Astro 3310Fall 2015

LAB #10:

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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 thefile 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 youkeep 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 sub-directory.

YOUR NAME: ______YourNetID: ______

The purpose of this lab is to analyze photometry data taken at the Hartung-Boothroyd Observatory of an exoplanet transit.

The HartungBoothroyd 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

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