Sh2-129 – Flying Bat Nebula and Ou4 – Squid Nebula
Sh2-129, known as the Flying Bat Nebula, is an extensive emission nebula in the constellation Cepheus, with an approximate magnitude of +10. Embedded within this region is Ou4, known as the Squid Nebula, a very faint bipolar structure that stands out primarily through its OIII emission. Photographed as an HOO composition, these objects have been among the most difficult I have captured because of Ou4's extremely faint signal. Processing was also particularly complex because the Squid's faint OIII emission overlaps the intense Hα emission from Sh2-129. Nearly 24 hours of integration and several additional hours of processing were required to reveal the complex's faintest structures. The data were captured over seven sessions on 28, 29 and 30 September, 17 and 18 October, and 4 and 5 November 2023.
General information
- Constellation
- Cepheus
- Category
- Nebulae
- Date
- 5 November 2023
Capture
- Total time
- 23h 50min
- Subframes
- 300s (Ha: 66x bin1, OIII: 220x bin2). Mean airmass per session: Ha: 1,064–1,250; OIII: 1,065–1,350
- Gain / Offset
- 125 / 30
- Calibration
- 50 dark frames, 40 flat frames and 40 dark-flat frames, without bias frames
Equipment
- Telescope
- TS102 f/5.6 (f/7 with corrector-flattener 0,8x)
- Camera
- ZWO ASI294MM at -10 °C
- Filters
- Ha and OIII Astronomik, 36 mm and 6 nm
- Mount
- Sky-Watcher HEQ5 Pro with belt drive
- Guiding
- PHD2, Guide scope 60 mm f/4 + ASI224MC + PegasusAstro UCH + PPBMicro
- Focuser
- ZWO EAF
- Filter wheel
- ZWO EFW, 36 mm and 7 positions
Processing and environment
- Processing
- Stacked and post-processed with PixInsight 1.8.9-2; estirament with STF and HistogramTransformation; mapatge HOO with PixelMath (R = Ha, G = OIII, B = OIII)
- Acquisition
- NINA, Cartes du Ciel (CDC) and PHD2; autofocus enabled per filter and focusing every 60 minuts
- Location
- l'Ampolla
- Sky
- Bortle 4