NGC 3945 — S0-a in Ursa Major
S0-a in Ursa Major, 5.5 arcminutes across, its light 57 million years old. Measured by HyperLEDA, photographed by Pan-STARRS1. Recorded once.
About NGC 3945
What you are looking at
NGC 3945 is a lenticular galaxy: a disc galaxy that has largely used up the gas it needs to form new stars, so its disc is smooth and has no spiral arms. 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 92,000 light-years (taking its redshift distance, which for a galaxy this near is approximate), close to the width of the Milky Way.
What astronomers have recorded
SIMBAD, the reference database astronomers use, classes it as a member of a group of galaxies. It is cited in 268 scientific papers indexed by SIMBAD, and recorded there under 13 different catalogue designations.
When this light set out
Its light has been travelling for about 57 million years. When it left, an asteroid had ended the age of dinosaurs. The galaxy is moving away from us at about 1,187 km/s (2.7 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 3945 lies in Ursa Major. From most of the United States it never sets: it circles the north celestial pole all year, and stands highest on spring evenings, around April.
Its neighbours
At almost the same distance from us, and so its neighbours in space as well as on the sky: UGC 6691 (1.2° away on the sky, at least 1,190,000 light-years from it); NGC 4036 (1.6° away on the sky, at least 1,560,000 light-years from it); NGC 4041 (1.8° away on the sky, at least 1,800,000 light-years from it); UGC 7009 (1.9° away on the sky, at least 1,930,000 light-years from it), and 8 more.
By apparent size it is number 94 of the 12,657 galaxies on the Galaxy Origins register.
Measurements
| Catalogue | PGC 37258 |
|---|---|
| Morphological type | S0-a |
| Angular diameter | 5.55′ |
| Right ascension | 11h53m13.7s |
| Declination | +60°40′32.1″ |
| Constellation | Ursa Major |
| Inclination | 63.2° |
| Light travel time | 57 million years |
| Bar | yes, from the catalogue |
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 5.5 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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