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Transform Generator (TG) -- (Version 6.0)

The Transform Generator (TG) 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.

(Transform Generator was originally known as the Photometry Transformation Generation Program (PTGP).  The name was changed to Transform Generator (TG) with the release of version 5.5)

Purpose

TG 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 program processes instrument magnitude measurements of standard star reference fields – currently M67, NGC7790, NGC1252, NGC3532 and M11.  Instrumental 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. The export file can be directly imported into the AAVSO Transform Applier tool.

Release History

Version 6.0 – Maintenance and New Capabilities

  • Added support for NGC 1252 and NGC 3532
  • Error fixes
    • Correction to properly handle multiple VPHOT files containing both “True” and “False” measurements of the same star (usually caused when stars are saturated in some images and not others).
    • Correction causing some bright standard stars (brighter than 10th magnitude) to be excluded from calculations

Version 5.10 – Maintenance and New Capabilities

  • Added Support for M11 standards field
  • Changed 3 sigma error lines on plots (which had been based on the Transform slope error) to 2 sigma error lines (based on the “y axis” variance between measurements and the linear transform fit.)  This gives the lines more physical meaning – in theory 95% of all measurements will be within this 2 sigma error band.
  • Error fixes
    • corrected calculation of the error associated with color transforms
    • “Original Fit 3 sigma” line on plots changed to “All Measurements 2 sigma” line. Users see the 2 sigma error line calculated using all measurements (e.g. both active and inactive).  (In addition the error lines calculated using only the currently active measurements are displayed).

Version 5.8 – Maintenance Release (Required Update)

  • TG internal software changed to support new VSP API.  This is a mandatory update.  Previous TG versions will not run when the new VSP is released (within a few weeks of mid-August, 2015).

Version 5.7 – Maintenance Release and Mac OS X (v.10.10) Yosemite Support

  • Fix problem with deletion of saved transform
  • Support Mac OS X (v.10.10) Yosemite release

Version 5.6 – Maintenance Release

  • Star add/delete label on plots corrected
  • Error randomly causing one observation not to be included in transform corrected
  • Description in header of .ini export file enhanced

Version 5.5 – New Capabilities Release

  • Addition of 3 sigma error lines on transform plot
  • Addition of scrollbars to main menus

Operating Requirements

TG requires the use of Python 2.7 along with several additional libraries. It runs on Windows, Apple, and LINUX computers. The simplest installation uses an integrated set of Python software libraries known as Anaconda (https://store.continuum.io/cshop/anaconda/). Following the procedures below will ensure all of the necessary software is installed on your computer.

Operation requires an Internet connection.

Installation Instructions

File Download Required for All Installations

First download this zip file (TG_V6.0_installation_files.zip) which contains two files used in all the installations.  The two files are –

  • TG_V6.0.pyw – the program file
  • M67_T17_20140330_Photometry_Demo_instrument_mags.txt - a demonstration instrument magnitude measurement file

Windows Installation Instructions

Updating an existing PTGP V4.0 or TG V5.x installation:  If you previously installed PTGP or TG, installation only requires you copy the TG_V6.0.pyw file to the Photometry directory.  To create a new desktop icon to start the program, navigate to the TG_V6.0.pyw file using Windows Explorer.  Right click on the file name, and select “Send to” > "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 TG 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 Installations: TG 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 the Python 2.7 version -  https://repo.continuum.io/archive/Anaconda2-2.5.0-Windows-x86_64.exe  Run the installation, accepting defaults, EXCEPT (1) change the install directory to c:/Anaconda and (2) be sure you install 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://www.continuum.io/downloads to locate a compatible installation file.  Stick with Anaconda version 2.5.0.  Experience unfortunately has shown that new releases sometimes have errors that might prevent TG 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 TG_V6.0.pyw and the 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 TG_V6.0.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. If Windows requests you identify what program to use to execute TG_V6.0.pyw, navigate and select c:/anaconda/pythonw.exe.

For operational details see the TransformGenerator_V6.0_Users Guide.

Mac Installation Instructions

Updating an existing PTGP V4.0, TG V5.x installation:  If you previously installed PTGP or TG, installation only requires you copy the TG_V6.0.pyw file to the Photometry folder.  Then create a new desktop icon for the Mac.  Refer to the paper Create Mac Icon to Start TransformGenerator V6.0.pdf.  NOTE: this create icon document refers to TG_V5.10.pyw.  Change this to TG_V6.0.pyw.

Also, note it can take over 15 seconds to launch the program.   Please be patient.

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 TG 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:   TG 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 Max OSX machine, download the Python 2.7 version -
https://repo.continuum.io/archive/Anaconda2-2.5.0-MacOSX-x86_64.pkg

During the installation this window appears:

Select “Install on a specific disk…” and this window appears:

Select "Macintosh HD" then "Continue".

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 2.5.0 of Anaconda for Python version 2.7.  Previous Anaconda versions contain errors preventing TG from running properly.

After successful installation of Anaconda, navigate to  /Anaconda using Finder and create a new folder “Photometry” – e.g. /Anaconda/Photometry.  Copy the program TG_V6.0.pyw and the 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 TransformGenerator_V6.0.pdf. Double click the icon to start the program. Note it can take over 15 seconds to launch the program. 

For operational details see the TransformGenerator V6.0 Users Guide.
 

User's Guide

The User's Guide is available here:  TransformGenerator V6.0 Users Guide


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