Observatory uses abbreviations for many tags. "oc" for open cluster, "g" for galaxy, "en" for emission nebula, etc. Please see the description/table in
https://codeobsession.com/observatory/doc/#sidebar-libraryIt uses many standard abbreviations, but also many non-standard ones. For example "pl" for planet. So, the "Planets" smart album displays images with the "pl" tag, not with the "planet" tag. Observatory's tag field originally was very small, but has been increased in size lately, and maybe we should change "pl" into "planet" by now.
You can use the histogram action menu to quickly adjust the stretching.
To make a smart album for, say, NGC objects, you could create one that just matches the "ngc" tag, and add that tag manually. You can find the images with NGC objects using the quick filter in the browser. Select "Tag" in that search box's menu and enter "ngc". It will list the images with "ngc" in their tag. It's not ideal. There is already an action item for automatically adding a tag for the catalog source (e.g. "messier"), so at one point this will be automatic.
Adding commonly used names for objects as tag I hesitate to do. Many objects have multiple of these names, in different variations, they tend to be very long, and Observatory is used in many countries for which these names have no meaning.
If you match an image of a planet that contains a timestamp, Observatory will also automatically attempt to tag it. Right now it's more of a bonus feature, not fully fleshed out, and oftentimes you will not be able to because of the short exposure duration, but for Uranus/Neptune (and Pluto) it may work. I have bigger plans for that (more than one dwarf planet, minor planets, etc), but no ETA whatsoever.
