Transcript Powerpoint version

Astronomical observation
Olivier Ravayrol
Summary
 A bit of history
 A bit of theory
 In practice
 What to watch and with what?
 What materials for what budgets?
 Links
 Questions ?
Astronomical observation
Copyright © 2013 Olivier Ravayrol - All rights reserved.
2
A bit of history: Key dates
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1543: Copernicus's heliocentric system defined
1609: Kepler states his laws of planetary motion
1610: Galileo built a reflector and observe the satellites of Jupiter
1655: Huygens observed Saturn's ring and its moon Titan
1687: Newton built a reflector and published his law of gravitation
1774: Messier publishes its deep sky object catalog
1781: Herschel discovers Uranus
1846: Le Verrier, and Galle discovered Neptune
1905: Schwarzschild predicts the existence of black holes
1916: Einstein presented his theory of General Relativity
1929: Hubble discovers and measure the expansion of the universe
1948: Gamow develops his theory of Big Bang
1970: V. Rubin hypothesized dark matter
1978 - 1989: The Voyager probe approached planets close
1995: Michel Mayor and Didier Queloz discovered the first extrasolar planet
Astronomical observation
Copyright © 2013 Olivier Ravayrol - All rights reserved.
3
A bit of theory: The coordinate systems
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Coordinate system
• The observer on Earth is at the center mark
• Imaginary lines are represented on the celestial sphere
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Azimutal type: depends on the place and time !
• Azimuth : origin = South [0° at 360°]
• High:
origin = Horizon [0° at 90°]
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Equatorial type: uniform system
• Declination ( projected Latitude): origin = celestial equator
[-90° à 90°]
• Right Ascension ( projected Longitude) : origine = Vernal pt
[0° à 360°] (intersection between the ecliptic and the celestial
equator)
• Example : M31 => AD=00h 42’ 44’’ ; Dec=+41°16′ 07’’
• The type Equatorial + is suitable for astronomy can track
objects with the Earth's rotation
Astronomical observation
Copyright © 2013 Olivier Ravayrol - All rights reserved.
4
A bit of theory: Units
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Apparent magnitude: used to measure the
brightness of a celestial object
• + it’s high – it’s light (inverse log scale)
• Polaris = 2,09 ; Vega = 0 ; Sirius = -1,46 ; Soleil = -26,78
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Measure of astronomical distances
• AU (Astronomical Unit) = Dist Terre / Soleil ~= 150 M km
• Distance Sun / Mars ~= 1,5 AU
• Distance Sun / Saturne ~= 9,5 AU
• LY (Light Year) : distance traveled by 1 light year ~= 10 000
Billion km ~= 63 000 AU
• Nearest star: 4,22 AL ; Pléiades cluster: 400 LY
• Diameter of the Milky Way : 100 000 AL
• Distance of the Andromeda Galaxy : 2,5 M LY
Astronomical observation
Copyright © 2013 Olivier Ravayrol - All rights reserved.
5
Practice: Getting the mount aligned
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Advantage of the equatorial mount
• Rotational axis of the earth (almost) aligned with the polar star
for the northern hemisphere => Frame alignment ease
• Equatorial mount has "just" to follow the earth's rotation
(manually or automatically)
• Getting the mount aligned (equatorial type) :
• To level the mount
• Alignment on the polar star (manual or semi-automated via
software)
• Without drive and without GoTo: we hold the coordinates’
object through graduate axes of the mount and manually track
with the AD axis wheel
• With GoTo: preliminary 3 stars alignment for an automatic
pointing objects via the remote control
Astronomical observation
Copyright © 2013 Olivier Ravayrol - All rights reserved.
6
Practice: Effects of light pollution
Astronomical observation
Copyright © 2013 Olivier Ravayrol - All rights reserved.
7
Practice: Sky with clear light pollution
Astronomical observation
Copyright © 2013 Olivier Ravayrol - All rights reserved.
8
In practice: Sky with moderate pollution
Astronomical observation
Copyright © 2013 Olivier Ravayrol - All rights reserved.
