Witches brrom narrowband

[blinky]

Im not totally happy with this, still have guiding issues at 800mm/0.98arcsecs  - Think I might just go back to the frac for now until I get the EQ6 retuned in a year or so...…  THis is only 15x5min subs in Ha/O3/S2 in the hubble colour scheme, cant get to grips with the central bright star, cant get a mask on it and the surrounding colour in Pixinsight and have messed about with it enough!

[wimvb]

Very nice image despite your troubles. As for a star mask to single out the big one, try this. 

In pixinsight use the cursor/pixel selector to determine the centre coordinates of the star. These will show at the bottom of the pi window. Then move to the right edge of the star. Note the change in x coordinate and determine the difference with the centre x coordinate. This will become your radius

Then use pixelmath:

Inellipse(x_c, y_c, radius, radius). Create a new mask image with the same width and height as that of your image, but gray scale, not colour. You may need to redo this a few times to get good coverage of the star. Finally use convolution to blur the mask. You can combine this mask with an ordinary star mask if you want. Again pixelmath:

Max(circle_mask, star_mask) applied to either the circle mask or the star mask. 

Good luck

Edited October 3, 2019 by wimvb

[blinky]

Brilliant idea! Will try tonight and post the result