This is an amateur astronomy tool, intented to help astrophotographers like myself to plan their photos. Although there are many other similar tools out there, I built this one because I find it handy this way and because it is backed by my own search engine (csillagtura.ro/dso) too with fine tuned parameters.
I wrote this tool for my own joy, but others might also find it very useful.
Approximate position of the Sun :sun
Approximate position of the Moon :moon
List Messier objects around M31 in a 5 degree radius: m31 context:5deg contextcatalog:m
List Caldwell objects brighter than or equal to 7 magnitudes which are at least 35 degrees high on the sky of the observer (location checked with GPS, defaults to CJ), sorted by altitude (current time) minalt:35deg catalog:caldwell minlum:7 sortby:alt
List objects brighter than or equal to 6 magnitudes which are always below the horizon from the observer, sorted by brightness horizon:0 minlum:6 sortby:mag
List Messier objects sorted by Messier number catalog:m sortby:catalog
List Caldwell objects sorted by Caldwell number catalog:c sortby:catalog
List Messier objects around M31, 15 degrees m31 context:15deg contextcatalog:m
List Caldwell objects below the equator, sortby Caldwell number catalog:caldwell maxdec:0 sortby:catalog
List some known asterisms. Some are obvious (like the Owl Cluster), some are like wtf, but someone put them in a table :asterisms
List planetary nebulae from the Caldwell and Messier catalog catalog:mc type:pn sortby:mag
List galaxies from the Caldwell and Messier catalog catalog:mc type:galaxy sortby:mag
List nebulous objects marked to be nice photo targets, that rise to above 20 deg nebulae :niceasphoto minaltindarkness:20
List non-Messier and non-Caldwell objects that have been marked to be nice as photo targets at any focal length -catalog:mc niceasphoto:*
List nice photo targets for 200mm, that are available tonight niceasphoto:200 minaltindarkness:30
Some other shortcuts are :nicenebulae :niceclusters :nicegalaxies :niceplanetaries. Try this one: :niceglobulars :onsky minaltindarkness:35
Nice photo targets for this night, from this geolocation :nicefortonight
Nice spiral galaxies for tonight, from this geolocation :nicespirals minaltindarkness:35
List nice photo target galaxies for 200 and 750, that reach at least 25 degrees altitude while the Sun is below -18 degrees. :nicegalaxies:200~750:25
List galaxies around the Needle galaxy (NGC 4565) needle galaxy context:1deg contexttype:galaxy
List DSOs in Andromeda (constellation) brighter than 10 magnitudes const:andromeda minlum:10
List DSOs brighter than 10 magnitudes available at the geolocation of the observer minlum:10 :onsky sortby:mag
Select DSOs that based on their luminosity, size and position, the user's position and the position of the Sun and the Moon, are ready to be photographed. This means the objects reach a certain height above the horizon while the Sun is still below -18 degrees, ie full night, and are far from the Moon. :phototargets
View exact coordinates, no other arguments accepted. Format: HH MM SS SDD MM SS 08 40 24.000 +19 39 60.0
IF in the photo planner, use plot: to add or clearplot: to remove-all-previous-then-add a marker for each search result. Plot Messier and Caldwell objects of a minimum luminosity of 8mag. plot: catalog:mc minlum:8
Intended for the csillagtura.ro/dso interface. Might fail here.
general search keywords -negatedkeyword "multi word expression" -"negated multi words"
catalog:K - where K may be M, C, NGC, PGC, UGC, IC, messier, caldwell
minmag:M, maxmag:M - limit magnitude (the catalog is big)
minlum:M, maxlum:M - limit magnitude, maxlum=minmag, minlum=maxmag
mindec:D, maxdec:D - limit declination
:mayrise - limit to objects with suited declination-latitude pairing; can be negated
:onsky - limit to objects above the horizon, assuming Bucharest time and CJ as location
sortby:S - can be size, mag[nitude], c[aldwell], m[essier], or "catalog" if catalog:K was specified
type:T - can be oc,gxy,gc,neb; can be negated
minsize:D - many objects have size data. D is degrees
const:T - constellation, should be the international abbreviation, but also works with some common names
:context - context:10min, see below
context:C - list objects around result's radius C arc minutes sorruondings
contexttype:CT - limit context objects to CT type
contextcatalog:CT - limit context objects to CT catalog
minaltindarkness:D - limit to objects that reach at least altitude D in degrees while the Sun is below -18 degrees altitude.
at:ra,dec,radius - search for objects at given position within given radius. The implicit unit is degree (decimal format), but many formats can be given. Like at:XXhXXmXXs,XXdXXmXXs,0.2rad ie hour-minute-second, degree-arcminute-arcsecond, radians
:zenith, at:zenith - search for objects around the zenith, default radius is 10 deg
at:zenith,radius_deg - search for objects around the zenith with radius
HH MM SS SDD MM SS - raw coordinates invoke an at:HHhMMmSSs,DDdMMmSSs,tolerance search. Tolerance needed due to floating point values.
niceasphoto:F - looks nice at focal length F with Canon APS-C senzor (a common setup). For F I use values, 18, 50, 135, 200, 400, 600, 750, 1200, the most common being 200 and 750. This is my personal and incomplete selection. Use it like what it is.