Tutorial on Creating Solar System Targets in APT
Four examples of creating a Solar System target in the JWST Astronomer's Proposal Tool (APT).
See also: JWST Astronomers Proposal Tool Overview
- Defining a Level 1 "standard target" planet
- Defining a non-"standard" Level 2 satellite
- Defining a Level 3 feature
- Defining a Level 1 minor body
To learn how to download APT and start a JWST proposal, see Moving Target APT Instructions. After this tutorial you may want to read Tutorial on Creating Solar System Targets in APT and Tutorial on Visualizing Dithers of a Solar System Observation in APT.
The following examples are by no means exhaustive. If you have questions please contact the help desk.
Getting started creating a new Solar System target
To create new targets, select the Targets folder and click the New Solar System Target button.
Words in bold italics are buttons
or parameters in GUI tools. Bold
style represents GUI menus/
panels & data software packages.
To define your first target, select the Unnamed Target folder. Inside you will see that there are three "levels" to defining a Solar System target.
- Level 1 Type: Observation will track the center of a planet, comet, asteroid, etc.
- Level 2 Type: Observation will track a feature, satellite, ring, position angle, etc. of the Level 1 target.
- Level 3 Type: Observation will track a feature, satellite, ring, position angle, etc. of the Level 2 target.
See also APT Targets for a more general discussion. The following examples illustrate a subset of the Solar System targets that may be defined.
Example 1: Defining a Level 1 Standard Target planet
The simplest target to define is a Level 1 Standard Target.
Type the name of your target in Name in the Proposal, select Planet from the Keyword drop-down choices, and add a description. The keyword is for archiving purposes only. Note that if you choose Dwarf-Planet for Keyword but select Mars as the Level 1 target, the Keyword value remains unchanged, even though it is not an accurate description (making this mistake will not affect the evaluation of your proposal). Therefore, to properly define your target type, select a value among the three "level" parameters: for a simple observation of Jupiter, select Standard Target from the Level 1 Type drop-down choices.
Example 2: Defining a non-"standard" Level 2 satellite
If you are observing a satellite that is not listed among the "standard targets," you can define it. This can work in any of the levels, but we will illustrate it at Level 2 by creating a new satellite for Jupiter.
Create a new target sub-folder, select Satellite from the Keyword drop-down choices, and enter a name and description. As in the example above, select Jupiter as the Level 1 Standard Target. Then in the Level 2 drop-down choices, select Satellite.
Example 3: Defining a Level 3 feature
At Level 3, you can define a feature to track on a Level 2 target. In this example, we will define the location of a volcano on the surface of the Jovian satellite Io.
Select Feature from the Keyword drop-down choices, Jupiter as the Level 1 Standard Target, and Io as the Level 2 Standard Target. Finally, select Planetographic from Level 3 to set the Level 3 target's coordinates to be in longitude and latitude relative to the Level 2 target. You can find the full list of coordinate frames in the article Solar System Targets Position Levels 2 and 3.
Example 4: Defining a Level 1 minor body
Most minor bodies such as asteroids, comets, and KBOs are not considered standard targets and must be selected from either the Comet or Asteroid categories, the latter including outer Solar System minor planets. For example, to define the trans-Neptunian object Sedna, select Asteroid from the Level 1 drop-down choices.
Download the Astronomer's Proposal Tool