TRGBtool Determine the Tip of the Red Giant Branch using Maximum Likelihood Algorithm
Installation:
You have to add TRGBtool directory to the MATLAB path either by using the addpath function, or by selecting File:SetPath to edit the path.
Usage:
trgbtool runs the graphical interface trgbplot draws the result plot
TRGBtool:
The top left panel allows to load photometry files and save the results. The Galaxy edit box contains the name of the galaxy. AV and AI do not implemented. The trgbtool DOES NOT apply any correction for galactic absorption. You can load either text photometry and fake files, or previously stored trgbtool session.
Parameters panel allows regulate the start point of the minimization. TRGB - position of TRGB jump a - RGB luminosity function slope b - jump level at TRGB position c - AGB LF slope
Fix check boxes allow to fix several parameters and remove them from minimization.
Bounds edit boxes allow to define domain range.
Range [-1,+1] determines the domain range of LF in respect to the TRGB position. The stars with magnitude [TRGB-1,TRGB+1] will be included in minimization process.
Alpha is a value between 0 and 1 that specifies the confidence level as 100(1-alpha)%. Default is 0.317 which is rough corresponded to 1 sigma level.
Graphical panels consist of CMD and set of graphics: completeness, distribution of errors, luminosity function and log of LF. These graphics can be hidden or shown using buttons "C", "B", "#", "L" correspondingly.
The first approximation of TRGB position can be made by mouse click on graphic panels, CMD or LF diagrams.
CMD panel: It shows photometry with gray dots. The cyan dash lines bound the selection region. The bounds can be changed using mouse. If first approximation of TRGB position already pointed then the selected stars are shown by red dots. Magenta curved line shows running mean of distribution of stars.
LF and log LF diagrams: The blue line shows smoothed luminosity function of stars in selected region. Green line corresponds to smoothed edge detection filter of LF. The starting point and domain region are shown by red lines. Fitting result is shown by bold magenta and cyan lines. The cyan line is model and magenta one is model with applied photometric effects.
Information panel: The fitting results are shown in format = X (Left,Right), where X is the best approximation, Left and Right show the confidence interval defined by Alpha. Color of TRGB position and its error are given for tip position and for tip+0.5mag. Color is the robust estimation of running mean.
Dmitry Makarov