Early in the summer, the Charlottesville students visited Green Bank to tour the NRAO telescopes located there, to meet members of the Green Bank staff, and to attend the annual picnic on 29 June. One highlight was a tour of the Green Bank telescope ( GBT ), the world's largest steerable telescope. It is an offset parabaloid, 110m across the longest axis, incorporating over 16 million lbs of steel in the moving structure. In the photo above, students stand on a mound built to hold a metrology laser as Ron Maddalena points out the 'Goldman Effect'. A movie is also available, showing the student tour.

The students gave a series of 15 minute talks on their projects during a lunch symposium in Charlottesville before they left for the summer. They produced a short report describing their summer research (sent under separate cover).

3. Summer Activities, Green Bank, WV

The 2002 REU/RET program at NRAO/Green Bank was under the direction of Ron Maddalena and Sue Anne Heatherly. There were six students and three teachers in the 2002 Summer Research Program at NRAO-GB. Four of the students were supported by the NSF Research Experience for Undergraduates (REU) program. In the above picture we see (left to right) top row: Zach Manganello (GRP), Brian Kent (REU), Tammy Kjonaas (GRP), Chris Orban (REU). Middle row: Brian Tandy (REU), Troy Fakes (NRAO co-op student), Jeyhan Kartaltepe (REU), Michael Lacasse (NRAO co-op student). Bottom row: Steve Ostaff (RET), Chelen Johnson (RET), David Fleming (RET).

This summer the RET teachers very heavily involved with the infrastructure of radio telescope operations, dealing with detection of RFI, mitigation of RFI, and determination of noise diode intensity for the GBT. A couple of the REU students also dealt with GBT infrastructure, while the others investigated OH megamasers, 3He in planetary nebulae, and testing for extra-solar planet detection capability.

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4. Summer Student Activities, Socorro, NM

The 2002 REU program at NRAO/Socorro was under the direction of Crystal Brogan and Greg Taylor. Dr. Brogan is Jansky Postdoctoral Researcher at NRAO/Socorro. There were 15 students in the 2002 Summer Student Research Program at NRAO-Socorro, seven of them under the NSF Research Experience for Undergraduates (REU) program. Pictured above are (left to right) back row: Eilleen Chollet (REU), John Kelly (REU), Melissa Douthit (REU), Daniel Perley (DM), Jared Crossley (REU), Karen Peterson (REU), James Anderson (GRP), Brian Metzger (REU), Lindsey Pollack (REU), and Katie Devine (GRP). Front row: Corina Vogt (DM), Claudia Cyganoswski (GRP), Therese Fukuda (GRP) and Jason Ye (DM). Highlights of the summer were the two student-led observational projects, one with the VLA to search for water masers around the Galactic X-ray binary black hole candidate A0620-00, and the other with the VLBA to try to detect a small scale jet from the Crab pulsar. While both observations resulted in non-detections, the students enjoyed the experience of planning and conducting both programs and reducing the data entirely on their own.

This was the first year for RET participants in Socorro, with two participants. The RET program was run by Robyn Harrison and Dave Finley. During their summer tenure RET teachers participated in the same activities as REU students. Due to their later arrival, they missed some activities during the first 4-5 weeks. They did experience most of the special astronomical talks and also had the opportunity to visit a local high school where a teacher had his students design and construct whisper dishes similar to those at the VLA.

We're very excited about the Atacama Large Millimeter Array , which was selected as the top priority for a new astronomical instrument in the 90s back at the beginning of the decade by the Astronomy Survey Committee. Students and teachers got to see it take shape as the first year of construction gets underway, highlighted by the arrival of the prototype antenna at the VLA Antenna Test Facility .

5. Summer Student Activities, Tucson, AZ

The 2002 REU program at NRAO/Green Bank was under the direction of Jeff Magnum. There were two students in the 2002 Summer Student Research Program at NRAO-Tucson, one support by the NSF REU program and the other by the NRAO GRP program. Highlights of the program included a series of introductory level lectures on a variety of topics designed to give the students an overview of astronomy. Of particular emphasis in these lectures is the role of radio astronomy in a variety of astronomical topics. Regular "lunch chat" sessions were also held where the students were encouraged to ask general questions about astronomy.

