IdeaWazaWiki - User contributions [en]

Chest x-ray

2008-06-02T10:56:08Z

88.104.206.4: /* Mediastinum */

==ID==
*name
*date
*modality

==Marker==
*Right or Left

==Position==
*Medial ends of the clavicles should be equidistant from the spinous processes at the midline to rule out rotation

==Quality==
*Penetration
**thoracic disc spaces should be just visible through the heart
***overexposure → too dark
***underexposure → too white

==Respiration==
*good inspiration → 6th anterior, 10th posterior ribs at MCL
*right hemidiaphragm at 6th anterior rib
*poor inspiration:
**poor aeration, vascular crowding, widened central shadow

==Hardware==
*Comment on any lines, lead placements, tubing, etc.

==Bones==
*C-spine, T-spine → alignment, disc space spacing, lytic or blastic lesions
*shoulder girdle, ribs, humerus, sternum → fractures, osteopenia, deformities
*vertebra OA (lateral view)
**subchondral (beneath the cartilage) sclerosis
**subchondral cysts
**narrowing of joint space
**osteophytes

==Extrathoracic soft tissue==
*breast shadow, nipple
*supra-clavicular, axillary areas → masses
*subcutaneous emphysema

==Mediastinum==
*size, shape
*mainstem and segmental bronchi, lymph nodes
*great vessels
*hila → relationship, size

==Trachea==
*position (centered, some rightward shift at level of carina)
**shift - pneumothorax, mass
**carina widened - LA enlargement, subcarinal node

==Heart Shadow==
*cardiothoracic ratio (only on full inspiration PA views)
**should be < 50%
*enlarged chambers
**LA - double shadow on right border
**RA - ↑ width of right hemidiaphragm
**LV - ↑ heart width
**RV - lateral view: retrosternal space ↓
*calcifications
*aortic knuckle - unfolded due to age

==Chest Wall==
*follow pleura for signs of pneumothorax
**loss of lung markings in the periphery
**line of visceral pleura seen on expiration view
*pleural thickening
**↑ width of white line along inside of ribcage, esp. near diaphragm
*costophrenic angles → pleural effusion
**small effusions (< 100 mL) may be only seen in the lateral view

==Diaphragms==
*compare hemidiaphragms
**obscured → lower lobe pneumonia, pleural effusion
**flattened → hyperinflation, tension pneumothorax
**elevated → phrenic nerve paralysis, hepatomegaly
**air under diaphragms → perforated GI tract

==Lung Fields==
*compare lung fields in the ICS on L vs. R, up vs. down

==Air Space Disease==
*cardinal features:
**air bronchogram
**fluffy, patchy poorly marginated appearance
**lobar or segmental distribution
*ddx:
**pus (pneumonia)
**fluid (pulmonary edema)
**blood

==Interstitial Disease==
*pathology involves the interlobular connective tissue
*cardial features:
**linear densities - Kerley B lines (< 2 cm long, 1 mm thick, reach lung edge)
**reticular pattern (thin, well defined linear densities, honeycomb arrangement)
**nodular pattern
*ddx: pulmonary edema, collagen disease (fibrosis), sarcoidosis, viral pneumonia

==Pulmonary Edema==
*edema initially collects in the interstitium
** loss of definition of pulmonary vasculature
**peribronchial cuffing
***bronchi seen end-on appear as white rings
*in CHF, the normally thin-walled bronchi become framed in interstitial fluid
** best seen in vicinity of hila
*Kerley B lines
*reticulonodular pattern
*thickening of interlobar fissures
*with progression, fluid begins to collect in the alveoli, causing diffuse air space disease (bat wing or butterfly pattern), tend to spare the intermost lung fields
*ddx: cardiogenic, renal failure

==Atelectasis==
*cardinal signs:
**deviation of a fissure
**crowding of vessels
**hilar, mediastinum shift
*common causes: obstructive, compressive
*'''in absence of a known etiology, bronchogenic carcinoma must be ruled out'''

==Lymphadenopathy==
*lymph node groups: paratracheal, hilar, aorto-pulmonary window, subcarinal
*hilar, AP window → widen mediastinum, flatten AP window contour
**lung cancer, lymphoma, sarcoidosis, and tuberculosis
*subcarinal - ↑ angle of tracheal bifurcation to 90°

==Abdomen==
*liver size
*spleen size
*stomach (gastric bubble)
*colon (bowel gas)
- free air under diaphragm - pneumoperitoneum
==Misc==
===CHF===
*upper lobe redistribution of vessels
*Kerley B-lines (usually seen near diaphragm)
*right effusion at base
*perivascular cuffing
*pulmonary edema (interstitial, then airspace consolidation)
*venous engorgement
**normally extend 2/3 of the distance to periphery
**vessels seen to extend farther than normal

