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Sol'Ex - 2025042x

Now that spring appears to have arrived, I have got the Sol'Ex out again and have connected it to the SVBony 80mm F7 refractor that is my workhorse. As I need to try and capture full disk images, I am also using a 0.8 Focal Reducer specifically designed for imaging with this telescope.

There is a  ND8 Urth professional filter fitted in a homemade 3D printed housing to absorb most of the sunlight (importantly the heat). This appears to be working OK or rather, I haven't shattered the slit again. Camera is a ZWO ASI178MM Mono.

First tests with the new setup were carried out on last Sunday evening (20250420), not an ideal time of day as there was distinct high level cloud and the sun was quite low in the sky..

The change in optics from the smaller 60mm f4 refractor that I had previously used resulted in a much more detailed image. What is initially obvious is the cloud on the left of the image but all in, I was quite pleased with this.

The JSolex application that I use to process the images produces a few variations, including doppler shifted images. This allows you to calculate the rotation speed of the Sun for example. There is also a variant of an eclipsed Doppler image. The large prominence at the top right (North West) showed a very interesting doppler pattern.

This is a 100% sized crop. Careful examination shows the Blue (plasma moving away from you) and Orange (plasma towards away) to be twisted in a whirlwind formation. I assume that this is a tornado class prominence but it doesn't fit with the standard descriptions. More investigation required!

I used the Sol'Ex for the next 3 days. One thing that I have noticed is that the new optical setup accentuates any errors in the Sol'Ex optical train. The following day, I noticed that the images were being cropped when imaging the CaK spectral line. The crop was still within the boundary of the camera sensor so was being lost elsewhere. Carefully shimming the grating improved matters but now caused the same problem at Ha but on the other side of the camera sensor. Nothing of significance for the 21st April as I was trying to resolve this problem.

That particular problem is still work in progress.

On the 22 April, I tried again at Ha.

A very cut down image but the long looping prominence to the North East looks very interesting. 

The doppler image:

The sharp edges are a processing artefact but you can see that the bulk of this prominence is moving towards us (with the rotation of the sun) with the top edge of the prominence moving away.

Finally, on the same day, this is the West North West hemisphere in Ha.

 I suspect that the prominence is still the same prominence that I observed 2 days earlier. The image does give a good indication of the resolution and hence detail that can be seen using a spectroheliograph.

The tornado seems to be going strongly, in fact, I think the spiral is more obvious in the image.

 

20250328 - Evolution of a large Prominence

I didn't expect much today. The White Light Sunspot count only revealed 3 groups in the North Hemisphere but this included one new large single spot group  (AR 4046).

Observing in Ha using the SCASTRO 60mm Lunt Telescope, I noted a large prominence just above the newly emerged sunspot. This was observed for just over two hours and the evolution captured in a number of frames. There were breaks during the observation due to heavy cloud and eventually ended when rain arrived

Telescope: Lunt ST60 with Baader modular Barlow Lens ~ 2x - ZWO ASI 138MM Camera.

The solar disk is heavily over exposed. The prominence is very dim compared to the brightness of the photosphere. Where light cloud passed over, the chromosphere (Solar atmosphere) become just about visible as an apparent series of speckles.

This initial colourised image is a combination of a correctly exposed photosphere merged with a a correctly exposed image of the prominence.

Imaging commenced at 12:06UT and ended at 14:12UT.

 

 

DSLR Cameras for Astro photography

At my level, I prefer to think of Astrophotography as "Astronomy with a Camera". I am definitely not into producing Hubble-esque  images. I have neither the time, the money or the location to spend hours and hours imaging one object. There is so much more I would like to observe.

For me, "Astronomy with a Camera" is about enhancing my own experience of the night sky, to pick out the detail that I can't quite manage with my aging eyesight and to keep a record of things that have caught my attention.

I recently gave a talk on Basic Astrophotography ("Astronomy with a Camera") at my local club (South Cheshire Astronomical Society - SCASTRO) on getting started  using basic consumer cameras - Smartphones, Compact Cameras and Digital SLR Cameras - with some hints and tips based on my own experience. It was while I was giving this talk that I realised that I hadn't used a dSLR for Astronomy for many years. I thought it would be interesting to step back and try again.