A highlight of this year's program in Tucson was a trip to NRAO-Socorro and the VLA site. Shown in the picture above are the 2002 REU program students in front of one of the VLA antennas (Sara Flynn on the left and Selby Cull on the right). In addition to the interesting aspects of the VLA, the first prototype antenna of the Atacama Large Millimeter Array was being erected when we visited. The students found it particular instructive to see a radio telescope in the process of being assembled, and gave them a better understanding of exactly how a radio telescope works.

Tucson Summer 2002 Schedule

Date	Time	Speaker	Title
July 17	10:30 AM	Simon Radford	The Cosmic Microwave Background
July 17-18	8:30 AM	All	Trip to AOC/VLA in Socorro, NM
July 24	9:00 AM	Jeff Mangum	Planetary Astrophysics and Star Formation
July 30	10:30 AM	Darrel Emerson	Radio Astronomy Techniques
August 7	10:30 AM	Mark Holdaway	Imaging

(All lectures given in Steward Observatory N505)

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This section lists short summaries of the projects for participant in the NRAO Summer Student program, including the REU participants. The symbol to the right indicates students who were supported under the National Science Foundation (NSF)'s Research Experiences for Undergraduates (REU) program. All other students were supported under the NRAO Summer Student program.

Michele Casey, of Dartmouth College
worked with Rich Bradley on

Lisa Glendenning, of The University of New Mexico
worked with Athol Kemball on

Antone Kom, of The University of Idaho
worked with Gareth Hunt on

All of my summer work can be found on my NRAO website at: http://www.cv.nrao.edu/~tkom/

Clay Sheaff of The University of Nebraska, Lincoln
worked with John Effland on

Clay developed a software class that controls a radio frequency power meter. The power meter measurement algorithms included routines to measure repeatedly the power until the calculated standard error was below a specified threshold. His report is at http://www.cv.nrao.edu/~jeffland/SumStu/Sheaff/Anritsu.pdf.

Clay also developed a system to test and optimize the linearity of a square-law detector, which converts radio signal power into voltages. Software was developed to record onto a spreadsheet both power meter readings and voltages from a precision multimeter. He then graphed the data and a quantitative figure of merit was developed and used to optimize the square law detector response. Clay developed all the tools required to optimize the square law detector response, but his term ended before he could provide the final optimization. As discussed above, Mr. Sheaff met all of the goals of three of the four major tasks assigned to him during his summer term, and completed about 90% of the final goal. His progress was quite remarkable in light of his having completed just a few elementary electronics courses. Clay's final report can be found at http://www.cv.nrao.edu/~jeffland/SumStu/Sheaff/FinRpt.pdf.

Timothy Thacker, of Virginia Tech
worked with John Effland on

Tim also supported the system tests during the development of the local oscillator by installing and operating the LO system in our SIS mixer cryogenic test system. In addition, he integrated software routines written by our other summer student along with additional software to collect data and document the performance of two different the millimeter-wave triplers. See http://www.cv.nrao.edu/~jeffland/SumStu/Thacker/TripComp.pdf. Mr. Thacker met all of the goals assigned to him during his summer term. His final report is at http://www.cv.nrao.edu/~jeffland/SumStu/Thacker/FinRpt02.pdf.

Matthew Strait of Carleton College
worked with Dan Homan on

James Anderson, of New Mexico Tech
worked with Jim Ulvestad on

Eileen Chollet, of Rice University
worked with Lorant Sjouwerman on

Jared Crossley, of New Mexico Tech
worked with Michael Rupen on

Claudia Cyganowski, of Harvard University
worked with Miller Goss on

Katie Devine, of Carleton College worked with Crystal Brogan on

Melissa Douthit, of Calif. St. Univ. San Marcos
worked with Boyd Waters and Tim Cornwell on

Once she and John had nailed down the VOTable spec for our archive, she implemented a procedure in Glish that accepted the output of John's "e2equery.g" -- a Glish record -- and transformed it into a VOTable stream; she used the Glish XML functions written by Ray Plante at the NCSA ( link1, link2).

