Is my target observable tonight?

Here is a very easy guide to determine whether your target, being a regular star, a galaxy, a nebula, an exoplanet, a comet, an asteroid or a solar-system planet (you name it, even custom ones!) is observable in a given place, at a given date.

Once you are logged in, open the Night Explorer page (formerly known as iObserve, available from the “Nights” menu):

Select an Observing Site in the upper bar. You can search by site or telescope name (i.e. for instance “VLT”, or “Keck”). If you don’t find your Observing Site, you can create one. Follow this very quick guide.

To import a target, open the Import modal by clicking the “+” button on the upper-left.

It shows on the left a list of possible ways to import targets.

Regular known target

If you know the name of your target, and you know it is a known and regular target, simply use “Resolve Name”, enter the name and click “Resolve”.

Before clicking “Import” once your target is resolved, you can select a curve color by clicking the small color rectangle (the round arrow is to choose a random color). Color can be modified later on, of course.

Known exoplanet

To search inside the latest data of the NASA Exoplanet Archive for a known exoplanet, simply enter its (partial) name. Multiple matches, if any, will appear in a table below, where you can pick the one you want.

Solar system planet

Probably the simplest. Pick the one you want in the list.

A comet or an asteroid

Similarly to objects and exoplanets, you can enter here the name of an asteroid or a comet, and Arcsecond will attempt to resolve it using the latest data from NASA JPL Horizon service.

Is it finally observable?

Once you have imported your targets. Select them all, and see which one are visible, and which ones not. In the example below, the comet “12P/Pons-Brooks” is not visible (its label barely appears at the very bottom of the plot), while all other objects are well visible that night.

GRS 1915+105 is clearly observable at the beginning of the night, the exoplanet 51 Peg b is observable best at the middle of the night, while Jupiter starts to be barely observable at the end of the night.

Note the presence of the moon (white curve), which will rise slowly during the night. Activate the curve tracking to get all Moon and curve details (such as Moon illumination fraction).

Your plans is not for tonight ? Simply choose another date! This plot is heavily customizable. Use the gear button on the bottom-left of the plot, to discover all the options. Or read our dedicated documentation.