Transforms: Everything you need to transform your CCD observations

This page serves as a central location for the tools AAVSO voulnteers have developed and promulgated to help fellow photometrists transform their observations, making them compatible and more useful to the professional astronomy community.

These include:

  • Standard Field Charts - Use these special charts of "Standard Fields" to start the process. Standard fields are star fields for which the magnitudes of selected stars are known very precisely in several colors. For your convenience, the AAVSO has prepared standard sequences for a number of star clusters, which were selected on the basis of several factors including their range of colors and quantity of stars that will conveniently fit into one CCD image.
  • Transform Generator (TG) - A tool to compute the transform coefficients. Details of this program can be viewed at: TG is a Python application that will run in Windows, Mac, Ubuntu and Linux environments. Author: Gordon Myers.
  • TransformApplier (TA) - This tool will take your coefficients and observations and output transformed data. To learn more about this useful tool and download it to your computer please visit If you subscribe to this page, you will be notified of any changes or updates to the code. TA is a Windows application. Documentation is included in its help screen. Author: George Silvis.
  • Boxter & AAVSO Report Utilities - Tools for aggregating your observations (including timeseries). These programs can be downloaded together in a zipped file. For Windows users only. Author: Richard Sabo.