Therese Fukuda, of University of Denver worked with Athol Kemball on

John Kelly, of University of Virginia worked with Henrique Schmitt on

Brian Metzger, of University of Iowa
worked with Dale Frail on

Daniel Perley, of Cornell University worked with Athol Kemball on

Karen Peterson, of Yale University
worked with Travis Rector on

Andreea Petric, of Columbia University worked with Chris Carilli on

Lindsey Pollack, of UC Berkeley
worked with Greg Taylor on

When I arrived in Socorro the data had already been calibrated. After editing, imaging and self-calibrating in DIFMAP and imaging in AIPS, I spent a large part of the summer writing programs in IDL which would measure meaningful source properties. As more and more properties were measured, new and interesting questions about these sources became evident. I continued to write more programs while reading journal articles and comparing our data to the literature. At the end of the summer I gave a powerpoint presentation about our project.

While we are still interested in as of yet unmeasured source properties such as the degree of jet bend, the current goal is to submit a paper to the Astrophysical Journal by October. Due to the insufficient number of BL Lac type objects in our sample, many of our results will be more speculative rather than concrete. However, we do have a large enough number of quasars to add support to the claims that there exists a correlation between jet axis angle and polarization angle in the jet. I plan to continue working on this study throughout the year and to present our findings at the January AAS conference.

Jeyhan Kartaltepe, of Colgate University
worked with Toney Minter on

Brian Kent, of West Virginia University
worked with Jim Braatz on

Tamara Kjonaas, of DePauw University
worked with Dana Balser on

Zachary Manganello, of Middlebury College
worked with Jeff Acree on

Chris Orban, of University of Illinois
worked with Glen Langston on

Brian Tandy, of University of Houston
worked with Dave Parker on

Sarah Flynn, of State University of New York at Stony Brook
worked with Jeff Mangum on

Selby Cull, of Hampshire College
worked with Simon Radford on

Jason Ye, of Brown University
worked with Athol Kemball on

Josh designed education inquiry units for use in his classroom: parabolic dish investigation, modeling radio astronomy using basic physics and household objects to simulate the physics of radio astronomy behavior, using on-line sky survey archives for astronomical investigation in all parts of the electromagnetic spectrum (see figure above. He further created a website (http://doversherborn.org/~bridger/Astronomy/projects/radio/main.htm) outlining much of what he researched and developed. He also created three conceptual designs for visitor center exhibits on gravitational lensing, interference, and active galactic nuclei.

David Fleming, of Concord College
worked with Jay Lockman on

Stray Radiation at the Green Bank Site

David Dave teaches astronomy and computer science in Athens, WV. This summer he worked in Green Bank on a project to remove stray radiation from data taken with the 140 Foot telescope, developing software to do this semi-automatically. This is accomplished by factoring in the structure of the telescope, its environment, and frequency specific radio emission of the sky, so that an estimate of the stray radiation component can be determined. Software developed with the 140-foot telescope will then be used with determined response attributes of the new Green Bank Telescope to enable estimates of stray radiation for future HI observations of the galactic plane.

He plans to develop a more involved project in computer science for his students. His students will be required to develop software from a given concept to completion with the aspect of maintaining a sizeable, real software task.

Chelen H. Johnson, of Breck School
worked with Ron Maddalena on

Noise Diode Intensity of the GBT

Chelen is a high school teacher in Minneapolis, MN. She worked this summer in Green Bank comparing the observed and engineer's values for the noise diode intensity of the GBT 1-2 GHz, 2-3 GHz, 4-6 GHz, and 8-10 GHz receivers. Traditional engineering methods for such determinations use hot-cold loads and generally are only accurate to 5%. Using GBT observations of standard astronomical flux calibrators and comparing power generated by the noise diodes to the calibrators, determination of the temperatures of noise diodes to 1% accuracy were achieved. This also turned out to be a more time efficient method for making the determinations.

She developed a classroom project to create and compare radio continuum maps of the Orion region using recent GBT data and 140-foot telescope data. Her high school students will use this data with the inquiry based software, Hands-On-Universe, to analyze the region. This will show students in a direct way that radio telescopes do not "hear" sounds from space.

