HAWK-I p2 Tutorial
This tutorial provides a step-by-step example of the preparation of OBs with HAWK-I, the high acuity wide-field near-infrared imaging instrument for the VLT. To follow the tutorial, you should be familiar with the essentials of the use of p2. Please refer to the p2 web page and associated sub-pages (see the menu on the left of that page) for an overview of p2 and generic instructions on the preparation of Observing Blocks (OB).
General about infrared observations:
Infrared observations require accurate sky subtraction procedures. This is due to the high sky brightness and its rapid variability, but also to the detector cosmetics and instabilities. Hence, the observing strategy in the Infrared must be adapted to the nature of the science target and on the ability to construct suitable sky frames for background subtraction purpose. Jitter imaging is the most efficient method to take care of sky background issues with a minimum loss of on-source observing time. By observing the same field on the sky with small offsets (jitters) around a central position for each exposure, it is possible to measure the sky background variations. However, this technique gives good results only in case of sparse field targets. In fact, when the science object is extended or is in a crowded field then a good sky background subtraction is achieved only if one monitors the sky variability in a region far away from the target, resulting in an unavoidable loss of on-source observing efficiency. Finally, when the science target is quite bright and the goal of the observations is to monitor the brightness variability of a source with very high time resolution then one may not need to monitor the sky background (providing that an additional source is taken as a reference template).
Here below we provide a tutorial of OB preparation for three different science cases: