NGC 6643 — Sc in Draco
Sc in Draco, 3.3 arcminutes across, its light 71 million years old. Measured by HyperLEDA, photographed by Pan-STARRS1. Recorded once.
About NGC 6643
What you are looking at
NGC 6643 is a late-type spiral: a small central bulge and open, loosely wound arms full of young stars and star-forming gas. Its disc is steeply tilted, about 63° from face-on, so it appears as a long oval. From edge to edge its visible disc spans about 69,000 light-years (taking its redshift distance, which for a galaxy this near is approximate), about 70% of the Milky Way’s width.
What astronomers have recorded
Two supernovae have been recorded in it, the first in 2008; the most recent include SN 2008bo, SN 2008ij. It is cited in 322 scientific papers indexed by SIMBAD, and recorded there under 28 different catalogue designations.
When this light set out
What a telescope records of NGC 6643 is light that left it about 71 million years ago; on Earth, dinosaurs were at their peak. The galaxy is moving away from us at about 1,484 km/s (3.3 million mph), carried by the expansion of the universe. For a galaxy this close, its own motion through space is a large share of that speed, so the distance worked out from it is approximate; distances measured from individual stars in it can differ.
Finding it in the sky
NGC 6643 lies in Draco. From most of the United States it never sets: it circles the north celestial pole all year, and stands highest on summer evenings, around August.
Its neighbours
At almost the same distance from us, and so its neighbours in space as well as on the sky: NGC 6654 (1.4° away on the sky, at least 1,760,000 light-years from it); UGC 11331 (1.6° away on the sky, at least 2,020,000 light-years from it); NGC 6654A (1.7° away on the sky, at least 2,070,000 light-years from it).
By apparent size it is number 411 of the 12,657 galaxies on the Galaxy Origins register.
Measurements
| Catalogue | PGC 61742 |
|---|---|
| Morphological type | Sc |
| Angular diameter | 3.32′ |
| Right ascension | 18h19m46.4s |
| Declination | +74°34′06.2″ |
| Constellation | Draco |
| Inclination | 62.7° |
| Light travel time | 71 million years |
| Bar | not recorded |
Check every figure above in the NASA/IPAC Extragalactic Database
What is sold
A print of this galaxy and the record of the calculation, once. When it sells it leaves the register and is not offered again. We assign no names and no ownership — nobody can sell you those.
At 3.3 arcminutes this is a Exceptional galaxy, which is the tier where a real photograph shows clear structure and dust lanes. The tier comes from the measured diameter, not from a price list.
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