1. Table of 2003 NRAO Summer Program Participants

2. Summer Student Activities, Charlottesville VA

The 2003 Summer Student program at NRAO/Charlottesville was under the direction of John Hibbard and Al Wootten. There were seven students in the 2003 Summer Student Research Program at NRAO-Charlottesville, one of them under the NSF Research Experience for Undergraduates (REU) program.

Highlights of the program included a series of introductory level lectures on aspects of astronomy, particularly radio astronomy. These lectures are intended to introduce the students to the fundamentals of radio astronomy and to acquaint them with the research conducted by various NRAO staff members. We are priviledge to be able to take advantage of being on the campus of the University of Virginia (UVa) and to have their faculty also participate in this lecture series. The lectures are listed in the CV Summer Student Schedule below. In addition to the activities listed below, students also took part in a weekly joint NRAO/UVa pizza lunch on Thursdays, and the joint NRAO/UVa colloquium series. Students also went on informal trips to nearby attractions, such as Washington D.C., the Appalachian Trail, Skyline Drive, the James River, and Kings Dominion. The summer program participants from Green Bank often participated in these trips.

3. Summer Activities, Green Bank, WV

The 2003 REU/RET program at NRAO/Green Bank was under the direction of Ron Maddalena and Sue Anne Heatherly. There were six students and two teachers in the 2003 Summer Research Program at NRAO-GB. Five of the students were supported by the NSF Research Experience for Undergraduates (REU) program. In the above picture are (left to right): Justin Atchison (REU), John Cascarilla (RET), Andy Cowan (uGRP), Rob Sparks (RET), Shannon Wells (REU), Regina Flores (REU), Aaron Geller (REU), Kate Rubin (REU).

The Green Bank summer student/teacher calendar is given below. Events include the Hands On Universe (HOU) teacher workshop, the NASA/NRAO teacher workshop, and Society of Amateur Radio Astronomers (SARA) meetings, which students participated in to various degrees. There was also a weekly Science Lunch with the students every Thursday, a Volleyball game every Sunday, and a bi-monthly Science Film Festival. In mid-July the Green Bank summer participants traveled to Charlottesville to meet their counterparts. During this visit the students gave short presentations on their research topics to each other, took a tour of the NRAO Charlottesville facilities, including the Central Development Laboratory, and were entertained by the UVa astronomy faculty and graduate students. A picnic for the students was held at UVa's facility on nearby Fan Mountain, which was attended by both NRAO and UVa astronomers.

4. Summer Student Activities, Socorro, NM

The 2003 REU program at NRAO/Socorro was under the direction of Greg Taylor, Yancy Shirley and Travis Rector. Drs. Shirley and Rector are Jansky Postdoctoral Researcher at NRAO/Socorro. There were 12 students in the 2003 Summer Student Research Program at NRAO-Socorro, eight of them under the NSF Research Experience for Undergraduates (REU) program. This was the second year for RET participants in Socorro, with one participant (Matt Williams; pictured above). The RET program is run by Robyn Harrison and Dave Finley. During their summer tenure RET teachers participated in the same activities as REU students. Pictured above are (standing, left to right): Tiffany Borders (REU), Matt Williams (RET), Itziar de Gregorio-Monsalvo (GRP), Alicia Soderberg (GRP), Laura Spitler (REU), Richard Cool (GRP), Miranda Nordhaus (REU), Chris Clearfield (REU), Chun Ly (REU), Emily Landes (REU); (sitting) Holly Maness (REU). Not pictured are Katie Chynoweth (REU) and Urvashi Venkata (GRP).

Highlights of the summer were the three student-led observational projects, two using the VLA and one using the VLBA. One group observed Holmberg IX, an ultraluminous X-ray source, to try and determine if the emission originated from beaming or some other mechanism. Another group observed a White Dwarf candidate, finding that the separation between the radio source and the white dwarf was too large for the two to be related. A third group observed a Young Stellar Object.

In addition to the scheduled events listed below, there were weekly activities for the students, including a "Tuesday Lunch" (free pizza for students!), a Wednesday Science Tea held in the upstairs lounge, weekly scientific colloquia, soccer on Tuesday and Thursday evenings, and Ultimate Frisbee on Wednesday and Friday evenings.