Vic Moore, of Tillamook High School
worked with Phil Dooley on

The VLA Visitor Center's Small Radio Telescope

Vic is a high school physics and astronomy teacher in Tillamook, Oregon. He spent the first part of his appointment attending the NRAO Synthesis Imaging Summer School to gain a basic understanding of radio astronomy. He then worked with engineer Phil Dooley in Socorro to refine both the hardware and the software for the Small Radio Telescope at our visitor center.

He designed several projects for his classroom using a Small Radio Telescope for which he is currently writing a grant. He conducted visitor use surveys to determine the ease with which the public could use the telescope and worked on tweaking the software accordingly. He also developed an activity for visitors using the telescope, for which they would receive a certificate upon completing the activity.

Steve Ostaff, of Ritchie County Middle School
worked with Jeff Acree on

Interference Mitigation at Green Bank

Steve is a 7th grade teacher in Ellenboro, WV. He worked in Green Bank this summer with Dave Parker and Jeff Acree of the Green Bank Interference Mitigation Group to help measure and mitigate the RFI coming from the shielded control room for the GBT, and other on-site sources. He found that the effectiveness of the shielding around the control room had degraded since it had been built. His baseline measurements showed that the walls that are painted with copper paint and covered with copper flectron, were still good, but the windows and doors, as well as any penetrations by pipes seem to be the source for leaks. He helped correct these problems. He also helped install a small radio telescope (SRT) to help measure radio frequency interference (RFI). A site for the SRT was chosen and underground wires were located and marked. When operational, the SRT will be able to be targeted on the control room to monitor RFI coming out of it.

He built and his students tested test a "field strength meter" as a means of measuring interference at his school. They did this as part of a class project involving AM radio propagation in relation to sunspot activity. The meter was able to detect interference in a qualitative manner, but was not directional to sufficiently identify sources.

[9.05U] Web Services for Astronomical Databases: Connecting AIPS++ to the Virtual Observatory

M. C. Douthit (NRAO & California State University, San Marcos, Department of Physics and Computer Science)

In the year 2010, the NRAO will be operating four of the world’s most powerful radio telescopes: GBT, EVLA, VLBA, and ALMA (with international partnership). Multi-Terabyte data sets will quickly accumulate with a rate of twenty-five to fifty Megabytes of data per second generated by ALMA and EVLA each. It will be imperative for scientists to possess software capable of automated data reduction, image synthesis, and archiving. With the evolution of AIPS++ and the recently developed concepts of the image pipeline, the participation of the NRAO in the virtual observatories of the future is now on the horizon giving birth to the need for fast archive access and web service development in AIPS++. When the software package began over 10 years ago, it was not designed for data transfer via the web. In response to the demands of the NVO, we have designed and implemented an application layer that will allow our system to communicate with others.

Sponsored by the NRAO and California State University, San Marcos.

[11.12U] Testing the Unified Model with a Sample of Seyferts Selected by Isotropic Properties

J. P. Kelly (NRAO & University of Virginia), H. R. Schmitt (NRAO)

In this study we test some of the implications of the Unified Model with a sample of 62 Seyfert 1s and 125 Seyfert 2s selected by a mostly isotropic property, their 60\mum fluxes. The 3.6cm continuum data was obtained using the VLA in A-configuration and optical data was retrieved from the DSS. As well, sources from the VLA archive and from the literature were added. We performed statistical tests to examine differences between Seyfert 1s and 2s based on radio luminosity, infrared luminosity, radio extent, and host galaxy inclination. We find the radio and infrared luminosities to be nearly isotropic, fitting the believed structure of the circumnuclear torus, and the ratio of 25\mum to 60\mum luminosities confirms models concerning the distribution of radiation in the torus. The results of radio extent measurements do not show the expected excess of radio large Seyfert 2s, however we discuss factors that could lead to this result. Finally, we show that a relatively larger number of Seyfert 2s reside in edge-on galaxies, which may be due to the galactic plane acting as a putative torus.

