Important recent Changes (since Periods 96 and 97) regarding La Silla Instrumentation and Facilities

This section describes important changes which took place during Period 96 and 97, as well as changes expected to take place during Period 98.

ESOFORM:

  • Seeing and Image Quality:  Starting from Period 96, the  seeing information to provide in Box 3 of a proposal is the seeing in the V band at zenith. This change now ensures that the scheduling tool uniformly takes the seeing into account. Service mode users for approved programmes will enter the Image  Quality for the airmass and  wavelength of interest required for their observations as constraint during Phase 2. The Messenger article `On the Difference between Seeing and Image Quality: When the Turbulence Outer Scale Enters the Game' by P. Martinez et al. describes the meaning of these two quantities.
             
    Accordingly, the Exposure Time Calculators have been modified and clearly distinguish between the two quantities, using a slightly modified version of the formula given in the above article.

Exposure Time Calculators:

Instruments

  • HARPS:
    • A commissioning of the Laser Frequency Comb took place during April 2015. Additional commissioning activities will take place during Periods 97 and 98 to make the system ready for operations. Interested users are invited to consult the HARPS News page before the start of their run.
    • The upgrade of the optical fibers successfully took place in May and early June 2015. See the HARPS News page and the Messenger article. Most noteworthy outcomes of this upgrage are
      • radial velocity systematics due to slight de-centering and de-focussing have been eliminated;
      • the broken sky fiber of EGGS has been repaired;
      • HARPS has gained in throughput by at least 30%;
      • however, a constant offset is expected to be introduced in the radial velocity measurements taken after the fiber exchange (May 28th, 2015).

Large Programmes

  • Large Programmes are not offered on the NTT in Period 98.
  • Large Programmes on the 3.6-m telescope may span up to Period 100. See the Call for Proposals for Period 98 for details.