Category : The Sun

Partial Solar Eclipse 10th June 2021

After days of hot and sunny and cloudless skies of course on the day of the solar eclipse it was nearly 100% cloud cover. I nearly didn’t even both opening the observatory roof. But I still did and it wasn’t until about 11.30am that the clouds started to clear. The actual partial solar eclipse was scheduled to end in the UK around 12.30pm.

My mount was not aligned or ready to slew to point me at the Sun, so it was a matter of loosening the mount clutches and moving the scope around until I found the Sun in the eyepiece I had attached.

I performed all my imaging using a homemade Mylar solar sheet that I had turned into a cover for the end of my Altair Astro 80mm triplet telescope. I also added a Williams Optics 0.8x flatenner, some extension tubes and of course the ASI120 MM camera. See my other post for more information and images of my set up.

I used Firecapture software to capture my video and it took me a while to get the settings perfect (as well as the focus) as the lingering clouds were messing things up for me.

Here are the settings I ended up using:

File type=AVI
ROI=1280×960
FPS (avg.)=27
Shutter=0.130ms
Gain=8 (8%)
Gamma=95

This was with no UV/IR or Solar Continuum filters.

I wanted to grab as many frames as possible in each video, but  I was worried about getting too many and bringing blur into the final image. I finished off with about 20 videos with the solar eclipse at different stages.

After bringing the video files indoors I used a mixture of AutoStakert and GIMP to give the images some false colour as all my images were in mono from the mono camera.

Partial Solar Eclipse June 2021

Solar Partial Eclipse 2021

Ending of the Partial Solar Eclipse 2021

 

 

 

Preparing for the June Partial Solar Eclipse 2021

Well it’s been a while, but on Sunday I cracked open the observatory shed roof and started to prepare for the partial solar eclipse on 10th June 2021.

I have decided to image the solar eclipse in white light using a solar filter that I previously made. I shall be using my trusty ASI 120MM-S mono camera, The software I am going to use is FireCapture.

Well it took a bit of remembering what to do software wise, regarding EQMOD toolbox, focusers and using FireCapture. I started getting all the camera attached and then finding the sun and then trying to get focus.

It then dawned on me I probably would not get focus as the camera was too close to the focuser. It then took me a while to hunt for some extension tubes with the correct adaptors and then try again. Finally I managed to get focus but found out the Sun was too large when using the 80mm triplet telescope to fit on the screen/chip.

Back I go indoors to find out what focal reducers I had. I had a 0.8x Williams Optics focal reducer so used that, and then had to get the correct adaptors again to make it all join together.

Now the Sun just fits onto the chip of the ASI120MM-S.

I remembered all the problems of trying to focus and see the actual screen of the computer when the sunny sky is above your head. It was a lot better to go indoors and remotely connect to the observatory PC and view the screen indoors.

But that’s only half the story it was then time to try and work FireCapture. I ended up recording in SER format. Which I don’t like as the video seemed a bit grainy. I shall change to AVI format next time. I brought the video  into the house and used Registax 6 to stack it and then GIMP to add some false colour to the final image.

The Sun 5th June 2021

Here’s the setup I’m going with:

Partial Solar Eclipse Setup Partial Solar Eclipse Setup

Shown in the images:

  • Williams Optics x0.8 Focal Reducer/Flattener
  • 2x small extension tubes
  • T2 to 1.25″ converter
  • ASI 120MM-S camera
  • Altair Astro 80mm triplet telescope

 

Mercury Transit 2019 Report

The Mercury transit 2019 for the UK was on Monday 11th November with it hitting the middle of the Sun at about 3pm UK time. Start time was around 12.30. Not the best time to have a transit in the winter when the Sun is so low down all day and it sets really early at about 4pm.

The weather was not kind either a 20mph wind with heavy rain in the morning and lots of cloud. But at one point there was a clear section for about 10 minutes. I did not bother opening up the observatory and imaging properly with a high frame rate camera once I saw the pouring rain and cloud cover. Instead I decided to just get the Coronado PST out on a simple tripod and have a look.

It’s so funny when you first start looking for Mercury on the face of the Sun, you expect it to be bigger than it is. Here I am looking for a big black dot, when in reality it’s a tiny black dot, which seems only a few pixels across.

I tuned out the H-alpha part of the spectrum on the PST in order to get a better contrast and a plain orange Sun. I then tried my Moto G6 phone against the eyepiece (the PST has a really narrow FOV) the phone really over saturated the image, so I grabbed my Canon DSLR with the kit lens and put that up against a 20mm eyepiece in the PST and imaged by hand. Again auto mode on the camera over exposed the images, so I changed to a faster shutter speed.

I took them into my favourite image editor and tweaked them a little to try and bring out the little black dot (Mercury) some more, and here they are:

Mercury Transit

Mercury Transit 2019 no1 with arrow

Mercury Transit

Mercury Transit 2019

They are not that great, but I best I could do without a tracking mount and a proper camera attached. I was happy to have something.

Transit of Mercury 2016

Today was the transit of Mercury 2016. I had two set-ups today – my Coronado Ha PST telescope with my ASI120-MMS camera in it and my Meade 127mm refractor with a white light filter on it, on this scope I tried my Atik 460 and Canon DSLR but none of these images came out that well, these cameras are just not made for solar imaging, all images from these cameras were too bright.

I imaged the transit of Mercury with the PST on its own and with a Televue 2.5x Powermate. The problem with the PST is that it does not do well when trying to image the whole of the solar surface as the etalon does not cover the whole of the solar disc so you can get bright and dim areas of the surface. The Coronado PST works best with the Televue 2.5x Powermate.

Previously I used a lot of the Imaging Source DMK CCD cameras, and I never really suffered from Newton’s rings. Thing is now I have an ASI120 camera which is a CMOS camera, it does seem to suffer badly with Newton’s rings. When trying to remove the rings it seems you can either buy a tilt adaptor or take flat frames.

I have always taken flat frames for deep sky imaging, but never for solar, lunar or planetary imaging. I did try taking some dark frames to remove the Newton’s rings but that never worked. Taking flat frames does work though.

I only tried taking flat frames when I took zoomed in images of the Sun with the 2.5x Powermate. You begin taking your normal video and then keep all the settings the same but just de-focus your telescope and then take a video of exactly the same length of time.

All the work is then carried out in AutoStakkert. Begin by loading your video of the de-focused Sun and select “Image Calibration” > “Create Master Frame” – then you will be asked to name the TIF file. Once completed you can then select “Image Calibration” > “Load Master Flat” and load your TIF file. Then load your AVI or SER video file and process it normally. You will now see all your Newton’s Rings disappear and your dust bunnies or doughnuts will also have disappeared.

It’s a pain to keep having to remember to take flat frame videos all the time, but as long as you don’t change your field of view or exposure, gamma or gain settings you should be OK and be able to use the same flat frames.

Mercury Transit

Solar Surface Details

Mercury on this is at the top right hand corner, taken very close to first contact.

full solar mercury transit

The Sun in Hydrogren Alpha with Coronado PST

This image of the Solar disc was taken on Saturday 6th July 2013. It was taken using a standard Coronado PST and an Imaging Source DMK21 AU618 Mono camera. I did use a Short ‘C’ mount adaptor in order to allow the PST to gain focus, without having to use a Barlow lens.

As the DMK21 is only 640×480 I have to take 4 videos and then process each one in turn using Registax 6. I then imported them into Photoshop and used the Photomerge software to align them all up into one image. I then gave the mono image some false colour.

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