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

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