Observing with TBL

The Bernard Lyot Telescope currently hosts the Neo-Narval spectro-polarimetric instrument.

This instrument is made of 2 parts:

  • The spectrograph is in a triple chamber, which allows a temperature control with a precision of 0.01°C. The grating itself is in an isobaric chamber. The monitoring of a Fabry-Perot lamp shows an accuracy of 2m/s over a few hours.
    An Echelle grating allows spectroscopy on the whole optical range (370nm-1090nm) with a resolution power of 50000. The data processing chain allows to reach a resolution of about 65000 (super-resolution).
  • The polarimeter is located at the Cassegrain focus of the telescope, and allows to select the different Stokes parameters: linear (Q,U) and circular (V).
    Note that the polarization function does not prevent the use in spectroscopy only.

The Neo-Narval and SPIP instruments (the latter planned for 2023) mean that the targets of interest are mainly stars, although extended objects (solar system bodies, nebulae, galaxies) can also be addressed.
The pointing limitations are:

  • declination between -24° and +76
  • hour angle between -5h and +5h

An ETC is available on: https://wwwtbl.bagn.obs-mip.fr/ETC

Applying time for TBL:

  • Through regular french calls:  AO 2023B
  • Through EU Trans-National Access Programmes ORP : Calls


The observations are made in service mode, directly by the TBL staff. The requests for a semester are classified in a database, in which the program of each night is built, according to the priorities of the PIs and the TAC, but also of the weather.
The reduced observations are delivered the next morning on an ftp site.

Example of observations are available at: PolarBase

Contact: directiontbl   @   obs-mip.fr

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