The Heart Nebula
IC 1805 · Melotte 15 · SHO + RGB stars · 2021–2022
Click the image for the full-size view.
The Heart Nebula in Cassiopeia was one of my first big narrowband projects – and one that stretched over almost two years. I used the TS 130 in two configurations, with reducer and with flattener; in total the telescope spent 8 nights on IC 1805.
At its centre sits the young star cluster Melotte 15. Its hot, massive stars are only a few million years old. Their radiation and stellar winds have blown out the huge cavity and sculpted the pillars and arcs along its rim. At the upper right glows IC 1795 with NGC 896, the brightest part of the complex – the so-called Fish Head Nebula.
Hydrogen, oxygen and sulphur each go into their own colour channel (SHO, the “Hubble palette”). Golden tones mainly show hydrogen and sulphur, blue areas ionised oxygen close to the hot stars. The stars come from short RGB exposures so that they keep their natural colours.
My image of the Heart Nebula has a very personal meaning for me: at my wedding, I dedicated it to my wife in front of all our guests.
About the object
| Designations | IC 1805, Sh2-190, Westerhout 4; cluster Melotte 15 / Collinder 26; brightest part NGC 896 |
|---|---|
| Type | emission nebula (H II region) with open star cluster |
| Constellation | Cassiopeia |
| Distance | about 6,500–7,500 light-years (depending on the source), in the Perseus Arm of the Milky Way |
| Apparent size | about 150′ × 150′ – roughly five full Moons across |
| Discovery | William Herschel, 3 November 1787 (NGC 896) |
| Position (J2000) | RA 02h 33m · Dec +61° 27′ |
Acquisition details
| Observatory | New Horizons Observatory, Münster (Westphalia), Germany |
|---|---|
| Telescope | TS Photoline 130 (flattener 910 mm and reducer 730 mm) |
| Camera | ZWO ASI6200MM Pro |
| Filters | Chroma 3 nm Ha/OIII/SII, Chroma R/G/B |
| Total | 62.4 hours over 8 nights |
| Software | N.I.N.A., PixInsight (WBPP, Drizzle 2×), RC-Astro BlurXTerminator / NoiseXTerminator / StarXTerminator, AstroWizard |
Exposure per filter
| Ha | 356 subs (180 / 360 s) | 20.7 h |
| OIII | 315 subs (180 / 360 s) | 17.5 h |
| SII | 349 subs (180 / 360 s) | 20.1 h |
| R | 29 × 180 s | 1.5 h |
| G | 28 × 180 s | 1.4 h |
| B | 28 × 180 s | 1.4 h |