The California Nebula (NGC 1499) is a large, nearby region of gas ionized by UV photons from the star Xi Persei. Students will use the GBT to map continuum emission from the California Nebula at two frequencies (probably 1.4 GHz and 9 GHz, weather allowing). The telescope beam properties and calibration will also be characterized at each frequency. By comparing the sky intensities at these two frequencies it should be possible to determine what emission mechanism(s) are responsible for the observed radio nebula.

The WMAP maximum entropy method foreground emission map was recently used to identify star forming complexes in the Galaxy (Rahman & Murray 2010). It has been found that 13 most luminous WMAP sources produce more than half the total ionizing luminosity of the Galaxy. This implies that half the total number of O stars in the Galaxy should be residing in these sources. These O stars are believed to be part of massive clusters (M < 10⁴ M^sun) embedded in the WMAP sources. The project aim at constraining the ionizing spectrum (thus mass) of these clusters and to study the effect of propagation of Ly continuum photons to larger distances from these clusters. Recombination lines of hydrogen and helium are effective tools to do this study. Since the helium ionization potential is higher than that of hydrogen, detection (or upperlimit) of lines from both these atoms will give strong constraints on the ionizing spectrum. Attempting detection of helium lines at distances away from the clusters can give information about the propagation of the ionizing photons. Spectroscopic observations near 1.4 GHz toward the WMAP source G49.3-0.3 can be used for such a study.

The Smith Cloud is several million solar masses of Hydrogen on a collision course with the Milky Way. It is being disrupted by its encounter with the Galaxy's hot halo and is fragmenting. This project make a deep map in 21cm HI emission of a few square degrees of the cloud that is being shredded and showing instabilities. Students will learn to use the GBT to map HI, reduce the data and analyze the results.

The GBT will be used to observe the redshifted 21cm neutral hydrogen line from two or more galaxies within the Great Observatories All-sky LIRG Survey (GOALS). The students will choose the objects based on availability and source properties, plan the observations, carry out the observations, and reduce the data. The students will derive the total amount of hydrogen gas from the data and compare with previous measurements.

Radio Telescopes directly measure the temperature of astronomical objects, revealing very important astrophysical effects. Our project is a striking example of how simple measurements can yield remarkable results. We will measure the temperature of planets Venus, Mars and Jupiter. Our observations of Venus will show the Greenhouse effect is very strong on Venus. The observations of Mars and Jupiter will show the very cold temperatures of planets in the outer solar system.

The project illustrates how we connect measurements in the our Laboratory with the physical conditions in the distant universe, through careful calibration and accurate modeling of the optical properties of the Green

In this project the students will re-discover a newly found pulsar blindly and then measure various key parameters of the system and the interstellar medium.

This project is designed to demonstrate the fundamentals of spectral line observing. Two separate "hands-on" groups will observe the 21-cm HI emission of the same galaxies with either the GBT or Arecibo radio telescopes. At Arecibo, we will simultaneously search for the 18-cm mainlines of the OH molecule in these galaxies. This project is to carry out the GBT observing. All chosen targets are known to have HI distributions that extend to distances comparable to, or beyond, the angular size of the Arecibo beam. After data reduction, the Arecibo and GBT spectra, and parameters derived from these, will be compared for agreement/disagreement. Beam maps will also be made with the Arecibo telescope (and hopefully the GBT telescope) in order to provide both beam patterns and sizes.

This exercise will illustrate the fundamentals of spectral line observing, including restrictions due to beam sizes, side lobes, etc. All the spectral-line observations will be made with the position-switching technique. In this, the target position is observed first, followed by a blank-sky (off-source) position. The blank-sky observation is used to remove atmospheric and system noise, and to bandpass calibrate the on-source spectrum. With single dish telescopes, position switching provides the simplest means to eliminate standing waves and other instrumental effects from spectra. The Arecibo beam maps will be produced via continuum "spider scans".

In order to measure the continuum flux of a source, the Arecibo Telescope is driven in a cross pattern across the source. As the telescope crosses the source, this appears as an increase in the flux measured by the receiver. From the position at which the source appears in each arm of the cross, the precise position can be calculated to better than the normal telescope pointing accuracy, and the measured flux can then be corrected for the offset in order to find the true flux at the peak. From measurements made at a number of frequencies, the spectral index of the source can be found, which can be used to identify the physical nature of the source.

Students will formulate a question or hypothesis regarding the neutral hydrogen (HI) properties of galaxies as they relate to other characteristics. They will select a sample of galaxies to observe for testing the hypothesis. Possible hypotheses are listed below.

HI properties that can be derived from the observations include hydrogen content, total hydrogen mass, redshift, line width, rotational velocity, and line profile morphology.

