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Photometry Transformation Generation Program -- (Version 5.0)

The Photometry Transformation Generation Program (PTGP) was conceived and written by AAVSO member/observer Gordon Myers in response to a need for an easy-to-use program which will aid the observer in the computation of their transformation coefficients. The AAVSO acknowledges and greatly appreciates Gordon's 100% volunteer effort.

Purpose

PTGP generates telescope transformation coefficients used in stellar photometry. The program makes the process much easier for users – no longer requiring the extensive use of spreadsheets. The new version 5.0 processes instrument magnitude measurements of standard star reference fields – currently M67 and NGC7790.  Instrument magnitude measurements files can be generated using AIP4WIN or MaxIm, or can be downloaded from VPHOT.  The program accesses the AAVSO VSP data base in real time to obtain the necessary standard magnitudes (requiring an Internet connection) and calculates all standard transformation coefficients.  Users may then plot the results, remove discrepant observations, finalize and save a set of transformations.  The program also enables the user to compare different sets of transformations (typically taken at different times and/or days), average them and then export a final transformation set for use.

Major Updates in Version 5.0

Major changes since Version 4.0 include –

  • Calculation of transform one sigma error estimates
  • Calculation of transform “r-squared” measure
  • Use of AUID or “Boulder” star ids
  • VSP standard star magnitudes retrieved from the AAVSO web site (requiring an active Internet connection)
  • VPHOT download file interface
  • MaxIm instrument file interface
  • Change of transform names to use AAVSO standard (previously saved 4.0 transform sets are lost)
  • Added V-I transforms (Tvi, Tv_vi, Ti_vi, Tr_vi)
  • Instrumental magnitudes are averaged if multiple values provided
  • Changed format of final transform export file to match .ini format used by AAVSO tool TransformApplier

Requirements

PTGP was developed in Python enabling it to run in Windows, Mac, Ubuntu and Linux environments. It uses Python 2.7 along with additional libraries. Following the procedures below will ensure you have all of the necessary software to run the program. Operation requires an Internet connection.

Initial File Download for All Installations

First download this zip file (PTGP_V5.0_install_files.zip) which contains two files used in all the installations.  The two files are –

  • PTGP_V5.0.pyw – the program file
  • M67_T17_20140330_Photometry_Demo_instrument_mags.txt - a demonstration instrument magnitude measurement file

Windows Installation Procedure

Updating an existing PTGP V4.0 installation:  If you previously installed PTGP V. 4.0, installation only requires you copy the PTGP_V5.0.pyw file to the Photometry directory.  To create a new desktop icon to start the program, navigate to the PTGP_V5.0.pyw file using Windows Explorer.  Right click on the file name, and select “Send to” à Desktop (create shortcut).

Installing into Existing Python Installations: There are many different Python 2.7 installation alternatives – not fully compatible with each other. If you have one installed, try to run PTGP in that environment.  If it does not run successfully, the best approach is probably to do a clean installation using the “Anaconda” environment below.

New Installation: PTGP runs with the standard Python 2.7 suite known as Anaconda which contains the various libraries needed to complement the basic Python 2.7 package.

If you are on a 64-bit Windows machine, download http://repo.continuum.io/archive/Anaconda-2.0.1-Windows-x86_64.exe  and run the program, accepting all defaults – except be sure you install it for “All Users” – not “Just Me”.  This will install Anaconda into the folder c:/Anaconda.

If you don’t have a 64-bit computer, visit https://store.continuum.io/cshop/anaconda/ to locate a compatible installation file.  Stick with Anaconda version 2.0.1.  Experience unfortunately has shown that new releases sometimes have errors that might prevent PTGP from running properly.

After successful installation of Anaconda, navigate to c:/Anaconda using Windows Explorer and create a new subdirectory “Photometry” – e.g. c:/Anaconda/Photometry.  Copy the program PTGP_V5.0.pyw and a demonstration file M67_T17_20140330_Photometry_Demo_instrument_mags.txt into the Photometry directory.  Then create a desktop icon to start the program by navigating to the PTGP_V5.0.pyw file in c:/Anaconda/Photometry; then right click on the file name, and select “Send to” > Desktop (create shortcut).

Double click the icon to start the program. For operational details see the PTGP V5.0 Users Guide.

Mac Installation Procedure

Updating an existing PTGP V4.0 installationIf you previously installed PTGP V. 4.0, installation only requires you copy the PTGP_V5.0.pyw file to the Photometry folder.  Creating a new desktop icon for the Mac takes some extra work.  Refer to the paper Create Mac Icon to Start PTGP Program.pdf.  Note the first time you use the new icon, it can take over 15 seconds to launch the program.  Subsequently the program will open rapidly.

Installing into Existing Python Installations: There are many different Python 2.7 installation alternatives – not fully compatible with each other. If you have one installed, try to run PTGP in that environment.  If it does not run successfully, the best approach is probably to do a clean installation using the Anaconda environment below.

New Installation: On a Mac, Anaconda version 1.9.1 must be used. PTGP will not run with the newer version 2.0.1 on a Mac.

If you have a 64-bit Mac, download Anaconda v. 1.9.1 from  http://repo.continuum.io/archive/Anaconda-1.9.1-MacOSX-x86_64.pkg and install it by selecting the downloaded package. This installation creates a new top-level folder “/anaconda” containing all the Python software required to run PTGP.  Do the following to ensure Anaconda is installed properly -

During install this window appears:

Select “Install on a specific disk…” -

Select Macintosh HD -

Select “Continue” to proceed.  The anaconda folder will be placed on the Macintosh HD drive as a top level folder.

The installation process will continue to completion.

This installation package supports OS X  on a 64 bit Mac.  If you have a different Mac computer, visit https://store.continuum.io/cshop/anaconda/   to locate other available downloads. Be certain to download version 1.9.1.


After successful installation of Anaconda, navigate to  /Anaconda using Finder and create a new folder “Photometry” – e.g. /Anaconda/Photometry.  Copy the program PTGP_V5.0.pyw and a demonstration file M67_T17_20140330_Photometry_Demo_instrument_mags.txt into the Photometry folder.

Creating a new desktop icon for the Mac takes some extra work.  Refer to the paper ‘Create Mac Icon to Start PTGP Program.pdf’. Double click the icon to start the program. Note the first time you use the new icon, it can take over 15 seconds to launch the program.  Subsequently the program will open rapidly.

For operational details see the PTGP V5.0 Users Guide.

User's Guide

The User's Guide is available here:

PhotometryTransformationGenerationProgramUsersGuide_V5.0.pdf


Send questions and comments to Gordon Myers - gordonmyers @ hotmail.com

Copyright © 2014.

AAVSO 49 Bay State Rd. Cambridge, MA 02138 aavso@aavso.org 617-354-0484