Tangra - Release Notes


Version 1.4 (31 Mar 2012)

Changes to the Light Curve Reduction

  • Added a new background method for light curve reductions - "Background Median"

  • The PSF photometry is now slipt into "Numerical Quadrature in Aperture" and "Full Analytical Quadrature". The old version of PSF fitting was the numerical in aperture. The new Full Analytical Quadrature will simply compute the full Gaussian integral rather than integrating it in aperture. The default value is still numerical quadrature in aperture.

  • Now on the LightCurves form when looking at a light curve, if the Data -> "Show PSF Fits" is seleted as a view, the amplitude of the PSF fits will be also displayed

  • Double clicking on a .lc file will not crash anymore but the file will be opened as expected

Changes to Astrometry

  • Added support for a local copy of the PPMXL star catalog

  • A crash that may happen if magnitude fit has not been selected when doing multi frame astrometry has been fixed

  • Added a few improvements and fixed a number of small issues


  • Minor improvements and bugfixes

Version 1.3 (28 May 2011)

Changes to the Light Curve Reduction

  • A few minor bugs around selection of targets have been fixed

  • Now the background annulus is displayed for the selected target in the zoomed area

Changes to Astrometry

  • Added an automatic levels adjustment to darken the background level


  • Now Tangra's functionality can be extended by implementing add-ins. Download the Software Development Kit (SDK) from Tangra's web site

  • The auto-update process now works better with User Access Control (UAC) on Windows Vista and Windows 7

Version 1.2 (29 Jan 2011)

Changes to the Light Curve Reduction

  • Added a new 'Field Rotation' flag which should prevent the measurement tracking from failing due to large field rotation in videos recorded with Alt-Az mounted telescopes

  • Now the light curves viewing form allows you to choose the normalisation method when normalising a light curve. The supported methods are: 4 point average, 16 point average, point for point and linear fit

  • An Excel file export issue with unnecessary added white spaces has been fixed

  • The message shown by Tangra when the time duration derived from the timestamps entered by the user differs from the duration computed from the video frame rate will now also includes the computed frame rate, not just the time difference

  • A couple of rare crashes caused mostly by the different rendering engines have been fixed

Changes to Astrometry

  • Now there is no need to enter the limitting magnitude for each of the videos. Tangra will compute this automatically after the initial plate solve. As a result the initial (very first plate solve) may take a little longer than before.

  • Added a maximum number of stars option. Tangra will not use more than this number of reference stars on any of the frames. This has been done to speed up the plate solving of crowded fields. The default is 100 stars which corresponds to 0.05" fit error based on 0.5" error of the individual star positions in the star catalog.

  • Added option to exclude non stellar objects such as hot pixels based on FWHM and Elongation. This should help when there is a large number of hot pixels. The option is not set by default as it slows down the image alignment. Using dark frames is however the recomended for dealing with hot pixels but may not be always possible (i.e. when you haven't taken a dark frame video at the time of the recording)

  • A number of improvements to the field alignment have been done to speed up the alignment process and reduce the number of unsolved plates. The field alignment should now work faster and better.

  • Updated the URLs for access to the MPC web services for object identification. Those services are currently being migrated by MPC to new servers and are considerably faster


  • Remembering the main form position on the screen after restart.