[35.06]The Undergraduate Research Experience from a Personal Point of View

J.S. Kartaltepe (Colgate University)

As an undergraduate at Colgate University, I have had many opportunities to get involved with research. I spent the summer after my first year on a project at Colgate that extended into a junior research course and I have also worked at two very different national programs (National Radio Astronomy Observatory at Green Bank and the Space Telescope Science Institute). As a result, I have gained research and observing experience at different observatories, including the Foggy Bottom Observatory at Colgate, Lowell Observatory, and the NRAO at Green Bank. From these diverse experiences I have learned a great deal about research in astronomy in general as well as what some aspects of the field are like specifically. For instance, I have learned about quasars, weak gravitational lensing, and HI absorption. I have come to appreciate things about astronomy that one never learns inside of a classroom. By having the chance to try out different types of research, I have gotten a better idea of what areas of research I might like to pursue in the future. These experiences have given me some highly beneficial skills for my future career in research.

[46.10] A Search for Cyclotron Emission from known Extra-Solar Planets

G. I. Langston (NRAO), C. M. Orban (UIUC), T. S. Bastian (NRAO)

All magnetized planets in our solar system emit intense cyclotron maser radiation. Like Jupiter, the recently discovered extra-solar planets are probably magnetized. If in addition, there is a source of energetic (keV) electrons in their magnetospheres, it is likely that extra-solar planets are also cyclotron-maser emitters.

We present Green Bank 100m Radio Telescope observations at 330 MHz of 20 Extra-solar planets around nearby stars. Using the GBT spectrometer, we produced high time and frequency resolution observations, searching for flaring events. The calibration, radio interference and sensitivity limits are presented. Since cyclotron maser emission from Jupiter is episodic, long observations may be required to detect Extra-solar planets.

The National Radio Astronomy Observatory (NRAO) is a facillity of the National Science Foundation operated under cooperative agreement by Associated Universities, Inc.

[48.17U] VLBI Polarimetry of 177 Compact, Flat-Spectrum Sources

L.K. Pollack (NRAO/UCB), G.B. Taylor (NRAO), R.T. Zavala (NRAO/NMSU)

We present VLBA observations and a statistical analysis of 5 GHz VLBI polarimetry data from 177 sources in the complete, flux-density-limited Caltech-Jodrell Bank flat-spectrum (CJF) survey. We compare a broad range of source properties for quasars, galaxies and BL Lacertae objects, with an emphasis on their jet properties. We find that the electric vector position angle in quasar cores is preferentially oriented perpendicular to the jet axis. Furthermore the correlation is found to be even stronger for those quasars with short projected jet lengths. Contrary to previous claims in the literature, no correlation is found between the jet polarization angle and the jet axis in either quasars or BL Lac objects. With this large, homogeneous sample we also examine the size-redshift relation. While consistent with Friedmann cosmologies, these observations do not provide any meaningful constraints on the deceleration parameter. We also use our sample to search for source evolution, but find no strong trends. Based on these results we suggest that the formation and evolution of parsec-scale radio jets function independently of the large scale (> 1 kiloparsec) conditions.

LKP acknowledges support from the Research Experience for Undergraduates (REU) program at NSF.

[50.01] A high resolution VLA HI Absorption Mosaic of the Central 200pc of the Galaxy

C.J. Cyganowski (Harvard, NRAO), C.C. Lang (U. of Iowa), W.M. Goss (NRAO Socorro, NM), J.H. Zhao, S. Kim (CfA)

HI absorption towards the central 200pc of the Galaxy was observed with the Very Large Array (VLA) in the DnC and CnB configurations in a five pointing mosaic. The combined data has ~15" angular resolution, ~2.5 km s^-1 velocity resolution, velocity coverage from ~150 km s^-1 to ~150 km s^-1, and is sensitive to extended structure up to ~15' in size. The continuum image created from the line-free channels in this dataset is one of the sharpest 20cm images of the entire central 200pc to date. The overall goals of this study are to clarify the nature of the physical associations among the unique radio continuum sources of the Galactic Center (GC) and the atomic and molecular components, to determine the relative distances of these components along the line of sight, and to estimate the column densities.

