The high-resolution FIbre-fed Echelle Spectrograph (FIES)

FIES is a cross-dispersed high-resolution echelle spectrograph with a maximum spectral resolution of R = 67000. The entire spectral range 370-830 nm is covered without gaps in a single, fixed setting. Extended coverage up to 900 nm is available with minor inter-order wavelength gaps. To isolate it from sources of thermal and mechanical instability, FIES is mounted in a heavily insulated building separate from and adjacent to the NOT dome.

The optical fibres that connect the telescope with the spectrograph are permanently mounted with a movable 45-degree mirror near the focal plane of the telescope. The fibres run from the instrument adapter through the telescope and azimuth axis to the spectrograph enclosure. Being a permanently mounted instrument, FIES can be used at any time, also for short periods of time while other instruments are mounted.

The currently installed octagonal-fiber bundle D contains a high-res 1.3 arcsec fibre offering a spectral resolution of R=67000. This bundle also provides two 1.3 arcsec fibres giving R=46000 (med-res), and a fibre with a larger entrance aperture of 2.5 arcsec but a lower spectral resolution (R=25000, low-res).

An exposure meter is available to predict the S/N of an ongoing exposure, allowing to optimise the exposure time.

A recent (2014) paper describing FIES can be found here or here.

Questions about FIES should be directed to the instrument specialist, John Telting.

Advantages and drawbacks

The particular advantages of FIES compared to other high-resolution spectrographs are:

• A high degree of mechanical and thermal stability which allows good precision in radial-velocity determinations.
• The freedom to schedule observations with FIES independently of the instrumentation mounted at the main focus, and thus to follow variable objects with periods of the order of weeks without blocking the telescope for other programmes in the meantime.

Data reduction

FIES comes with dedicated reduction software (FIEStool), which provides a fully reduced spectrum for (quick-look) analysis after the end of each exposure, using the most recent library calibrations. The same software is also available to observers for final analysis of the data using the nightly calibration frames.

General documentation FIES commissioning report, octagonal fiber bundle D (installed July 2017) FIES commissioning report, fiber former bundles A, B, C Commissioning the new CCD15 (installed 30/9/2016) Images and technical drawings of FIES FIES project development pages (old docs) Staff pages (Staff only!)

Instrument specifications Instrument efficiency, count rates, PSF, fringing Spectral format (orders, dispersions) Wavelength/velocity zero-point accuracy Detector setup and readout times ,   gain/RON monitoring Exposure-time calculator ,   exposure-meter count calculator Atmospheric Dispersion Corrector (ADC) More detailed information

Standard stars and Data reduction Flux standards,   radial-velocity standards FIEStool info and distribution FIEStool master-frame database Thorium-Argon maps: blue atlas (CCD13, 360-730 nm), blue atlas of aging Hereus ThAr lamp (CCD13, 360-730 nm), red atlas (CCD13, 410-820 nm), atlas of fresh and aging Photron ThAr lamp (CCD15, 370-900 nm)

Observing guides and tools FIES Quick Reference Guide ,   NOT/FIES Observers Cookbook FIES Fiber Guiding (fibguider) Sequencer command lists:   FIES,   STANCAM,   TCS Sequencer scripts:   FIES/STANCAM,   TCS Create TCS target catalogue,   NOT observing tools FIES for ALFOSC user,   FIES for MOSCA user,   FIES for NOTCam user Known CCD-software problems and their suggested solution, Trouble shooting the FIES observing system