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The Chinese Dragon NGC 6559
David Cruz · Astromidnight
In Sagittarius, next to the Lagoon Nebula, hydrogen glows red around young, hot stars. At the edges of the cloud, dust reflects the light of those stars in blue and breaks up into dark filaments.
| Catalogue | New General Catalogue, 1888 · Sh 2-29 |
| Type | Emission and reflection nebulae |
| Distance | ≈ 4,000 light-years |
| Field | 80.9′ × 103.4′ |
| Real width | ≈ 94 × 120 light-years |
| Scale | 0.90″ / pixel |
| Orientation | −1° · north up |
| RA (centre) | 18h 09m 43s |
| DEC (centre) | −23° 54′ 48″ |
| Constellation | Sagittarius |
| Objects in field | NGC 6559 · IC 1274 · IC 1275 · vdB 115 · M 1-41 · NGC 6546 |
Distance to the region from the young cluster Collinder 367, at the centre of IC 1274 (Gaia DR3, Hunt & Reffert 2023, 1,220 parsecs), consistent with the Gaia parallaxes of 11 Sgr (≈ 3,900 light-years) and HD 165872 (≈ 4,400 light-years). ESO gives about 5,000 light-years for NGC 6559. The real width assumes 4,000 light-years. Position of NGC 6559 from the NGC 2000.0 catalogue and of IC 1274 from the HII region in the WISE catalogue (SIMBAD), because the SIMBAD coordinates for these two nebulae are rounded and fall outside them. The AstroBin label "11 Sgr" sits on HD 166464; according to SIMBAD, 11 Sgr is the double star V3903 Sgr, inside IC 4685. The remaining positions are from SIMBAD.
9 h 30 min of light
Each tick is one exposure. 134 in total, with the camera at −10 °C and gain 100. Calibrated with 50 darks, 40 flats and 50 bias. The Moon stayed below 10 % illumination throughout.
TS-Optics 150mm/6" ONTC f/4 Newtonian (carbon tube)
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TS-Optics Maxfield .95X Coma Corrector · ZWO EAF
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