Integrated, continuum-weighted HI spectra were made towards 41 continuum sources, consisting of both known sources and newly-identified compact sources. A subset of this HI spectral catalog will be presented. In addition, images of the HI opacity distribution towards the GC Arched Filament Complex will be presented, along with preliminary comparisons to molecular data. The distribution of atomic gas along the line of sight towards this region is complex. Higher HI opacities towards the Western Arched Filaments in the range of v~-15 to -65 km s^-1 support the suggestion by Lang, Goss & Morris (2001) that the ionized regions of the Eastern Arched Filaments (E1 and E2) are more intermingled with the molecular material of the -30 km s^-1 cloud than those of the Western Arched Filaments. In addition, we detected HI at ~40-50 km s^-1 and ~60-70 km s^-1 towards the Western Arched Filaments and E2, not detected by Lasenby et al (1989).

[52.16U] The Green Bank Telescope OH Megamaser Survey

B. Kent (NRAO/West Virginia Univ.), J. Braatz (NRAO), J. Darling (Carnegie Observatories)

The Green Bank Telescope has been used to search for OH Megamasers (OHMs) in ultra-luminous infrared galaxies. This survey, begun in June 2002, complements extensive searches done at the Arecibo Observatory (Darling & Giovanelli 2002) and elsewhere which in total have produced a catalog of approximately 100 known OHMs. Using similar selection methods as Darling and Giovanelli, we have observed 47 sources and detected 10 new OHMs. Intensities of the new sources detected in our survey range from 4 to over 70 mJy. The survey is an ongoing effort.

Candidate sources were taken from the Point Source Catalog Redshift survey (Saunders et al. 2000). We selected sources at the high end of the 60 micron power distribution, and we eliminated those in the declination range covered by Arecibo (0 deg < declination < 37 deg). We also restricted the redshift range of candidates (z < 0.25) so that the OH lines fall within the L-band frequency range. Spectra of both detected and undetected galaxies and other preliminary results of this survey are available online at http://www.gb.nrao.edu/~bkent/ohmaser.html.

This project was supported by the National Science Foundation Research Experiences for Undergraduates Program.

[53.02] Explorations in Radio Astronomy for High School Students

J. Bridger (NRAO (RET))

Few educational resources in Radio Astronomy are aimed at a high school audience. This rich field, however, utilizes several areas of physics studied at the secondary level, from interference and electromagnetism to relativity and geometry. During the summer, J. Bridger developed a series of web-based projects and hands-on explorations specifically targeted at secondary students. In addition, these projects were adapted into designs for exhibits for a modern visitor center at the Very Large Array.

The projects developed emphasize interactive, exploratory investigation as a means to conceptual understanding. Multi-antenna interferometry is modeled using microphones and parabolic dishes, and many astronomical phenomena (AGN and Gravitational Lensing) are simulated using simple inexpensive classroom materials. In addition, many projects were developed that enable students to use sky survey data to develop long-term original research projects, emphasizing the value of multi-wavelength observation.

The final project, developed as a web page, also includes sections on history, modern research and interferometry theory. The site will be accessible from the NRAO site and can serve as a general secondary resource for teachers wishing to incorporate a Radio Astronomy unit into their science curriculum.

[53.07] Research Experience for Teachers at NRAO-Green Bank: Calibration of Data from the Green Bank Telescope and Classroom Activities in Radio Astronomy

C.H. Johnson (Breck School), R.J. Maddalena (National Radio Astronomy Observatory)

The NSF-funded "Research Experience for Teachers" project provides teachers an opportunity to work on a current scientific or engineering research project. This paper will present the results of research conducted with the Robert C. Byrd Green Bank Telescope (GBT) as well as classroom activities that will use GBT data.

In order to determine the accuracy of the calibration of receivers on cm-wave radio telescopes, engineers must periodically determine the equivalent temperature of a receiver's calibration noise diode. The traditional methods utilize hot-cold loads and usually achieve an accuracy of no better than 5%, have a very coarse frequency resolution, and require days of labor. Using observations with the GBT of standard astronomical flux calibrators, we measured the noise diode temperatures for four receivers that cover 1 to 10 GHz. By comparing the detected power from the calibrators to that generated by the noise diodes we were able to determine the temperature of the noise diodes to an accuracy of 1% with very good frequency resolution (1 MHz). The astronomically determined values agree, with few exceptions, to the less accurate values generated by the receiver engineer. In contrast to the methods employed by engineers, the astronomical determinations took only a few hours.

