Fish Head Nebula
| Polish version is here |
IC 1795, also known as the Fish Head Nebula, is a fascinating astronomical object. Located in the constellation Cassiopeia, it lies approximately 6,000–7,000 light-years from Earth.
Emission nebulae such as IC 1795 are clouds of interstellar gas—primarily hydrogen—that glow as a result of ionization. This ionization is driven by the intense ultraviolet radiation emitted by young, hot stars within the nebula. In the case of IC 1795, the characteristic red hue predominantly arises from ionized hydrogen.
These H II regions serve as sites where molecular clouds become compressed under gravity, leading to the formation of protostars. Over time, these protostars contract and reach temperatures sufficient to initiate thermonuclear reactions in their cores, transitioning into main-sequence stars.
IC 1795 is part of a larger star-forming complex stretching along the Perseus Arm of the Milky Way. Nearby objects include the Heart Nebula, the Soul Nebula, and the Double Cluster in Perseus. All of these objects are the focus of intense investigation, both from observatories on Earth and via space telescopes.
Observations
August 1, 2024, around midnight – Katowice (Poland)
urban environment, very high level of light pollution
Like any diligent observer, I carefully prepared for this night by checking the weather forecast, which predicted nearly cloudless skies. I gathered my trusty equipment and, of course, warm clothing, as nights can be cold even in summer. The forecast proved less than perfect—occasional clouds disrupted data collection—but I ultimately captured Photo 1.
The names of cosmic objects often reflect great imagination, and it’s not always easy to tell where they come from. That’s not the case with the Fish Head Nebula—one can easily make out the outline of a fish’s head in side profile, complete with a gill cover, eyes, and a mouth-like opening. The latter, which is the brightest part of the nebula, has its own designation: NGC 896.
Despite minor challenges, observing IC 1795 was a truly enjoyable experience for me. Whenever I observe deep-sky objects, I’m reminded of how small I—and all of humanity—are compared to the Universe, and how many mysteries the night sky still holds. Each observation is a journey through time and space, allowing us to momentarily disconnect from everyday worries and draw closer to the secrets of the Great Mystery.
Photo 1 Parameters:
- Total exposure time: 90 minutes (stack of 90 RAW frames at 60s each, using an appropriate number of dark, bias, and flat frames)
- Canon EOS 60D
- ISO: 1500
- Maksutov-Cassegrain telescope (100/1400), prime focus exposure
- A filter was used to reduce the effects of artificial light pollution and atmospheric glow
- Mount: equatorial mount with tracking, aligned using the drift method and controlled by a custom-built system.
Further readings:
- Gendler R., Niebo, Carta Blanca, 2007
Marek Ples