NGC 1491, also recorded as Sh 2-206, is an emission nebula in Perseus. NASA's WISE account places it about 10,700 light-years away, in the Milky Way's Perseus arm. That is an approximate distance reported by that account, not a direct measurement made by this almanac. The nebula belongs to the class called H II regions, where hot stars ionize surrounding gas. Their radiation also heats dust, which radiates in the infrared. These are environments associated with star formation. Source: NASA/JPL, https://www.jpl.nasa.gov/images/pia14092-nebulae-not-as-close-as-they-appear/.
The same WISE image provides a useful lesson in depth. NGC 1491 and BFS 34 belong to one cloud complex, whereas Sh 2-209, appearing nearby on the sky, lies farther away. The image therefore combines objects that share a physical environment with another that shares only their direction. WISE's displayed colours represent selected infrared wavelengths. They should not be interpreted as the colours of the scene through an eyepiece. Source: NASA/JPL, above.
The phrase emission nebula asks us to think about the origin of the light. A nebula can occupy the same field as stars without being a collection of unresolved stars. For this target, the interesting observation is extended light between and around the points. A visual sketch should distinguish the stellar positions from the boundaries of the faint patch. This is an observing question suggested by the object's catalogued nature, not a promise that every photographically recorded structure will be visible.
Its two designations serve different practical purposes. NGC 1491 is the New General Catalogue identity used by the stored observing list; Sh 2-206 is the alternative recorded in the normalized object facts. The almanac associates both with permanent object 163, so the account should be reused wherever this object returns. A number in the Finest NGC list describes the list entry, not another nebula. Naming consistency matters especially when comparing a chart, a photographic caption and an observing log.
The stored position is approximately right ascension 4h 03m and declination +51° 19′. At latitude 45° N, its geometric upper culmination is about 84°, calculated as 90° minus the difference between latitude and declination. Its declination also makes it circumpolar there. At latitude 35° S, the maximum altitude is only about 4°, making the same object a much poorer practical prospect. These calculations ignore refraction, terrain and buildings. Position source: the preserved Finest NGC catalogue and normalized object record 163.
For a search, establish the Perseus field at low magnification, then match the surrounding stars at the recorded coordinates before looking for diffuse light. Do not substitute the appearance of the much larger California Nebula for this smaller, separately identified target. A detailed finder still needs to be checked against the almanac's accepted geometry; this account does not yet certify a particular star-hop. Once the field is secure, compare the patch with nearby blank sky and record what is consistently seen rather than tracing a remembered photograph.
An observing log can separate three outcomes: the field was identified, extended nebulosity was detected, or internal structure was detected. That distinction makes a modest observation useful without overstating it. Repeat the comparison when transparency changes, using a similar field and magnification. The enduring story explains what the target is; the weekly almanac supplies Moon interference, darkness and observing times. A circumpolar position alone settles none of those conditions.