9
Practice: Triangle of summer
Astronomical observation
Copyright © 2013 Olivier Ravayrol - All rights reserved.
10
What to watch and with what ? (1/2)
 Eyes
(Wait 10 minutes before observation and not look lighting then !)
 You have to identify from the pole star :
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• From the "Big Dipper" to find the North Star
• With a compass, look north to 45 °(France) to find the North Star
• With software as Stellarium or applications on Smartphones
Some constellations and star clusters (the Pleiades)
The Milky Way and the Andromeda galaxy
Shooting Stars
The ISS and some satellites (Iridium)
 Binoculars:
• Some open clusters and globular star cluster
• The moon but only with a lunar polarizing filter
• The sun but only with a solar filter
Astronomical observation
Copyright © 2013 Olivier Ravayrol - All rights reserved.
11
What to watch and with what ? (2/2)
 The refractor: for the wide field (extended objects)
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The large open star clusters (the Pleiades)
Extended nebulae (Orion, America)
The Great Andromeda Galaxy
Moon with a filter, planets, comets
The tasks and solar prominences with filters
 The reflector: for the narrow field (smaller objects)
• Galaxies
• Small nebulae (Horse's head nebulae)
• Planetary nebulae (Ring Nebula)
Astronomical observation
Copyright © 2013 Olivier Ravayrol - All rights reserved.
12
What materials for what budgets ? (1/5)
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Promote the diameter of the instrument
• The brightness of the object increases with the diameter
• The resolving power increases with the diameter
• We can always increase the focal length (and thus the magnification) with
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Barlow lens
Too much magnification with a small diameter will give less sharp
images!
F/D > 10 => Planetary
F/D < 5 => Objects less bright
Binoculars: allows a 3D effect
• Focus on model 7 x 50 (D = 50 mm; Gr = 7x)
• Beyond 7x, a tripod is required because the magnification is too large: 10
x 70 models are good but expensive !
Astronomical observation
Copyright © 2013 Olivier Ravayrol - All rights reserved.
13
What materials for what budgets ? (2/5)
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Refractor or reflector ?
• In the previous slide: the diameter should be preferred
• The refractor may not exceed D = 100mm because prices are exponential
above ! (The reflector’s mirror is less expensive to manufacture than the lens of the
refractor)
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Choice of instrument for observation :
• Refractor: limited diameter
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• +: Less bulky than a large reflector’s diameter
• -: For use of the planets or wide field photo
Reflector: F / D low
• + It’s doing everything (but less "stung" than the refractor)
• -: It must be regularly "collimated" (for Newton type)
Astronomical observation
Copyright © 2013 Olivier Ravayrol - All rights reserved.
14
What materials for what budgets ? (3/5)
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Choice of eyepieces and filters
• Eyepieces
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Magnification = Finstrument / foculaire
3 eyepieces => Wide field: 25mm to 35mm; 12mm medium field;
Magnification 6mm to 8mm with wide angle 60 ° to 100 °
Barlow lenses
• 2x: increases the focal length and thus magnification by a factor 2
• 5x (Max): allows to see the red spot of Jupiter
Visual filters
• For the Moon: variable polarizing
• For the Sun: Solar Filter for sun spots (H-Alpha for the protuberances but very
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expensive)
For deep sky (light pollution filter removed): Type UHC or CLS
For planets: different colors can improve the contrast according to the
observe planet type
Astronomical observation
Copyright © 2013 Olivier Ravayrol - All rights reserved.
