AR2759 in High Res Again | HA & CaK | April 4th 2020

[MalVeauX]

Heya,

Woke up to another fairly good sky, figured I'd take a look again. AR2759 has diminished and its umbra of the spot is very tiny now, a mere pore. The AR is still lively with a good plage and filaments but the sunspot is virtually gone at this point. Seeing was pretty good, lots of sub-arc-second time, so I grabbed information on the AR and local larger prominences. I finished up with a partial disc to showcase the AR and the two main prominences this morning at a courser scale.

High res data gathered from a 150mm achromatic doublet refractor with an internal sub-aperture D-ERF, 50mm, in the focuser before the filters. No front mounted ERF/D-ERF needed and the local seeing and OTA seeing conditions were not an issue as atmospheric seeing was good and the resolution was realized.

I gathered all this data in each wavelength & image scale in 24 minutes, with the same 24 minutes recorded in the SSM to show seeing conditions through the entire fast session. No waiting around or hunting for seeing as it was pretty consistently good. SSM data provided below with times of capture; note the SSM was not used to trigger, merely to measure seeing.

Colored:

B&W:

Seeing Conditions (SSM data; plenty of sub-arc-second seeing today; no issues with local seeing conditions from environment, observatory walls, OTA internal turbulence, etc).

Equipment:

CR150HD 150mm F8 Doublet Achromatic Refractor with Baader Glasspath 1.25x (F10)
Baader Red CCD-IR Block Filter, 2", as internal sub-aperture D-ERF in focuser
PST etalon + BF10mm + ASI290MM for High Res HA
Baader Blue CCD-IR Block Filter, 2" as internal sub-aperture D-ERF in focuser
Lunt Cak B1200 + 2x Barlow + ASI290MM for High Res CaK

ED80 + SM60II DS Etalon + PST Etalon + BF10mm + ASI290MM for partial disc HA

Very best,

 

[Sunshine]

Some truly phenomenal work here to say the least.

[Altocumulus]

Some folk have all the luck!

Great shots.....

 

ps. what do you use your Lunt Cak module in - the 150mm?

[MalVeauX]

4 minutes ago, Altocumulus said:

 

 

ps. what do you use your Lunt Cak module in - the 150mm?

Hello, yes, I use it with the 150mm F8 achromatic doublet, sometimes I mask to 120mm F10, today was 150mm F16. I use a Baader Blue CCD-IR Block filter in front to handle additional thermal load.

Very best,

[MarkAR]

Amazing images, well done.

[Mick J]

I have to agree with @Sunshine,   wonderful stuff.

[Altocumulus]

14 hours ago, MalVeauX said:

Hello, yes, I use it with the 150mm F8 achromatic doublet, sometimes I mask to 120mm F10, today was 150mm F16. I use a Baader Blue CCD-IR Block filter in front to handle additional thermal load.

Very best,

Thanks -  I know Lunt recommend <100mm, so wondered how you managed to counter the extra size. Do you know what the

tolerance is on that < 100mm - +/- 10mm (say)? I'm going to assume a 102 isn't stretching things too much - thinking ahead a wee bit now.....

[MalVeauX]

6 hours ago, Altocumulus said:

Thanks -  I know Lunt recommend <100mm, so wondered how you managed to counter the extra size. Do you know what the

tolerance is on that < 100mm - +/- 10mm (say)? I'm going to assume a 102 isn't stretching things too much - thinking ahead a wee bit now.....

100mm is 102mm frankly for this purpose. The idea is to maybe consider a D-ERF of some kind, in front of the Lunt module, when going into the 120~150 or larger apertures (assuming refractor). For any other design, a full D-ERF is needed anyways (Newtonian, SCT, Mak, etc). But refractors are ideal (the longer the focal ratio, the better, for 393nm performance).

Very best,

[Pete Presland]

Superb set of images.