4MOST - 4-metre Multi-Object Spectroscopic Telescope
4-m Multi-Object Spectroscopic Telescope

"First sky-light" for 4MOST fibres and spectrographs

by Henri Boffin on 2023-12-20

Science slit integration from the side into LRS-A.

As part of the 4MOST assembly, integration and test (AIT) activities in the AIP integration hall, the science fibre-slits were installed into the Low-Resolution Spectrographs (LRS-A and LRS-B) and the High-Resolution Spectrograph (HRS), replacing the previous test-slit-units, reports LFF Workpackage Manager, Andreas Kelz.

Using various lamp sources and the 4MOST calibration system, exposures were taken to obtain both continuum and emission line spectra. These spectra have been successfully processed by the 4MOST QC1 pipeline to verify the spectrograph performance in wavelength coverage, spectral resolution, and image quality (FWHM) with the final fibre-slits in place.

"The installation of the science slits went smoothly and judging from the first impression, the performance of these final slits seems excellent, thanks to the entire team that developed, built and carefully measured the slit assemblies", said Kelz. More detailed analysis with respect to the three spectrograph arms (i.e., the blue, green, and red channels) is ongoing.

Using an addition setup, skylight was coupled into the fibre system. For the first time, hundreds of solar spectra were obtained with 4MOST - and the fibres and spectrographs have been "on-sky"!

Please see the attached photos courtesy of Andreas Kelz (AIP).

Science slit integration from the top into HRS.

Skylight (solar) spectra recorded with the LRS blue, green and red cameras (from top to bottom).

Skylight (solar) spectra recorded with the HRS blue and green cameras (from top to bottom) with ThAr light in the simultaneous calibration fibres.