Bug / Butterfly Nebula (NGC 6302 / Caldwell 69)
Coordinates, HST expansion distance (1.03 kpc), scorching 220,000 K central white dwarf, and observing guide for NGC 6302 in Scorpius.
Provenance-Backed Scientific Measurements
Every measurement below preserves its unit, uncertainty interval, observational method, reference epoch, quality status, and primary catalog source. See Uncertainty & Provenance for how competing measurements are handled.
| Parameter | Value | Uncertainty | Method & Epoch | Quality Status | Source Archive |
|---|---|---|---|---|---|
| Integrated visual magnitude (V) | 9.6 mag | ± 0.2 mag | Integrated CCD aperture photometry | definitive | Revised New General Catalogue and Index Catalogue (RNGC/IC) |
| Heliocentric distance | 3360 ly | ± 230 ly | HST multi-epoch expansion parallax + 3D kinematics (1.03 ± 0.07 kpc) (J2016.0) | high-confidence | SIMBAD Astronomical Database (CDS) |
| Apparent wingspan | 3 arcmin | ± 0.3 arcmin | Bipolar optical lobes (3.0′ × 1.0′) | definitive | Revised New General Catalogue and Index Catalogue (RNGC/IC) |
J2000 Equatorial Sky Chart & Culmination Altitude
The chart below plots Bug Nebula (NGC 6302 / Butterfly Planetary) at RA 17h 13m 44.21s, Dec -37° 06′ 15.9″ within Scorpius, alongside peak meridian transit altitudes for 40°N and 30°S observers. Use the RA/Dec Coordinate Converter to compute exact culmination altitude for your latitude.
Astrophysical Context & Structure
The Bug or Butterfly Nebula (NGC 6302, Caldwell 69) is one of the most extreme, violent, and chemically complex bipolar planetary nebulae in the Milky Way, located 3,360 light-years (1.03 ± 0.07 kiloparsecs) away in the stinger of Scorpius. First sketched from Parramatta, Australia, by James Dunlop in 1826 and popularized by Edward Emerson Barnard in 1907 as the 'Bug Nebula,' NGC 6302 became famous worldwide in September 2009 when NASA released the inaugural Wide Field Camera 3 image from the newly serviced Hubble Space Telescope—showcasing two ragged, 3-light-year wings of glowing gas erupting at >260 to 600 km/s.
Pinching the waist between the two wings is a massive, dark equatorial torus containing roughly 1–2 solar masses of molecular gas and dust rich in both oxygen-bearing crystalline silicates (forsterite and diopside) and carbon-rich PAHs, along with crystalline water ice and quartz.
Hidden inside that dusty waist—and finally detected directly in 2009 using narrowband HST ultraviolet filters—is one of the hottest central stars ever found in a planetary nebula: a ~0.64-solar-mass white dwarf with a surface temperature around 220,000 to 250,000 K (descended from a massive ~4–5 solar-mass progenitor star) whose hard UV and S-shaped iron-jet outflows ionize lines up to [Si VI] and [Fe VII].
Practical Visual Observing Guide
- Located 3.8° west-northwest of Shaula (λ Scorpii) in the Scorpion's stinger, and 2° north of the cat's-paw stars μ¹ and μ² Scorpii.
- Even an 80–100 mm telescope at 80×–120× shows an obvious east-west elongated bow-tie or peanut shape with a bright central waist.
- In a 150–300 mm telescope at 120×–220× with a UHC or O-III filter, the dark central dust lane slicing across the waist and the hooked, asymmetric western and eastern 'butterfly wings' stand out vividly.
Catalog Cross-Identifications & Aliases
Common Aliases: NGC 6302 · Bug Nebula · Butterfly Planetary Nebula · Caldwell 69
| Catalog Authority | Identifier |
|---|---|
| NGC | NGC 6302 |
| SIMBAD | NGC 6302 |
| WIKIDATA | Q15839 |
Related Objects, Comparisons & Guides
Butterfly Cluster (Messier 6 / NGC 6405)
Coordinates, Gaia DR3 distance (459 pc), magnitude 4.2, BM Scorpii orange supergiant contrast, and observing guide for M6 in Scorpius.
Ptolemy's Cluster (Messier 7 / NGC 6475)
Coordinates, Gaia DR3 distance (279 pc), magnitude 3.3, Baade's Window background globulars, and observing guide for M7 in Scorpius.
Eight-Burst Nebula (NGC 3132 Southern Ring)
Coordinates, Gaia DR3 distance (774 pc), JWST First Images multi-star binary shaping, and observing guide for NGC 3132 in Vela.
Surface Brightness & Extended Objects Guide
Why surface brightness (mag/arcsec²) governs nebula and galaxy visibility more than integrated magnitude, and how exit pupil controls eyepiece contrast.
Angular Size, Separation & Field of View
How angular diameter (degrees, arcminutes, arcseconds), spherical angular separation, and small-angle physical diameter relate to telescope field of view.
Scientific Sources & Dataset Provenance
- Revised New General Catalogue and Index Catalogue (RNGC/IC) (2024/2026 edition): Steinicke, W. 2010, Observing and Cataloguing Nebulae and Star Clusters (Cambridge Univ. Press); Verga, M. OpenNGC (CC-BY-SA 4.0 / data tables) — Wolfgang Steinicke / OpenNGC
- SIMBAD Astronomical Database (CDS) (2026-10 release): Wenger, M., et al. 2000, A&AS, 143, 9 (The SIMBAD astronomical database) — Centre de Données astronomiques de Strasbourg
- ESA Gaia Archive — Data Release 3 (DR3 (2022-06-13)): Gaia Collaboration, Vallenari, A., et al. 2023, A&A, 674, A1 (Gaia Data Release 3) — European Space Agency / Gaia DPAC