NATIONAL ASTRONOMY AND IONOSPHERE CENTER |
PROGRESS REPORT SUMMER 2003
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Eight students were selected for the 2003 REU Summer Student program at Arecibo Observatory from a pool of 130 applicants. In addition, NAIC supported two students (an undergraduate, Nerlyn Echevarría and a graduate, Romina Nikoukar), and we had 2 visiting graduate students (Mike Nicolls, Cornell University, and Michael Jouteux, Ecole Normale Superieure of Lyon, France) who came with other funding. We also had a middle school science teacher working at the Visitor Center and in the teacher-training workshop with José Alonso. This summer was saddened and deeply affected by a tragic fatal accident to two young students who were hiking near the Observatory. One of whom was an REU student. The program had to be rearranged due to these events, which occurred at the very beginning of the summer, and it was only possible to complete the student program thanks to the collaboration and dedication of the whole staff at the Observatory. All of the students were able to acquire experience with observations, either as part of their individual research projects or during the hands-on project of their choice. The amount of telescope time scheduled for particular research projects varied. The hands-on projects meant that all the students worked through the process of preparing for observations, data taking, data reduction and interpretation. Each hands-on project was scheduled 2 hours of telescope time and the students prepared short presentations of the results at the end of the summer. The astronomy students will present the results of their summer research at the 203rd Meeting of the American Astronomical Society in Atlanta, Georgia, in January 2004. The staff prepared a series of lectures, which gave the students an introduction to radio astronomy and the atmospheric sciences. The lectures were complemented with guided tours of the observatory facilities that gave them a unique opportunity to see the applications and instrumentation referred to in the lectures. This summer each student was presented with two textbooks: “An Introduction to Radio Astronomy” by Burke and Graham-Smith and “The Solar-Terrestrial Environment: An Introduction to Geospace the Science of the Terrestrial Upper Atmosphere, Ionosphere and Magnetosphere” by Hargreaves. During this summer, Joe Taylor and Joel Weisberg had research projects scheduled on the telescope and they visited the Observatory. The students were delighted to be able to learn about their project and talk with them personally during the nights when they were observing. Another visitor was a former NAIC summer student (1974), Randy Kimble, currently at NASA/Goddard Space Flight Center. Randy gave the students a talk on his work at NASA, which also included some memories of the time when he was a summer student. All members of the observatory staff were helpful with the extracurricular program for the students, in particular Mayra Lebrón, Diego Janches, Paulo Freire and Luis Murray spent a great deal of time with the students. One of the new opportunities for entertainment this summer was a weekly film as part of the “Noche de Película” series. Each Thursday evening an international film is presented at the Visitor Center auditorium at the Observatory. Another extracurricular activity was scuba diving. All the summer students took scuba diving lessons and became certified. Diego Janches organized a weekend trip to the island of Mona, which the students enjoyed very much. Some of the students already knew Spanish and were able to practice their spoken skills with staff and employees. Others took salsa lessons, which they put to practice at the Patron Saint Festival of Hatillo, to the rhythms of one of Puerto Rico's best salsa groups. We had a tour of Old San Juan in which the visit to the “El Morro” fortress was a favorite. The students joined observatory employees and their families on a day excursion to La Parguera in Lajas organized by the A.O. Kayakers Club. We also had the visit of the former REU director at Arecibo, Jo Ann Eder, and during the time she was at the Observatory she helped organize a hike to the “El Yunque” rain forest and a trip to the beach at Arecibo for the 4th of July. 2003 SUMMER STUDENT PROJECTS Supported by NSF REU Funds: Graham Alvey (University of Illinois, Urbana-Champaign) worked with Sixto González on a project using the Arecibo Observatory incoherent scatter radar capabilities to probe the ionosphere. Graham studied how to determine the velocities of O+ and H+ plasmas when the respective ion is the majority species and also how to assign the error bars for the measurements and calculations. His project involved programming with ASP and MATLAB. Graham attended the CEDAR workshop in Longmont, Co, in which he had the