Astro 3310 Fall 2015
LAB #10:
-----Please copy this document to the REPORT sub-directory from the
expanded LAB10_Data_Package_FA15.tar.gz. Then, edit it to write
your answers in all the "______" areas. When finished, create a
tar.gz archive of the REPORT directory and all of its contents, then
scp the file to datafarm.astro.cornell.edu and place it in:
/data/Courses/A3310/FA15/”your netid”/LAB10/
Remember that you will only get credit for the files that you put in
the REPORT sub-directory and copy to datafarm. Please make sure
that you keep a Matlab workbook with all of the commands you used to
answer the questions in the lab. Feel free to comment and organize
your workbook so that it will be easy for us to follow your
algorithms when we execute the code. If you generate any functions
for the lab, ensure that they are also in the REPORT sub-directory
and properly called from the workbook file. For you convenience,
there is a template for the workbook file already in the REPORT subdirectory.
YOUR NAME: _______________________________
Your NetID: __________
The purpose of this lab is to analyze photometry data taken at the
Hartung-Boothroyd Observatory of an exoplanet transit.
The Hartung Boothroyd Observatory houses a 25” telescope that is
used for development and testing of astronomical instruments and in
the Astro 4410 Experimental Astronomy observational course. It is
equipped with a very high quality Andor CCD camera with high quantum
efficiency, low read noise and negligible dark current.
In the DATA directory are a series of FITS files of an observation
of the exoplanet WASP-10b observed on 9/17/2015 over the course of
about 3 hours. The observing conditions were excellent, and the
signal of an exoplanet transit is readily observable in the data.
In order to extract the transit, you need to identify (see the
images and finder chart) and extract the total flux from the star
with a transiting planet. Since there are systematic effects
(variation in the transmission of the atmosphere) that affect the
quality of the photometry, which can be taken out by measuring the
photometry of some or all of the other stars in the images. Aside
from the star with a transiting planet, the other stars are
essentially constant in brightness, so can be used to calibrate
atmospheric transmission and any other systematic effects.
In the data package are the observations of the transit in files
labeled wasp10b_30s_R-xxx.fit; bias calibration frames and flatfield
frames taken of a uniform source on the dome. Flatfield frames
calibrate the transmission of the optics and detector, especially
issues like dust on the optics or CCD. Flatfielding is critical as
the imperfect tracking of the telescope causes the images of the
star to move across different pixels in the detector.
The challenge in this lab is to produce the most accurate possible
light curve by identifying and correcting for the systematic effects
by calibrations of reference stars. The raw transit depth of 4% is
just detectable with simple analysis, but is dominated by systematic
errors. Observations with comparable telescopes have been used to
produce transit light curves with accuracy approaching 0.1% with
care in the analysis.
Background:
Winn, Transits and Occultations
http://arxiv.org/abs/1001.2010
Mandel and Agol Light Curve Tools
http://www.astro.washington.edu/users/agol/transit.html
Finder chart in BACKGROUND directory.
Potentially useful, but not essential: MATLAB astronomy package,
especially aperture photometry routine aperphot.m
http://webhome.weizmann.ac.il/home/eofek/matlab/