Hughsie

Detached Prom 17072024.mp4

The Sun may be bright but an imagers future isn't. From my archive we have 25th June 2020 when the Sun was quiet and imaging gear was cheap. I wonder how many of us will still be into this hobby then.

Definitely more dust to one side, almost like the Cocoon rolled through the sky. Here’s my attempt; https://www.astrobin.com/t7l9a4/C/?nc=collection&nce=2346

I agree with the above, however, I would set c1,000 alignment points and if I am capturing a feature near the limb where I know prominences are located then I will also drop the brightness to zero to set alignment points in the dark areas where the proms are. If seeing is ok I will aim to collect a SER file made up of 5,000 frames. If there is some modest ‘wobble’ then maybe 2-3,000. If it’s total rubbish, pack up and do something else more constructive! When choosing the number of frames to stack once the analysis is finished I will use the video slider and move it over to the right and watch the quality count drop from 100 to say 75%. AutoStakkert will report the number of frames that fall into that quality range. If I can get 100-120 frames with minimum quality of 75% then great. If I have more than 120 frames at 75% then I will reduce the number of frames used aiming for 80/85% but keeping it around the 100 frame mark. It’s a bit suck it and see striking a balance between quality, detail and keeping the noise down. Best thing is to take the resulting stacked image and play with it in processing then restack using more or less frames. Over time you will get to know what works for your set up.

Prominence.mp4

Hello Dunc. I use the Lunt 60mm and ASI 174mm. Like you I also started with the asi 120mm and was unable to remove the dreaded Newtons Rings even with a tilt adaptor. With my current set up there are some rings but they can be corrected with the tilt adaptor. My biggest worry now is dust motes!

That’s a great site too, I use it to identify the AR numbers for the images I am capturing so I can label them correctly in the final picture. Sometimes there may only be a single spot or none at all then the GONG site may help as you can identify any proms on view and adjust the camera orientation accordingly. The SpaceWeatherLive site also has a good activity archive. I will refer potential solar flare images taken to the solar flare section to see whether I actually did catch a flare in action 🔥

Camera pixel size with this scope combo will result in a slight over-sampling in good ‘seeing’ conditions. Binning 2x2 might also be tried. Seeing at 200mm aperture will also be a challenge to acquiring a good image. Whilst nothing can be done to change the ‘seeing’ I prefer imaging in the morning when temperatures are lower and none of my neighbours roofs have warmed up!

Unlike deep sky and lunar imaging, the solar surface whether photosphere or chromosphere is continuously moving. It is therefore important to capture as much data as possible within the shortest time possible. In effect you need to ‘fix’ the seeing. This is achieved through taking very short exposures typically around 2-3 ms for around 10 seconds, typically 1,000 to 1,500 frames depending on the camera. Taking long exposures of 2 minutes will acquire more light but this is the Sun we are imaging, we have plenty of that. Longer overall exposures may have great individual frames but when stacked they will become blurred. Remember the solar surface when you started the exposure will look different 2 minutes later. So, the key factors are; 1) Exposure time - typically milliseconds. 2) Gain - a higher gain setting will allow you to reduce exposure time. You might ask won’t increasing gain increase noise? Well, the total exposure time is around 10 seconds so no. 3) FPS - needs to be as high as possible. Low exposure times help. Reduce ROI helps. Imaging in 8-bit rather than 12 or 16 bit will help. At a gain of 250 and exposure time of 7ms I can achieve c130FPS with the ASI174mm with a double stacked Lunt and 4x Powermate. FPS increases to c160 with a 2.5x or 3x Barlow as I can use an even lower exposure time as the image is brighter. 4) Appropriate settings in your acquisition software will help generate high FPS but your computer needs to be able to keep up. USB 3 and writing to an SSD is a must otherwise you will just ‘drop’ frames resulting in a longer overall capture time and lower FPS. 5) Camera - mono over colour is preferred. Cameras with high FPS like the ASI174mm and Player One solar cameras fit the bill. Large pixel size also helps (the 174 has 5.86um pixels, the top Player One camera for solar is near twice that of the 174). The 585 I believe has a max. FPS of 46 so you facing a challenge here. So, initially you will need to tweak 1 to 4 above to reach this unless you want to purchase a different camera. John PS - I image in H-alpha and just seeing the post from Elp notice you are referring to white light. Certainly play around with exposure and gain and use the histogram to make sure you are not blowing out any of the highlights. Points 3 and 4 remain relevant whether imaging in white light or H-alpha.