Using data collected from the GBT and the NRAO 140-foot telescope, high-school students at Breck School in Golden Valley, MN will use the Hands-On Universe (HOU) software to analyze fits files containing data from a 100 square-degree region of the Orion Nebula. Instead of always relying on optical images from personal observations or the HOU groups at Lawrence Hall of Science or Yerkes, students can now use radio images. Comparing radio images with those derived at optical wavelengths should prove enlightening for students, many of whom have misconceptions concerning radio astronomy.

[LATE ABSTRACT] Research Experience for Teachers at NRAO-Green Bank: Reducing the Unwanted Effects of Stray Radiation from Radio Telescope Observations

D. M. Fleming (Concord College), F. J. Lockman (National Radio Astronomy Observatory)

Some fraction of the signal detected by a radio telescope typically consists of unwanted signals from directions off the main line of sight. This so-called stray radiation is undesirable, as it limits the dynamic range of observations and in some cases dominates the total signal received. Stray radiation in data from a given telescope can be estimated, and possibly removed, if the response of that telescope can be determined in all directions on the sky. Considerations such as the size and shape of the feed support legs, the receiver housing, the dish shape and defects, and even the surrounding terrain determine the response pattern. Given the all-sky response of a telescope, and maps of the radio emission from the sky at the frequency of interest, the cross-correlation of the two functions gives an estimate of the stray component in the data.

The goal of this project is two-fold: First, we wish to develop software that uses the already-determined response attributes of the NRAO 140-foot telescope at Green Bank and removes stray radiation from observations made by that telescope. Second, we wish to determine the response attributes of the new 100-meter diameter Green Bank Telescope (GBT) so that the same software can be used to estimate stray radiation in GBT observations as well.

This research experience will also be brought into the classroom through a specially designed computer science course. A typical CS course usually focuses on smaller and more academic problems for the purpose of teaching specific concepts. This special course will go beyond that, since it will present students with the challenge of designing, implementing, and maintaining a large real-world software project.

[75.07U] Modelling the Precessing Jets in SS433

J.H. Crossley (NMT/NRAO), M.P. Rupen, V. Dhawan (NRAO)

We compare earlier models for the relativistic precessing jets in SS 433 with optical and radio data, including new observations with the Very Large Array (VLA). The published models do not agree with the new data, and there are also disagreements between the Eikenberry et al. (2001) optical fit and the published models based on radio data (e.g., Hjellming & Johnson 1981). We attempt to reconcile the optical and radio data sets and address the question of the kinematic distance to SS433.

The VLA is a facility of the National Radio Astronomy Observatory, which is operated by Associated Universities, Inc., under cooperative agreement with the National Science Foundation. This work was conducted as part of the NRAO Summer Student Program, with partial support from the National Science Foundation.

[86.09U] A Search for Proper Motion in the Parsec-Scale Radio Jet Components of High-Energy Peaked BL Lacs

K. C. Peterson (Yale University), T. A. Rector (NRAO, Socorro), D. C. Gabuzda (University College Cork, Ireland)

In the standard unified model, BL Lacs are believed to be low-luminosity FR-1 radio galaxies viewed at small angles to their jet axes. However, the relationship between high-energy peaked BL Lacs (HBLs) and low-energy peaked BL Lacs (LBLs) is still unclear. Studying BL Lacs with VLBI techniques is promising because the properties of their parsec-scale jets are strongly dependent on the orientation and Lorentz factor of the jet. Due to their relative radio-faintness, HBLs have not been as well studied on VLBI scales as LBLs. We present results of a 2-epoch VLBI survey of 12 HBLs, the first search for proper motion in the parsec-scale radio jets of HBLs. Based on the measured positions of jet components in two epochs, velocities are consistent with no motion, but we are able to place upper limits of approximately 2c on the apparent motions. We present these results and their implications for the HBL jet orientation angles and Lorentz factors, important parameters in BL Lac unification models. This research was carried out as part of the NSF's Research Experience for Undergraduates (REU) program at the NRAO in Socorro, New Mexico.

