NGC 7541 / 7581 – a Vera Rubin Galaxy
| Designation(s) | NGC 7541, NGC 7581 (dup), NGC 7537 |
| Object Type(s) | Galaxy |
| Relevant Catalog(s) | All (Chron), NGC |
| Obs. Lat/Long | 42° 17', 073° 57' |
| Constellation | Pisces |
| Date and Time Observed | 2025-11-19 18:34:00 |
| Instrument | EdgeHD 8" w/f7 reducer-1,422mm FL |
| Camera | Player One Apollo-M Mini |
| Image Details | Up is 259.4 degrees E of N. Transparency: Fair. Seeing: Good. Total integration time was 40m 15s. Exposures 15s@225g, No filter. Dithered and recentered in SharpCap. No guiding. |
| Description | In researching my Arp talk, I downloaded and read Vera Rubin's classic paper published in 1980 where she measured the rotation curves of 21 spiral galaxies ("Sc" or "Sbc" in the Hubble system) and hypothesized the existence of Dark Matter. She found "Neither high nor low luminosity Sc galaxies have falling rotation curves. Sc galaxies of all luminosities must have significant mass located beyond the optical image." This was the first galaxy I've observed on a challenging night with lots of intermittent high clouds interrupting capture, and the first time this season that I was observing in below freezing temps. The target itself is a handsome spiral paired with NGC 7537. Note that NGC 7681 is generally accepted as a duplicate entry to NGC 7641, Rubin was observing at Kitt Peak Observatory in Arizona, when Geoffrey Burbidge was the Managing Director there. Most of the galaxies were observed using the 2.1 meter telescope there. |
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