One image and one timelapse. The timelapse runs from 06:54 to 07:39 UTC then clouds drifted by. If you stare at it long enough you might see it move before you fall asleep.

That is a cracking first image David. The double stack PST looks really good. You have a nice bright center and the limb darkening is even all around the disc which means you have a good one. If I may though I would like to add some observations; 1) Orientation. We are floating around in space so what is up and what is down seems irrelevant, however, if you look at most images they tend to have North top and East to the left. Your image appears flipped around the horizontal which can easily be fixed within the acquisition software and a bit of camera rotation. I use https://gong2.nso.edu/products/tableView/table.php?configFile=configs/hAlpha.cfg to see what is happening on the solar disc and try and match my images to the orientation on Gong. 2) If this was my image I would bring back the contrast and sharpening a little, less is more. But it's your image and if that is what you like then that is all that matters. 3) If you haven't already, sign up to the free SolarChat Forum https://solarchatforum.com/ There are some great resources there for new and experienced solar images and members have been very helpful when I have asked questions. Welcome to the bright side! John

A short test timelapse....

The constellation Cassiopeia is named after the Ethiopian Queen Cassiopeia, mother to Andromeda who was saved from the whale, Cetus, by the Greek hero Perseus. You would have been forgiven for thinking that I had spent a short dark night taking a photograph of Cassiopeia but this is in fact the asterism, Kemble 2. Given its similar "W" shape, Kemble 2 is also known as 'The Little Queen' or 'Mini Cassiopeia' and can be found in the constellation Draco located RA 18h 35m 32.4s Dec +72° 22' 38.353" it is approximately one degree south east of chi Draconis. This asterism was discovered by the Franciscan friar and amateur astronomer, Father Lucian Kemble in August 1994. Father Luc was a keen observer of the Saskatchewan skies in Canada building upon his first observations as a child from the dark prairies of Canada. Over the years he became an accomplished observer receiving the RASC Messier certificate, Astronomical League of America Herschel 400 certificate, RASC Amateur Astronomer of the year 1989 and the Webb Society award of excellence 1997. As the name would suggest there is a predecessor Kemble 1, also known as Kembles Cascade, a beautiful line of unconnected stars located in the constellation Camelopardalis and Kemble 3 (The Kite) which can be found in Cassiopeia. It is my aim to photograph these remaining two asterisms later in the year when they are higher in the night sky. Being a man of faith some would assume there could be a contradiction between his religious belief and scientific interest. In fact in an interview he was once asked about the relationship between his interest in astronomy and his faith. He replied; This is a question that often intrigues people. I know people who say, “Gee, if you’re interested in science, then how can you believe […] the Bible? Or if you’re a theologian, how can you believe in science?” They see it as a contradiction, I see it as complementary. I have no conflict at all. One bolsters the other. My theology is made richer by learning the real cosmos in which we live […] and vice versa; my interest in astronomy just overwhelms me sometimes with the beauty and the order and the precision and the absolute awesome wonder of the universe. So my prayer life is just as much at the telescope as it is in the chapel. Father Luc passed away in Regina, Saskatchewan on 21st February 1999. His obituary can be found here: https://articles.adsabs.harvard.edu/cgi-bin/nph-iarticle_query?1999JRASC..93..151.&defaultprint=YES&page_ind=0&filetype=.pdf

Stand by your scopes.

Well done on your first mosaic. There are lots of panoramic stitching software available that can bring the panes together. Personally, I use Affinity Photo and it’s Panorama tool, but that comes at a one off cost (currently £68) but they do from time to time offer great deals. Alternatively, you could try https://sisik.eu/pano which is free. A fellow astronomy club member uses it and has had good results with up to 7 panes so that might be worth a go.