Temperatures may have been up in the low 30's on the hottest day of the year, but things are much hotter on the sun. This animation represents several weeks of trial and error and modifications of the 0.2m Airylab HaT.
Firstly, this animation was captured at the same cadence as the AIA imaging rig on the solar dynamics observatory, ie 1 frame every 13 seconds. Straight away this demonstrated the importance of short exposure runs, as at this image scale temporal distortion can be a real problem in blurring images. Indeed, I may try and increase the cadence still further and achieve 1 frame every 10 seconds in an animation. This was done using the PGR Blackfly GigE IMX249 camera; however using the Chameleon 3 and 2x2 binning should give a much faster exposure, frame rate and cadence, and the original image size will make capture of the frames and post processing easier in terms of computing power. This incidentally is currently the biggest hurdle to overcome in terms of pushing the animation envelope further.
Secondly, and more minor, was the relocation of the Hutech solar guider directly by the aperture of the HaT, and this along with tightening backlash in the gears on the HEQ6 mount has resulted in much better tracking, with fewer errors and drift.
Thirdly retrofitting a Starlight SCT microfocuser in the place of the original focuser on the HaT has made focusing, both visually and for imaging an absolute dream and doddle and is whole heartedly recommended for all users of the Airylab HaT.
Finally the introduction of the Tempest SCT Cooling Fan system to the HaT has made a real improvement in image stability. Just to come back to the start of the post, this animation was made with a 0.2m scope on the hottest day of the year. Normally observing with such large apertures would be impossible, restricting use to smaller scopes, however the cooling fan makes a real difference. The principle of this product originates for night time astronomers, where as the ambient temperature cools down in an evening / night this is not matched by the cool down of the SCT telescope which then introduces thermal gradients within the scope as different parts of it cool down at differential rates. The converse principle operates during the daytime, in so much as the ambient temperature is often rising and hotter than the temperature in the scope. The exit beam from the HaT is 'warm' too, so there will be some heating of the air (and also components) within the tube assembly. Regardless of whether it is hotter or cooler the point is it is not in equilibrium, and this is what introduces convection of the air within the OTA and it is this which affects the seeing conditions in a negative way. It was quite clear with the TEMPest that it was having an effect, turning the fan on it was apparent on the laptop screen that the image was noticeably steadier, turn the fan off and within about 30 seconds the instability started to get greater. Turning the fan back on and after about 30 seconds it would calm down again. There was a clear correlation with fan off / fan on. The system works by having one fan draw air into the OTA and the other fan drawing air out of the OTA. This introduces a flow of air over the mirror that prevents thermal gradients forming over the mirror or around the walls of the OTA. The effect is not subtle, and draws the question of whether this principle could help other solar scopes, especially where a full aperture ERF is not used and there is heat build up in the scope. A cooling fan on the Tal100R for CaK work may be a future project to look at!
This timelapse is over 10 minutes and was taken with the Airylab 203.2mm HaT telescope, a double stacked Daystar etalon at 5.6m focal length using the PGR Blackfly GigE IMX249 camera. The link to the full size animation can be found here.
Wednesday, 20 July 2016
Tuesday, 5 July 2016
A really nice hedgerow prominence visible today, taken with the 0.2 metre Airylab HaT at 5.6m focal length with a double stacked etalon and the PGR Blackfly GigE IMX249 camera. I suspect by wednesday this will be a filaprom, and by thursday this will be a filament as it moves across the face of the sun.
This bit of sun on the western limb was quite interesting; subtle filaments and choppy plasma around S5353. Taken with the Airylab HaT at 203mm aperture, 5.6 metre focal length with a Daystar Quark double stacked with a PST etalon using a PGR Blackfly GigE IMX249 camera.
There were some interesting filaproms visible today - cooler clouds of plasma held aloft the solar surface with magnetic fields. Taken with the 0.2 metre Airylab HaT and a double stacked Daystar etalon with a PGR Blackfly GigE IMX249 camera.
I had hoped this area of plage that rounded the limb yesterday would have a bit more activity associated with it, but a day on this just seems to be a relic corpse of magnetic froth with no major sunspots. Oh well! Taken with the 60mm scope at 1500mm focal length with the homebrew CaK filter and the PGR Chameleon 3 USB3 camera.
Taken with the ED80 at 60mm and 600mm focal length, this is a 2 pane mosaic of our sun taken in CaK light with the homebrew CaK filter and the PGR Chameleon 3 USB3 camera. This shows very well just how quiet our star is becoming as we head towards solar minimum in a few years time.
