The Munich Difference Imaging Analysis (MDia) package is a tool for photometry in (very) crowded fields. The software is written in C++ and part of the ``mupipe'' package, which has been developed at the University Observatory in Munich for the use in a pixel-lensing project. The underlying algorithm has been proposed by Alard and Lupton in 1998 (http://arxiv.org/abs/astro-ph/9712287ApJ...503..325A) and later improved by Alard in 2000 (http://www.edpsciences.org/articles/aas/pdf/2000/11/ds8706.pdf?access=okA&AS..144..363A).
Creating light curves with MDia is a two step process. The first step is the creation of a ReferenceFrame using the best seeing images. In the second step, this ReferenceFrame is used to create difference images of all RegriddedFrames one wants to analyze. Using the difference images, precise photometry is obtained via PSF-fitting. In this way, light curves are created and stored in the database for further analysis.
The MDia code can be found in:
opipe/Experimental/MDIA/MDia.tar.gz
Extract this archive to whatever directory you like. After that follow the instructions given in the README file. Up to now, the code is tested for 32-bit machines only. The MDia code needs the library ``ltl'' which is usually installed during the awetomatic process.
The ReferenceFrame is created using the images (typically 10) with the
best seeing. These can be selected by using the psf_radius property of
any ReducedScienceFrame or RegriddedFrame. Try to reject images
with high background in order to get an optimized S/N
In order to get good results the astrometry of all images you want to combine
must be as good as possible. Therefore use global astrometry on the best seeing
images and regrid again if needed. Having prepared the final list of
RegriddedFrames you can create a ReferenceFrame in three different
ways:
where best_frames is a list of filenames of the RegriddedFrames
you want to combine.
After having created a ReferenceFrame, one can use it together with a
number of RegriddedFrames and create light curves of multiple sources
simultaneously. The database object of use is an instance of class MDia
which takes as input the ReferenceFrame, a list of RegriddedFrames,
optionally some SourceLists and a set of process parameters
(MDiaParameters). The output consists of N
Again, the astrometric accuracy is crucial in this step. The recommended
procedure is the following:
To create lightcurves in AWE use one of the following ways:
where reference_frame is a list with one item, namely the filename of
the ReferenceFrame and frames is a list of filenames of the
RegriddedFrames you want to analyze.
A manual with detailed description of all process parameters as well as the
underlying software will be avialable soon on the
http://www.astro-wise.orgAstro-WISE web pages.
awe> dpu.run( 'Reference', i='WFI',
... reg_filenames=['Sci-USER-WFI-#844-Reg-54653.3.fits',...], C=1 )
awe> from astro.recipes.Reference import *
awe> task = ReferenceTask( reg_filenames=['Sci-USER-WFI-#844-Reg-54653.34244.fits',...],
... commit=0)
awe> task.execute()
awe> from astro.main.ReferenceFrame import *
awe> ref = ReferenceFrame()
awe> ref.OBJECT = 'OTSF-1c'
awe> ref.regridded_frames = best_frames
awe> ref.make()
awe> ref.store()
awe> ref.commit()
1.1.5 Creating Lightcurves
awe> dpu.run( 'MDia', i='WFI', ref_filename=['Sci-USER-WFI-#844-Ref-54653.3.fits'],
... reg_filenames=['Sci-USER-WFI-#844-Reg-54653.3.fits',...], C=1 )
awe> from astro.recipes.MDia import *
awe> task = MDiaTask( ref_filename=['Sci-USER-WFI-#844-Ref-54653.3.fits'],
... reg_filenames=['Sci-USER-WFI-#844-Reg-54653.34244.fits',...],
... commit=0)
awe> task.execute()
awe> from astro.main.LightCurve import *
awe> my_lightcurves = LightCurve()
awe> my_lightcurves.reference_frame = reference_frame
awe> my_lightcurves.regridded_frames = frames
awe> my_lightcurves.make()
awe> my_lightcurves.store()
awe> my_lightcurves.commit()
1.1.6 Documentation