AY3: Freshman Seminar (Automated Discovery of the Universe)

Astronomy is and will continue to undergo a profound change. When I was a graduate student (in the last century) astronomy was a data starved area of science. It took great effort to simply collect the data. The analysis tools were rather modest (not surprisingly). In contrast, today, our field is inundated with data -- thanks to technological progress which has given us large format detectors, decreasing costs for unit telescopes, advances in electro-mechanical systems (allowing robotocizatoin) and of course all the advances in computers and related areas.

Who will succeed and make discoveries in the new era? Those who will have ability to deal with big data sets, connect diverse catalogs and invent new algorithms whilst being grounded in astronomical pheneomenology and physics.

The purpose of this class is to give you a taste of the new era. After accounting for holidays we have 26 1-hour meetings. The spirit of the class is to expose you and get excited about research. In that spirit there is no final exam. Success is defined by whether you are excited by research.

  1. Introduction to the Course [4 Jan, 2016]
  2. The Zwicky Transient Facility (ZTF) [7 Jan, 2016]
    Talk by R. Smith & lab tour
  3. The Gaia Mission [8 Jan, 2016]
    Talk by Dr. N. Blagorodnova
  4. Time & Calendar [11 Jan 2016]
    Solar day, Cesium clock second, Gregorian calendar, Julian Day Number
  5. Astronomical Coordinates (RA, DEC) [14 Jan 2016]
    Altitude, Azimuth, Right Ascension, Declination
  6. Local Sidereal Time & Offsets [15 Jan 2016]
    Sidereal time, LST at midnight, Computing angular offsets (spherical trig; arcseconds)
  7. Photometry & Magnitude [21 Jan 2016]
    Poisson noise, Background, Aperture Photometry
    Magnitude, Zero point (AB, Vega), Error on Magnitude
  8. Introduction to UNIX [22 Jan 2016]
    pwd, cd, mkdir, ls, cat, rm, mv, rmdir, more, less, head, tail,
    which, info, man, wc, wget, curl, compress, uncompress, paste,
    grep, sed, [.,*,..,#,|,~,$] cut, sort, uniq, tr, df, du
    find, perhaps the most complex Unix command
    Helpful sites:  |  grep  |  sed  |  awk
  9. Introduction to Python [22 Jan 2016]
    Nadia's Python presentation  |  Supernova lightcurve data file
  10. Data Set I: RR Lyrae from PTF [25 Jan 2019]
    Goal: read ASCII files and fold time series to given period.
  11. Fourier Transforms [28 Jan 2016]
    Introduction to Fourier Transform
    FFT demonstration (Matlab/SRK) .
  12. Using FFTs [29 Jan 2016]
    Demonstrate FFT usage with python code.
  13. Understanding Fourier Transforms [1 Feb 2016]
    SRK Notes
    Pulsar Data Base
  14. Application to Pulsar Discovery [4 Feb 2016]
    Notes on FFT
    An example analysis of pulsar data analysis (Matlab).
  15. Find best period & fold [5 Feb 2016]
    Note on Folding
  16. The PTF Galactic Marshal [11 Feb 2016, Dr. Adam Miller]
    Introduction to Periodogram. Showcasing of various periodic stars.
  17. The Kepler Mission [12 Feb 2016, Jessie Christensen]
    Analysis of a delta-scuti star (Kepler data)
  18. Introduction to variable stars [18 Feb 2016]
    Variable Star Naming Convention
  19. Presentation by students (RR Lyrae Project) [19 Feb 2016]
    Rules for Giving Talk
  20. PTF data: An introduction to periodic stars [22 Feb 2016]
    Dr. Thomas Kupfer
  21. Periodogram: introduction and application to PTF data [25 Feb 2016]
    Dr. Thomas Kupfer
  22. Searching for pulsators & planets with Kepler [26 Feb 2016]
    Dr. Jessie Christensen (Kepler Scientist)
  23. [29 Feb 2016]
  24. Fresh PTF Light Curves [3 March 2016]
    Dr. Kupfer has prepared PTF light curves of likely white dwarf systems (identified via color). Your chance to discover!
    PTF Data for Discovery
    For Unix system, "tar -xvzf PTF_data.tar.gz" to unpack the data.
    test case: data file 12. Explore P=0.001 to P=0.6 step with step size 1E-5 days. Answer: Period=0.0793526 days
  25. Report from Class [4 March 2016]
    Class to report on discoveries made from PTF light curves given on the previous day.
  26. Fresh PTF Data sets [7 March 2016]
    In lieu of a "final exam" each student is assigned a set of "fresh" (not inspected by any human eye!) PTF light curves (all prepared by Dr. Kupfer). Students analyze data and report the best periods (if a periodic star) to the instructor. The goal is to publish in a refereed journal as a concrete outcome of Ay3.

Data Set I: RR Lyrae

RR Lyrae are pulsating stars of spectral class A. These stars have played a major role in the development of modern astronomy. The average absolute magnitude of RR Lyrae stars is 0.75 (about 40 times brighter than the Sun). What makes them interesting is that there exists a relation between the pulsation period and the absolute magnitude. Thus merely measuring the pulsation period of an RR Lyrae (when combined with the apparent magnitude) immediately informs you of the distance to the star. RR Lyraes allow us to measure the distances to Globular clusters (and thence set the scale of our Galaxy).

The periods of RR Lyrae range from 0.2 to 1 day. A collection of "time series" for a number of RR Lyrae stars (the data is from the Palomar Transient Factory or PTF) can be at RRLyrae. For each RR Lyrae there are two files, the .txt file (data) and a .jpg (pulse profile). The data files looks like

54907.843191 16.026 0.022
54907.941112 16.084 0.028
54961.730973 15.881 0.009
54961.788813 15.957 0.009
54961.839863 16.004 0.008
54961.904593 16.049 0.009
The first column is the MJD and is followed by R-band magnitude and error in magnitude. The periods of the objects can be found in periods.txt. My simple MATLAB program can be found here and the output found here.

Students: Your first major task is to read any of the txt files and fold the data at the period and plot the folded curve. Compare your folded light curve with the corresponding .jpg file. These data sets are your "training and testing" data sets as you develop period finding algorithms.