Comparison with other Telescopes

CSO, JCMT, HHT, KOSMA, SEST

Like the SPST, these are single-dish submillimeter-wave telescopes. All except the SEST are in the Northern Hemisphere and cannot effectively observe south of declination = -40^o. The SEST does not operate at wavelengths shorter than 650µm. None is capable of observing in the 200µm atmospheric windows. The SPST will have an improved optical design with low reflected and scattered radiation, low cross-polarization, and a field of view capable of feeding very large focal plane arrays. The average data acquisition rate of the SPST will be about two orders of magnitude faster than these instruments, and the superior sky will allow deep observations which are currently limited by sky noise.

 

 

AST/RO and Viper 

These South Pole telescopes are each less than 2 m diameter. They are not capable of high-resolution studies, nor do they have the collecting area needed to study high-redshift galaxies. In particular, they cannot resolve the Sunyaev-Zel'dovich effect in distant clusters.

 

 

DASI and CBI 

These special-purpose millimeter-wave cosmic microwave background instruments do not operate at frequencies above 50 GHz, nor can they observe at spatial scales smaller than 4'. The complementary high-frequency, high-resolution capabilities of the SPST will allow separation of thermal and velocity Sunyaev-Zel'dovich effect in detected anisotropies.

 

SOFIA 

This airborne telescope will have much better atmospheric conditions than the SPST. It is an order of magnitude smaller in collecting area and its beam area is an order of magnitude larger. Flight operations do not allow for continuous, long-term use or for deep integrations. For some projects, it is of particular importance that the angular resolution of the SPST, 4'' at 200µm, matches that of SOFIA at 50 µm.

 

FIRST 

This spacecraft has no atmospheric problems and a low thermal background. Continuum sensitivity is limited by the relatively small aperture. The submillimeter-wave search for high-redshift objects will be confusion-limited by a beam area an order of magnitude larger than that of the SPST. Telescope lifetime and the size of its detector arrays are limited by the inability to replace cryogenic liquids. 

 

SMA and ALMA

These interferometric array instruments have large collecting area and very high resolution. Interferometry requires the use of relatively complex heterodyne detectors, and the cost and complexity of the correlator limit the available bandwidth and number of detectors. These instruments are not frequency agile and do not operate in the 200µm windows. Continuum sensitivity for blank-sky surveys is limited by a small instantaneous field of view. The field of view is too small for CMB measurements on the interesting spatial scale between 30'' and 20'. The SPST will serve as a wide-field survey instrument which will greatly improve the effectiveness of these powerful array instruments.

 

MAP and Planck

The data sets from these satellites will contain a confusion-limited contribution from S-Z effect in galaxy clusters. The SP 10 will resolve these clusters and will have the spectral coverage required to separate the S-Z contribution from the contribution due to primary anisotropy.