opportunity to get a broad introduction to the field of atmospheric sciences. Jacqueline Hodge (California Polytechnic State University), together with her advisor Avinash Deshpande, worked on a project that consisted of Monte-Carlo simulations to examine the statistical description of the HI density distribution in the interstellar medium were it to be driven entirely by supernova explosions. Two different approaches with many simplifying assumptions were explored, including one in which a detailed evolution was followed. Possible sensitivity of the results to certain assumptions was assessed. The power-spectral description of the simulated 3-d distributions revealed a red power-law nature in almost all the cases, with power-law slopes in the range -4 to -2.5. Jacqueline developed the necessary simulation software as part of her project. Adam Mott (Arizona State University) searched for new pulsars within several data sets from observations of globular clusters at 327 MHz with his advisor Paulo Freire. Adam worked with three data sets: observations of M13 and M5 from May 13, and an observation of M5 from May 30, 2003. These searches were conducted by varying two parameters: the dispersion measure and line-of-sight acceleration. To visualize the search results in both parameters, Adam wrote a Java program that creates grayscale plots of signal-to-noise ratio as a function of both dispersion measure and acceleration for each suspect periodicity. These searches resulted in several as-yet unconfirmed new pulsar candidates in M5, including a 2.141-ms candidate at a DM of 29.12 cm-3 pc, a 2.144-ms candidate at a DM of 29.64 cm-3 pc, a 10.352-ms candidate at a DM of 29.68 cm-3 pc, and a 1.343-ms candidate at a DM of 29.12 cm-3 pc. Each of these candidates appeared in one observation for some nonzero line-of-sight acceleration and for a range of dispersion measures. Work continues to try and confirm these candidates by detecting them in more than a single observation Catherine Neish (University of British Columbia) worked on several aspects of analyzing radar astronomy observations of asteroids under the joint supervision of Ellen Howell and Mike Nolan. She investigated fitting techniques to use the ephemeris information after the observations to correct for image drift from frame to frame. She also compared the results of different calibration methods. Catherine also analyzed radar images of the asteroid 5381 Sekhmet, observed at Arecibo Observatory during its close approach to Earth in May 2003. These images show the presence of a previously unknown asteroidal satellite. This is the seventh binary system detected by radar within the near-Earth asteroid population. Based on range extents at 45-m resolution, she finds the average diameters of the two asteroids to be 1000 m and 300 m, with rotation periods of 2.7 ± 0.4 h and 10 ± 2 h, respectively. She estimates the orbital period of the binary to be 12.5 ± 0.3 h, with an orbital radius of 1.54 ± 0.12 km. The orbital velocity of the secondary was measured to be 0.215 ± 0.012 m/s. The rapid rotation rate of the primary indicates that the viewing geometry must be nearly equatorial. These measurements imply a density of 1.98 ± 0.65 g/cm3 for the asteroids, assuming a circular orbit, and the same composition for both primary and satellite. Matthew Phillips (University of Colorado) studied the Seasonal Variations of Atmospheric Gravity waves through the use of the Resonance Lidar facilities and data. Matthew wrote and modified IDL programs to read, process and analyze Na and K lidar data. The data was used to investigate seasonal variations at Arecibo over the past 3 years. He had the opportunity to work at the lidar lab and participate in Na and K resonance lidar measurements with his advisor Shikha Raizada. Matthew also attended the 2003 CEDAR conference. Kristopher Reilly (New College of Florida) was jointly supervised by Tapasi Ghosh and Chris Salter. His research was to focus on the 430-MHz continuum mapping of a region within Loop I (the North Polar Spur) where a semi-circular emission arc is superposed upon the larger feature, showing apparent interaction. This arc is likely to represent the remnant of a second-generation supernova resulting from star formation within the compressed cool shell of the Loop I supernova remnant. As such, the object is a promising candidate for the “reheating event" which has often been invoked to explain the X-ray emission of Loop I. The map has a ten-fold smaller beam area then any previous survey of the interaction region, and should aid understanding of the nature of the arc, and its relation to Loop I. Elizabeth Schmidt (Carthage College) used the Arecibo Standard Point Source Catalog and the Atlas of galactic Neutral Hydrogen by Hartmann and Burton (1997), to find high velocity clouds (HVC’s) and intermediate velocity