15
What materials for what budgets ? (4/5)
Instrument
Jumelles
Modèle
Diamètre
(mm)
Fabriquant Monture
Jumelles
Jumelles
Jumelles
7 x 50
10 x 60
15 x 70
50
60
70
Perl
Kepler
Kepler
En option
En option
En option
Lunette achromatique
Nextar 102 SLT
102
Celestron
Azimutale
Lunette achromatique
OmniXLT 120
120
Celestron
Lunette achromatique
120 / 1000
Goto
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Photo Coût (€) Remarques
Non
Non
Non
79
150
140
Non
529
Equatoriale Optionnel Non
608
120
Sky Watcher Equatoriale Optionnel Non
570
80
Orion
Equatoriale Oui
Oui
1300
Supports de prismes haut de gamme
Très bon rapport qualité / prix
Lunettes
Lunette apochromatique Sirius EQ-G 80ED
Oui
Livré avec 2 oculaires (25 et 9 mm)
Bonne monture (CG4)
Livré avec un oculaire 25 mm
Bonne monture (NEQ5)
Livré avec un occulaire 25 mm
Idéal pour la photo grand champ
Livré avec un oculaire 25 mm
Télescopes
Télescope Dobson
GSO 300/1500
305
Kepler
Azimutale
Non
Non
750
Télescope Dobson
SkyQuest XT12
305
Orion
Azimutale
Non
Non
990
Télescope Newton
200/1000 Black Diamond sur NEQ5 203
Sky Watcher Equatoriale Optionnel Non
640
Télescope Newton
200/1000 Sirius EQ-G
Orion
1200
203
Equatoriale Oui
Oui
Ideal pour l'observation du ciel profond
Livré avec 2 oculaires 30 et 9 mm
Ideal pour l'observation du ciel profond
avec une aide au pointage
Livré avec 2 oculaires 25 et 10 mm
Bon rapport / qualité prix
Livré avec 1 oculaires 28 mm
Idéal pour la photo
Livré avec un oculaire 26 mm
Astronomical observation
Copyright © 2013 Olivier Ravayrol - All rights reserved.
16
What materials for what budgets ? (5/5)
Instrument
Modèle
Oculaires pour le grossissement
Fabriquant Photo Coût (€) Remarques
Oculaire
Hypérion 8mm 68°
Baader
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125
Oculaire
Ethos 8mm 100°
Televue
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485
Bon rapport qualité / prix
La Rolls des oculaires ! (très bon piqué et
contraste)
2,5x
5x
Powermate 2,5x
Powermate 5x
Kepler
Kepler
Televue
Televue
Non
Non
Oui
Oui
30
45
167
167
1er prix
1er prix
Très bonne qualité pour la photo
Très bonne qualité pour la photo
Polarisant variable
Astrosolar safety film
Filtre rouge
UHC visuel
CLS
Orion
Baader
Kepler
astronomik
astronomik
Non
Oui
Non
Oui
Oui
35
25
15
99
69
Filtre à faire varier en fonction de la luminosité
Feuille A4 à fixer sur l'objectif
Prendre plusieurs couleurs
Plus dédié au ciel profond
Applicable à tous les objets (excepté les planètes)
Lentilles de Barlow
Lentille de Barlow
Lentille de Barlow
Lentille de Barlow
Lentille de Barlow
Filtres
Filtre lunaire
Filtre solaire
Filtre coloré
Filtre anti pollution lumineuse
Filtre anti pollution lumineuse
 Average budget for visual observation: 900 €
 Average budget adapted for photo: 1630 € (without the Reflex and
accessories)
Astronomical observation
Copyright © 2013 Olivier Ravayrol - All rights reserved.
17
Links
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Training sessions at “Ferme des étoiles” (Gers, France)
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Softwares
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Planetarium (Open Source) : Stellarium (http://www.stellarium.org/fr/)
SkyChart (Open Source) : http://www.ap-i.net/skychart/fr/telechargement
Various softwares : http://www.astrosurf.com/logiciels/
Useful links
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Magasins / Fournisseurs de matériels pour l’astronomie :
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Optique-Unterlinden : http://www.optique-unterlinden.com/
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La clef des étoiles (Toulouse): http://www.laclefdesetoiles.com/
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Pierre-Astro : http://www.pierro-astro.com/
Amateurs forum: http://www.astrosurf.com/
Association « La ferme des étoiles » : http://www.fermedesetoiles.com/
Visibility prevision: http://www.meteoblue.com/fr_FR/meteo/charts/seeing/
Nebulosity : http://www.meteociel.fr/observations-meteo/nebu.php
Astronomical observation
Copyright © 2013 Olivier Ravayrol - All rights reserved.
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www.astrosurf.com/olivierr31