5. Summer Student Activities, Tucson, AZ

6. NRAO Summer Student Program Project Summaries

The UV spectrum of the flare star EV Lac

Superluminal Motions in Quasars and AGN

Although we did see components near the core at the higher frequency, and did trace out the outer components at the lower frequency for some cases, very close to the core a common feature in the plots showed a blend of components near the core. Observing at different frequencies can lead to a 'core shift' (not more than 1 milli-arcsecond) which can cause these differences. This is because the jet is optically thin and the core is optically thick and the 'VLBI' core may be different at different frequencies and not the actual core. Eight quasars from the sample were also common to the sample studied by Jorstad et al. at 43 and 22 GHz. Close to the core, more components were observed at these higher frequencies, as expected. However, further out from the core, components that were detected at 15 GHz and 8 GHz were unresolved at 22 and 43 GHz, and hence there were no measured speeds for the unresolved components. Speed comparison was therefore not possible with this sample.

Investigating Jet Bending and Projection Effects in Active Galactic Nuclei

The Design and Test of LO Sources for ALMA

Low Frequency Component of the Solar Burst Monitoring Station

Low Frequency Component of the Green Bank Solar Radio Burst Spectrometer

The HI Environment of Ellipticals with Anomalous Light Profiles

This summer, Jodie looked for evidence of a gaseous merger history in two samples of early type galaxies (17 test galaxies and 19 controls), using 21cm neutral hydrogen spectral line observations taken with the GBT Spectral Processor. The test sample consisted of early type galaxies with central spikes in their surface brightness profiles which may indicate a former dense star formation region. The control sample consisted of early type galaxies without central spikes (and presumably without as recent or as densely located star formation events). Both samples covered a similar range of distances and sizes and were chosen to be free of dust and active galactic nuclei.

The spectra were reduced by removing the radio frequency interference, calibrating via the noise diode and position switching, averaging the multi-integrated spectra, baselining, and calibrating the flux via the observation of a standard source (3C295). The spectra of three galaxies were contaminated by continuum sources in the beam. The spectra of nine more galaxies displayed one or more 21cm lines. Three of these galaxies are members of the test sample and 6 are controls. After comparing the positions and velocities of neighboring galaxies which may also contribute to the observed spectral features, the probability that environmental gas can be associated with early type galaxies with central spikes is slightly higher. However, the numbers are too low for an adequate statistical analysis and mapping may be required to isolate the location of the detected gas.

Investigating the Polarization Response of the VLA Antennas

Because of the increased sensitivity that the EVLA will provide, detailed, full-polarization models of the VLA beam is necessary in order to do high-fidelity, noise-limited observations of all four Stokes parameters. We incorporate into AIPS++ full-polarization model corrections of the VLA beam patterns. These model corrections are generated from the antenna simulation program Grasp8. We then apply these corrections to observations of 3C286 at two pointings: on axis and at the half-power point. Although parallel hands (Stokes I, V) model well, we find that the the cross-handed data (Stokes Q, U) are not stable enough on-axis to allow us sufficient confidence in our off-axis results. Nevertheless, we compare the observations with our predictions.

The Relationship between CCS and Ammonia in Class 0 Protostars

For quiescent, starless cores there is a clear anticorrelation between emission from CCS (sometimes denoted as C₂S) and NH₃. The NH₃ emission traces the more dense, inner regions of the core, while CCS occurs slightly outside this region. On the other hand, CCS is rarely found to be associated with active star forming regions. However, both CCS and NH₃ have been detected in the Class 0 (i.e., deeply-embedded) protostar B335, suggesting that a combination of both molecules can be used as a tool for studying the environments of the very youngest protostars.

