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Tangra a new light measurement toolHristo Pavlov4-th Trans Tasman Symposium on Occultations5 April 2010, CanberraA brief history of the projectStarted as project for AstrometrySignificant learning for me, read many papers on the topics of Photometry and AstrometryShifted the main focus from astrometry to asteroid occultation measurementsFirst line of code written in April 2009In closed beta testing since January 2010Planned release date as public beta May 2010

Why a new tool?Improved trackingEasier to reduce light curves by new users and more control for advanced usersAbility to save and send a small in size light curve file that can be used by others to do additional reductionsMore ways to do photometryAbility to correct for Flats and Darks

Learning type of articlesImage Calibration (Darks & Flats)Digital FiltersPhotometry algorithmsPhotometry standard system as filtersPhotometry - variable star methodologyAstrometrySpacecraft Star Orientation lost in space algorithmsPackages for stellar photometryCCD and Video camera documentation

Learning specific publicationsStetson. P., 1986, "DAPHOT: A computer program for crowded-field stellar photometry", http://adsabs.harvard.edu/cgi-bin/bib_query?bibcode=1987PASP...99..191S&db_key=AST

Stetson. P., 1989, "The techniques of least squares and stellar photometry with CCDs", http://nedwww.ipac.caltech.edu/level5/Stetson/Stetson4_2.html

Mighell, K., 1999, "Algorithms for CCD Stellar Photometry", http://www.adass.org/adass/proceedings/adass98/reprints/mighellkj.pdf

Fadeyev, V., 2004, "PSF Photometry Lecture", http://panisse.lbl.gov/snphot/lec8_vitaliy_PSF_fit.pdf

PrototypeApril September 2009: Built a prototype to test the photometry and astrometry algorithms that are going to be usedJune July 2009: Acquired and reported astrometry of bright asteroids and comets using the prototype to test the astrometry precision (~ 0.3)October 2009: Did tests of the photometric algorithms with real star fields. Published the results on my web site at: http://www.hristopavlov.net/Articles/VideoPhotometry.html

7Demo - AstrometryTangraDeveloped between November 2009 April 2010Used code from the prototypeRewrite of the tracking to add significant improvementsIn closed beta testing since January 2010Demo simple light curve reductionDEMO1 - 2000AJ55 (17h 56m 36s -26d55'42'').AVI 12:12:35 12:13:05

Demo windy videoDEMO2 - REC_049.AVI 9:11:08 9:12:08

Demo manually positioned apertureDEMO3 - DEMO3 - 071231_Nealley 41m25s.AVI 10:41:18 10:41:31

Demo single drift-through starDemo - .lc file without the videoDEMO5 - Dione.lc

Demo software integration

Questions ?