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Addis Ababa University

1. Asmamaw, Chanie. STUDY OF SECOND AND THIRD ORDER IONOSPHERIC EFFECT ON GLOBAL POSITIONING SYSTEM (GPS) SIGNALS ALONG THE EQUATORIAL REGIONS .

Degree: 2013, Addis Ababa University

Ionosphere is the major source of error for geodetic applications despite the fact that it’s possible to remove most of the effect using its dispersive nature. However, it’s only the first order of the ionospheric effect that can be removed using dual frequencies signal observations. The second and third order ionosphere effect cannot be removed though we can model their effects on geodetic applications such as their effects on Global Positioning System (GPS) signals. The study mainly focuses on the assessment of higher order (second and third) ionosphere effects on GPS for accurate positioning along the equatorial regions. Some stations at higher latitudes were also included in our GPS data processing for comparison purposes. GAMIT/GLOBK software was used to process the GPS data including a suite of other ancillary information. The time series of the residuals from the final GAMIT/GLOBK result were compared with the geomagnetic field effects and solar cycle (sunspot activities). High ionopheric effects on the GPS signals from stations along the equator were observed relative to stations at higher latitudes due to the fact that total electron content density is high along the equator. In addition to this, the contribution of Equatorial Electrojet (EEJ) to ionospheric disturbances is higher along the equator. Higher total electron content was also observed for the stations from the equatorial region in particular on years 2002 and 2012 as these are the years where solar activity were at maximum. Advisors/Committee Members: Dr Adisu Hunegnaw (advisor).

Subjects/Keywords: GPS; Higher order ionosphereic effects; Total electron contents density; Geomagnetic field

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6th Edition):

Asmamaw, C. (2013). STUDY OF SECOND AND THIRD ORDER IONOSPHERIC EFFECT ON GLOBAL POSITIONING SYSTEM (GPS) SIGNALS ALONG THE EQUATORIAL REGIONS . (Thesis). Addis Ababa University. Retrieved from http://etd.aau.edu.et/dspace/handle/123456789/4294

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Chicago Manual of Style (16th Edition):

Asmamaw, Chanie. “STUDY OF SECOND AND THIRD ORDER IONOSPHERIC EFFECT ON GLOBAL POSITIONING SYSTEM (GPS) SIGNALS ALONG THE EQUATORIAL REGIONS .” 2013. Thesis, Addis Ababa University. Accessed November 15, 2019. http://etd.aau.edu.et/dspace/handle/123456789/4294.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

MLA Handbook (7th Edition):

Asmamaw, Chanie. “STUDY OF SECOND AND THIRD ORDER IONOSPHERIC EFFECT ON GLOBAL POSITIONING SYSTEM (GPS) SIGNALS ALONG THE EQUATORIAL REGIONS .” 2013. Web. 15 Nov 2019.

Vancouver:

Asmamaw C. STUDY OF SECOND AND THIRD ORDER IONOSPHERIC EFFECT ON GLOBAL POSITIONING SYSTEM (GPS) SIGNALS ALONG THE EQUATORIAL REGIONS . [Internet] [Thesis]. Addis Ababa University; 2013. [cited 2019 Nov 15]. Available from: http://etd.aau.edu.et/dspace/handle/123456789/4294.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Council of Science Editors:

Asmamaw C. STUDY OF SECOND AND THIRD ORDER IONOSPHERIC EFFECT ON GLOBAL POSITIONING SYSTEM (GPS) SIGNALS ALONG THE EQUATORIAL REGIONS . [Thesis]. Addis Ababa University; 2013. Available from: http://etd.aau.edu.et/dspace/handle/123456789/4294

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

2. Mariaud, Christian. Etude des systèmes binaires galactiques à très haute energie avec HESS et HESS-II : Study of galactic binary systems at very high energy with H.E.S.S. and H.E.S.S. II.

