5 replies to this topic

[FlankerOneTwo]

Had a go at some deep sky imaging with the RedCat 51, first attempt with the RedCat and first attempt with an OSC cam (ASI1600MC-Cool). Conditions were far from ideal (Rho Ophiuchi was a complete bust) due to 87% moon, persistent thin high cloud layers, and imaging location just outside of Las Vegas, although seeing was actually quite good. I finally managed to get the M48 adapter unthreaded to install a 2" LPro filter in front of the ASI1600MC. Imaging train was an Orion TOAG with an ASI290 mini guide cam, followed by the ASI1600.

Although I wish for a motorized focuser (I seem to recall that William Yang did mention at NEAF that they were working on one), I did find that using the stock helical focuser it was not difficult to achieve good focus with the Bahtinov mask.

 

This is a stack of 58 frames x 120 sec, processed in PixInsight. I found the processing somewhat challenging due to the incredibly high number of stars in this field as can be seen in the second image below - these are 33% reductions and of course jpg'ified so sharpness suffers.

I'm not really happy with the results from MorphologicalTransform even after fiddling with the settings some - there are some weird threadlike artifacts between star remnants (haven't experimented with the Interlace setting yet, would this help?) and the small stars in the corners all turned into colored dots.

I haven't gotten proficient enough with Adam Block's Star DeEmphasis technique, but want to give that a try on this next.

 

Haven't yet done a detailed analysis of the stars, to my relatively inexperienced eyes there appears to be some chromatic aberration near the edges (radial asymmetric blue halos) as well as tilt in my imaging train because the stars in the top corners, especially top left, appear comatic in shape. Not sure if this is coming from the TOAG or the sensor itself.

 

Full sized JPG at https://www.astrobin.../full/410275/0/

 

If anyone has more experience analyzing refractor performance and wants raw FITS subs, let me know.

As always, thanks for looking and any helpful comments or critques are much appreciated!

 

Clear skies all!

 

[FlankerOneTwo]

So many stars!

 

[bobzeq25]

Try MorphologicalTransformation with these settings.

 

Operator: Morphological Selection

Iterations 5

Amount 0.20

Selection 0.25

Size 7 (49 elements)

Click the second row, second icon from the left.  Circular Structure.

 

Everything else is the default.

 

A refinement is to apply a Star Mask so MT only operates on the stars.  Good practice, not absolutely necessary.

 

If that is pleasing to you, you can do it more than once, or fiddle with the settings.  If it's too much, dial back the amount.

 

Here's an Ha NAN that I did something similar with, just to give you the idea.  It may be "too much", but I really hate it when stars detract from the main target.  As always, bad CN jpg, fullsize here.

 

https://www.astrobin...364025/?nc=user

 

 

Edited by bobzeq25, 13 June 2019 - 07:24 PM.

[FlankerOneTwo]

Hi Bob,

 

Thanks, in conjunction with some improved masking, that does seem to produce a better result. Really nice image!

[Astroman007]

Gorgeous images both! (Posts #1 and #2).

[44maurer]

That RedCat really performs. Great job, I like #1 best.