By Lindsey A. Whitesides and Florin D. Ciocanu University of Northern Colorado Frontier of Science Institute OBSERVING THE MIRA VARIABLE STAR S LEO USING CCD PHOTOMETRY

PURPOSE Observe the Mira variable S Leo Obtain accurate data Create a partial light curve Find the faintest point of the period Submit results to AAVSO Contribute to scientific community

INTRODUCTION Variable star Mira variable Long period Red giants Cool (3500 K) Magnitude scale Magnitude varies 2.5 to 10

INTRODUCTION Charge-coupled device (CCD) Photoelectric effect Pattern of electrons translated into image Photometry Eliminates most error Figure 1: CCD chip.

INTRODUCTION CCD importance to astronomers Amateur astronomers Professional-Amateur collaborations AAVSO VPhot

METHODS Global Rent a Scope (GRAS) Telescopes G1 & G7 Figure 2: Global Rent a Scope website. Figures 3a & 3b: Global Rent a Scope telescopes.

METHODS Generate a plan Coordinates of the star Picture count Filter Exposure time Plate-solve Automatically upload to VPhot

METHODS Reservation Local time and date Weather forecast Position compared to moon Load plan Images taken by UNC students Process replicated with different star (TrES-3)

METHODS VPhot Load GCVS Load AAVSO comp stars Aperture and sky annulus Removing useless comp stars Check star Photometry Report

Figure 5: VPhot program.

RESULTS

Magnitude increased then decreased Faintest day about March 26 th Partial light curve constructed Average error Standard deviation

RESULTS Figure 6: A graph of magnitude vs. time for S Leo.

RESULTS Figure 7: Results plotted against data from AAVSO light curve.

DISCUSSION Very low error Accurate enough for AAVSO Partial light curve matches Some images were unusable More images should have been taken

ACKNOWLEDGEMENTS Sponsors: Dr. Richard Dietz Lori Ball Nick True Abby Davidson, Nathan Kirkley and Zabedah Saad Karen Allnut and Klois Broeker

REFERENCES Bucheim, R.K. (2007). The sky is your laboratory: Advanced astronomy projects for amateurs. Chichester, UK: Springer-Praxis Clayton, M.L. & Feast M.W. (August 11, 1969). Absolute magnitudes of Mira variables from statistical parallaxes. Monthly Notices of the Royal Astronomical Society, vol. 146, p doi: 1969MNRAS C O’Connell, Robert (September 8, 2003). Magnitude and color system. Retrieved from Richmond, M. Introduction to CCDs. Retrieved from Robertson, B.S.C. & Feast M.W. (July 16, 1980). The bolometric, infrared and visual absolute magnitudes of Mira variables. Monthly Notices of the Royal Astronomical Society, Monthly Notices, vol. 196, July 1981, p doi: 1981MNRAS R Roger A. Freedman, William J. Kaufmann III (2008). Universe: Stars and Galaxies (3 rd edition). New York, NY: W.H. Freeman and Company Templeton, M. (April 14, 2011). Variable stars and the stories they tell. Retrieved from Templeton, M. (September 13, 2010). Stellar evolution. Retrieved from