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Lilian Domínguez
AF2 Instrument Specialist



AutoFib2+WYFFOS (AF2) is the multi-object, wide-field, fibre spectrograph working at the Prime focus of the 4.2m William Herschel Telescope (WHT). It contains 150 science fibres each of 1.6 arcsec diameter, and 10 fiducial bundles for acquisition and guiding. At the Prime focus, the fibres are placed onto a field plate by the robot positioner Autofib2 at user-defined sky coordinates. Object light is transmitted along fibres 26 metres in length to the Wide Field Fibre Optical Spectrograph (WYFFOS). The path from Prime focus to the spectrograph consists of a prism, fibre button, 26 metres of fibre, finger, microlens and the facet block.


August 2016: Due to a delay in the delivery of WEAVE, AF2 will be available throughout 2017A.

February 2016: Semester 2016B will be the last one for AF2+WYFFOS. Observations will not be possible after the end of 2016B, due to modifications of the GHRIL Nasmyth enclosure to accomodate the WEAVE spectrograph.

September 2015: Version 3 of the data reduction pipeline has been released. It includes some enhancements from the previous version, outstading the improvement of the sky subtraction method, the upgrades in the wavelenght calibration routines and flat-fielding algorithm, as well as the fixing of some important issues related to data sampling. New procedures to inspect output spectra from pipeline, and to check the pipeline installation have been also implemented.

September 2014: Version 2.25 of the data reduction pipeline has been released. It includes some enhancements from the previous version, outstading the new and more reliable method for fibre tracing, the automatic detection of CCD type, allowing reduction of data taken with either WHTWFC or RED+4, and the IRAF compatible final products.

August 2013: AF2/WYFFOS has received several performance-enhancing upgrades during 2013A, and is offered to observers for 2014A.

(1) The rms accuracy with which science targets can be acquired onto fibres has been substantially improved, via: implementation of a new automatic field-acquisition tool; better characterisation of geometric distortions in the focal plane; and an improved algorithm for fibre placement.

(2) A new 4k x 4k red-sensitive CCD with very low-fringing, Red+4, has been successfully commissioned and is offered as the default detector for WYFFOS.

(3) New calibration lamps (a QTH continuum lamp and ThAr, Cd and Zn arc lamps), have been purchased and tested.

In addition, an extensive investigation of the throughput of AF2/WYFFOS has been carried out, including on-sky throughput measurements with both the Red+4 and WHTWFC detectors, and microscopic inspection of all fibre input-end microprisms.

A more detailed description of the recent enhancements and investigations can be found here.

Teams considering submission of an AF2 proposal are encouraged to contact the AF2 instrument specialist if they have any queries.

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Contact:  (AF2 Instrument Specialist)
Last modified: 02 August 2016