Andromeda 4x2 RGB + 2x1 Ha mosaic - Work in Progress

[Padraic M]

I know that this is likely to be the start of a multi-year project, especially as for some reason the weather tends to be rubbish whenever Andromeda is in prime imaging position, this year being almost the typical example. But, as with all things that will take too long, the sooner you start the sooner it will be finished.

I have two set-ups for imaging:

- SW Esprit 80 & ASI1600MM Pro that I use for mono Hydrogen Alpha imaging in the city; this gives me 1.9"/pixel.

- SW 150PDS & ASI553MC Pro that I use for OSC RGB imaging under dark skies. Scale is 1.1"/pixel.

 

I had already captured some Ha as a 2x1 mosaic, giving all of Andromeda in frame. This weekend I had an unexpected clear and dark sky, with a little over an hour of Andromeda  remaining before it set behind the hills (actually the boiler house roof but whatever!). An ideal time to start an RGB mosaic - NINA showed that I would need a 4x2 mosaic with the 533 to cover much the same sky as the 1600MM 2x1.

 

Given that the weather is as it is, I decided to go for broke and get a small amount of data on each panel - 2x5 minutes on each of 8 panels to be exact. The good news is that the skies stayed clear for the 80+ minutes needed for that pass; the bad news is that there seems to be a gremlin either in NINA's mosaic planning or the sequencer; I haven't figured out the full coordinate map just yet, but there's a gap in the data between the frames in row 1 column 3 and row two column 3 if you know what I mean. 

 

I can always come back later, or in later years, and fill that data gap while capturing more data for the full FOV. In the meantime, APP did a really good job registering all 8 panels, and adding in the Ha mosaic, but it struggled with the data gap in the middle. Multi-band Blending (MBB) at 20%, Local Normalisation Correction (LNC) off gave the best results. Also the colour rendering is off slightly between the top half and lower half (stacked separately).

 

So, a work in progress, but encouraging for continuing with the project.

 

Data to date: 4x2 OSC RGB 2x5mins each panel + 2hrs 40m Ha 2x1 (1hr + 1:40)