[87.01] Low Frequency Observations in the Region of G11.2-0.3

K. E. Devine (Carleton College), C. L. Brogan (National Radio Astonomy Observatory), C. Tam (McGill University), N. E. Kassim, J. Lazio (Naval Research Laboratory), M. Nord (Naval Research Laboratory/ University of New Mexico), M. Roberts (McGill University), C. Lacey (University of South Carolina)

Supernova remnants (SNRs) are a critical tool for exploring the universe, and statistical studies of supernova remnant ages, distribution, and energetics are critically important in numerous areas of astrophysics. For example, by observing Galactic SNRs, we can better understand the star formation history of our Galaxy. Based on predicted levels of high mass star forming rates in the early Galaxy, there should be many more SNRs than have been discovered to date. In large degree this lack is thought to be the result of selection effects acting against the discovery of old, faint, large remnants as well as very young, small remnants due to poor sensitivity and spatial resolution at low frequencies, where SNRs are brightest. In order to search for these missing SNRs we have imaged a 1.5 degree field centered on the Galactic supernova remnant G11.2-0.3 at 74, 330, and 1420 MHz with the Very Large Array radio telescope in the A, B, C, and D configurations and at 235 MHz with the Giant Metre Radio Telescope. These data have yielded the highest resolution and sensitivity images of this region of the Galactic plane at frequencies below 1.4 GHz to date. In addition to adding much needed low frequency flux measurements for two known Galactic SNRs, plus a number of other Galactic HII regions and extragalactic sources, we have also detected three new SNR candidates. We show that these SNR candidates have steep spectral indices as expected for non-thermal emission and have shell like morphologies. By more than doubling the number of SNRs within a single 1.5 degree field of view, we have begun to gain a significantly more accurate understanding of the SNR distribution in the galactic plane. This research was supported by the National Science Foundation and the National Radio Astronomy Observatory (NRAO).

[112.25] Sub-A.U. Structure In Galactic HI

A. H. Minter, D. S. Balser (NRAO), J. S. Kartaltepe (Colgate)

We have observed fluctuations in the neutral hydrogen (HI) absorption measured towards the pulsar PSR B0329+54 using the 100 meter Green Bank radio telescope (GBT). Due to the sensitivity and sky coverage of the GBT, the brightness of PSR B0329+54, and the large proper motion of this pulsar, it is feasible to measure fluctuations in the HI absorption on time scales of less than one day. We report on initial results from these observations which indicate that structures in the cold (< 100 K) HI exist with size scales less than 1 A.U.

[115.09] Movie and Description of the 43-GHz SiO Masers in S Per

T.A. Ostrowski-Fukuda, R.E. Stencel (University of Denver), A. Kemball (NRAO), G. Harper (CASA), P.J. Diamond (AD(MERLIN/VLBI National Facility))

The Very Long Baseline Array (VLBA) has been used to monitor the 43 GHz SiO (v=1,J=1-0) maser emission in the red supergiant star, S Persei, monthly since 1999. SiO masers act as probes of the gas motions and magnetic fields of this star allowing us to investigate its extended atmosphere. Here we report the preliminary results of this on-going project. Many epochs of data have been reduced and pieced together in a time-lapse movie fashion, allowing us to follow the motions of the individual maser regions. The motion of twenty-three maser spots are followed through the selected epochs, revealing velocity and ring structure information. Proper motions are detected by using a pairwise separation test and the average expansion velocity will be discussed. Finally, the relation between the pulsational phase of the star and the SiO maser emission will be discussed. The results of this study provide the first SiO maser movie of a red supergiant star and allow us to make a comparison between S Per, and Mira-type red giant stars, such as TX Cam. This work is supported by the University of Denver's Menzel Scholarship Fund and in conjunction with the National Radio Astronomy Observatory, Socorro, NM.

Bulletin of the American Astronomical Society, 34, #4
© 2002. The American Astronomical Soceity.