2013-07-31

Photon Rain

I am pleased to announce the availability of next release of Munipack. This release is 0.5.4 and named Photon Rain because I developed the implementation of the photometric calibration which satisfy my wet dreams for the first time.

The developed implementation along with the new matching algorithm are superseding importantly of Classical release.

The implemented features are two extremely difficult tasks:
  • transformation between photometric systems
  • full photometric calibration
Even more, the fundamental quantity used for calibration are photons (magnitudes has been omitted). The photon approach enable us use of amazing properties of both Poisson's and robust statistics.

The calibration implements all single-filter calibration against to a catalogue and the multi-filter simultaneous calibration with the photometric system transformation matrix. Also the photometric system transformation can be easy determined from observations. Magnitudes are implemented just for compatibility.


Photometry enhancements

Developed a new approach to photometry reductions on base of observed counts and expected photons. Using of basic of Poisson's statistics and added statistical robustness.

Implemented calibrations of single-filter observations along with multi-filter case. The photometry system transformation is developed.

For Details, see Photometry Overview.


Astrometry enhancements

Astrometry is also important part of enhancements.
  • Removed superfluous loops (speed-up about 100x), matching has additional criterion for similarity of observed counts and expected photons (improve robustness in crowded fields where stars can be easy interchanged, also reduces back-tracking tree and therefore importantly improve the algorithm speed).   The computing of   angle between stars in normal space is included as an independent quality test. The star sequences are closed paths now to reduce length of sequences and improve robustness.
  • UCAC4 is now default astrometry catalogue.
  • Proper motion is introduced.
  • Just stars with valid aperture photometry are used for matching (all detected sources had been used and the approach may produce a lot of garbage for improperly corrected images).

Other enhancements

The release includes also these enhancements:
  • Developed a new approach for frame photometry pre-corrections (bias, dark, flat). Renamed (and redesigned) modules for the corrections. A single command  for the corrections (replacing darkbat and flatbat) has been introduced.  It is implemented possibility of masking of a part of image.
  • Basic FITS header modifications are implemented including to update of header's  keywords. A FITS file can be dumped to a text file and restored again (useful to create of tables).
  • Internal FITS tables has different column naming schema to be more compatible with Virtual Observatory conventions. Also some command-line options has been modified for that reasons.
  • For known data sources, the long options (--col-ra, --col-mag ..) has default values and ones can be provided optionally.
  • Structure of both FITS tables and extensions has been changed drastically  and any older preprocessed data are no more compatible (!) with files produced by this version.
  • Building system - Building scripts (in dist/) has been improved to separate the installation to independent bundles (packages) and as the system-wide   one. There is also possibility to install Munipack without wxWidgets.
  • Developed light-curve (or any quantity) time series FITS-flavor format as a simpler version of SimpleTimeseries.
  • GUI updated to match modern desktop conventions (for GNOME 3/ Gtk 3+).
  • Huge expansion of documentation.


Corrected problems:
  • using of shell-environment variable containing substring DATE-OBS
  • A negative declination is recognised as a number (not as a command-line   confusing switch).


Known Issues:
  • GUI has only minor improvements (=practically none).
  • None from New features has no support in GUI (except new photometric quantities box in side panel of View).
  • There are problems with non-English locales. Numbers with commas (replacing dots) are still recognised unsatisfactory (the behaviour is perhaps random and very difficult for testing by myself).



Warning (!)

Many, really many, changes has been prepared against to previous releases. Please, check carefully every self-evident presumption about usage, command-line parameters or data formats.
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