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Principle of Operation:
Integral Field Spectroscopy ( Fig.
1 ) with fiber-coupled lens array and fiber spectrograph ( Fig.
2 )
Telescope Data:
f/10.0 RC focus station, f=35000mm, effective light-collecting area
8.153 m², aperture diameter 3500mm, diameter of central obscuration
1367mm, plate scale 5.89 arcsec/mm
Integral Field Unit:
16x16 element lens array, 1mm x 1mm square spatial elements ("SPAXELS")
with 1mm pitch,
future upgrade to 32x32 elements in preparation ( Fig.
3 ). Foreoptics with 3 different magnifications through interchangeable
lenses: default scale 0.5 arcsec x 0.5 arcsec
per lens, corresponding field-of-view of 8
arcsec x 8 arcsec (for 0.75" and 1.0" options contact PMAS Team).
Optical Fibers:
Polymicro FVP 100/110/140 (blue enhanced, high OH), core diameter 100um,
fiber bundle in groups of 16, individual fiber length 1.8m ( Fig.
4 ).
Fiber Spectrograph, Gratings :
Dedicated fiber spectrograph with nominal input focal ratio f/3, refractive
collimator 150/450mm, pseudo-slit length 96mm, telecentric input, fiber
coupling in immersion to first collimator lens.
Reflective diffraction grating 206 mm x 154 mm on grating rotator,
angle position unrestricted from 0 to 360 degrees. Set of interchangeable
gratings, stored in cartridges, manually inserted and removed. See Grating
Table .
Refractive f/1.5 camera 180/270mm, free of central obscuration, camera
field-of-view 12 degrees corresponding to 4K x
4K / 15um pixel focal plane array ( Fig.
5 , Fig. 6
)
Major Functional Units ( Fig. 7 ) :
CCD Controllers:
Dedicated ACE controllers for spec and acq CCD systems,
exposure control and data acquisition with SPARC station "lea" (mounted
in ELRACK).
Field Acquisition and Guiding:
Calibration Sources:
Internal flatfield exposures from integrating sphere, waveguide-coupled
to various continuum and spectral line lamps, each lamp with individual
shutter timing allowing for flexible combination of different light sources.
Typical exposure times are 2sec for Lamp1 ... Lamp5, and >120 sec for Lamp6.
Lamp6 (ThAr) has been provided as an option for simultaneous wavelength calibration for precision radial velocity spectroscopy (future upgrade). It is only recommended for high dispersion work (1200 gr/mm) and calibrations at daytime.On special request, it is possible to replace pencil style lamps (Lamp2 ... Lamp5) by other line lamps of the same type, e.g. ORIEL 6034 (HgNe), 6033 (Xe), 6030 (Ar), 6031 (Kr). For calibrations at daytime, it is also possible to couple non-standard user-specific calibration sources to the Calibration Unit by use of a waveguide. Contact PMAS Team for special requests.
Format of Fiber Spectra ( Fig.
8 ) :
256 spectra, dispersion along CCD
rows, spacing from spectrum to spectrum perpendicular to the direction
of dispersion: 14 pixels . Scale: 100um
fiber core projecting onto 60um on the CCD,
i.e. 4x4 pixels. Corresponding width of spectra perpendicular to dispersion
with ~ 4 pixels FWHM. Typical
crosstalk from nearest neighbour: 1% of peak intensity (corrected for by
data reduction).
>> Because of oversampling, 2x2 pixel binning
of spec CCD is highly recommended.<<
Data format of raw data: standard FITS (~17MB for single full frame,
unbinned)
Instrument Control Functionality:
Quick Look and Data Reduction Software:
Planning Observations, S/N Estimates:
| 360 nm | 440 nm | 550 nm | 700 nm | 900 nm |
| 3.8 % | 12.7 % | 18.7 % | 16.9 % | 7.7 % |
Remarks:
