Observational Astronomy

Transcription

1 Observational Astronomy Astronomy 101, Fall 2007 Pomona College Instructors: Lecture: Dr. Bryan E. Penprase Laboratory: Dr. Phil Choi Office and Phone: (909) ; Millikan Class Meetings: Mon+Wed, 1:15PM, Andrew 158, Pomona College Lab Sessions: Tuesday nights and by arrangement; Brackett Observatory and TMO Observatory Some additional observing sessions or field trips may be arranged as needed. Course Web Site: I. Introduction In this course we will explore the practical details of observational astrophysics in the modern age. Many people imagine observational astronomy involves climbing a rickety ladder in the cold night air and peering through an eyepiece attached to a telescope the size of a naval vessel looming above to view an image of a galaxy. The reality of modern astronomical research is that while the telescopes are indeed the size of naval vessels, they often are in space in orbit above the earth or in another building being controlled by computer. In addition the astronomer today peers instead into computer screens at images of objects sometimes in the light of optical, X-ray, infrared or other wavelengths. Many telescopes in modern astronomy also do not fit the commonly held perception, and consist of vast fields of radio telescopes tens of miles across, large arrays of crystal detectors in orbit, or even a large laser powered Michelson interferometer for detecting gravity waves. This course will introduce the current 'state of the art', and allow us to explore the fundamental techniques necessary for conducting observational astronomical research. We will explore details of optical theory behind telescopes and instruments, the procedures for handling astronomical coordinates and finding charts, and the techniques and results of photometry, spectroscopy, and non-optical imaging. We will also provide experience in preparing accurate laboratory reporting, accounting for observational uncertainties, and a realistic simulation of the research environment including collaborative writing and journal clubs.

2 Along the way we will explore in depth many of the fascinating new types of data available to modern astronomers, from radio and infrared surveys of the entire sky, to huge digital images of star-forming regions and the Hubble Ultra Deep Field. The course will be conducted with a combination of lectures and laboratory exercises. The lectures on Monday and Wednesday will develop the necessary background for the type of observations conducted in the laboratory. The observing session on Thursday nights will be more practical, and will focus on details of the technology being used, relevant software and hardware, and other immediate details behind the observations. A total of four observing laboratories will be completed during the semester; at least one of which will involve telescopic observing at the Pomona College 1-meter telescope at Table Mountain. In addition, a final project will be conducted in which each student will devise an observational problem, determine the telescopes and instruments optimal for the project, and propose the schedule for obtaining the observations. Data reduction and analysis will be conducted using UNIX workstations and advanced image processing packages to measure and remove background sources and to extract photometry and spectra from electronic cameras. II. Course Details a). Laboratory Exercises The labs are the main part of the grade for this course. The labs will be performed by groups of two or three students. Each group will analyze, tabulate and present their results in a lab report, which will be a collaborative effort. Collaboration is essential to modern science and astronomy in particular, and in writing these reports it is expected that the groups will share responsibilities of writing and divide the work effectively. The lab write-ups are very important and constitute 40% of the grade. The write-ups will all have a structure similar to research papers in the astronomical literature, and should display technical writing skills which clearly explain the scientific concepts behind the observations, as well as the techniques of observing and the analysis of the results. The write-ups will be graded for clarity and accuracy of writing as well as technical merit. In order to keep to our schedule, Late lab writeups will be marked off 10% per day late (our policy also reflects the fact that in modern research, if one does not publish in a timely way, there is a price!). b). Final Project There will be a final project in lieu of a final exam. This project will be an observational study designed by the individual student and is the single largest component for the grade,

