| Basel 5 |
Likely an asterism caused by patchy extinction in a dense field; Gaia DR2 astrometry is too dispersed for a real cluster. More details in Appendix A of the article. |
| Collinder 306 |
Listed in WEBDA but with no parameters. Multiple studies report inability to identify a real cluster. More details in Appendix A of the article. |
| Collinder 471 |
Catalogue parameters are highly discrepant. No clear radius or kinematic signature identified. More details in Appendix A of the article. |
| Loden 1 |
Initially proposed as an old nearby cluster, but radial velocity studies show no co-moving group; not physical. More details in Appendix A of the article. |
| Melotte 28 |
Originally catalogued as a sparse cluster overlapping NGC 1750 and NGC 1758. Modern studies find no distinct third object; considered non-existent. More details in Appendix A of the article. |
| NGC 1252 |
Long debated object; multiple studies disagree on its reality. Gaia DR2 and spectroscopic data show no coherent kinematic group. Currently considered an asterism or non-physical object. More details in Appendix A of the article. |
| NGC 1520 |
Flagged as non-existent in the Revised NGC; included in some catalogues with estimated parameters but generally considered a remnant or non-physical object. More details in Appendix A of the article. |
| NGC 1557 |
Not in WEBDA and classified as non-existent in early catalogues; later works list it as a cluster remnant with highly discrepant distance estimates. More details in Appendix A of the article. |
| NGC 1641 |
Originally associated with the LMC; later considered a Milky Way open cluster remnant. Sparse CMD and uncertain parameters; listed as a remnant in recent catalogues. More details in Appendix A of the article. |
| NGC 1663 |
Historically described as poor and irregular. Gaia DR2 data show large dispersion in proper motion and parallax, inconsistent with a physical cluster. More details in Appendix A of the article. |
| NGC 1963 |
Flagged as non-existent in the Revised NGC. No convincing photometric or kinematic evidence for a real cluster. More details in Appendix A of the article. |
| NGC 2132 |
Not studied in detail and classified as non-existent in early catalogues. Later catalogues list it as a possible remnant with uncertain parameters. More details in Appendix A of the article. |
| NGC 2180 |
Investigated multiple times as a dissolving cluster, but Gaia DR2 proper motions and parallaxes show no coherent group; confirmed as an asterism. More details in Appendix A of the article. |
| NGC 2220 |
Described as poor and scattered; flagged as non-existent in the Revised NGC. Included in some catalogues but generally regarded as a remnant candidate. More details in Appendix A of the article. |
| NGC 2348 |
Loose grouping marked as unverified or non-existent. Listed in catalogues with parameters but commonly classified as a cluster remnant. More details in Appendix A of the article. |
| NGC 2394 |
Flagged as non-existent in the Revised NGC. Sparse CMD-based estimates exist, but it is considered an asterism in recent compilations. More details in Appendix A of the article. |
| NGC 3231 |
Non-existent according to the Revised NGC. Gaia DR2 shows no coherent kinematic group; possibly a remnant or field fluctuation. More details in Appendix A of the article. |
| NGC 4230 |
Present in WEBDA without parameters. Distance estimates are highly discrepant; density profile compatible with random fluctuation. More details in Appendix A of the article. |
| NGC 5269 |
Marked non-existent historically; some Gaia-based work suggested a small co-moving group, but overall reality remains doubtful. More details in Appendix A of the article. |
| NGC 5998 |
Non-existent per Revised NGC. Catalogue distances vary widely; no clear observational confirmation. More details in Appendix A of the article. |
| NGC 6481 |
Flagged as non-existent. Proposed members show no coherent proper motion or parallax distribution in Gaia DR2. More details in Appendix A of the article. |
| NGC 6525 |
Historically non-existent. Large proper-motion dispersion and weak density enhancement suggest it is not a physical cluster. More details in Appendix A of the article. |
| NGC 6554 |
Marked non-existent; searched for unsuccessfully in several studies despite catalogue entries. More details in Appendix A of the article. |
| NGC 6573 |
Classified as non-existent in early catalogues. Large discrepancies in distance and age estimates; likely not physical. More details in Appendix A of the article. |
| NGC 6588 |
Non-existent in early catalogues; literature distances and ages are highly discrepant, reflecting uncertain nature. More details in Appendix A of the article. |
| NGC 6994 |
Extensively studied; modern astrometry and radial velocities conclusively show it is an asterism. More details in Appendix A of the article. |
| NGC 7036 |
Flagged as non-existent; Gaia DR2 data show no coherent kinematic group despite proposed members. More details in Appendix A of the article. |
| NGC 7055 |
Non-existent in early catalogues. Sparse and contradictory age and distance estimates exist. More details in Appendix A of the article. |
| NGC 7084 |
Marked non-existent. Proper-motion analysis confirms lack of a physical cluster. More details in Appendix A of the article. |
| NGC 7127 |
Poorly studied object with highly discrepant age and distance estimates; physical reality uncertain. More details in Appendix A of the article. |
| NGC 7193 |
Non-existent according to multiple studies. Gaia DR2 astrometry shows wide parallax spread inconsistent with a cluster. More details in Appendix A of the article. |
| NGC 7772 |
Compact grouping historically considered a remnant; Gaia DR2 and spectroscopy show no matching astrometric parameters, indicating an asterism. More details in Appendix A of the article. |
| NGC 7801 |
Long regarded as doubtful or non-existent. Included in some catalogues as a remnant, but evidence is weak. More details in Appendix A of the article. |
| NGC 7826 |
Classified as non-existent; Gaia DR2 and radial velocities confirm it is not a physical cluster. More details in Appendix A of the article. |
| Ruprecht 155 |
Listed as a remnant in catalogues but never studied in detail; physical nature uncertain. More details in Appendix A of the article. |
| Ruprecht 3 |
Appears as a tight group of bright stars, but Gaia DR1 and DR2 parallaxes and proper motions show it is an asterism. More details in Appendix A of the article. |
| Ruprecht 46 |
Density enhancement without meaningful CMD features; likely not a real cluster. More details in Appendix A of the article. |
