2017

Cloudy Nights at Kumeu

Since the last night imaging at Kumeu, we have had a run of some really bad weather, on Sunday the 9th after attending Neil deGrasse Tyson at Spark Arena I headed out to the observatory in the hope of clear skies but even with other parts of Auckland clear Kumeu was still under a pretty constant blanket of clouds, after waiting I drove home to find Coatesville clear but you could still see major clouds in the West. On Monday the 10th after attending the Auckland Astronomical Society meeting I headed out again in the hope of clear skies but it was raining on arrival so I attempted to wait out the clouds and rain by occupying myself with cleaning up the observatory but with no luck it was still heavy cloud when I left around midnight, I'm happy to report we have submitted all our current data to MicroFUN so all we need now is some clear sky to get back to work although fortunately there has been no new microlensing alerts in the meantime.

^ As you can see from this image of the cloud sensor graph clear patches have been few and far between, it's been frustrating because other parts of Auckland have looked relatively clear.

Posted by Jonathan Green

Tuesday, July 4, 2017

A Night of Two Halves

On Monday the 3rd of July, Jonathan Green decided to miss going to the Auckland Astronomical society meeting and head out to Kumeu instead, after a weekend of rain and clouds it looked like things were finally clearing up, after arriving around 6:15pm he opened up the dome setup and got a focus of a FWHM of 1.7 arc seconds per pixel ( not bad for having only just opened the dome ), he then got onto taking the normalisation data that we need to submit our latest microlensing data sets, so he started by imaging Ogle-Bulge-2017-1161, which was the priority target, he managed almost three hours worth of data before hitting the hard stop before the meridian crossing, this was the first time he had let the mount hit the hard stop, it made a beeping sound and he found when he tried to send it home that somehow the computer had lost communication with the mount.

Fortunately it was precisely at this moment that Steve Hennerley turned up, we resolved the issue with the mount and a few other issues we were having before getting back onto our target, we finished imaging Ogle-Bulge-2017-1161 after collecting three hours worth of data so hopefully that will be enough for normalisation, Steve headed home around 1 am and Jonathan stayed behind to continue imaging, he got started on the Ogle-Bulge-2017-1135 target, the first half an hour was plain sailing but the next 8 300 second images he took, took Jonathan until just after 3 am to grab, that was because we had big clouds coming in, he had to close the dome a few times out of fear of a downpour, the wind had also picked up by this stage so he could only grab one or two images in the brief gaps, after 3 am the situation deteriorated so he packed up and headed home around 3:40 am, so we only ended up getting just over an hours worth of normalisation data on the Ogle-Bulge-2017-1135 target so I'm not sure if that will be enough, after Jonathan made it home he sent all the calibrated image data to Steve Hennerley via the We-Transfer file transfer service to be prepared for submission to MicroFUN.

Obviously there has been a lot of rain over the weekend and things are starting to get a bit more muddy outside the observatory, it was really wet on the night as well with the humidity at a 93% level, Jonathan was very happy to see that at the end of the night we didn't have any sign of dew on our corrector plate so he thinks that the dew shield has proven to be the only thing we really need to keep the dew off, this is just as well because when you have to run the dew strap heater this adversely effects the images.

^Looking down the dew shield at a clean corrector plate after a nights observing in 93% humidity, note also how well baffled the dew shield is, David Moorhouse really did a fantastic job constructing this dew shield!

