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When entering the user is prompted for their e-mail address to log in and is
redirected to the search page. Here the user has the option to search for an
individual PN by its common name or PNG name, following the IAU format.
For the common name the prefix PN used by SIMBAD is excluded and for
the PNG name the prefix PN G used by SIMBAD is also excluded. In addition to searching for an individual object you can browse the entire database by going to Full List. The list can be ordered by common or PN G name. You can also search objects by galactic coordinates or within a range of them. Additional, extended search methods are listed below that exploit the small wavelength range covered by the Echelle orders. For example, you can search nebulae that show the presence or absence of the He II λ 6560 emission line, this serves as a method to search for high (evolved) or low (relatively younger) excitation objects. Likewise, you can search for objects in the database that lack the [N II] λλ 6548, 6583 Å emission lines in their spectra. These PNe are usually high-excitation objects located near the end of the constant luminosity track and about to start the turn down in luminosity. You can also direct your search to select objects that show the presence of the only carbon recombination line, C II λ 6578 Å, located within the wavelength range covered by the Hα order. During the course of putting together the catalogue we realized that there are a number of PNe that exhibit very wide Hα wings, some are likely produced by Raman scattering of Ly β photons into neighboring Hα frequencies from high density nebulae, some symbiotic nebulae seem to be involved in this sample, others show P-Cygni profiles and others do show extended wings in Hα and the [N II] λλ 6548, 6583 Å emission lines indicating true high-speed, low-emissivity, bipolar outflows. The database allows you also to retrieve those PNe that have been identified in different sources as containing a W-R or WELS type CS spectrum. Likewise, the catalogue also links PNe that are known to host binary and close binary central stars. PNe that exhibit high velocity outflows have also been provided a link, here the definition of high-velocity is usually applied, somewhat arbitrarily, for objects with outflows that show projected expansion velocities ≥ 70 km s-1 and for objects where deprojected velocities are known to fulfill this criterion. A coarse morphological classification has been applied to the nebula in the catalogue, describing just primary, main morphologies and descriptors. In some cases where the morphology was not clear from available images but it was clear enough from the spectra, the classification was done based on the latter. If the spectra can neither provide a main morphological class then the nebulae were classified simply as compact. In this way, PNe can be retrieved based on morphological class. As it was to be expected, we have come across with some nebulae that are known to be, or probably are, mimics. We are providing a link in this case to identify them, comments from the community that may help identify more of these cases from true PN are welcome. Additionally, it is also possible to select PNe based on their membership to a specific galactic population, as in the case with morphology, the classification is done only on primary descriptors, such as galactic location, systemic radial velocity and abundances in some instances, therefore revisions in some particular cases may be necessary. Every time a group of PNe is selected and listed, the opportunity is also presented to the user to plot the group by galactic coordinates and to display the thumbnail images with their slit locations for all the members in that group. Since the literature on the objects contained in the catalogue is so vast, we do not cite specific references for any of them, instead the catalogue provides a link at the top of the page for each PN to query SIMBAD automatically on that particular object if the user wishes to do so. Finally, at the end of the search page we have collected a number of related, useful www links. We welcome suggestions to include additional links in this section for the benefit of the user. |