Systems that map the skies and allow you to find a celestial object and frame it.
PhotoPills
Not strictly a planetarium app but one of those unique toolkits that help plan sessions, especially landscape astrophotograpohy
They say “No matter the type of photography you love: Landscape, Milky Way, Moon, Sunrise, Sunset, Architecture, Star Trails, Drone, Meteor Showers, Solar eclipse, Lunar Eclipse, Time lapse, Wedding, Portrait or Travel…
PhotoPills is your photography planning app. It helps you PLAN your photos ahead of time… So you’re always at the right place at the right time to capture the best photo possible.” Android, Iphone
Stellarium
Stellarium is a free open source planetarium for your computer. It shows a realistic sky in 3D, just like what you see with the naked eye, binoculars or a telescope. For PC/Linux/Mac £free
Cartes du Ciel
enables you to draw sky charts, making use of the data in many catalogs of stars and nebulae. In addition the position of planets, asteroids and comets are shown. The purpose of this program is to prepare different sky maps for a particular observation. PC/Linux/Mac/RPI £Free