Data Reduction Schema
The LINC-NIRVANA Data Reduction Software (LN DRS) implements a data reduction and image reconstruction pipeline (see figure 1). The software provides all steps necessary to reconstruct high-resolution images from several LINC-NIRVANA raw images. The flowchart in figure 1 represents the data flow (from top to bottom).
Figure 1: The flowchart represents the data reduction and image reconstruction pipeline.
Two different elements are shown in the flowchart. The blue rectangles represent data reduction and reconstruction steps; the other rectangles represent files with specific content. The processing steps are executed in the following order:
- Calibration: compensates detector and instrument effects like flatfield and bad pixels.
- Preprocessing: compensates observation effects like image rotation.
- Target Preprocessing: extracts the target from the preprocessed data.
- PSF Preprocessing: extracts the psf from the preprocessed data and removes the background.
- Reconstruction: reconstructs an image from target and psf images.
The LN DRS uses the files with the following content:
- RAW Data: the raw interferograms of the science target from the LINC-NIRVANA instrument.
- SKY: sky images.
- Flat: the flatfield map for compensating the pixel gain.
- Bad Pix Map: a map where all defective pixels are marked as bad pixels.
- Calibrated Data: the calibrated interferograms (without instrument effects).
- Preprocessed data: the preprocessed interferograms (without observational effects).
- Target: the extracted target.
- PSF: the extracted psf.
- Ref PSF: the reference psf (23m).
- REC: the reconstruction (not convolved).
- REC Convolved: the convolved (23m psf) reconstructed object.
An astronomer gets raw data images and calibration data (sky, flatfield, and bad pixel map) from an observation and can use the graphical user interface to inspect these data and parameterize the pipeline. By executing the pipeline, controlled by these parameters, a high resolution image will be reconstructed.
The software of the LINC-NIRVANA Data Reduction System (LN DRS) uses the IDL programming language and consists of several components:
- The idlastro library (mandatory) idlastro.tar.gz (4.7MB)
- The LN DRS package itself (mandatory) lndrs.tar.gz (65KB)
- A configuration file editor written in Java (optional) lndrs.jar (54KB)
- A tutorial and reference manual (LN-MPIFR-MAN-ASW-001) is available Online, as a PDF document, and can also be downloaded (2.1MB). The example data used in the tutorial is available as tar file NGC4151.tar.gz (121MB)
- A test report (LN-MPIFR-TN-ASW-001) is available Online, as a PDF document, and can also be downloaded. The data used in the test cases and the computed results are also available as several tar files:
- Dependency on the psf star brightness: J-Band input data, K-Band input data and the results as J-Band results, K-Band results.
- Dependency on the strehl deviation: J-Band input data, K-Band input data and the results as J-Band results, K-Band results.
- Dependency on the FFTS performance: J-Band input data, K-Band input data and the results as J-Band results, K-Band results.
- Dependency on the beam overlap: J-Band input data, K-Band input data and the results as J-Band results, K-Band results.
- Dependency on the target and calibrator spectra: J-Band input data, K-Band input data and the results as J-Band results, K-Band results.
Please download at least the first two packages from the web page at http://www.mpifr-bonn.mpg.de/lndrs/index.html and store them in a proper directory (e.g. ~/lndrs).
Installing the Software
After downloading all packages into a directory (e.g. ~/lndrs), please go into this directory and follow these steps:
- Unpack the idlastro library package with the command
tar xzf idlastro.tar.gz
A subdirectory with the name idlastro is created.
- If you use the bash as your shell, then include
in your .bash_profile file. If you are using the tcsh, then include
setenv IDL_PATH "<IDL_DEFAULT>:~/lndrs/idlastro/pro"
in your .cshrc file.
If you want to use the software from within any directory, you have to add the source code directory (e.g. ~/lndrs/idl) to the environment variable IDL_PATH.
- Unpack the LN DRS package with the command
tar xzf lndrs.tar.gz
A subdirectory with the name idl is created.
- If you downloaded the example file, unpack it with the command
tar xzf NGC4151.tar.gz
A subdirectory NGC4151 is created with all input files of a data reduction example.