clouds (IVC’s) that were located within ± 1° of strong continuum sources. Elizabeth was supervised by Mayra Lebrón and Carmen Pantoja. Once Elizabeth had located the clouds, she found the peak emission along with their approximate sizes, and central velocities. All information on each cloud was then recorded in a table according to the flux density of the adjacent continuum source. This list will be used for a search of molecular emission from HVC’s. The second part of Elizabeth’s project this summer was to reduce the HI data for observations she made of HVC W57. The data was reduced using IDL and aogridzilla, and a map of the HVC was made. Coral Wheeler (University of Akron) was supervised by Avinash Deshpande. Her project consisted of a review of the coherent dedispersion procedure and the key approximations made in the applications to the high radio-frequency observations of pulsars. Analytical expressions were rederived, now to include also the next order terms that were ignored earlier, with a view to refining to procedures to open the possibility of high time resolution studies of pulsars at decameter wavelengths. It was seen that the extra terms do reduce the residual dispersion smearing considerably, and would allow even micro-structure studies for a few nearby pulsars. Suitable FFT-based software was developed/configured for application to some pulsar data from direct sampling systems at AO and elsewhere. Supported by Other Funds: Nerlyn Echevarría (University of Puerto Rico-Mayagüez) worked in the development of software to improve the automation of the data-taking process of the existing clock comparison system for the atomic clocks and timing devices of the Arecibo Observatory. Nerlyn was supervised by Calixto Rodriguez. Her application was based/written in C language and Microsoft Basic running under a Windows environment. In this set-up a PC is connected to a Universal Counter (HP) using a GPIB interface cable. The Universal Counter is connected to the timing distribution device (multiplexer) that takes the timing signals from a plurality of clocks. The information is used to determine the operational stability of the timing/frequency standards (timing devices) of the Arecibo Observatory on a daily basis. Carlos Trinidad, is a physics teacher from the Daskalos private middle school in San Juan and was selected as the 2003 teacher in residence and worked with José Alonso. He spent eight weeks at the Observatory developing a handbook of 30 hands-on activities using the TI-83 graphing calculator for physical-science teachers. These activities were implemented during the two-week Ángel Ramos Foundation teacher workshop at our Learning Center. As part of the workshop, Carlos coordinated two field trips to the Caño Tiburones wetland. Participating teachers used the graphing calculator and the CBL interface to measure physical parameters such as temperature, salinity, water flow, pH, and oxygen content of the ecosystem. At the end of the workshop, each teacher gave a presentation regarding the results of his/her investigation. Romina Nikoukar (University of Illinois, Urbana-Champaign), was involved in a project simulating the next Arecibo World Day experiment. Her supervisor was Mike Sulzer and their goal is to develop a technique that will allow the very accurate computation of parameters such as temperature and composition; that is, they want the results to have very low bias, but do not want to sacrifice the speed of the measurements any more than absolutely necessary. The project used linear regularization to invert the "measured" lag profiles, yielding the underlying process, the lag profile that would be measured if it were possible to use a very short radar pulse. It was necessary to develop modulating waveforms for the radar that would give "measured" lag profiles that can be inverted without a large increase in noise. The simulation used amplitude-modulated sequences for this purpose, although phase modulation could probably be used as well. Romina’s project will continue as graduate work at the University of Illinois. Michael Jouteux (Ecole Normale Superieure, Lyon, France) worked on a project with Avinash Despande that investigated a long ignored technique of possible direct deconvolution to resolve complex one-dimensional profiles (e.g. pulse and spectral-line profiles). Apart from removing instrumental- and propagation-related smoothing, the possibility of partial direct deconvolution of the profile was considered to resolve profiles beyond the intrinsic width of the components. Michael determined suitable criteria to guide the iterative procedure developed for this purpose. A wide variety of complex profiles were simulated and subjected to this procedure, to assess its the strengths and limitations. As part of his project Michael developed the necessary software tools.
