First Narrowband, Difficult Subject: Planetary Nebula Sh2-313
10-May-2016
For my first foray into narrowband imaging, I have chosen a very dim & difficult target: planetary nebula Sh2-313, also known as Abell 35 and PK 303+40.1
This nebula shows a very distinct bow shockwave from the central star plowing through the excited oxygen. The central star is also spinning so fast it is close to tearing itself apart.
Image:
- 33x 900s H-alpha bin2x2 + 10 flat + 50x dark + 120x bias
- 27x 480s SII bin2x2 + 20 flat + 50x dark + 120x bias
- 39x 420s OIII bin2x2 + 10 flat + 50x dark + 120x bias
- Color Mapping:
- Red: 67% Ha, 33% SII
- Green: 67% OIII, 33% Ha
- Blue: 67% OIII, 33% SII
Total integration 16 hours 24 minutes.
Hardware:
- Celestron EdgeHD 1100
- SkyWatcher EQ8 Pro Mount
- Celestron 0.7x EdgeHD focal reducer
- QSI 683-ws Camera @ -15°C
- Astronomik Typ 2c RGB filters
- Orion StarShoot Autoguider
- Foresight Innovations On Axis Guider
- Starlight Xpress Adaptive Optics
Location:
- Orange zone in Brisbane, Australia. (Bortle 7)
- Imaged over 9 nights.
Software:
- Planning & camera alignment with Aladin 9
- Captured with AstroArt 6
- Guiding with PHD2 + PHD_Dither
- CCDInspector: Image analysis & rejection
- CCDStack 2+: Calibrate, align, stack, flatten background.
- Astra Image 4.0: Deconvolution.
- Photoshop CC: Reduce noise, high pass filter, merge Ha+SII+OIII, color balance, curves, reduce gradient, saturation, minimum filter.