PHY 517 / AST 443 - Observational Techniques

General Information

• Credits: 3 (PHY 517) or 4 (AST 443)
• Instructors:
  • Stanimir Metchev (metchev 'at' astro.sunysb.edu; ESS 452; 632-1302)
  • James Barrett (james.barrett 'at' stonybrook.edu; ESS 431/434; 632-1558)
• Required texts:
  • Astronomy Methods, H. Bradt (Cambridge University Press, 2007)
  • Practical Statistics for Astronomers, J.V. Wall & C.R. Jenkins (Cambridge University Press, 2008)
  • Handbook of CCD Astronomy, S.B. Howell (2nd ed., Cambridge University Press, 2006)
• Recommended text:
  • Data Reduction and Error Analysis for the Physical Sciences, P.R. Bevington & D.K. Robinson (2nd or 3rd ed., McGraw-Hill Inc., 1992, 2002)
• The required textbooks are available at the bookstore or through amazon.com, by following the above links
• Prerequisites: AST 203 or 205 for undergraduates: may be taken concurrently; no prerequisites for graduate students

Course Description

Astronomers explore the universe by detecting and analyzing photons with energies ranging from about 51 Joules to 10^-9eV, or a range of about 30 orders of magnitude. One needs very different techniques over this range. We concentrate on a subset of techniques for detection of photons from visible to radio wavelengths.

This is a three-quarters lab and one-quarter lecture course. The laboratory component entails obtaining and analyzing astronomical data with optical and radio telescopes. Three distinct observational experiments will be conducted, focussing on optical photometry/time-series analysis, optical spectroscopy, and radio interferometry. The students will be responsible for setting up and calibrating their telescope equipment, obtaining their own data, and analyzing the data in the IDL programming language.

The lecture component is intimately intertwined with the experimental aspects of the course. During a total of eight lecture periods the students will learn the basics of telescope and detector technology, the use of photometric, spectroscopic, and interferometric techniques, and methods of error, statistical, and time-series analysis.

The last of the three observational projects will involve writing a telescope observing proposal, which will be peer-reviewed. The observing proposal will emphasize the need for generating a testable hypothesis and justifying it through signal-to-noise or other appropriate statistical arguments. The peer evaluations will not affect the proposer's grade, but will rather serve to assess the evaluator's ability to critically assess the quality of the other proposals.

The students will prepare journal-style written reports on each of their observational projects and a final oral presentation on one of the projects.

Lectures

• Lecture 2, Jan 25, 2012, Astronomical Concepts
• Lectures 3+4, Jan 30 / Feb 1, 2012, Photon Detectors, Spectrographs
• Lecture 5 and Prof. Koda's radio astronomy slides, Feb 6, 2012, Radio Astronomy and Interferometry
• Lecture 6, Feb 20, 2012, Statistics, Error Analysis, and Hypothesis Testing
• Lecture 7, Mar 14, 2012, Lab Status and Tips
• Lecture 8, Mar 26, 2012, Writing Telescope Proposals

Experiments

• General guidelines:
  • The guidelines are mostly identical to those laid out in the course notes for PHY 515 / 445. This is mandatory reading.
  • The following notes are specific to PHY 517 / AST 443. (Also mandatory.)
• Group A. Imaging and Photometry
  • 1. Transiting extrasolar planets. Perform time-series photometry of stars with known transitng planets. Multiple measurements are needed to attain precision at the 0.1% level, needed for detecting planet transits. This is an exercise in obtaining high-precision measurements and in time-series analysis.
    • Experiment description
    • Catalog of known transiting planets at exoplanet.eu
    • Finding chart service from the STScI Digital Sky Survey (use images from POSS2/UKSTU Red plates)
  • 2. Interstellar dust extinction. Measure stellar fluxes in astronomical images in three different electromagnetic bands. Build a color-color diagram, i.e., a diagram of the flux ratios among the bands, for an extincted globular cluster in the galactic plane and compare it to the known colors of stars with no dust extinction. The offset between the two sets of (extincted and non-extincted) data gives the extinction vector and hence the amount of interstellar dust along the line of sight toward the globular cluster.
    • Experiment description
    • Padova database of stellar evolutionary models
    • Finding chart service from the STScI Digital Sky Survey (use images from POSS2/UKSTU Red plates)