Our aim was to study the protostar B1-IRS(IRAS 03301+3057) in ammonia (23.69 GHz), CCS (22.35 GHz) and water masers (22.24 GHz) using the VLA at 4" resolution to get information about the dynamics and the evolutionary stage of the cloud, using the properties of these molecules. CCS results show a clumpy and redshifted distribution around the IRAS source. We obtained three different clumps with a gradient of velocity from red- to blueshifted velocities towards the IRAS source, probably due to the interaction with the outflowing material, traced by a reflection nebula detected in the 2MASS k-band image. Water maser emission is elongated in the same direction of the reflection nebula, possibly tracing a jet. Ammonia emission is extended and anticorrelated with CCS. This is the first time that this anticorrelation is observed at small scale (~4") in a star forming region. We conclude that the relationship between CCS and ammonia can be use to characterize the evolutionary stage of star forming regions using observations at high angular resolution.

Imaging Algorithms for Radio Astronomy

Investigating the Connection Between Supernovae and Gamma-Ray Bursts

HI Absorption Studies of Compact Radio Sources

Emily's project was to understand the distribution and kinematics of HI absorbing gas associated with the compact radio source 4C12.50. This entailed reducing and analyzing VLBA spectral line data. At a frequency of 1266 MHz strong HI absorption was detected against the counter-jet, weak absorption against the northern edge of the core and no absorption against the jet. The absorption line velocity centroid is close the systemic velocity. In addition, a velocity gradient was found in the east-west direction. Most likely the absorption traces a circumnuclear, almost edge-on torus. The velocity gradient, near 25 km/s/pc,in the east-west direction together with the constant velocity in the north-south direction is consistent with the torus rotating 1800 km/s/pc. Assuming a radius of 60 pc and a Keplerian orbit, the enclosed mass is on the order of 10¹⁰ solar masses.

Searching for Radio-Quiet BL Lacs, and Active Galaxies at Milliarcsecond Resolution in the NOAO Deep Wide-Field Survey: Cetus Field

Observations of 27 objects were made at a frequency of 8.4 GHz using the NRAO Very Large Array on 20 and 21 April 2003. The array was in D configuration with 27 antennas operating. BL Lac candidates were observed for approximately 14 to 16 minutes each. Flux densities were bootstrapped from 3C48 on April 20th and 3C286 on April 21st. The typical noise level in each snapshot was 30-50 microJy/beam. Data were reduced using the NRAO AIPS software package, following standard procedures from the AIPS Cookbook.

Katie found four detections at the positions of the candidate BL Lac sources with a flux density >3 sigma above the background noise level. For non-detections, an upper limit on the peak flux was calculated. All detections were point sources with the exception of J114137.1-002, which is an apparent double.

For the second project, Katie used the NRAO VLBA at 5.0 GHz to image 53 FIRST sources the Cetus field of the NOAO Deep Wide-Field Survey. The FIRST sources were chosen because they are compact and bright (>10mJy), and are therefore expected to be active galaxies. Active nuclei were detected in nine of these FIRST sources with the VLBA at 4-milliarcsecond resolution, above a 6 sigma threshold. Eight of the detections were point sources, while the ninth has complex extended structure. The 44 sources not detected could still contain active nuclei weaker than our detection threshold. Therefore at least 17% of compact FIRST sources contain active nuclei. Eventually, the spectral energy distributions of the active nuclei will be constrained by combining the VLBA data with photometric data from the NDWFS, Chandra, and SIRTF, as those data become available.

Katie calculated and compared the recovered flux density percentage and spectral index for all sources. It was expected that for the VLBA detections, the spectral index would steepen as the the percentage recovered flux decreased. The expected relationship was confirmed.

