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Ionospheric Techniques

The Millstone Hill Observatory maintains or hosts a variety of instrumenst for studuing the Earth's ionosphere and upper Atmosphere. These are described below. The Atmospheric Sciences Group is also active in several new initiatives, including ISIS, DASI and AMISR .
M.I.T. (Foster) [1965 - present]. 440 MHz, 2-5 MW, dual-transmitter incoherent scatter radar. 68-m zenith and 46-m steerable parabolic antennas. E and F region ionospheric studies; lower and upper thermosphere. Operates 1000+ hours/year; supports World Day and CEDAR campaigns.

U. Massachusetts/Lowell (Reinisch) [1987 - present]. Digisonde Portable Sounder (DPS-1) 0.5-30 MHz digital ionospheric sounder. 25-m rhombic 300 W transmit antenna; directional receiving array. Operates continuously with 15-min resolution. (Latest Ionogram)

All-Sky Imager
Boston University (Mendillo/Baumgardner) [1987 - present]. Image intensified TV camera. Observes atomic oxygen lines (630 nm, 558 nm). Nightglow and SAR arc studies. Operates 1 week either side of new moon.

MIT/U. Pittsburgh (Sipler/Biondi) [1989 - 2005]. 100 mm field-widened Fabry-Perot interferometer. Automated continuous observations of atomic oxygen 630 nm nightglow.

MIT Lincoln Laboratory (Coster) [1991 - present]. A real-time synoptic ionospheric monitoring system that predicts the total electron content (TEC) in any direction around the radar site. These TEC measurements extend out to the altitudes of GPS satellites, approx. 20,000 km.

Imaging Spectrometer
Boston University (Mendillo/Baumgardner) [1992 - present]. Meridian slit dispersed by grating onto image intensified TV camera. Observes spectrum of meridian slice for background measurements and calibration of other instruments. Operates 1 week either side of new moon.

MIT/U. Pittsburgh (Sipler/Biondi) [1993 - present]. All-Sky Doppler Interferometer consisting of a Fabry-Perot interferometer coupled to an all-sky lens. The image of the sky is superimposed on the interferometer ring pattern so that each ring corresponds to a different elevation angle on the sky. The detector is a back-thinned CCD, which has good quantum efficiency up to around 900 nm. Filter wheel installed in 1997 with filters for 630 nm, 558 nm oxygen lines and 800 nm OH line. More information is available here.

MIT (Sipler) [1994 - present]. Fabry-Perot interferometer with broadband plate coatings covering 500 - 1000 nm. A back-thinned CCD detector will enable the instrument to make measurements out to around 980 nm. Used for E-region measurements of atomic oxygen green line (557.7 nm) and OH lines in the D-region.

MEASURE Magnetometer
UCLA/IGPP; Mark Moldwin (UCLA) [1999 - present]. Millstone Hill is one of five stations on the NSF sponsored MEASURE array, with a fluxgate magnetometer and GPS receiver designed to sample the background terrestrial magnetic field variations at 1 Hz. The MEASURE array studies ULF wave propagation, substorms, sudden impulses, and other inner magnetospheric phemonena. Automated continuous observations are made.

UCAR/UNAVCO [2001 - present]. GPS and weather station. Part of a distributed network of GPS observatories designed to observe ionospheric TEC and atmospheric PWV. Operates all the time with 1 minute resolution at 15 minute intervals. Data is available locally on

ARL (Bust) [2002 - present]. Coherent Ionospheric Doppler Receiver array deployed at the MIT Haystack Observatory and available for observing satellite beacons for TEC inversion and scintillation monitoring. A total of three receivers are currently deployed with a fourth one waiting for a decision on a location. Operates all the time. Currently data products may be requested from ARL.



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