===Unilateral Left Sided Effusion===
*trauma, infection, SLE, PE, malignancy

===Mediastinal Mass===
*anterior mediastinum
**thyroid masses, thymomas, teratomas, lymphomas
*middle mediastinum
**lymphadenopathy, lymphoma, aortic aneurysm
*posterior mediastinum
**aneurysm of descending aorta, esophageal masses, hiatus hernia
*lateral view
**RVH
**effusion → accentuation of lines of major and minor fissures
==Other OSCE modules==
{{OSCE}}
[[Category:Medicine]][[Category:OSCE]]

Astronomy

2007-03-08T17:44:24Z

88.104.51.69: /* Level 1 */

{{nav|School:Physics and Astronomy}}

[[Image:Cellarius ptolemaic system.jpg|thumb|right|200px]]
'''Welcome to the Department of Astronomy!'''

Astronomy is the science of celestial objects and phenomena that originate outside the Earth's atmosphere, such as stars, planets, comets, aurorae, galaxies, and the cosmic background radiation. It is concerned with the formation and development of the universe, the evolution and physical and chemical properties of celestial objects and the calculation of their motions.

==Welcome==

Astronomy is a new Department at Wikiversity, and it's growth depends on participation from everyone who seeks to learn here. The basic philosophy is to learn by doing. This is reflected in the content of lessons and activities. But this means more than just reading a lesson and following the directions. We also hope that you will participate in the process of creating lessons.

To get started try the lesson on [[Stellar Evolution]] or the activity on [[Observational astronomy]].

For a glimpse of some of the topics that we hope to cover in the future see the [[Topic:Astronomy/Courses]].

If you have any questions about astronomy or requests for topics that you would like to learn, post them to the [[Topic:Astronomy/Help_desk|astronomy help desk]].

==Things to do==
* Cleanup all astronomy related pages and organize
* Link to information about supernova/asteroid online searches
** [[Portal:Asteroid Surveys]]
* Link to data sources
* Link to amateur astronomers societies (and get amateur astronomers to this page)
* Load in the astrophysics source code library
* Create links at Wikipedia to related pages here.

== Courses ==
Get to work writing courses! Simply make a link to the name of the course and start writing!
== Level 1 ==
*[[Introduction to Astronomy]]
*[[Solar System and Stellar Astronomy]]
**[[Stellar Evolution]]
*[[Galactic and Extragalactic Astronomy]]
*[[Cosmic Evolution]]
*[[Introduction to the Planets]]
*[[Observational astronomy]]
*[[Light and Optics]]

== Level 2 ==
*[[Topic:Introduction to Astrophysics|Introduction to Astrophysics]]

== Level 3 ==
*[[Topic:Stellar Evolution|Stellar Evolution]]
*[[High Energy Astrophysics]]
*[[Introduction to General Relativity]]
*[[Topic:Cosmology|Cosmology]]
*[[Galactic Astronomy]]
*[[The Interstellar Medium]]
*[[Binary and Variable Stars]]
*[[Galaxies Beyond the Milky Way]]
*[[Directed Readings in Current Literature]]
*[[Stellar Astrophysics]]
*[[Radiation in Planetary Atmospheres]]
*[[Astronomical Instrumentation and Techniques]]
*[[Clusters of Galaxies]]
*[[Astrophysical Dynamics]]
*[[Computational Methods]]
*[[Astrophysical Hydrodynamics]]

==Active participants==
The histories of Wikiversity pages indicate who the active participants are. If you are an active participant in this school, you can list your name here (this can help small schools grow and the participants communicate better; for large schools it is not needed).

*[[User:Roadrunner]]
*[[User:Suto]]
*[[User:Mu301]]

Are you interested in Astronomy? Would you like to create instruction material and help out with people studying this topic? Sign up to be a participant by adding your username to this list!

==School news==
* '''August 17, 2006''' - School founded!

==Research projects==
*[[Learning project]]: [[Astronomy Project]] - students access public astronomy databases and explore outer space.
*[[Astrophysics Source Code Library]] = ASCL
*[[BoomCode]] - GPL Type II supernova collapse code

==Resources==
Know any good resources for scholars of this topic? Add them here!

