5. Explore data

Once we have reduced data, we probably want to look at. In fact, even before we start the reduction, we should look at the raw data in case of issues.

DRAGONS is not an analysis package. But it does offer a basic way to display images.

The display and inspect primitives can be used to visually inspect the data with ds9. Those are primitives not recipes, yet reduce can run individual primitives.


ds9 must be launched by the user ahead of running the primitive.

5.1. Display

To display an image to ds9:

reduce -r display N20160102S0271_stack.fits

It is possible to display to different buffer in ds9, eg. to allow blinking between the frames.

reduce -r display N20160102S0271_stack.fits -p frame=2

5.2. Inspect

It is recommended to inspect the raw data prior to reducing the data. A quick visual inspection can catch obviously bad data, or flag some frames for more detailed inspection. Having to run display on each frame individually would be painful. The primitive inspect can be used here. It accepts a list of file and will display each frame in sequence, adding a short pause between the frames. The length of the pause can be controlled with the pause parameter.

reduce -r inspect @stdstar.lis
reduce -r inspect @stdstar.lis -p pause=1