All our data is ingested into HASH PN database produced by Prof. Quentin Parker and now maintained by Dr. Andreas Ritter at The University of Hong Kong : Parker, Bojicic & Frew 2016
. The status of observed PN candidates is updated in HASH accordingly by Prof. Quentin Parker.
Figure 2 shows the different statuses of the observed objects (status on September 2020) and the origin of their discovery (amateur or professional discovery).
There are 3 major statuses for PNe :
- True PN
which means that the object is confirmed as a PN. The optical spectrum must show clear evidence of PN characteristics. But this is not the only condition to be met. The confirmation requires the compliance of multiple criteria based on the analysis of multi-wavelength surveys (X, UV, optical, NIR, MIR, radio...),
- Likely PN
which means at this point that the object is still a PN candidate, but with a good probability of being a True PN. The object needs more investigations (deeper spectrum, better S/N ratio spectrum...),
- Possible PN
which means that the object might be a PN but further investigation is needed.
Sometimes PN candidates turn out to be objects completely unrelated to PNe. These objects are PN mimics categorized as "other" in the figure 2 (below) and are mainly HII regions, emission line galaxies, supernova remnants, emission line stars... or simply objects of unknown nature based on available data.
The amateur spectroscopic observations are not only focused on amateur discoveries but also on professional discoveries which lack an optical spectrum. The origin of the discoveries is somewhat controversial. Several recent discoveries attributed to amateurs have been in fact already noticed years ago by professionals. But their discoveries are yet unpublished.
shows that amateurs have helped to confirm nearly 130 True PN both from amateur or professional PN candidates lists. This is an appreciable amount (5%) of the total number of known True PNe (~2600 True PN in HASH Database). Amateurs observations can also provide a good first estimation for deeper further investigations.