Uncataloged objects
On this page, a list of previously likely uncataloged objects, which where mostly found in the results of the Northern Sky Narrowband Survey, is presented.
Some of these objects may already be known or part of a largely unknown catalog. The data sources that where used for object identification are listed in section Data sources.
Tables
The object list is a merged, revised, and improved version of an earlier attempt to catalog unknown objects. Both versions are available in a GitHub repository, providing proper documentation of changes and updates.The new list is divided into three categories, resulting in three tables (click the links): The new list is divided into three categories, resulting in three tables (click the links):
- HII regions
- These objects were first detected in Hα images. Because OIII and SII data (of the Northern Sky Narrowband Survey) became available later, it turned out that many of these objects also emit in other emission lines.
- OIII regions
- These objects were detected in OIII data. Many of them are also visible in Hα and/or [SII], but usually [OIII] emissions are dominant.
- Possible bubbles
- These objects were detected in emission line images. Some of these structures may be random; some may be projections of spherical bubbles and might have been formed by supernovae or stellar winds.
Column description
Columns of all tables are the same:
| Column | Description |
|---|---|
| 1 | Link to a query for images on this site. |
| 2 | An identifier consisting of a letter corresponding to the category (‘H’: HII; ‘O’: OIII; ‘B’: bubbles), the rounded galactic longitude in degrees, and optionally (if the longitude alone is ambiguous) the galactic latitude in degrees. Identifiers in brackets mark related objects, e.g., possible ionization sources or child-structures. |
| 3, 4 | Equatorial J2000 coordinates. Column 3: Right ascension in hours, minutes and seconds. Column 4: declination in °, arcminutes and arcseconds. |
| 5, 6 | Galactic coordinates in ° as decimal number. Column 3: longitude. Column 4: latitude. |
| 7 | Major axis diameter in arcminutes. |
| 8, 9 | Minor axis diameter in arcminutes (column 8) and orientation angle of the major axis in ° (column 9; 0 means north and 90 means east). These values are omitted if major and minor axis diameter are equal. |
| 10 | Old name used in the first version |
| 11 | Date when the entry was published in the GitHub repository. (Except of object A1 (formerly AA1) which was published in Cloudynights forum.) |
| 12 | Comment |
Data sources
These data sources were used for object identification, i.e., only nebulae that cannot be found there are listed in the tables above.- The SIMBAD database was queried for all objects that could not be found in the catalogs below.
- Messier, Caldwell and NGC catalog from OpenNGC (Verga, 2022).
- LDN (Lynds, 1965) catalog with J2000 coordinates calculated by VizieR. Mostly reflection nebulae. Positions are inaccurate.
- LDN (Lynds, 1962) catalog of (more or less) dark nebulae with J2000 coordinates calculated by VizieR. Positions are inaccurate.
- VdB (Van den Bergh, 1966) catalog with J2000 coordinates calculated by VizieR. Mostly reflection nebulae.
- Galaxies from HYPERLEDA catalog (Paturel+, 2003).
- SH 2 (Sharpless, 1959) and RCW (Rodgers+, 1960) catalogs with J2000 coordinates calculated by VizieR. Mostly emission nebulae. Positions are very inaccurate.
- Catalog of HII regions of the Northern Milky Way This compilation contains objects cataloged by Dubout-Crillon+ (DU, 1976), Courtès (CO, 1951) and Sivan (SI, 1974). J2000 coordinates where calculated by VizieR.
- Objects from the catalog of CO Radial Velocities Toward Galactic H II Regions (Blitz+, 1982).
- PN (Acker+, 1992) catalog of planetary nebulae.
- SNR (Green, 2024) catalog of supernova remnants.
- Galaxy Map Nebula catalog (Jardine, 2013) using the H-alpha map from Finkbeiner, 2003.
- Objects from planetarynebulae.net (Le Dû+, snapshot from Oct 11 2024, 1226 objects)
Rules
The tables above shall only contain objects that appear to be discrete and cannot be found in popular catalogs (namely those described in the previous section). Nebulae that seem to be part of larger structures or superstructures of known objects have therefore not been imported from the old lists. This also includes some remarkable ones, which are mentioned in then Appendix.Furthermore, that does not mean that all objects in the tables above can be considered unknown. For example, H066.0 is clearly visible in Finkbeiner (2003), but cannot be found in the catalogs above or in Simbad.
Here is a summary of the rules for listing an object in the tables above:
- Point sources (e.g. found using SIMBAD) are not used to identify large extended objects (but smaller ones)
- Emission nebulae that are (incorrectly) classified as reflection nebulae are considered known / cataloged.
- The list does not contain objects that are only extensions of known structures.
- Nebulae that seem to be part of the galactic filaments (galactic cirrus, integrated Flux Nebulae) are ignored. (Most objects in the LBN and LDN are part of these structures.)
- In Hα light, the galactic plane is full of arcs and filaments. No attempt is made to identify them or assign them to a larger structure. Bubbles shall only be listed if they are real with a certain probability.
- Objects that are superstructures of known objects are not included in the tables above.
Appendix: Removed objects
Tables
The tables contain objects from the old lists that have not been imported into the revised list or that were removed from the tables above. The Column format of the tables is the same one as described above.- HII regions and OIII regions
- that could be identified in the meantime, are too uncertain, or were renamed because it turned out that the object is significantly larger.
- Reflection nebulae
- in the old list seem to be bright parts of the galactic cirrus (like most LBN and LDN nebulae) and therefore have not been imported.
- Arcs/rings/bubbles
- that are too incomplete or too uncertain.
Remarkable objects
Some remarkable objects from the old list were not imported into the new one because they do not satisfy the rules. Click on the link with the old name to find images of the object on this site.- E5
- Large HII region that contains SH2-86 to SH2-88 and DU 26 to DU 30. Ionized by the VUL OB1 association.
- F1
- HII region that is ionized by the CMa OB1 association and which contains the Seagull Nebula (at least the body) along with various other emission nebulae, including SH2-295 to SH2-297. The Distance is about 1000 pc.
- H1
- Huge HII region that lies behind molecular clouds in Taurus and Perseus (because it is obscured by them), with the brightest part being the California Nebula.
- FA1
- Identified as the Gemini Hα ring.
- B9, B10
- Strange elliptical structures visible in continuum light. What 3-dimensional object is projected to an ellipse? Maybe just a random structure. (In order to improve the visibility In the JavaScript viewer, toggle the plots on and off by pressing the '2' key.)