Posted by Jonathan Green

Saturday, July 1, 2017

A Perfect Winters Night

On Thursday the 26th of June, Jonathan Green headed out to Kumeu Observatory early so he could grab more flat field calibration image files, before he left home he had copied the coordinates of the latest microlensing targets, after taking the flats he checked where the targets were located, only to find they were all still below the tree line so instead of wasting time waiting for them to rise he slewed to the star cluster Westerlund 2 and grabbed 20 x 100 second exposures, by the time that was done the galactic bulge had cleared the trees so he then immediately set about collecting microlensing data, but before he got started he re-focused the imaging system to a FWHM of 1.5 arc seconds per pixel on a magnitude 8.6 star, Jonathan imaged the target OGLE-2017-BLG-1135 until he hit the meridian, he was joined out at the observatory by Steve Hennerley just after 10 pm, while waiting for our targets to pass the meridian Steve and Jonathan used the break to find our target stars we were a little bit concerned that the signal we were recording wasn't strong enough but after a quick phone call to Grant Christie he assured us that our images would provide useful photometry, Steve ended up heading home around 1 am with the understanding that Jonathan would send him all the calibrated data from the night to be readied for submission, I think this is a method that we will employ from now on, after a full nights imaging you feel really tired and that's when mistakes happen so best to have someone who is fresh in the morning to go over the data and make sure it's all sent off correctly, although Steve also showed Jonathan how to prepare the data for submission just in case he ever needs to do it himself.

After preforming the meridian flip we changed targets to OGLE-2017-BLG-1161 as Grant had mentioned that this was the priority target, we ended up getting 34 x 500 second exposures of this target before it got into the fog and mist of the western horizon, we got 32 x 500 second exposures of the OGLE-2017-BLG-1135 target and we also managed to grab 8 x 500 second exposures of OGLE-2017-BLG-0019, one thing I noticed over the night was that some images would not automatically solve in PinPoint so I think we might need to adjust our settings in PinPoint when solving images in the bulge, by 5am I was losing my guide star due to the mist and clouds that were hanging around low in the West, so this was a natural stopping point for the nights imaging. I calibrated all our data and copied it onto a USB data stick, shut down the dome and headed home around 5:30am, when I got home I immediately copied the data onto my computer and sent the files to Steve via the We-Transfer file transfer service, all in all it was a very productive night and I was happy to see when I woke up an e-mail from Grant saying that he had no problem running our images of OGLE-2017-BLG-1161 through Pysis and that the photometry looked good, we are now looking forward to the next clear night so that we can capture the normalisation data for our new targets.

<- The Galactic Bulge not long before Jonathan stopped for the night, thin clouds and fog made auto-guiding impossible and with not being able to auto-guide he couldn't continue capturing 300 second exposures anymore, so this became a natural stopping point.

Posted By Jonathan Green

Wednesday, June 28, 2017

A half decent night finally.

On the 27th of June Jonathan Green headed out to Kumeu Observatory at 7:30 pm, there was still a lot of thin clouds about on arrival but the forecast looked pretty promising so he opened the dome and setup for a nights worth of imaging, he targeted OGLE-2017-BLG-0019 to be able to capture some normalising data that is needed to be able to submit our data, he found he could still auto guide through the clouds without too much issue, we only lost the guide star twice over the 1st half of the night.

The Sky conditions looking towards the Galactic bulge for the 1st half of the night. 
Just after 10 pm Steve Hennerley turned up and after a brief chat we decided to just keep imaging the microlensing target OGLE-2017-BLG-0019 for the entire night, we continued imaging without any issues until we hit the Meridian crossing, so we paused to wait for our target to cross the Meridian before preforming a "Meridian Flip", we took the chance while we had a break in the action to fix up the dual monitors of the downstairs computer workstation and then refocused on a mag 8.3 star and got a result of a FWHM of 1.5 arc seconds per pixel, my initial focus was only 1.9 so obviously the "seeing" must have improved, I went out side and found that almost all the clouds had dispersed, Steve needed to go to work early so he hung around to make sure the 1st couple of images came down successfully then headed home, Jonathan Green stayed on imaging until 4:46 am by which stage the target was getting pretty low in the sky in the West, he could tell the images were getting worse at this point and could see via the fits header that he was imaging through an Airmass of 1.8, we had captured 78 x 300 second images of the target so we have plenty of data now, of course our next goal is to actually submit our data, after Jonathan closed up the dome he headed home around 5:30 am.

