Chapter 13. HIFI Baseline Removal

Table of Contents

13.1. Introduction
13.2. The FitHifiFringe Task
13.3. The FitBaseline Task
13.3.1. Introduction to FitBaseline
13.3.2. Running FitBaseline
13.3.3. Re-running FitBaseline
13.3.4. FitBaseline Options
13.3.5. Caveats

Last updated: 29 February, 2016.

13.1. Introduction

HIFI spectra produced by the Level 2 pipeline often show baselines that are offset, sloped, curved, and/or rippled. In many cases, these are leftovers from instrumental instabilities inherent to heterodyne techniques, and not completely removed by reference or sky subtraction in the HIFI pipeline. Depending on the science application, you may want to flatten the baseline, either by subtraction, or, in the presence of real continuum emission, by division. This can be done in HIPE at the Level 2 stage, using the tasks described in the next sections.