I got literally 20 minutes this afternoon and noticed the bright spec in the centre of the sun spot; not notice that before. When I was looking at my initial images, I thought I had processed too hard but the bright speck in the middle of the spot is real. Any ideas?
Sounds like your imaging the light bridge which is currently crossing the umbra. Visible in white light, Ha and CaK.
This is usually a precursor to the spot splitting.....let's see what happens.
Mark,
Thanks. The DIY CaK filter seems to be working well. Really needs a f15 - f20 beam to give a good bandwidth....
No up front ERF. But the "Cak" filter is actual an stacked assembly of four filters.
The front 2" Baader Blue CCD acts as an ERF, then a 390nm UV cut filter, a 80nm wide band CaK filter followed by the 2A narrowband CaK filter...
Mirko,
Thanks.
In the absence of a Lunt or Coronado CaK filter, the DIY does seems to do a creditable job, at about a 1/4 of the cost!!
Onwards and Upwards
Enjoyed your images Ken, and everybody elses, hope to get another chance at AR2738 before it rotates out of view. Time and clouds aren't always in tune with my ambitions. Am getting a little curious about CaK filters now as well, not sure that is a wise thing.
Jeff,
CaK is a completely different view of the Sun...
The flocculation, plage and sunspots, fibrils are are seen at a different height from Ha. Slightly lower than in the core of the Ha.
The resolution (theoretical) is much higher than Ha (636/380 = x1.7) but the seeing is equally worse!
Unfortunately Coronado no longer produce their CaK filters...only Lunt left in the game unless you DIY.....
Nice pics Ken - this was an interesting sunspot esp. as there is not much activity at the moment. Re; your CaK stack - can you see the resultant wavelength visually? I know its in the UV region. Regards, John W.
I had the opportunity to have a look through a CaK scope just out of curiosity and was quite surprised with what I was able to see. I hadn't seen the video image beforehand and it matched up well. I'm 58 (with my own corneas).
Steve,
You did well!
I'll have to stick to CaK imaging....
The SHG.. good question. I now have three variants:
1. The ST80 (f5) with a Classical spectrograph.
2. The TS102 (f11) with the Spectra-L200.
3. The Carton 100mm (f15) spectroheliograph.
#1 and #2 have been a bit disappointing - problems traced to focal ratios and undersized collimators/ gratings.
The SHG looks very promising but a bit heavy for the available HEQ5 mount.
Needs "perfect" conditions and no wind....
The ASI 183MM I bought for the SHG turned out to be "not suitable for solar narrowband" and ZWO replaced it with the ASI 1600MM - still to be seriously tested. In the meantime I have the ASI 174 but this shows some terrible banding in the spectral image.....no answers as yet.
So, no images at the moment...
Weather permitting, the SHG is ready to use. Let's hope it can be used on AR 2738.
Onwards and Upwards.
Hi Ken, that's a carton alright. Admirable dedication and once the camera is sorted this should give great results. Is this able to be turned into a SH-scope as well, the type that can synthesise full disk? Poor lil Vixen rail though
Mirko,
Well spotted! The Vixen rail has already been replaced by the wider Losmandy rail....
No, this is an imaging SHG. To turn it into a visual SHS would require modifying the layout and adding Anderson prisms and a second exit slit.
Another project on the never ending list....
nice work Ken
