The Microlensing Experiment

The purpose of the experiment:

Learning the basics of gravitational lensing
Practicing linear and non linear chi2 fitting and comparing the results with simulations
Practicing and understanding statistical techniques

Reading Assignments and Instructions

Please read carefully the followings:
  • Statistics, R. Barlow, Chapter 4 & 6.
  • Numerical Recipes in C, Press et al., Chapter 15.6
  • Lectures on Gravitational Lensing (all up to section 2.3.3) - (The same source with figures).
  • Basic article about gravitational lensing in the Astropedia


    Data from OGLE


    First week - read ALL the reading material indicated above, and talk with your instructor.
    On the first day of the experiment, call the instructor (sometime between 12:00-17:00) and ask for additional details or any changes! Set a date for the preliminary test.
    Second/third week - The test will usually take place in Kaplun 501, morning/noon on the first day of the second week.
    Fourth week - writing the report. The report should be submitted within 29 days from the formal beginning of the experiment. Under exceptional circumstances, the instructor may extend this time limit.
    A report that will be submitted by up to one week after this date, will lose 10 points.
    A report that will be submitted later than one week from this date, will get 0.


    The final grade is based on the report, exam, and instructor evluation.

    The Report

    General lab instructions
    - Short description of your work + main results.
    - Why ML is important in the context of your work.
    - The OGLE experiment - objective, experiment settings, frequency of measurements, etc. refer to bibliography where needed.
    - The specific event(s) you chose to analyze

    Should NOT include the history of ML since Einstein!
    Should include:
    - short explanation of the main formulas you use, notions, units. refer to bibliography where needed.

    - Explanation of the algorithm you used to fit the data (short!)
    - Error analysis
    - Statistics

    - The extracted parameters + errors
    - Chi^2 per DOF
    - Plots, figures, graphs, fits...

    - Goodness of fit
    - Comparison to results of other research groups (OGLE)
    - Scientific discussion



    The paper part should include ONLY THE FINAL STAGE of your analysis, i.e., extracting the full set of parameters. It should span up to 10 pages. All the other stages, which are executed for educational purposes, should appear in your logbook.
    if you use use ANYTHING from some other source, please make sure that you provide the propper reference.
    When writing the report please take into consideration the following criteria:
    1. All plots should contains labels and errors.
    2. Error analysis should be properly explained.
    3. Very Large tables should appear in an appendix.
    4. Add the logbook of the experiment in an appendix.
    5. Give the chi^2/dof of each fit.
    6. Read the report before submission and correct, as you can, for grammer and spelling mistakes.


    please download the tadrich from here.
    some relevant Matlab tips can be found here.

    Yakov Faerman
    Instructor of the Microlensing experiment

    Room: Kaplun 501
    Phone: 972-3-6409158