Nebulae - Barry Wilson
DWB 111 The Propeller Nebula

DWB 111 The Propeller Nebula

I have wanted to image this target for a couple of years now and I chose to mount my WO FLT132 rather than my widefield FSQ85 to help get closer to the target. The Propeller sits within a much wider emission nebula complex in Cygnus and is often imaged with NB filters, regularly in the strong Ha signal and also in HST palette with the much fainter SII and OIII.

The Propeller is also referred to as Simeis 57, and I have also read that this is its 'proper' catalogue designation and DWB 111 is incorrect; I'm not sure what is correct. I wanted to present the Propeller in a RGB format as well as the Ha mono and have captured first Ha over the last couple of weeks and then latterly the RGB data as the moon waned later in the twilght. It is still quite early in the summer nebula season and I was quite anxious about the RGB data, especially the Blue channel as by the time 2:30/3:00am arrives the target is still some way from it's meridian, although it is relatively well placed high in the sky. It is always good practice to capture the Blue channel at its highest to minimise the greater atmospheric dispersion and diffraction of the channel in comparison to the Red and Green - it can result in odd colourful ringing and flares in stars, especially bright ones. So rather than align the RGB to my previously processed Ha during calibration and pre-processing, I made a straightforward change to my normal workflow and aligned the Red and Green to the Blue and then subsequently aligned the Ha to the RGB image.

Details: WO FLT132 at F5.6; QSI683 wsg-8; 10 Micron GM1000HPS; Astrodon 5nm Ha; E-series Gen II RGB filters Captured with SGP and Processed in PI 15 x 1200s Ha; 21 x 300s each of RG&B Total integration 10.2hrs.