Possible questions that might be considered are:

• how do HI properties relate to the optical morphology?
• how do HI properties correlate with optical or infrared flux?
• how does HI mass relate to optically derived mass?
• how do HI properties vary with distance or redshift?

Students will make Zeeman observations os a number of sources with the Arecibo telescope and learn polarization calibration and data reduction techniques.

An Ultra Luminous Infrared Galaxy (ULIRG) is a galaxy in which gas is turning into stars extremely rapidly within its circumnuclear volume. Such starbursts are often triggered by external dynamical disturbances such as galaxy mergers. The dust heating associated with these intense bursts of star formation within giant molecular clouds can produce hugely increased IR luminosity and conditions favorable for radio maser emission. The strong 18-cm OH megamaser emission in some of these galaxies is many orders of magnitude more luminous than its counterpart in our Galaxy (Darling & Giovanelli, 2002, AJ, 124, 100.)

The prototype ULIRG, Arp 220, has recently been found to possess a rich molecular-line spectrum between 1.1 and 10 GHz (Salter et al., 2008, AJ, 136, 389). Some of the molecular species detected are considered to be prebiotic. To see how unusual Arp 220's spectrum is for this class of galaxy in general, a sample of 20 other ULIRGs have now been observed between 4.3 and 5.3 GHz. Preliminary analysis has shown two of the twenty, IC860 and Zw049.057, to have remarkably similar line spectra to Arp 220.

In this Hands-on-Project, the observing team will take spectra between 1.1 and 1.75 GHz for IC860 and Zw049.057 to see to what extent their spectra over this lower frequency range, (usually referred to as the "L-Band") resemble that of Arp 220. L-Band contains potential detections for neutral atomic hydrogen, HI (1420 MHz rest frequency), main-line OH molecules (1665 \& 1667 MHz), satellite-line OH (1612 \& 1720 MHz) isotopic 18OH (1637 \& 1639 MHz), Formic Acid (HCOOH; 1638 MHz), HCN (1346 MHz) and HCO+ (1270 MHz). Detectability of some of these transitions is likely to be affected by the presence of radio frequency interference (RFI) which the team needs to distinguish from celestial emissions. Despite RFI, a number of line detections are anticipated.

This project is designed to demonstrate the fundamentals of spectral line observing. Two separate "hands-on" groups will observe the 21-cm HI emission of the same galaxies with either the GBT or Arecibo radio telescopes. At Arecibo, we will simultaneously search for the 18-cm mainlines of the OH molecule in these galaxies. This project (AO-5) is to carry out the Arecibo observing. All chosen targets are known to have HI distributions that extend to distances comparable to, or beyond, the angular size of the Arecibo beam. After data reduction, the Arecibo and GBT spectra, and parameters derived from these, will be compared for agreement/disagreement. Beam maps will also be made with the Arecibo telescope (and hopefully the GBT telescope) in order to provide both beam patterns and sizes.

This exercise will illustrate the fundamentals of spectral line observing, including restrictions due to beam sizes, side lobes, etc. All the spectral-line observations will be made with the position-switching technique. In this, the target position is observed first, followed by a blank-sky (off-source) position. The blank-sky observation is used to remove atmospheric and system noise, and to bandpass calibrate the on-source spectrum. With single dish telescopes, position switching provides the simplest means to eliminate standing waves and other instrumental effects from spectra. The Arecibo beam maps will be produced via continuum "spider scans".

Pulsars, neutron stars with rotation periods ranging from a few seconds down to little more than a millisecond, are known for behaving like accurate natural clocks. They emit a radio pulse on each rotation, with the intervals between successive pulses being very precise. But in 2006 a new class of radio-loud neutron stars was discovered: Rotating Radio Transients (RRATs). RRATs emit a pulse only occasionally, from a few times a minute to once per many hours. Since then, the 1.4GHz Pulsar-ALFA (PALFA) survey at Arecibo has found several intermittent objects similar to the RRATs. We want to understand pulsar intermittency as a vehicle to clarifying what drives the coherent radio emission mechanism of pulsars. As a first step, we want to distinguish genuinely intermittent objects from those that only appear to be intermittent because of observational biases.

Pulsar flux densities tend to decline steeply with increasing frequency. For pulsars with steep spectra, only the brightest pulses may be detectable at 1.4GHz, while the underlying periodic emission may be uncovered if the pulsars are observed at lower frequencies. PSR J0627+16, a pulsar with a period of 2 seconds detected as an intermittent source at 1.4GHz by PALFA, was found to be a normal pulsar when observed at 0.33GHz. We will observe at 0.33GHz the rest of the PALFA sources classified as intermittent at 1.4GHz and attempt to detect normal periodic emission. We will go through the stages of pulsar data reduction, searching for periodic signals and single pulses. This project is science in action and our findings may be included in a future publication: these objects have never been observed at a frequency lower than 1.4GHz and we do not know the result in advance.