Degree: Docteur es, Astroparticules et cosmologie, 2018, Paris Saclay

En astronomie gamma, les systèmes binaires sont des objets stellaires impliquant une étoile massive et un objet compact, le plus léger des deux en orbite autour de l’autre. Ils émettent de façon régulière à haute et très haute énergie (E > 100 GeV) et peuvent être détectés par le réseau de télescopes H.E.S.S.. Malgré leur faible nombre, ils présentent une grande diversité de comportement et sont caractérisés par une modulation de flux dépendant de la position de l’objet compact. 2 systèmes binaires sont étudiés : LS 5039 et PSR B1259–63, en effet un jeu de données conséquent est disponible puisque ces sources sont observées maintenant depuis plus de 10 ans. En 2012, le cinquième télescope de plus grande taille a commencé ses observations et permet ainsi de faire la connexion avec le domaine du GeV.Une modélisation de ces deux systèmes binaires dans le cas d’une diffusion anisotrope inverse Compton dans le régime de Klein–Nishina sera aussi proposée avec une prise en compte du disque circumstellaire pour PSR B1259¡63. Les données recueillies lors d’une observation peuvent être détériorées par une atmosphère dégradée, affectant ainsi le flux de photons ° collectés. Un coefficient traduisant la qualité de l’atmosphère est donc nécessaire. De plus les gerbes peuvent être déformées à cause de laprésence du champ magnétique terrestre, les études de ces phénomènes sont donc nécessaires pour essayer de corriger ces effets.

Binary systems in gamma astronomy are stellar objects involving a massive star with a compact object, the lightest in orbit around the other. They emit regularly at high energy and very high energy (E > 100 GeV) for detection by H.E.S.S. telescopes. Despite their low relative number, they are all characterized by a modulation of gamma photon flux which depends on the position of the lightest object. We will focus more on 2 binary systems : LS 5039 and PSR B1259–63, we have a susbstantial data, H.E.S.S. telescopes have regularly observed these objects for more than 10 years. In 2012, a fifth telescope much larger size, began observations and enables to get events at lower energy and then make the connection with other experiments such as Fermi-LAT. A modelling of these two binary systems in anisotropic inverse Compton in Klein–Nishina regime are also presented and the circumstellar disk is taken into account for PSR B1259–63. Data taken by theH.E.S.S. telescopes can be improved. During observations, atmosphere can be degraded and thus affecting the flux of gamma photons collected. It’s therefore important to know the transparency coefficient of the atmosphere during an analysis. Furthermore, the electromagnetic air showers are more distorted because of the Earth’s magnetic field, a study of these phenomenas is necessary to correct these effects.

Advisors/Committee Members: Naurois, Mathieu de (thesis director).

Subjects/Keywords: H.e.s.s.; Coefficient de transparence; Systèmes binaires; Effets géomagnétiques; LS 5039; PSR B1259–63; Diffusion inverse Compton; H.e.s.s.; Transparency coefficient; Binary systems; Geomagnetic effects; LS 5039; PSR B1259–63; Inverse Compton scattering; 539.720 72

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6th Edition):

Mariaud, C. (2018). Etude des systèmes binaires galactiques à très haute energie avec HESS et HESS-II : Study of galactic binary systems at very high energy with H.E.S.S. and H.E.S.S. II. (Doctoral Dissertation). Paris Saclay. Retrieved from http://www.theses.fr/2018SACLX030

Chicago Manual of Style (16th Edition):

Mariaud, Christian. “Etude des systèmes binaires galactiques à très haute energie avec HESS et HESS-II : Study of galactic binary systems at very high energy with H.E.S.S. and H.E.S.S. II.” 2018. Doctoral Dissertation, Paris Saclay. Accessed November 15, 2019. http://www.theses.fr/2018SACLX030.

MLA Handbook (7th Edition):

Mariaud, Christian. “Etude des systèmes binaires galactiques à très haute energie avec HESS et HESS-II : Study of galactic binary systems at very high energy with H.E.S.S. and H.E.S.S. II.” 2018. Web. 15 Nov 2019.

Vancouver:

Mariaud C. Etude des systèmes binaires galactiques à très haute energie avec HESS et HESS-II : Study of galactic binary systems at very high energy with H.E.S.S. and H.E.S.S. II. [Internet] [Doctoral dissertation]. Paris Saclay; 2018. [cited 2019 Nov 15]. Available from: http://www.theses.fr/2018SACLX030.

Council of Science Editors:

Mariaud C. Etude des systèmes binaires galactiques à très haute energie avec HESS et HESS-II : Study of galactic binary systems at very high energy with H.E.S.S. and H.E.S.S. II. [Doctoral Dissertation]. Paris Saclay; 2018. Available from: http://www.theses.fr/2018SACLX030

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