Radio Observations of Black Hole Binaries & Microquasars

VLBA Water Maser Observations of the Early B Protostar G192.16

A Detailed Study of the Structure of the Pre-protostellar Core Lynds 1498

When reducing the data, Miranda concentrated on the sky opactiy, as it is the most prominent source of noise in submillimeter wavelengths. She compared sky opacity measurements at 350, and 1300 microns with skydips at 450 and 850 microns to fully characterize the opacity behavior during the observations. She modeled the source using a one-dimensional radiative transfer code that self-consistently calculated the temperature distribution and calculates the SED and radial intensity profiles at 850 and 450 microns by convolving the model with the actual telescope beam and simulating chopping. During the modeling, she simulated attenuation of the ISRF more realistically by adding 0, 1, and 5 magnitudes of extinction to the outer edge of the core. The best-fit model consists of a Bonner-Ebert sphere with a central density of 10⁴ cm^-3 with Av = 1 mag and a nearly isothermal temperature profile of approximately 10.5K. A central density of 10⁴ cm^-3 is 10 to 100 times LOWER than other modeled PPCs (Evans, Rawlings, Shirley, & Mundy 2001, ApJ, 557, 193), suggesting that the core may be very young. This is an interesting result because L1498 was previously considered a core on the verge of collapse. We now believe that this core may be a nascent, slowly accreting PPC. Our temperature and density profile will promote better modeling of molecular line observations which will provide an improved understanding of the core's chemistry and kinematics.

VLBA Observations of Compact Symmetric Objects

VLBA/VSOP Multi-Frequency Polarimetry of Gamma-ray Blazars

VLBA 43GHz images of Radio Jets

Chun found that most of the target sources were point-like, but there appears to be some low-level extended emission in the direction of the large scale jets seen at lower frequency VLBI observations. M87 was observed as a calibrator, and the resulting image is similar to previous high resolution images, confirming their results. Also, NGC 4374 is a good candidate for future observations because of its high flux densities. More sensitive observations will help us understand how jets are collimated very close to the black hole.

A paper has been submitted the Astronomical Journal.

Export Formats for Data from the Green Bank Telescope

Modeling the Contamination of the Microwave Background by Radio Sources

A Search for HI in Massive Low Surface Brightness Galaxies

Modeling the Galactic Magnetic Field

Laser Metrology of the Green Bank Telescope

GBT Mapping of HI in the M81 Group

The Physical and Kinematic Structure of the DR21(OH) Star Formation Region

1. Derive the spatial density structure with a goal toward identifying the densest regions within the DR21(OH) molecular cloud. To this end, we used our molecular spectral line measurements in combination with a Large Velocity Gradient model of the radiative transfer to derive the spatial density within the dense cores of DR21(OH).
2. Study the outflow properties of the dense objects in the DR21(OH) region in order to characterize the relative youth of the dense cores in this region. Our CS and CO measurements were used to identify the source of the outflow emission in this region.
3. Relate the information gained from the analysis of the kinetic temperature, spatial density, and outflow structure to derive the history of star formation in the Cygnus X region. The dense core properties in combination with the outflow analysis has clarified the history of the star formation process in this region.

An Improved Control System for the ALMA Test Facility

Her first task was to study the RTAI watchdog (a type of failsafe to prevent the system from locking up). Jessica wrote a test program for the watchdog and used it to produce a document for future RTAI work, detailing the watchdogs use and noting several bugs.

ALMA Band 6 SIS Mixer Test Systems

7. NRAO RET Program Project Summaries

This section lists short summaries of the projects for participant in the NRAO RET program.

VLA and VLBA Observations of Water Masers around Young Stellar Objects

Matt will incorporate his experiences into his math curriculum by creating projects in which the students will become aware of the applications of trigonometry and geometry within the field of radio astronomy. He is also currently seeking funding for a Small Radio Telescope for his school.

GBT Commissioning Activities

In John's classroom, this data will be reduced by his physics students using Psi-Plot software to look for similar features that can tell them more about the physical characteristics of the area. They will calculate antenna temperatures for the left and right polarizations to create three-dimensional contour maps of the Galactic Center. Additionally, they will use the FITS files of these observations, compiled by B. Cotton, to inspect this region using both FITSView and Hands-On Universe. Blinking and Tricolor overlays will help students clearly identify varying features. John will create a series of web pages to introduce some essential radio astronomy concepts, which also serve as a platform from which the data files and FITS images will be downloaded by students. This will be supplemented by lecture and activities to demonstrate the use and application of the software. The project will be done to complement a study of the electromagnetic spectrum with students in a senior-level Physics course with the project expected to last about two weeks.

Observing and Analyzing GBT Data

Robert plans to incorporate his experience into a multi-wavelength approach to astronomy. His students will use Sky View and Hands On Universe to compare radio and optical images. He will discuss RFI as a primary element of lessons on light pollution.

8. Poster Titles for the AAS 203rd Meeting, January, 2004