Photometry Transforms Generation with ptgp (Abstract)

Volume 43 number 1 (2015)

Gordon Myers

5 Inverness Way, Hillsborough, CA 94010; GordonMyers@hotmail.com

Ken Menzies

318A Potter Road, Framingham, MA 01701; kenmenstar@gmail.com

George Silvis

194 Clipper Road, Bourne, MA 02532; gasilvis@gmail.com

Barbara Harris

1600 South State Road 415, New Smyrna Beach, FL 32168; barbharris1@hughes.net

Abstract

(Abstract only) Historically the development of photometry transformation coefficients required extensive manual effort and the use of large spreadsheets. A new release—version 5.0—of the Photometry Transformations Generation Program (ptgp) achieves the goal of generating transformation coefficients without the use of spreadsheets—saving considerable time and ensuring data accuracy. ptgp version 5.0 works directly with the AAVSO Variable Star Plotter (VSP) to retrieve the most recent standard star reference magnitudes (currently for M67 and NGC 7790). It then processes instrument magnitude file(s) downloaded from vphot or exported from aip4win or maxim. Either AUID or “Boulder” star identifications can be used for aip4win and maxim. When using vphot data or “Boulder” star identifications, ptgp determines the AUID names for each of the reference standard stars. All standard transforms are calculated. Plots of each transform’s data can be reviewed, and individual star observations added/deleted. Transform sets can be saved for further use. Transform sets can be compared and selected sets averaged. The averaged sets can be exported in a file format compatible with the AAVSO ta tool. The presentation will provide a brief overview and demonstration of the tool. It will also discuss the implications of using python for the development—both benefits and potential problems. The program runs on both PCs and Macs. A subsequent presentation will discuss the use of vphot and ptgp to generate transforms and the testing of the impacts of varying key vphot and ptgp parameters.