HARPS-N USER MANUAL
HARPS-N USER MANUAL - Telescopio Nazionale Galileo
HARPS-N USER MANUAL - Telescopio Nazionale Galileo
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TNG-MAN-HARPN-0002 31<br />
4.5.3 Centering errors<br />
Opposite to <strong>HARPS</strong>@ESO, for which a de-centering of 0.5 ′′ introduces a RV offset of 3 m/s, no such<br />
effect has been observed on <strong>HARPS</strong>-N thanks to the use of octagonal fibers.<br />
4.5.4 Thorium calibration errors<br />
A total instrumental error of about 0.5 m/s must be expected due to the Thorium simultaneous<br />
reference and calibration (drift tracking and zero point). The zero point error is by far the<br />
dominant source with a contribution of 0.3 to 0.4 m/s.<br />
5 Preparing the observations<br />
5.1 Introduction<br />
<strong>HARPS</strong>-N uses the way of observing based on pre-prepared Observing Blocks. This chapter<br />
describes the philosophy behind this concept, the available tools and the <strong>HARPS</strong>-N specific input.<br />
In order to reach the full performance of <strong>HARPS</strong>-N with respect to the determination of accurate<br />
radial velocities, the following items should be noted:<br />
1. to achieve an accurate solar system barycentric Radial velocity, correction of 0.3 m/s, the target<br />
coordinates must be known to within 3 ′′ including proper motion<br />
2. The RV of a star needs to be known to within 1-2 km/s to give the pipeline a reasonable starting<br />
point for the RV computation.<br />
5.2 Introducing Observing Blocks<br />
An Observing Block (OB) is a logical unit specifying the telescope, instrument and detector<br />
parameters and the actions needed to obtain a “single” observation. It is the smallest “schedulable”<br />
entity, which means that the execution of an OB is normally not interrupted as soon as the target<br />
has been acquired and centered on the fibre. An OB is executed only once; when identical<br />
observation sequences are required (e.g. repeated observations using the same instrument setting, but<br />
different target), a series of OBs must be built.<br />
Usually, one OB consists of two separate entities: the acquisition template and the observation<br />
template(s). For normal science observations <strong>HARPS</strong>-N uses four different acquisition templates<br />
(different for the various observing modes) and one common observing template.<br />
5.2.1 Observing blocks<br />
There are three different observing blocks defined:<br />
OB_SCIENCE<br />
OB_CALIBRATION<br />
OB_TECHICAL<br />
5.2.2 Science templates<br />
<strong>HARPS</strong>-N uses the science template to preset the telescope and to set up the instrument<br />
configuration for the selected observing mode. The following acquisition templates are available:<br />
<strong>HARPS</strong>-N_ech_ acq thosimult<br />
HARPN_ech_acq_ wavesimult<br />
HARPN_ech_acq_ objA<br />
HARPN_ech_acq_ objAB<br />
HARPN_ech_acq_ eff<br />
for simultaneous Th exposures<br />
for simultaneous Fabry-Perot exposures<br />
for fibre spectroscopy (no sky)<br />
for fibre spectroscopy (with sky)<br />
for fibre spectroscopy (sky in both fibers)
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