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.
- Please bring your computers to the class (starting week 3)
- Please have UNIX/LINUX or appropriate Windows/UNIX interface loaded up.
- Please have Python loaded up
- Introduction to the Course [4 Jan, 2016]
- The Zwicky Transient Facility (ZTF) [7 Jan, 2016]
Talk by R. Smith & lab tour
- The Gaia Mission [8 Jan, 2016]
Talk by Dr. N. Blagorodnova
- Time & Calendar [11 Jan 2016]
Solar day, Cesium clock second, Gregorian calendar, Julian Day Number
- Astronomical Coordinates (RA, DEC) [14 Jan 2016]
Altitude, Azimuth, Right Ascension, Declination
- Local Sidereal Time & Offsets [15 Jan 2016]
Sidereal time, LST at midnight, Computing angular offsets
(spherical trig; arcseconds)
- Photometry & Magnitude [21 Jan 2016]
Poisson noise, Background, Aperture Photometry
Magnitude, Zero point (AB, Vega), Error on Magnitude
- 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
perhaps the most complex Unix command
- Introduction to Python [22 Jan 2016]
Nadia's Python presentation
|  Supernova lightcurve data file
- Data Set I: RR Lyrae from PTF
[25 Jan 2019]
Goal: read ASCII files and fold time series to given period.
- Fourier Transforms [28 Jan 2016]
Introduction to Fourier Transform
FFT demonstration (Matlab/SRK) .
- Using FFTs [29 Jan 2016]
Demonstrate FFT usage with python code.
Understanding Fourier Transforms [1 Feb 2016]
Pulsar Data Base
Application to Pulsar Discovery [4 Feb 2016]
Notes on FFT
analysis of pulsar data analysis (Matlab).
Find best period & fold [5 Feb 2016]
Note on Folding
- The PTF Galactic Marshal [11 Feb 2016, Dr. Adam Miller]
Introduction to Periodogram. Showcasing of various periodic
- The Kepler Mission [12 Feb 2016, Jessie Christensen]
Analysis of a delta-scuti star (Kepler data)
Introduction to variable stars [18 Feb 2016]
Variable Star Naming Convention
Presentation by students (RR Lyrae Project) [19 Feb 2016]
Rules for Giving Talk
- PTF data: An introduction to periodic stars [22 Feb
Dr. Thomas Kupfer
- Periodogram: introduction and application to PTF data
[25 Feb 2016]
Dr. Thomas Kupfer
- Searching for pulsators & planets with Kepler [26 Feb
Dr. Jessie Christensen (Kepler Scientist)
[29 Feb 2016]
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
test case: data file 12. Explore P=0.001 to P=0.6 step with
step size 1E-5 days. Answer:
Report from Class [4 March 2016]
Class to report on discoveries made from PTF light curves
given on the previous day.
Recently astronomers repeated seeing repeating bursts (Arecibo
Repeater FRB). The Dispersion Measure (an integral of the
interstellar/intergalactic electrons) can be found
Review the "chi-squared" framework. Using
the chi-squared test the hypothesis that the Dispersion
Measure is the same for all ten bursts.
- 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
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
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
These data sets are your "training and testing" data sets as you
develop period finding algorithms.