E-Print Archive

There are 3882 abstracts currently viewable.


Advanced Search
Main Page Add New E-Print Submitter
News Help/FAQ About Preferences
Manage Key Phrase
Influence of misalignments on the performance of externally occulted solar coronagraphs. Application to PROBA-3/ASPIICS View all abstracts by submitter

Sergei Shestov   Submitted: 2018-01-23 00:54

Context: The ASPIICS instrument is a novel externally occulted coronagraph that will be launched on board the PROBA-3 mission of the European Space Agency. The external occulter will be placed on one satellite ∼ 150 m ahead of the second satellite that will carry an optical instrument. During 6 hours out of 19.38 hours of orbit, the satellites will fly in a precise (accuracy around a few millimeters) formation, constituting a giant externally occulted coronagraph. The large distance between the external occulter and the primary objective will allow observations of the white-light solar corona starting from extremely low heights ∼ 1.1R . Aims: We intend to analyze influence of shifts of the satellites and misalignments of optical elements on the ASPIICS performance in terms of diffracted light. Based on the quantitative influence of misalignments on diffracted light, we provide a recipe for choosing the size of the internal occulter (IO) to achieve a trade-off between the minimal height of observations and sustainability to possible misalignments. Methods: We considered different types of misalignments and analyzed their influence from optical and computational points of view. We implemented a numerical model of the diffracted light and its propagation through the optical system and computed intensities of diffracted light throughout the instrument. Our numerical approach is based on the axisymmetrical Fourier-based model of the coronagraph, published recently. Here we extend the model to include nonsymmetrical cases and possible misalignments. Results: The numerical computations fully confirm the main properties of the diffracted light that we obtained from semi-analytical consideration. We obtain that relative influences of various misalignments are significantly different. We show that the internal occulter with RIO = 1.694 mm = 1.1R is large enough to compensate possible misalignments expected to occur in PROBA-3/ASPIICS. Besides that we show that apodizing the edge of the internal occulter leads to additional suppression of the diffracted light. Conclusions: We conclude that the most important misalignment is the tilt of the telescope with respect to the line connecting the center of the external occulter and the entrance aperture. Special care should be taken to co-align the external occulter and the coronagraph, which means co-aligning the diffraction fringe from the external occulter and the internal occulter. We suggest that the best orientation strategy is to point the coronagraph to the center of the external occulter.

Authors: S. V. Shestov, A. N. Zhukov
Projects: None

Publication Status: In print
Last Modified: 2018-01-23 11:51
Go to main E-Print page  Fine Structures of Solar Radio Type III Bursts and their Possible Relationship with Coronal Density Turbulence  Observations of Electron-driven Evaporation during a Flare Precursor  Edit Entry  Download Preprint  Delete Entry 

Go to main E-Print pageGo to main E-Print page.
Previous AbstractPrevious Abstract.
Next AbstractNext Abstract.
Download PreprintDownload Preprint.
Submitter's HomepageSubmitters Homepage.
Edit EntryEdit Entry.
View All Abstracts By SubmitterView all abstracts by submitter.
Delete AbstractDelete abstract.

Latest Entries
The origin of the modulation of the radio emission from the solar corona by a fast magnetoacoustic wave
Indirect solar wind measurements using archival cometary tail observations
Helium abundance and speed difference between helium ions and protons in the solar wind from coronal holes, active regions, and quiet Sun
Always a Farm Boy
Effect of transport coefficients on excitation of flare-induced standing slow-mode waves in coronal loops
Study of Three-dimensional Magnetic Structure and the Successive Eruptive Nature of Active Region 12371
Statistical study of magnetic non-potential measures in confined and eruptive flares
Quasi-periodic Counter-propagating Fast Magnetosonic Wave Trains from Neighboring Flares: SDO/AIA Observations and 3D MHD Modeling
Negative flare in the He I 10830 Å line in facula
Time resolved spectroscopic observations of an M-dwarf flare star EV Lac during a flare
Two Episodes of Magnetic Reconnections During a Confined Circular-ribbon Flare
Enhanced stellar activity for slow antisolar differential rotation?
Quasi-periodic pulsations in the most powerful solar flare of Cycle 24
GONG Catalog of Solar Filament Oscillations Near Solar Maximum
Chromospheric response during the precursor and the main phase of a B6.4 flare on August 20, 2005
Unambiguous Evidence of Coronal Implosions During Solar Eruptions and Flares
Two Types of Long-duration Quasi-static Evolution of Solar Filaments
Oscillations of cometary tails: a vortex shedding phenomenon?
Observations of Running Penumbral Waves Emerging in a Sunspot
Reconnection in the Post-Impulsive Phase of Solar Flares

Related Pages
MSU Solar Physics.
Max Millennium Science Mail Archive.
Max Millennium Message of the Day Mail Archive.
Max Millennium Flare Catalog

Archive Maintainer
Alisdair Davey

© 2003 Solar Physics Group - Montana State University