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Detection of an OIII arc in Gemini An arc-shaped emission nebula in the constellation Gemini with dominant OIII lines and an apparent length of about 14° is presented. The object has already been recorded in far UV surveys. What is new, however, is that this object can be seen in visible light and ...

Aurora display on May 10/11, 2024 Auroras caused by an extreme geomagnetic storm that began on May 10, 2024 where captured with sky surveillance cameras covering visible and infrared wavelengths. Because this forum only allows to post videos hosted on vimeo or youtube (and I do not plan to open an ...

SH2-185 (gam Cas Nebula, Ghost of Cassiopeia) SH2-185, also known as the γ Cas nebula or the Ghost of Cassiopeia, is a mixed emission/reflection nebula in the constellation Cassiopeia. The nebula is ionized and illuminated by the star γ Cas and formed by its stellar wind. The region also features s...

Milky Way from Perseus to Cassiopeia A 35°×25° wide-field view of the Milky Way in constellations Perseus, Camelopardalis and Cassiopeia is presented in different color composites. This region is full of known and unknown nebulae. Click on the preview images for detailed information and full resolu...

SH2-101 (Tulip Nebula) and jet nebula from black hole Cyg X-1 SH2-101 (also known as Tulip Nebula) is an emission nebula in constellation Cygnus. The images also show a nebula formed by the jets of Cygnus X-1, a black hole in a binary system which is accreting its companion star. Click on the image...

Discovery of an emission nebula in direction of Tarazed An emission nebula has been discovered in close apparent proximity to Tarazed (aka γ Aql). The diameter of the nebula is about 27.4 arcmin and its center is about 7 arcmin away from Tarazed, which is known to be an X-ray source. However, it is...

Comets C/2022 E3 (ZTF) and C/2022 U2 (ATLAS) near the galactic plane On Feb 06, 2023 there was a close apparent approach between comets C/2022 E3 (ZTF) and C/2022 U2 (ATLAS). In that night ZTF also crossed the galactic plane. That unusual event was observed between 17:10 and 00:40 UTC. Click on the...

Milky Way in Cassiopeia and Cepheus A 24°×35° wide-field view of the Milky Way in constellations Cassiopeia, Cepheus and the north-eastern part of Cygnus is presented in different color composites. This region is full of smaller emission nebulae. For many of them the ionization sources an thus the ...

HII region around California Nebula (NGC 1499) Around the California Nebula (NGC 1499) there is a huge HII region which lies behind the dust in constellations Perseus and Taurus and thus is only visible in the voids and less dense regions of these molecular clouds. A 30°×30° wide-field view is pres...

Milky Way in Cygnus A 32°×26° view of the Milky Way in the constellation Cygnus is presented in different color composites. This region is full of emission nebulae which are partially obscured by dark nebulae near the galactic plane. Click on the selected previews below for detailed information, fu...

Milky Way from Monoceros to Gemini A 21°×40° view of the Milky Way in the constellations Monoceros, Orion and Gemini is presented in different color composites. That part of the sky is full of famous HII regions (e.g. Monkey Head Nebula, Cone Nebulae, Rosette Nebula, Seagull Nebula), but there are ...

Milky Way from Vulpecula to Aquila A 30°×28° wide-field view of Milky Way in the constellations Vulpecula, Sagitta and Aquila is presented in different color composites. That region is characterized dense dark nebulae at the galactic plane and only a few larger emission nebulae in constellation Vul...

M63 in H-alpha and continuum light (final version) M63 is a spiral galaxy in constellation Canes Venatici. The image is calculated with and without H-alpha information. By toggling between the two variants the correlation between HII gas clouds and bluish regions (containing young stars and probabl...

NGC2403 and NGC2404 in H-alpha and continuum light (final version) NGC 2403 is a spiral galaxy in Camelopardalis. NGC 2404 is one of many large HII region within the galaxy. The image is calculated with and without H-alpha information. By toggling between the two variants the correlation between HI...

Milky Way from Scutum to Ophiuchus A 50°×16° wide-field view of Milky Way that covers large parts of the constellations Scutum, Serpens Cauda and Ophiuchus. That part of the sky is characterized by HII regions near the galactic plane, the large emission nebula SH2-27 (Zeta Ophiuchi Nebula), and den...

Then we view stars through an Hα filter, almost all the light we see is from ionized hydrogen, not from the (thermal) continuum. That is, most of the light emitted at 656 nm by stars (including cool ones) is from ionized hydrogen. Depends on the width of the filter pass band. If you observe the sun...

I agree to Ann. It is often overseen that narrow band filters also capture continuum. In the APOD the black levels for green and blue are chosen higher than black levels for red channel such that all faint regions become red. Without that trick, some of the red structures would be white because they...

NGC 4244 (Caldwell 26) in H-alpha and continuum light (final version) NGC 4244 (also known as Caldwell 26) is an edge-on spiral galaxy in constellation Canes Venatici with extended star-forming regions showing strong H-alpha emissions. The image is calculated with and without H-alpha information. B...

M101 in H-alpha and continuum light M101 (also known as Pinwheel Galaxy) is a large spiral galaxy in constellation Ursa Major. It contains many bright HII regions. Some of them even have their own NGC numbers. The image was calculated with and without H-alpha information. By toggling between the tw...

M51 in H-alpha and continuum light (finale version) M51 (also known as Whirlpool Galaxy) are two interacting galaxies in constellation Canes Venatici. The larger one (M51A or NGC 5194) is a spiral galaxy, the smaller companion (M51B or NGC 5195) is a distorted a dwarf galaxy. The image is calculate...

NGC 4565 and NGC 4562 in continuum light (final version) NGC 4565 is a edge-on spiral galaxy in constellation Coma Berenices. Together with the smaller smaller NGC 4562 it belongs to the Coma I group. Click on the picture for detailed information and full resolution pictures. http://www.simg.de/gal...

IC 2574 in H-alpha and continuum light IC 2574 (also known as Coddington's Nebula) is a very faint dwarf galaxy in Ursa Major. It is a member of the M81 group and contains very active star-forming regions showing strong H-alpha emissions. The image is calculated with and without H-alpha information...

M94 in H-alpha and continuum light (final version) M94 is a spiral galaxy in constellation Canes Venatici with two ring structures. The inner ring is an active star formation region and contains a lot of young blue stars and HII regions, the broader outer ring is very faint. The image is calculated...

NGC 2903 in H-alpha and continuum light (final version) NGC 2903 is a barred spiral galaxy in constellation Leo. The image is calculated with and without H-alpha information. By toggling between the two variants the correlation between HII gas clouds and bluish regions (containing young stars and a...

Pleiades (M45) Different views (up to 6.3° × 3.9°), resolutions (up to 63MP) and color composites (false color with near infrared and true color) of the Pleiades and the surrounding reflection nebulae. Click on the image for detailed information and full resolution pictures. http://www.simg.de/nebu...