C11 attempts 28th May 2020

[Montana]

Please don't laugh, I had a good go at using the C11 this morning. Pre-cooled overnight in the greenhouse, then covered with my blackout material while I added the Aries ERF.

First off Calcium K however the 3x telescentric was just blurred (too much) I settled on my Celestron 2x Barlow, this was the best at 07:40 UTC

Sun_074044_28_05_2020 by Alexandra Hart, on Flickr

Sun_074044_28_05_2020_f colour by Alexandra Hart, on Flickr

I then tried the PST mod with the 2x Barlow and I just can't get it on band, it is a bit like my broken Quark. I did try and move the screw so I could move the etalon round a bit but it didn't make much difference. I can only get on band on one side of the camera chip at a time which is very annoying.

Sun_082630_28_05_2020 by Alexandra Hart, on Flickr

Sun_082914_28_05_2020_f colour by Alexandra Hart, on Flickr

Sun_082914_28_05_2020 by Alexandra Hart, on Flickr

I am sorry I am not as good as Alfred, he gets much better results than me but I am trying honest. I was quite pleased with the last Halpha as I could get the off band bit in the dark space

Alexandra
PS still not a wink from Televue, maybe it will take another 2 months for the next email?

[EGRAY_OBSERVATORY]

Hello Alexandra.
I can see that it appears that out of focus would have been the problem, but the rim of the disk confirms correct focus.
Fairly obviously I know that you would have taken this during a clear-sky and also knowing that from the earlier satellite-imagery most of England had such a clear sky as we did in the south-east, so hopefully somebody else will come to your rescue and get this sorted asap...
One possibility though is:- do you sharpen the images as I was taught to do many years ago ???
Best Wishes
Terry

[JochenM]

Improving one step at a time, Alexandra. I'm sure you'll get there.

[RodAstro]

Hi Alexandra
I have had awful seeing the last two days, clearer skies today but the image never stopped still, I gave up in the end and got the eyepieces out, remember them
But seriously, you are not that far away from us, Peak District, do you think it could be seeing with such a big scope?
It looks so tantalisingly close, better than anything I got.

Rod

[krakatoa1883]

Hi Alexandra
the H alpha images contain many fine details, if you don't mind to send me the raw I'd like to give it a try.

In CaK images some details tend to form short streaks, may be that something in the imagin train was tilted.

[Highbury Mark]

They look pretty good to me Alexandra!
Also been admiring your sketching this afternoon (at the end of the BAA webinar on Solar Cycle 25 by Lyn Smith that was posted on YouTube)

[Montana]

Thanks everyone, I am sure it is the seeing, seeing seeing

Raf, hopefully you can download this but I am sure you won't find much in it (not like Alfred's )

Mark, oh dear, it was a lockdown challenge, I am no artist

Alexandra

Mmm Tif won't load, I don't get the place in line button, how does everyone post a Tif file then?

[Astrophil]

Alexandra, Tif files won't load for me but .png files will.

Phil

[marktownley]

Hi Alexandra, If the PST mod image goes off band across the fov it generally indicates there is some tilt - none of the adapters are cross threaded? What sort of view does the PST etalon give in the donor PST? If it is fine there then this would suggest a setup issue with the c11. I was out at the same time as you and was struggling in CaK at 100mm, did you get the SSM out?

I don't think TV will come back with anything productive, I seriously doubt they even considered the PM would be used for narrow band UV imaging when it was conceived. Perhaps Valery will enlighten us to how he gets it to work.

[Montana]

OK let's try a PNG

Mark, I will check but most things seem square. on the PST it seemed fine. It is like the on band is a thin ring, when you twist it expands outwards so the on band part is a thin stripe. When I started setting up at 7:50 BST the SSM readings were around 1 but going down regularly to 0.5 and 0.8. So on average around 0.5 to 2. When I got to he Halpha it was around 1-3.

Sun_082914_28_05_2020_lapl7_ap4775.png (2.82 MiB) Viewed 872 times

Alexandra

[eroel]

Alexandra, don´t worry, you soon will beat the big scope.
I still have not tamed my 10" f/20 Mak with a full Aries ERF.
Best wishes,

[marktownley]

OK let's try a PNG

Mark, I will check but most things seem square. on the PST it seemed fine. It is like the on band is a thin ring, when you twist it expands outwards so the on band part is a thin stripe. When I started setting up at 7:50 BST the SSM readings were around 1 but going down regularly to 0.5 and 0.8. So on average around 0.5 to 2. When I got to he Halpha it was around 1-3.

Sun_082914_28_05_2020_lapl7_ap4775.png

Alexandra

It just sounds like normal sweet spot behaviour tbh, the only other thing I thought looking at the above pic is that it's from the imx174, I seem to remember Valery using maybe something like a 1300x1000 (ish?) frame with his pst mod and c11. You may find with such a chip you are not just imaging the sweet spot but also the area outside of it, maybe ROI down?

[DeepSolar64]

Alexandra, you still captured that filament nicely!

[Carbon60]

Hi Alexandra,

With my 250mm RCT at its natural focal length the view is diabolical in Ha because of the simple optical design of my mod. Only a little part of the image is properly on-band. With a 2.5x PowerMate I get the dreaded bright centre spot until I further tilt the camera. The image is uniformly on-band, but the seeing conditions have to be exceptional to capture anything worth keeping.

I’ve now fixed on using a 1.5x Barlow, which still gives a decent image scale and a uniform view (within the sweet spot), but this has only come after a lot of tweaking to ensure everything is straight and square. I also collimate the scope every session. It usually requires a little tweak to get bang on.

I use a red filter (Ha 7nm) at the camera to enhance contrast and max out gamma.

I don’t know if any of this helps you, but it does take fiddling and experimentation to get there.

Stu.

[Valery]

I seem to remember Valery using maybe something like a 1300x1000 (ish?) frame with his pst mod and c11.

Close to the reality. It depends of the final on chip scale. Usually I do use a ROI of such a size that a sweet spot boundary is seen at the extreme corners only, which will be cut down in the AS!3 or in a postprocessing.


Valery.

[Freddie]

How is your collimation? It will need to be spot on for hi res imaging.