- H160 minutes (16 frames)
- O120 minutes (12 frames)
- S40 minutes (4 frames)
The emission nebula NGC 1491 is an emission nebula in the constellation Perseus.
This object is one of those listed in the original edition of the "New General Catalog".
The description and coordinates of NGC 1491 given by Herschel correspond well to this object. However, John Dreyer in the New General Catalog used the micrometer coordinates of the nebula measured by Vasily Engelhardt, which point to a star located 1.5' to the east of the brightest part of NGC 1491.
Description
NGC 1491, also known as LBN 704, SH2-206, or the Fossil Footprint Nebula, is a bright emission nebula located about 9,800 light-years from Earth in the constellation Perseus. The nebula gets its deep red coloring from many massive stars, such as BD+50 866, which emit large amounts of ultraviolet radiation, ionizing the hydrogen gas that makes up its core.
NGC 1491 is located in the northern part of the constellation, on the border with the constellation Giraffe. It is easily spotted, lying about 2° north-northwest of the star λ Persei, a white subgiant with an apparent magnitude of 4.25, which is easily visible to the naked eye.
Observations
The nebula can be seen with a moderate-power telescope, preferably with filters. Due to its northern position, it can be observed on most nights of the year from the northern hemisphere, but observations from the southern hemisphere are difficult. The period when the nebula reaches its greatest height above the horizon is from October to February.
History of discovery
The nebula was discovered by William Herschel on December 28, 1790 and catalogued as I 258. Herschel described it as "A very bright, irregular shape, round, brighter at the center, 5' long and 4' wide. Within the nebula is a fairly large star on the next side, but it is not associated with the nebula."
John Dreyer catalogued the nebula as NGC 1491 in his New General Catalog. Other designations for this H-II region include: LBN 704, Sharpless 2-206, S 206, Sh2-206.
Physical characteristics
The nebula has several measured distances: 3.0 kpc (9,780 light years) and 3.3 kpc (10,800 light years). The distance to the center of the Milky Way is about 11.1 kpc (36,200 light years). The electron temperature in the nebula was measured with a radio telescope and is 8350 K ± 1600 K.
| Photo | Date | Frames | Exposure | H | O | S |
|---|---|---|---|---|---|---|
 | 11 Mar 2021 | 32 | 05:20 | 02:40 | 02:00 | 00:40 |
Visibility chart of Emission Nebula NGC 1491 during the day
| Date | Moon Phase | Exposure | CCD Temperature | Gain | Offset | Filter |
|---|---|---|---|---|---|---|
- 2023ixf•
- 40 Eri•
- Abell 74•
- Artemis A868 SA•
- a Canis Minoris•
- C 2020 R4 ATLAS•
- C 2020 T2 Palomar•
- C 2021 S3 (PANSTARRS)•
- Haumea (2003 EL61)•
- HCG 68•
- HCG 92•
- IC 1318B•
- IC 1396•
- IC 1795•
- IC 1805•
- IC 1848•
- IC 1871•
- IC 3322A•
- IC 342•
- IC 4015•
- IC 405•
- IC 417•
- IC 434•
- IC 443•
- IC 4703•
- IC 5070•
- IC 5146•
- IC 63•
- M 1•
- M 101•
- M 103•
- M 109•
- M 13•
- M 15•
- M 27•
- M 3•
- M 33•
- M 42•
- M 45•
- M 5•
- M 51•
- M 57•
- M 63•
- M 64•
- M 74•
- M 76•
- M 81•
- M 82•
- M 86•
- M 87•
- M 94•
- M 97•
- NGC 147•
- NGC 1491•
- NGC 1499•
- NGC 1579•
- NGC 1961•
- NGC 2146•
- NGC 2239•
- NGC 2403•
- NGC 281•
- NGC 4236•
- NGC 4565•
- NGC 4631•
- NGC 507•
- NGC 508•
- NGC 5866•
- NGC 5907•
- NGC 6503•
- NGC 6823•
- NGC 6888•
- NGC 6946•
- NGC 6992•
- NGC 6995•
- NGC 7000•
- NGC 7023•
- NGC 7129•
- NGC 7217•
- NGC 7331•
- NGC 7380•
- NGC 7538•
- NGC 7635•
- NGC 7640•
- NGC 7822•
- NGC 891•
- NGC 896•
- NGC 925•
- PGC 54559•
- Sh2-155•
- Sh2-168•
- Sh2 103•
- Sh2 109•
- Sh2 132•
- T CrB•
- UGC 6930•
- V1405 Cas•
- Vesta A807 FA•