Automated
For the large majority of programs, FIREHOSE's automated object finder and spectral tracing code should work very well. To turn on this mode, select either "Fully Automated" or "Inspect Results" under object finding preferences in the preferences pane.
If you use "fully automated" you will get no feedback about what took place; this will be used commonly when running in scripted pipeline mode for future releases. For interactive reductions, "Inspect Results" is most appropriate.
The automated routine performs a first-pass sky subtraction to facilitate finding the object, since not all objects (especially fainter ones) will be visible without sky subtraction. The code then searches a 1D profile of the slit collapsed in wavelength, and centroids on the brightest object. This peak is then used to trace the object profile in wavelength from the top to the bottom of the slit, and the trace position and FWHM is saved into a structure located in the Object directory of the reduction path. This same structure will eventually hold the extracted spectra.
Once the object is located, firehose performs a second-pass sky subtraction, with the newly-located object masked out (so as not to bias the sky model). This new model is also saved to disk.
If "Inspect results" is active, an xatv window will launch at completion. This shows the sky-subtracted frame, with the object highlighted in a solid black line, and the +/- 2 sigma limits of the profile shown in dotted black lines.
Manual
If automated object finding did not work properly, or your object is very faint, or other bright objects appear on the slit, you may need to intervene manually in the object finding process.
The first method we recommend you attempt is "User initial guess" mode. In this setting, the user interactively selects which object should be extracted, and then the software automatically fits the trace profile for that object.
Failing that, it is possible to force the software to use exactly the aperture and trace you command, via the "User Specify" mode.