Instruments

SOAR SUBSYSTEMS

The Enclosure

Achieves precise heat control by means of forced ventilation through a small dome area, set above a small building.

Unusually enclosed design promotes highly accurate telescope tracking through its control of wind buffeting.

The building was designed in the US and constructed by local Chilean contractors.

The dome was built in Brazil, using fiberglass panels from a US firm.

The Mount and Drives

Built by Vertex-RSI Corp. in Texas.

Uses rolling element bearings for both altitude and azimuth.

2 arcsec rms blind pointing, 0.2 arcsec rms offsetting error, 0.2 arcsec rms tracking jitter.

Achieves very high pointing and tracking specs

Pre-assembled and tested in factory, thoroughly tested in its dome on Cerro Pachon before arrival of the optics system.

Throughout 2002, a 10-inch telescope mounted on the side of the main telescope was used to debug and verify pointing and tracking.

4.1m primary mirror

Very high optical quality: 17 nm rms surface,low thermal mass. Primary mirror is 4 inches thick.

Active optics system

120-actuator control of primary,secondary on active hexapod. Image analyzer permanently mounted at one instrument port.

Tip-tilt tertiary mirror

Rapid tip-tilt correction at all foci.

Features:

Many instruments are permanently mounted.

2 Nasmyth clusters, 3 instruments each

2 Folded-cassegrain foci

Rapid selection between instruments

60 seconds to switch

At least two instruments are always ready.

SOAR INSTRUMENTS

Goodman Spectrograph

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High-throughput optical spectrograph
High sensitivity in near-UV down to atmospheric cutoff
Built by the University of North Carolina, Chapel Hill (PI: Chris Clemens)
Detectors: two UV-optimized 2K×4K MIT/Lincoln Lab CCDs
High-throughput Volume-Phase Holographic (VPH) gratings 
Up to R = 1400 
Choice of long slit or aperture plate. 
Designed for rapid readout mode for monitoring short-period variability.

 

Spartan Infrared Camera

Near-IR imager combining wide field with high angular resolution
Built by Michigan State University (PI: Ed Loh) with substantial participation from Brazil
Initially two 2048x2048 HgCdTe detectors.
Two more detectors were added in 2005 for 4096×4096 pixels total
1–2.5 micron sensitivity
2 magnifications
3×3 arcmin2 FOV with 0.043 arcsec pixels
Matched to SOAR's K-band diffraction limit
5×5 arcmin2 FOV with 0.073 arcsec pixels

Optical Imager

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SOAR's first-light instrument
Built by CTIO (NOAO), PI: Alistair Walker
2×2048×4096 E2V CCDs
15 micron pixels
Atmospheric dispersion corrector.

OSIRIS IR Spectrometer/Imager

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Near-IR imaging spectrograph built by Ohio State University (PI: Darren Depoy)
On loan to NOAO
1024×1024 HgCdTe array sensitive between 0.95 and 2.4 microns
Intended as SOAR's IR spectrometer
Spectroscopy in J, H or K with R = 1200, 3000
Cross-dispersed mode covering IJHK simultaneously at R ~ 1200
Also provides imaging with large (0.14 or 0.35 arcsec) pixels over 1.3 or 3.3 arcmin FOV
Is being slightly modified for use on SOAR (installing narrower slit)

IFU Spectrograph

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Integral-Field, bench-mounted optical spectrometer
Built by University of Sao Paulo, Brazil (PI: Jacques Lepine)
Integral-field unit (IFU) fed from a pickoff mirror near telescope focus
Three interchangeable angular scales via interchangeable fore-optics in telescope focal plane
Lenslets in 30×50 grid
Coupled by a 5m-long optical fiber to spectrometer mounted on telescope azimuth structure
Detector: two red-optimized 2K×4K MIT/Lincoln Lab CCDs
Roughly 3 CCD pixels/fiber
R = 1000–40,000