• Group B. Spectroscopy
  • 1. Rotation of massive stars. Stars between 2 and 10 times the mass of the Sun have fully radiative interiors and can spin up to near-break-up rotation speeds. The rapid stellar rotation is detectable as Doppler broadening of the stellar absorption lines. Determine the projected rotation velocities of A and B stars from their optical spectra.
  • 2. The Spectrum of Earthshine: Detecting Earth's Biosignatures from Afar. Obtain a low resolution optical spectrum of the faint glow from the dark side of the Moon: sunlight that is doubly reflected from the Earth's and the Moon's surface. Proper calibration with respect to singly-reflected sunlight from the bright side of the Moon can reveal the visible spectrum of the Earth, and with it the tell-tale signatures of a habitable world: molecular oxygen, ozone, water, and vegetation.
  • Experiment description
  • HITRAN tool for simulating an atmospheric transmission spectrum
  • USGS Digital Spectral Library: a resource for spectra of vegetation and ocean water. Use, e.g., spectra entitled 'Grass_dry.5+.5green' and 'Seawater_Open_Ocean'
  
  Spectroscopy resources:
  • Instructions on how to use ATV, including for spectroscopic extraction.
  • NIST Atomic Spectra Database
  • Neon 5800-7500A spectrum with strongest transitions labeled

• Group C. Radio astronomy
  • 1. Angular diameter of the Sun. Michelson interferometry is a technique with broad applications in both physics and astronomy, and is used to date to directly measure stellar diameters. The Sun is a marginally resolved source for our home-built Stony Brook radio telescope when viewed in single-dish mode, but is well resolved when observed inteferometrically. Compare an intensity scan of the Sun to that of a known point source (a geostationary TV satellite) in single-dish mode and infer the Sun's angular diameter. Then repeat the experiment with the interferometer, recording the Sun's and the satellite's visibility amplitudes as a function of baseline for several different interferometer baselines. Your interferometrix measurents should yield a much more accurate solar diameter.
    • Experiment description
    • Positions of geostationary satellites: www.dishpointer.com
    • Solar positions: US Naval Observatory
    • Useful discussion on displaying FFT results in IDL.

• Test data:
  • Photometric sequence on WASP-36b
  • Spectra of Betelgeuse with three different slit widths, covering the entire free spectral range

• Student groups:
  • Experiment 1
  • Experiment 2
  • Experiment 3
• Log sheets for: imaging, spectroscopy, and radio observations.

Proposals

• Write a telescope observing proposal for the third and last laboratory experiment
• 5 pages maximum, including 2 pages for figures, tables, and object list. Use a 12-pt font, 1-inch margins, and single spacing.
• Due at 5pm on April 11, 2012 by email
• Will be discussed in class on April 16, 2012
• Mandatory proposal cover sheet
• LaTeX proposal template
• Example proposal
• Submitted proposals and review assignments: proposals.tar

Observing Calendar

Equipment

• Mt. Stony Brook 14-inch telescope. Our Department operates the Mt. Stony Brook observatory, housing a 14-inch Meade LX200-ACF telescope. This will be the workhorse telescope for the imaging and spectroscopic components of the course. Telescope manual and step-by-step instructions. Note that the current telescope manual refers to using the CCDOps software for CCD imaging observations, while you will be using CCDSoft, which allows more flexibility with guiding.
• Visible-light CCD camera. Imaging observations with the 14-inch telescope will be taken with the SBIG STL-1001E CCD camera. The CCD camera is mounted on the back end of the telescope and is controlled through a laptop computer. A set of standard broad-band BVRI and a narrow-band H-alpha filters are available. Summary information sheet; specifications; operations manual, CCDSoft quick-start guide, or CCDSoft v.5 manual.
• Visible-light spectrograph. Spectroscopic observations will be obtained with a spectrograph that offers moderate (500-5000) resolution between 3500 - 9500 angstroms. Manual and specifications; manufacturer's website (in German) with a sketch of the optical path, step-by-step instructions.
• Radio telescope and interferometer. Our two-element radio interferometer employs 1-meter siderostats to combine light onto a single commercial satellite dish. The interferometer has an adjustable 2-10 meter baseline and the reflective elements are well suited for observations at centimeter wavelengths. Single-dish radio observations can also be taken by flipping the satellite dish by 180 degrees and pointing it away from the siderostats.