One image that I did take many years ago (about 2010) with a dSLR was the Pleiades - M45 - which just showed the beautiful blue reflection nebulae.

(2010 - SkyWatcher 200mm F5 Reflector, EQ5 mount Konica Minolta 7D dSLR)

I wanted to try and recreate that image and if possible, improve on it. So for the past month or so, I have spent about 3 hours imaging and so far have not succeeded due to persistent high level cloud (and resultant sky glow) on the few nights that have apparently been clear. Hey, ho the joy of Astronomy in the UK.

However a couple of other targets have been fairly successful. All imaged using the same SkyWatcher 200mm Reflector and either a Canon 350D or a more modern Sony Alpha 58.

Firstly, the stunning Double Cluster in Perseus - officially NGC869 (left) and NGC844 (right).  I like clusters.  

(20250307 - SkyWatcher 200mm F5 Reflector, EQG mount Canon 350D dSLR)

I was quite pleased with that image, it's not stacked but has been tweaked very slightly in Registax to darken the sky and bring out a little bit more star detail. Camera was a Canon 350D

The next image was Messier M3, taken with a Sony Alpha 58. This took a couple of attempts. Although I couldn't actually see the cluster in the 'Live' viewfinder, pre-focussing and centring the object visually made this 3rd attempt fairly easy. Stacked from 10 images of 30 seconds exposure each and tweaked very slightly using Registax,

(20250324 - SkyWatcher 200mm F5 Reflector, EQG mount Alpha 58 dSLR)

The image has been cropped slightly.

 

Finally, Messier M81 in Ursa Major. At 12 Million Light years distance, I didn't expect very much:

(20250324 - SkyWatcher 200mm F5 Reflector, EQG mount Alpha 58 dSLR)

A little bit of detail lost while compressing from png (16 bit) to jpg (8 bit) format but what really surprised (and delighted) me is that the arms of this face-on galaxy are actually visible. This was a stack of about 30 exposures, each of 30 second duration - a total of 15 minutes exposure time.

I don't have a proper OSC (One Shot Colour) Deep Space Camera, this little experiment has proved to me that for the brighter Deep Space targets, a dSLR can be a very worthwhile tool in the Amateur Astronomers arsenal. More experimentation to come, I think.

20250318 - Haig Mount Time

The Haig mount was designed by a gentleman named George Haig and the original design was published in Sky and Telescope back in 1975.. It broadly consists of a hinged flap (or 'barn door') that opens at Sidereal rate (15 degrees per hour). A Camera on a ball mount is mounted on the opening door and this can then be used for imaging large scale items such as constellations. This Wikepedia article explains the principle.

I built my Haig mount about 17 or 18 years ago, I don't use it very often, I don't know why not as it keeps me occupied while my other telescopes are doing more serious work.

We had what appeared to be a clear night on 2025-13-18, in reality, it was actually pretty awful with high level cloud limiting naked eye magnitude to about Mag 2.5 or 3. Polaris was just visible and M45 was an averted vision fuzzy patch.

So while my 200mm F5 newton telescope was trying and failing to capture the nubulosity surrounding M45, I thought I would have play with my Haig mount.

I used my Sony A58 DSLR - not the best choice as the 'live view' viewfinder is very limiting on framing the image in the dark. and selected 3 targets

  • Orion and M42 as it was setting in the west
  • Cancer with M44 - I love M44 - my favourite open cluster
  • Leo - hoping to capture some of the galaxies (M65/M66).
Orion & M42

This made quite a good movie as the hedge slowly rose up. The mount tracked the constellation really well. Quite a few frames had to be discarded due to aircraft trails and some brighter satellite trails.

Cancer & M44

Quite a nice shot although there is some evidence of flaring on some of the brighter stars. I think I need to check that the lens is clean - it hasn't been used for years.

Leo

I didn't capture either M65 or M66 - it took me a while to navigate around the image. It didn't help that Denebola had been cropped off the left hand side. I have marked out the Greek letter star notations. Still quite a pleasing shot considering the conditions.

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