The Polar Large Telescope (PLT) is a facility that was proposed for a Design Study at the European Commission FP7 in 2010.
It consists of a wide field 2.5 m aperture range telescope primarily aimed to perform deep, periodically repeated, broad-band imaging surveys of several thousands square degrees, in the range 2-4 µm.
It would be equipped with a 250 Mpixels IR camera providing an angular resolution of ~ 300 mas across a field of at least 40 square arcminutes. It would operate from the Concordia station at Dome C, or any other Antarctic station to fully benefit from the exceptional atmospheric properties of Antarctica in this spectral range (high transparency, low thermal background sky emission, high stability of the PSF and excellent seeing conditions above the boundary layer).
First light is expected by 2020 and the overall raw estimation of the cost is ~ 100-150 M€ for a 10-yr operation period (2020 decade), including the data management.
It is a descoped version of PILOT, a project formerly proposed and studied in phase A by an Australian consortium (UNSW/AAO).
MAIN SCIENTIFIC OBJECTIVES
Synoptic surveys in the 2-4 µm range of large selected areas (up to several hundreds square degrees) of the sky (e.g. , fields selected for Spitzer, VISTA, HST, SDSS, Herschel...)
Distant universe: census of galaxies at large z, first generations of stars (Pop III), SN1a, instability pairs, transient events (GRBs), alerts and follow-up on alerts
Stellar formation and populations in the local group of galaxies
Systematic monitoring of variable populations in the Magellanic Clouds and selected areas of the Galaxy
Exoplanets and very low mass stars characterization in the thermal infra-red
Contribution to the census and characterization of small bodies in the Solar System
TOP LEVEL REQUIREMENTS
Primary mirror diameter: 2.5 m
Primary material zerodur/(possibly:aluminium/ SiC/ Corning ULE) (tbd)
Final focal ratio: f/5 (or less). Primary ~ f/1.2 (tbc)
FOV of the telescope ~1 degree (image better than 0.2" @ 2 µm)
Proposed combination: Ritchey-Chrétien with two Nasmyth foci (one being free for an additional instrument)
Depth in Kdark (centered at 2.4 µm): objective better than KA-B= 22 /visit, and 25.5 after a year
Angular resolution: limit of diffraction of a 2.5 m mirror in K ( FWHM~ 0.22'')
Measured median seeing condition (at ~30m above ice): ~0.3"
Tip-tilt and/or GLAO device to mitigate residual turbulence
Time resolution: at least 20 visits a year of every selected area.
Optimal low background design: low emissivity secondary, minimal central obscuration, no baffle, cold stop
Thermal control of the telescope (dry air flow. Equilibrium temperature ~ 220K in Winter)
Optimization (optical, coatings, detectors) for the spectral range 2.3-4 µm (Kdark and L bands)
FPA: 16 buttable arrays of 4 K x 4 K assembled end to end (HgCdTe HAWAII 4RG by Teledyne cooled down to 40K). 256 million pixels (linear dimension of the mosaic: d~22 cm)
Pixel scale: ~0.16" or 0.22 per pixel (of 10 µm, 15 µm, resp. e.g. ~ 42 ' x 42 ' up to more than 1°x 1°)