3 counting for 30% of the total grade. This project may use new data acquired from our telescopes or data from the astronomical literature and the internet. Each project must also include a substantial quantitative analysis component of this data. Examples would include monitoring variable stars, or galaxies, spectral classification of stars, or a redshift survey using our grism and observing nearby galaxies. Archive projects might include determining the shapes and colors of galaxies in archives of HST data, exploring applications of computer models of black holes or interstellar clouds, or examining X-ray images of distant clusters of galaxies. All of this data is available on the internet, to provide a wealth of possible research projects possible using only archive data. Many other possible projects exist, and we welcome creative ideas of interesting observational research projects for your final project. The final project should include an analysis of the data using one of the techniques covered by the observational labs: CCD imaging, CCD Photometry, Spectroscopy, or IR/Radio Astronomy. Students may also elect to conduct research in a topic of astronomy in which they have ongoing astronomical research (i.e possible senior thesis topics!). The final project writeup will be a complete research paper in the style of published research papers, which will include sections of abstract, introduction, observation and analysis, results and conclusions. The final report is due on December 17th, and will serve as the final exam for the course. c). Journal Club/Student Presentation To give students experience with the astronomical literature, we will conduct a 'journal club' session in which each student presents a summary of research related to their chosen final project topic using actual journal articles of their choosing to the class. Each student will meet in advance with the professor to review the journal articles and topics, and to summarize the topic to be covered during the class time. The student will present a 15 minute talk on the topic which summarizes the observational techniques used, the type of data needed, the plan for the final project observations, and the relevance of the work to astronomy. This talk and a 2-3-page summary of the main points covered will count for 10% of the course grade. d). Homework and Exams The main portion of the grade will be the completed laboratory reports. However, the lectures require a substantial amount of reading that needs to be completed before class. A few problem sets will be given to help clarify the readings, and prepare for the laboratories. These calculations will be chosen to be relevant to the project at hand, and will total to 20% of the grade, along with participation and attendance. Since this course is intended to be a practicum of modern research in astronomy, we will forgo having exams in the course, and instead

4 expect a high quality of writing in the laboratory reports. There will be no midterm or final exam. (hooray!) Summary of Grading: Observing Laboratory Write-ups (4): 40% Final Project : 30% Journal Club Presentation: 10% Problem Sets/Participation: 20% III. Field Trips and Observing Sessions We should have a couple of field trips available to the class. The first will be a chance to visit our 1-meter telescope at Table Mountain, near Wrightwood, CA. During September 19 we will take a field trip to attend a cutting-edge research conference The Keck Science meeting at Caltech in Pasadena. We will also visit the Palomar Observatory 200" telescope up close and help with an observing run using the "Giant Eye". After dinner we will help the team observe with the 200" telescope (largely by quietly observing them observe!). This should be a fantastic occasion, and we will determine the exact date and time for this trip soon. In addition to the field trips, some observing labs or final project observing will occur either at Table Mountain observatory, near Wrightwood CA, or using our remote linkup from the Millikan/Andrew building. The precise observing dates are outlined in the attached course schedule, and may be adjusted slightly due to weather and other considerations. IV. Texts The required textbook is the Fundamental Astronomy by Hannu Karttunen, et al. Some selections from Observational Astrophysics by Robert C. Smith and Handbook of CCD Astronomy by Howell et al will be circulated in class. A recommended textbook (available at the book store) is Astronomy Methods by Hale Bradt. In addition, there are a number of useful books that are available from our Seeley Mudd Science Library at Pomona, which are listed below. All are very authoritative reference works for further reading on any of the material in the course. They may also prove useful in preparing final project reports.

5 Detection of Light by Rieke is an in-depth description of the various detector types used at all wavelengths from the ultraviolet to the radio. It is extremely thorough and emphasizes the physics of the detector's operation, and is written for research astrophysicists. Physical Processes in the Interstellar Medium by Spitzer is a great reference for the physics of the interstellar medium. For this class, the most useful chapters are 2-4 since they cover the basics of radiative transfer and emission mechanisms. Radiative Processes in Astrophysics by Rybicki and Lightman is another graduate level text on emission mechanisms, but it is more rigorous and complete than Spitzer, so it may be easier to follow. Radiotelescopes by Christensen and Högbom is a general reference on (you guessed it) radio telescopes, including radio interferometers. It covers antennas and observing well has very little discussion of astronomy. Introduction to stellar astrophysics by Bohm-Vitense is a three volume set on all aspects of stellar astronomy, both theoretical and experimental. Astrophysics of Gaseous Nebulae by Osterbrock is the bible for spectroscopic studies of the interstellar medium, and has a complete description of the spectroscopic 'nebular diagnostics' and the underlying physics in the interstellar medium. It will be on reserve at Pomona.