The appearance of proms on the limb on sunday, and a look at the NASA STEREO spacecraft data would indicate that something a little more active was coming around the limb of the sun. Looking in CaK light often shows sunspots that can be hidden initially in Ha wavelengths and this image certainly hints at a possible spot, but certainly a brighter area of plage. Will be interesting to see in the days ahead if this is anything worthwhile; personally I think it is a dying or dead active region rather than one developing. Taken with the Skywatcher ED80 at 60mm aperture, 1500mm focal length with the homebrew CaK filter and the PGR Chameleon 3 USB3 camera.
S5346 is the innocuous name given to what is probably currently the most active region on the solar surface, a brighter patch of plage I was initially hopeful that it might develop into an active region, but alas no, not even any signs of any mores , certainly when I have been observing it. Taken with the ED80 at 60mm aperture, 1500mm focal length with the homebrew CaK filter and the PGR Chameleon 3 USB3 camera.
On a quiet sun in CaK light there is still plage visible, these are whiter frothy magnetically more active areas of plasma on the chromosphere of the sun. Here a small area passes towards the suns western limb. Taken with the ED80 at 60mm with a barlow combination to get to around 1500mm focal length using the homebrew CaK filter and the PGR Chameleon 3 USB3 camera.
Sunday, 3 July 2016
When the sun has few sunspots, in Ha wavelengths it is often the case that filaments are visible, cooler clouds of plasma held aloft the suns chromosphere by magnetic fields. This was the the case today with quite a few being visible. These were well revealed by the 203.2mm Airylab HaT telescope with a double stacked etalon and PGR Blackfly GigE IMX249 camera at a focal length of 5.6 metres.
The boffins at NASA say the face of our sun is currently blank; this is a relative term, and depending on how hard you look depends on how much you can see. This is where the 0.2 metre Airylab HaT comes into it's own. With a double stacked etalon the contrast was very high due to a lack of continuum leakage and as a result this un-designated region with its dark filaments and bright plage really stood out. Taken at 5.6m focal length with the PGR Blackfly GigE IMX249 camera. With a decline into solar minimum coming the larger apertures will continue to win out in solar observing, where the smaller scopes just don't have the resolution to view these smaller scale features of the chromosphere.
A nice hedgerow prominence to go with the filaments today, and possibly the hints of an active region thinking about getting going just off the centre of mid disk. Taken with the Lunt 50 etalon at 40mm at 600mm focal length, Coronado BF15 and the PGR Chameleon 3 USB3 camera.
Another day with very little in the way of activity on our star, possibly a new active region is hinted at on the lime with a faint hedgerow prom. Apart from that not much to be seen in CaK light. Taken with the ED80 at 60mm aperture, 600mm focal length with the homebrew CaK filter and the PGR Chameleon 3 USB3 camera.
Saturday, 2 July 2016
There may be no spots currently on the face of our star, but in Ha wavelengths at 656nm there were plenty of filaments to see. I was hoping to get 2 panes to make a full disk, but this was all I could manage with the gaps that I had. Taken with a Lunt 50 etalon at 40mm aperture at 560mm focal length withe the PGR Chameleon 3 USB3 camera.
The sun itself may be devoid of spots and blank at the moment, but that doesn't mean it's not possible to get something interesting passing over it. As I was recording my data for my full disk image I was pleasantly surprised to see a plane coming into land at Birmingham airport transit the face of the sun. Taken with the Skywatcher ED80 at 60mm aperture, 600mm focal length with the homebrew CaK filter and the PGR Chameleon 3 USB3 camera.
Friday, 1 July 2016
June has been one of the poorest months I can remember in a long time in terms of bad weather - cloud and rain, most un-seasonal in the weather we have been having, and, as a result this has had a real impact on solar observing with just 2 days possible, one at the start of the month and this at the end. This image was taken through my Lunt 50 etalon on a 40mm scope at 560mm focal length with a PGR Blackfly GigE IMX249 camera. It is a departure from the normal Coronado DS40 etalons normally used, as after one of them was decontacted, despite me recontacting it the performance has never been the same, and i've never really been happy with either of these etalons in any combination, with or without the LS50 etalon. As the LS50 etalon is a double stack certified etalon I really didn't expect it to work on its own in single stack, but it does and works well, which really surprised me. So, for now, until I can afford an LS50 scope to mate it with it will be used in single stack mode like this.
Posted by Mark Townley at Friday, July 01, 2016