Radio Astronomy

Radio astronomers at Arecibo Observatory observe a wide variety of phenomena in the Milky Way and in other galaxies. Current research areas include studying molecules in star-forming regions of our Galaxy, in starburst galaxies, and in active galaxies; searching for and studying pulsars; studying the Galactic magnetic field via its effects on continuum polarization; and surveying the local universe for previously-undiscovered galaxies through the 21-cm line of neutral hydrogen. Arecibo also participates in Very Long Baseline Interferometry experiments with other telescopes in the US and Europe, and with the RadioAstron orbiting radio telescope.

Recent REU projects have included searching for galaxies in neutral hydrogen data from the Arecibo Galaxy Environment Survey and from the Arecibo L-band Feed Array Zone of Avoidance Survey, analyzing molecular line data from starburst galaxies and active galaxies, discovering millisecond pulsars in unidentified gamma-ray sources discovered by the Fermi space telescope, and investigating the nature of rotating radio transients. Some REU projects are carried out on pre-existing data, and others rely on obtaining new data. Even in the former case students will normally have the chance to participate in hands-on observing with the 305-m William E. Gordon Telescope.

Solar System Radar

We observe near-Earth asteroids and obtain images and spectra. Much of the data has not been completely analyzed. Measurements of the spectra and images leads to size, shape and spin rate determination for these objects. We have image inversion software for analysis of the images to determine the 3-D shape. This can be applied to much of our data, though the program is not very user-friendly. There are many possible project opportunities involving modeling and analysis of these data, and fine-tuning aspects of existing models. Deriving a new shape model from existing radar images has been a popular student project in past years, and there are data sets that could be used for this.

We are collecting thermal infrared emission data for many of the near-Earth asteroids that are also observed with radar. The thermal properties of the surface tell us whether the material is fine dust, large boulders, or something in between. Comparing the thermal emission to the visible reflectance separates a cold reflective surface from a warm absorbing one. The thermal emission is routinely used to derive the size of the asteroid, which we can directly compare to the radar size. They do not always match. The shape model derived for these can then be applied to the spectral data to identify surface regions of particular composition or with unusual thermal properties. A new software package has been developed for this, and a student could work on this using an existing asteroid shape model.

The student will have the opportunity to observe asteroids with radar at Arecibo, and to remotely observe at the NASA IRTF in Hawaii for the thermal observations. The observing is done from Arecibo over the internet (sorry, no travel to Hawaii).

We expect to work with the student to identify a specific project of mutual interest. New observations will be made during the spring and summer, which may lead to new and exciting discoveries.

Atmospheric Science

The Space and Atmospheric Sciences program at the Arecibo Observatory uses the world's most sensitive incoherent scatter radar to study the Earth's ionosphere from negative ions and meteoric dust in the D-region (60-80 km altitude), molecular and metallic ions in the E-region (90-150 km), and light ions and electrons in the F-region and above. We also use optical instruments such as airglow imagers, photometers, spectrometers, and Fabry-Perot interferometers to study the neutral composition and dynamics of these same regions. Lidars probe the mesosphere and thermosphere from 80-105 km for metal atom chemistry, dynamics, and temperatures. These measurements teach us about plasma physics, Space Weather, meteor ablation, ion-neutral chemistry, waves, turbulence and other phenomena at the edge of space.

Recent REU projects include studies and analysis of basic ionospheric parameters, development of new analysis techniques using wavelet analysis, investigations of the effects of geomagnetic storms, the nature of neutral metal layers in the thermosphere, development and implementation of new airglow and lidar observational and calibration methods, and studies of the global effects of sudden warmings of the stratosphere over the winter pole. Students enjoy the camaraderie of REU students in radio and planetary astronomy, engineering and computing and participate in a group project in one of the three major research fields at Arecibo.

Electronics

The Electronics Department is in charge of the systems that move the radio telescopes (305m and 12m main reflector diameter), and transmit, receive, manipulate (signal conditioning) and digitize radio signals, in addition to monitoring the radio frequency environment (interference sources), and maintaining the communication infrastructure at the Observatory.

The Department is about 16+ people, including engineers and technicians, and is divided in different areas: Motion, Control and Communications, Transmitters, Receivers and Cryogenics, Intermediate Frequency (IF) Systems and Clock, and Backends (data-taking).

In the past, REU students had the to opportunity design, implement and/or test instrumentation systems. These are just few examples: Up-Down-Converter for 12m Antenna - Implementation and Testing, 2012; Doppler Correction FPGA Module for Radar, 2012; 10GbE High Speed Data Capture, 2011; Web Interface for Compressors Monitoring System, 2011; High Dynamic Range 430MHz Low Noise Amplifier, 2011-2012.

The tasks assigned to the student are generally part of actual projects at the Observatory, but sometimes are new ideas, or part of proposals with Universities.