===Wikiresources===
*[[Topic:Astronomy/Wikiresources]]

===External Resources===
*[http://adswww.harvard.edu/ Journal article database]
*[http://www.arxiv.org/ Preprints database]
*[http://ascl.net/ Astrophysics source code library]
*[http://cosmos.colorado.edu/stem/courses/common/documents/hypertext.html Dick McCray's Astronomy Hypertext]
*[http://webcast.berkeley.edu/courses/archive.php?seriesid=1906978334 Introduction to General Astronomy, Webcast from Berkeley]
*[http://academia.wikia.com/wiki/Amateur_Astronomy Amateur Astronomy] - wiki journal

== Related news ==
* '''March 6, 2007''' - [http://www.eurekalert.org/pub_releases/2007-03/uoc--asr030607.php New study produces mathematical rules of galaxy formation.]
* '''February 21, 2007''' - [http://www.universetoday.com/2007/02/21/exoplanet-is-hot-and-dry/ Astronomers are finally able to analyze the atmosphere of exoplanets]

==Careers==
* [http://www.hp-h.com/b/astromill/ Astrophysics job rumor mill]
* [http://members.aas.org/JobReg/JobRegister.cfm AAS Job Register]
* [http://www.aas.org/career/nonacademic/ AAS Non-Academic Astronomy Network]

[[Category:{{PAGENAME}}|Astronomy]]
[[Category:Wikiversity schools|Physics and Astronomy]]

Astronomy

2007-03-04T00:06:13Z

88.104.153.253: transferred courses from superfluous page to here

{{nav|School:Physics and Astronomy}}

[[Image:Cellarius ptolemaic system.jpg|thumb|right|200px]]
'''Welcome to the Department of Astronomy!'''

Astronomy is the science of celestial objects and phenomena that originate outside the Earth's atmosphere, such as stars, planets, comets, aurorae, galaxies, and the cosmic background radiation. It is concerned with the formation and development of the universe, the evolution and physical and chemical properties of celestial objects and the calculation of their motions.

==Welcome==

Astronomy is a new Department at Wikiversity, and it's growth depends on participation from everyone who seeks to learn here. The basic philosophy is to learn by doing. This is reflected in the content of lessons and activities. But this means more than just reading a lesson and following the directions. We also hope that you will participate in the process of creating lessons.

To get started try the lesson on [[Stellar Evolution]] or the activity on [[Observational astronomy]].

For a glimpse of some of the topics that we hope to cover in the future see the [[Topic:Astronomy/Courses]].

If you have any questions about astronomy or requests for topics that you would like to learn, post them to the [[Topic:Astronomy/Help_desk|astronomy help desk]].

==Things to do==
* Cleanup all astronomy related pages and organize
* Link to information about supernova/asteroid online searches
** [[Portal:Asteroid Surveys]]
* Link to data sources
* Link to amateur astronomers societies (and get amateur astronomers to this page)
* Load in the astrophysics source code library
* Create links at Wikipedia to related pages here.

== Courses ==
Get to work writing courses! Simply make a link to the name of the course and start writing!
== Level 1 ==
*[[Introduction to Astronomy]]
*[[Solar System and Stellar Astronomy]]
**[[Stellar Evolution]]
*[[Galactic and Extragalactic Astronomy]]
*[[Cosmic Evolution]]
*[[Introduction to the Planets]]
*[[Observational astronomy]]

== Level 2 ==
*[[Topic:Introduction to Astrophysics|Introduction to Astrophysics]]

== Level 3 ==
*[[Topic:Stellar Evolution|Stellar Evolution]]
*[[High Energy Astrophysics]]
*[[Introduction to General Relativity]]
*[[Topic:Cosmology|Cosmology]]
*[[Galactic Astronomy]]
*[[The Interstellar Medium]]
*[[Binary and Variable Stars]]
*[[Galaxies Beyond the Milky Way]]
*[[Directed Readings in Current Literature]]
*[[Stellar Astrophysics]]
*[[Radiation in Planetary Atmospheres]]
*[[Astronomical Instrumentation and Techniques]]
*[[Clusters of Galaxies]]
*[[Astrophysical Dynamics]]
*[[Computational Methods]]
*[[Astrophysical Hydrodynamics]]

==Active participants==
The histories of Wikiversity pages indicate who the active participants are. If you are an active participant in this school, you can list your name here (this can help small schools grow and the participants communicate better; for large schools it is not needed).

*[[User:Roadrunner]]
*[[User:Suto]]
*[[User:Mu301]]

Are you interested in Astronomy? Would you like to create instruction material and help out with people studying this topic? Sign up to be a participant by adding your username to this list!

==School news==
* '''August 17, 2006''' - School founded!

==Research projects==

[[Learning project]]: [[Astronomy Project]] - students access public astronomy databases and explore outer space.

[[Astrophysics Source Code Library]] = ASCL

[[BoomCode]] - GPL Type II supernova collapse code

==Resources==
Know any good resources for scholars of this topic? Add them here!

