I wish that I knew this yesterday. Long story. :(

Should you find in one of your narrowband images something that looks like a Planetary nebula and want to know what it is called, or, if you think you've discovered something new then the following may be helpful. 

Does it appear as something in a full annotation of your image, if not then further eliminate it using resources such as Simbad and see if it listed there. If you still cannot locate it then further checks are required. 

In your browser type in "planetarynebula.net". If your French language skills are like mine click on the UK flag to get it translated. From the list of tabs select "TABLES I,..."

You do not need to use the large list and should look further down where you can select from a short list by clicking on the boxes. True PN, Likely PN etc

Then to restrict the list to those relevant to your potential discovery, enter the RA values below before validation. 

Example attached. Clicking on an entry will give more details about the discovery. If it isn't listed then congratulations you may have discovered something new. :)

HTH