Multi-Element Array Receivers

Why build submillimeter arrays?

• Speed, speed and more speed. Instead of mapping (i.e. generating an image of an object in a spectral line) by slowly rastering a single pixel over the object by repeated motions of the telescope, a multi-pixel array can obtain more data for each pointing of the telescope. A molecular cloud could be mapped in dramatically less time -- especially when one realizes that the movement of the telescope is a serious source of overhead and loss of observing efficiency. Success at the highest submillimeter frequencies depends on one's ability to take advantage of precious periods of excellent weather. Array receivers will make this possible.

• Mapping consistency. Because the sky opacity changes rapidly with time at submillimeter wavelengths, conditions when you started a map may not be at all the same as when you finish the map. Unless very carefully calibrated, a map made with a single pixel detector will likely have structure due not to the astronomical source, but due to weather variability. This is especially notable for extragalactic observations. With a multi-pixel array, a larger region of the sky can be mapped under identical conditions, allowing for better internal consistency.

Array receivers will revolutionize submillimeter astronomy, just as CCD's and infrared arrays led to an explosion of new results at those wavelengths.

Building Multi-Element Arrays at SORAL

Two array receivers are being currently constructed at SORAL; a 7-pixel 345 GHz array receiver for the 10-meter Heinrich Hertz Telescope at the Submillimeter Telescope Observatory on Mt. Graham, Arizona, and a 4-pixel 810 GHz receiver destined for AST/RO at the South Pole. These will be the first submillimeter heterodyne receivers ever constructed!

Below are two images from the Hubble Space Telescope's WPFC2 cameras; one of the famous "pillars of creation" in M16, and one of the Hubble Deep Field. Overlaid atop each of these images is a representation of the 7 beams from our 345 GHz array receiver from the 10-meter HHT. The possibilites of mapping large regions with good angular resolution and small regions with very high sensitivity are nearly endless. Click on each image to view a full-size version.

You can learn even more about these innovative new receivers in the links below!

• A 7-Element 315-380 GHz array receiver for the SMTO

• A 4-Element 810 GHz array receiver for AST/RO