2003 NAIC Summer Student Program Talks June 3 The History of the Observatory [Daniel Altschuler, Arecibo Observatory] June 18 Asteroids [Mike Nolan, Arecibo Observatory] June 19 The Geology of Puerto Rico [Ellen Howell, Arecibo Observatory] July 2 Incoherent Scatter Radar I [Mike Sulzer, Arecibo Observatory] July 3 Incoherent Scatter Radar II [Mike Sulzer, Arecibo Observatory] July 7 The Radio Sky [Chris Salter, Arecibo Observatory] July 8 Electronics and Receivers [Lisa Wray, Arecibo Observatory] July 10 Signal Processing [Avinash Deshpande, Arecibo Observatory] July 15 Pulsars [Paulo Freire, Arecibo Observatory] July 16 Meteors [Diego Janches, Arecibo Observatory] July 16 The Wide Field Camera 3: A New Imager for the Hubble Space Telescope [Randy Kimble] July 23 The Earth’s Atmosphere [Sixto González, Arecibo Observatory] Summer Student Presentations: July 29 A Study of Seasonal Variations of Atmospheric Gravity Waves using the Lidar System [Matthew Phillips] July 29 Hands-on project presentation [Matthew Phillips, Jaqueline Hodge, Nerlyn Echevarría] July 31 The Coherent Dedispersion Procedure [Coral Wheeler] July 31 Hands-on project presentation [Coral Wheeler, Adam Mott, Graham Alvey] August 5 Asteroids, An Investigation of the Binary 5381 using Radar Astronomy [Catherine Neish] August 5 Hands-on project presentation [Catherine Neish, Michael Jouteux] August 6 Errors in Velocity Measurements for Topside Ionosphere O+ and H+ [Graham Alvey] August 6 Design and Improvements to the A.O. Timing/Frequency System [Nerlyn Echevarría] August 7 High Velocity Clouds against Strong Continuum Sources and Hands-on Project Presentation August 7 Pulsar Searches in Globular Clusters at 327 MHz [Adam Mott] August 18 Simulating the Arecibo World Day Experiment [Romina Nikoukar] August 18 Direct Deconvolution to Resolve Complex One-Dimensional Profiles [Michael Jouteux] August 27 HI Density Distribution Driven by Supernovae Ejecta: A Simulation Study [Jaqueline Hodge] Tours: · Welcome BBQ by the Pool, June 6 · Kayak trip to La Parguera, June 7 · Trip to Old San Juan, June 14 · Trip to the Beach in Arecibo, July 4 · Trip to El Yunque rainforest, July 5 · Trip to Hatillo Fiestas Patronales, July 16 Tanamá River Tragedy: A fatal accident occurred to one of the students from the Arecibo Observatory REU program. In this accident two undergraduate students lost their lives: Kristopher (“Kit”) Reilly an REU student from New College, Florida, and Mike Ewers, a student from Carleton College visiting with his professor to help with pulsar observations. On the afternoon of June 21, around 3:00 p.m., Kit, Mike and another REU student decided to take a hike to the Tanamá River that runs behind the Arecibo Observatory facility. Before they started, the students informed the observatory guards they were going there (as they had been instructed to do). Around 5:00 p.m., one of the students came back to the guardhouse to inform the guards that the other two were missing. The guards called 911, and the search for them was initiated that evening and continued throughout the night by the state Emergency Management Agency and Search and Rescue team. The parents of the missing students were contacted on June 22. On that day, the other 7 REU students met with 2 social workers and 2 psychologists from Blue Cross PR. On June 22 the parents of Kristopher Reilly arrived at the Observatory. On June 23, two psychologists specializing in crisis counseling arrived from Cornell University and met with the students and the parents over several days. The parents of Michael Ewers arrived on June 24. Following the recommendations of the psychologists, the Observatory took several steps to help the students and the entire observatory “family” to deal with this tragedy. We had a memorial service at the Visitor Center with the Ewers family present on June 26. Cornell and the NAIC staff paid for 4 students to attend the memorial service in Florida for Kristopher Reilly, June 28. Another memorial service for Kit was held on July 1st at the Visitor Center, which the students helped organize and which all the staff were able to attend. Kit was a remarkable person who became close to many people at the Observatory during his short time there. The students were offered the opportunity to extend their stay at the Observatory in order to complete their projects. The psychologists from Cornell were on call. We contacted the home departments of all the students so that when they started their classes their professors knew what had happened and also so the students could meet with a counselor upon arrival, if necessary. |