Computing Resources

• Math/Physics SINC site computers:
  • These will be available to you during open SINC site hours. Make sure that you have an account on them.
  • If you need to login remotely, make sure that you have an SSH client on your computer (for Windows, pick your favorite one at putty.org), and at the command line type:
    ssh -Y your_username@mathlab.sunysb.edu
  • If you need extra disk storage space (as you will for the transit planet lab), log in specifically to compute.mathlab.sunysb.edu and use one of the two local storage disks linked specifically to this computer: /space1 or /space2. Make a subdirectory for yourself on one of the two disks and transfer your files to your subdirectory. The local storage disks are not backed up, so make sure to have all important information saved in your home directory.
• Setup and initialization of IDL under Unix (for bash shell):
  • Add the following lines to the .bashrc file in your home directory:
    if [ -f ~/.idlstartup ]; then
    export IDL_STARTUP="~/.idlstartup"
    fi
  • Copy the file .idlstartup in your home directory
• Unix tutorials:
  • A detailed intro at the University of Surrey, UK.
  • Paul Twohey's guide for beginners. Note that some information is specific to UC Berkeley.
• IDL tutorials and resources:
  • Christophe Morisette's IDL Cookbook for beginners.
  • The IDL FAQ.
  • Coyote's Guide to IDL Programming, which includes a more comprehensive list of IDL-related websites.
  • The IDL Astronomy Users Library. You need to install these procedures, if they have not been installed already. (Check for the existence of an $IDL_DIR/external/astron/ directory, for example.)
  • The JHU APL IDL library.
  • Alphabetical list of IDL routines with on-line descriptions.
• Astronomical FITS image viewing programs:
  • SAOImage DS9
  • ATV: an interactive display tool for IDL
• Literature search:
  • NASA ADS: virtually all literature of astronomical interest can be found here.
  • astro-ph: the most up-to-date resource (updated daily), but incomplete.
• Typesetting in LaTeX:
  • You are required to typeset your lab write-ups in the format of the American Astronomical Society (AAS) journals. Here is a sample. You are welcome to use any text editor to produce this result. Should you choose LaTeX, AASTeX v5.2 (LaTeX 2e) is installed on the Math/Physics SINC computers.
  • Refer to the AASTeX package page for examples and hints on using AASTeX.
  • You are encouraged to use Natbib and AstroNat (a BibTeX package) to manage your citations. A copy of the Natbib style file is included with the AASTeX package, but AstroNat will require your own installation.
• Other tools:
  • Stellarium: a free open source planetarium for Windows/MacOSX/Linux. You may find it useful for finding your targets on the sky.
  • Airmass calculator: for your observation planning

Course Grading

The course grades will be assigned on the basis of the following:
• 75% projects and written reports (25% each)
• 10% observing proposal
• 10% final presentation
• 5% evaluation of peers' proposals and presentations

Course Policies

• Lecture notes: Select slides will be available after each lecture on the course website.
• Late work: Assignments up to one week old will be accepted with a 25% penalty. More than one week overdue assignments will not be accepted.

Stony Brook policies:

If you have a physical, psychological, medical, or learning disability that may impact your course work, please contact Disability Support Services (631) 632-6748 or http://studentaffairs.stonybrook.edu/dss. They will determine with you what accommodations are necessary and appropriate. All information and documentation is confidential.

Students who require assistance during emergency evacuation are encouraged to discuss their needs with their professors and Disability Support Services. For procedures and information go to the following website http://www.stonybrook.edu/ehs/fire/disabilities.shtml.

Each student must pursue his or her academic goals honestly and be personally accountable for all submitted work. Representing another person's work as your own is always wrong. Faculty are required to report any suspected instance of academic dishonesty to the Academic Judiciary. For more comprehensive information on academic integrity, including categories of academic dishonesty, please refer to the academic judiciary website at http://www.stonybrook.edu/uaa/academicjudiciary.

Stony Brook University expects students to respect the rights, privileges, and property of other people. Faculty are required to report to the Office of Judicial Affairs any disruptive behavior that interrupts their ability to teach, compromises the safety of the learning environment, and/or inhibits students' ability to learn.