Posted by Jonathan Green

Tuesday, June 27, 2017

Cloudy nights and a Rookie Mistake.

On the 25th of June Jonathan Green was involved in an astronomical outreach event at Smales Farm on the North shore, the event was a Matariki festival and members of the Auckland Astronomical Society provided telescope viewing to the public, we were ducking rain showers for most of the night but by 9 pm things had cleared up so sensing an opportunity I packed up and left the festival around 9:30 pm to head out to Kumeu, we have had a really bad run of weather lately so you really just have to take your chances when heading out to the observatory at the moment, the sky was still clear when I arrived but after I had opened up the dome and managed to get a decent focus heavy clouds began to roll in, I went outside and watched them for a while, the clouds became progressively thicker and the wind started to pick up, I was lucky to just beat a really heavy rain shower by racing up and closing the dome just in time, I attempted to wait out the clouds and rain by occupying myself with cleaning up the observatory and cleaning up the dew shield that David Moorhouse had built for the "Nustrini" C14, spiders had built lots of webs in it since we took it off when installing the Paramount GT100S, after I had done all that I found that it was still raining and with no gaps on the horizon I decided to head home around midnight.

^ Jonathan Green Shows a member of the public Jupiter through his 8' Meade LX90 SCT.

On the 26th of June Jonathan Green headed out to Kumeu Observatory at 7 pm in the hope of finally capturing some clear skies unfortunately the sky was completely clouded out when he arrived, the forecast was for a clear skies for the following day so in the hope the skies would clear sometime over the night he setup the newly cleaned dew shield onto the "Nustrini" C14 and opened up the dome, while waiting Alan Kane turned up also with the idea of doing some observing, I talked to Alan about the cloud sensor and how it was no longer logging data on the graph and he showed me how to reset it, so our cloud sensor is back to working properly again which I'm really happy about, by the time Alan had set up his Dobsonian the sky started to have a few gaps in the clouds, so I set about gaining focus, after many attempts the best I could manage was a FWHM of 2.5 arc seconds per pixel, not good at all compared to the other night, Alan also confirmed that the seeing looked average visually.

The clouds were coming and going so I attempted to get some work done in the odd gaps, what I wanted to do was take an hour or two of normalising data on the previous microlensing target that we got data on the last time it was clear, because you can't submit your data without the normalising data, I did manage to capture an hours worth of data but I was really not happy with the quality of the images even though I didn't have the dew strap on at all thanks to using the dew shield, using the graph window in MaxIm DL I could also see that the results were really jumping around, I went outside to talk to Alan about the sky conditions and he confirmed that even in the clear gaps we were still getting mist and thin clouds so this was no doubt what was causing the results to jump around, around 11 pm I had to stop due to deteriorating conditions, I went to calibrate all the data I had captured on the night so far only to find I had made a rookie mistake, all the data I had captured on the night was at 2x2 binning but we only have full calibration files for 1x1 binning, I guess my mind was a bit distracted as my e-mail accounts had been hacked that day and I was still getting phone calls about it while I was at the observatory, I just didn't notice that the binning was at 2x2 not 1x1, it was a painful lesson to learn as it meant the nights observations were useless but I know I won't be making that mistake again ( I hope ), on a positive note the dew shield worked perfectly, so I think we will be keeping that on the telescope from now on, by 11:30 pm the sky conditions had really become quite bad so Alan packed up and headed home, while Alan was packing up I managed to focus a star at a FWHM of 1.7 arc seconds per pixel during a break in the clouds, so not wanting to go home while I had a finally managed to get a half decent focus I stayed on, unfortunately the sky conditions just worsened so I ended up giving up around 2 am and packed down and headed home in defeat, hopefully the sky will be clear tonight so I can finally get the normalising data I need to start submitting microlensing data.

^ David Moorhouse's well constructed dew shield on the "Nustrini" C14

Posted by Jonathan Green

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.

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