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

Time Zone

All times on this page are in New Zealand Daylight Time in winter GMT +12 or summer GMT +13.