5 research outputs found
SSTRED: A data-processing and metadata-generating pipeline for CHROMIS and CRISP
We present a data pipeline for the newly installed SST/CHROMIS imaging
spectrometer, as well as for the older SST/CRISP spectropolarimeter. The aim is
to provide observers with a user-friendly data pipeline, that delivers
science-ready data with the metadata needed for archival. We generalized the
CRISPRED data pipeline for multiple instruments and added metadata according to
recommendations worked out as part of the SOLARNET project. We made
improvements to several steps in the pipeline, including the MOMFBD image
restoration. A part of that is a new fork of the MOMFBD program called REDUX,
with several new features that are needed in the new pipeline. The CRISPEX data
viewer has been updated to accommodate data cubes stored in this format. The
pipeline code, as well as REDUX and CRISPEX are all freely available through
git repositories or web download. We derive expressions for combining
statistics of individual frames into statistics for a set of frames. We define
a new extension to the World Coordinate System, that allow us to specify cavity
errors as distortions to the spectral coordinate.Comment: Draf
Multi-frame blind deconvolution and phase diversity with statistical inclusion of uncorrected high-order modes
Images collected with ground-based telescopes suffer blurring and distortions
from turbulence in Earth's atmosphere. Adaptive optics (AO) can only partially
compensate for these effects. Neither multi-frame blind deconvolution (MFBD)
nor speckle techniques restore AO compensated images to the correct power
spectrum and contrast. MFBD can only compensate for a finite number of
low-order aberrations, leaving a tail of uncorrected high-order modes. Speckle
restoration of AO-corrected data depends on calibrations of the AO corrections
and assumptions regarding the height distribution of atmospheric turbulence. We
seek to develop an improvement to MFBD that combines speckle's usage of
turbulence statistics to account for high-order modes with the ability of MFBD
to sense low-order modes that can be partially corrected by AO and/or include
fixed or slowly changing instrumental aberrations. We modify the image
formation model, supplementing the fitted low-order wavefront aberrations with
tails of random high-order aberrations that follow Kolmogorov statistics,
scaled to estimated or measured values of Fried's parameter, r0, that
characterize the strength of the seeing at the moment of data collection. We
refer to this as statistical diversity (SD). We test MFBD with SD with
noise-free synthetic data, simulating many different r0 and numbers of
AO-corrected modes. SD improves the contrasts and power spectra of restored
images, both in accuracy and in consistency with varying r0, without penalty in
processing time. With focus diversity (FD), the results are almost perfect. SD
also reduces errors in the fitted wavefront parameters. MFBD with SD and FD
seems robust with respect to several percents of error in r0. Adding SD to MFBD
shows great promise for improving contrasts and power spectra in restored
images. Further studies with real data are motivated.Comment: Submitted to Astronomy & Astrophysics. Abstract is abridge
GNU Data Language 1.0: a free/libre and open-source drop-in replacement for IDL/PV-WAVE
GNU Data Language (github.com/gnudatalanguage/gdl) release for the Journal of Open Source Software manuscript