Adding a Flat and Arc

Next, you will want to take a flat field and arc lamp observation. Drag over the "flat and an arc" observation from the template library. This time, when you drop it, you'll want to have the pointer over your array tests, and you should see a white and red arrow sign, with the arrow pointing straight down.

A note on the little arrow signs: The arrow pointing straight down indicates that when dropped, the new item will be placed below the one where the arrow appears. A diagnoally down/right arrow indicates that the idem will appear inside the one where the arrow appears. We'll see more of this later.

At this point, you might like to change the title of the flat and arc, for example to add a comment about which band this is. Do this in the same way that you edited the title for your science progam.

Now, we'll look inside the flat and arc at the components that make it up. Click in the little handle next to "flat and an arc" to expand the view. Notice how things inside other things get indented to the right (inside the flat and arc observation are four components, one of which is a "Sequence" component, itself containing more items). Whenever something contains things inside it, it has a little handle sign to it's left, demoting whether it's being displayed expanded (handle vertical) or condensed (handle horizontal). Simply click the handle to toggle this. Things should now look like this:

The "CGS4" component contains the instrument configuration for CGS4. Double click on it to bring up the CGS4 configuration editor into the right hand panel of the window:

Edit any of the values as necessary. Don't worry about the exposure time and coadds that you set here, as these ones aren't actually used - the exposure times for the flat and arc are set specifically, as we'll get to shortly. When you're happy with the values, click on the "Flat" component inside the sequence. You should get a flat component editor looking like this:

Note carefully: The parameters for the flat field observation don't automatically update if you edit the fields in the CGS4 configuration component. To have the software estimate the flat field parameters based on what's set in the CGS4 configuration component, click the "Default" button in the flat field editor. If you then go and change the settings in the CGS4 component, you'll need to go back into the flat field and hit default again. If after taking a flat, you find that the default values aren't quite right, then you can simply edit the exposure time etc directly in the flat field component.

Now go into the Arc component, and hit the default button to get the default arc parameters for the configuration you've selected.