===Wikiresources===
*[[Topic:Astronomy/Wikiresources]]

===External Resources===
*[http://adswww.harvard.edu/ Journal article database]
*[http://www.arxiv.org/ Preprints database]
*[http://ascl.net/ Astrophysics source code library]
*[http://cosmos.colorado.edu/stem/courses/common/documents/hypertext.html Dick McCray's Astronomy Hypertext]
*[http://webcast.berkeley.edu/courses/archive.php?seriesid=1906978334 Introduction to General Astronomy, Webcast from Berkeley]
*[http://academia.wikia.com/wiki/Amateur_Astronomy Amateur Astronomy] - wiki journal

== Related news ==
[http://www.universetoday.com/2007/02/21/exoplanet-is-hot-and-dry/ February 21, 2007 - Astronomers are finally able to analyze the atmosphere of exoplanets]

==Careers==
* [http://www.hp-h.com/b/astromill/ Astrophysics job rumor mill]
* [http://members.aas.org/JobReg/JobRegister.cfm AAS Job Register]
* [http://www.aas.org/career/nonacademic/ AAS Non-Academic Astronomy Network]

[[Category:{{PAGENAME}}|Astronomy]]
[[Category:Wikiversity schools|Physics and Astronomy]]

Astronomy

2007-03-04T00:00:37Z

88.104.153.253: /* Level 2 */

{{nav|School:Physics and Astronomy}}

[[Image:Cellarius ptolemaic system.jpg|thumb|right|200px]]
'''Welcome to the Department of Astronomy!'''

Astronomy is the science of celestial objects and phenomena that originate outside the Earth's atmosphere, such as stars, planets, comets, aurorae, galaxies, and the cosmic background radiation. It is concerned with the formation and development of the universe, the evolution and physical and chemical properties of celestial objects and the calculation of their motions.

==Welcome==

Astronomy is a new Department at Wikiversity, and it's growth depends on participation from everyone who seeks to learn here. The basic philosophy is to learn by doing. This is reflected in the content of lessons and activities. But this means more than just reading a lesson and following the directions. We also hope that you will participate in the process of creating lessons.

To get started try the lesson on [[Stellar Evolution]] or the activity on [[Observational astronomy]].

For a glimpse of some of the topics that we hope to cover in the future see the [[Topic:Astronomy/Courses]].

If you have any questions about astronomy or requests for topics that you would like to learn, post them to the [[Topic:Astronomy/Help_desk|astronomy help desk]].

==Things to do==
* Cleanup all astronomy related pages and organize
* Link to information about supernova/asteroid online searches
** [[Portal:Asteroid Surveys]]
* Link to data sources
* Link to amateur astronomers societies (and get amateur astronomers to this page)
* Load in the astrophysics source code library
* Create links at Wikipedia to related pages here.

== Courses ==
Get to work writing courses! Simply make a link to the name of the course and start writing!
== Level 1 ==
*[[Introduction to the Planets]]
*[[Observational astronomy]]

== Level 2 ==
*[[Topic:Introduction to Astrophysics|Introduction to Astrophysics]]

== Level 3 ==
*[[Topic:Stellar Evolution|Stellar Evolution]]
*[[High Energy Astrophysics]]
*[[Introduction to General Relativity]]
*[[Topic:Cosmology|Cosmology]]

==Active participants==
The histories of Wikiversity pages indicate who the active participants are. If you are an active participant in this school, you can list your name here (this can help small schools grow and the participants communicate better; for large schools it is not needed).

*[[User:Roadrunner]]
*[[User:Suto]]
*[[User:Mu301]]

Are you interested in Astronomy? Would you like to create instruction material and help out with people studying this topic? Sign up to be a participant by adding your username to this list!

==School news==
* '''August 17, 2006''' - School founded!

==Research projects==

[[Learning project]]: [[Astronomy Project]] - students access public astronomy databases and explore outer space.

[[Astrophysics Source Code Library]] = ASCL

[[BoomCode]] - GPL Type II supernova collapse code

==Resources==
Know any good resources for scholars of this topic? Add them here!

===Wikiresources===
*[[Topic:Astronomy/Wikiresources]]

===External Resources===
*[http://adswww.harvard.edu/ Journal article database]
*[http://www.arxiv.org/ Preprints database]
*[http://ascl.net/ Astrophysics source code library]
*[http://cosmos.colorado.edu/stem/courses/common/documents/hypertext.html Dick McCray's Astronomy Hypertext]
*[http://webcast.berkeley.edu/courses/archive.php?seriesid=1906978334 Introduction to General Astronomy, Webcast from Berkeley]
*[http://academia.wikia.com/wiki/Amateur_Astronomy Amateur Astronomy] - wiki journal

== Related news ==
[http://www.universetoday.com/2007/02/21/exoplanet-is-hot-and-dry/ February 21, 2007 - Astronomers are finally able to analyze the atmosphere of exoplanets]

==Careers==
* [http://www.hp-h.com/b/astromill/ Astrophysics job rumor mill]
* [http://members.aas.org/JobReg/JobRegister.cfm AAS Job Register]
* [http://www.aas.org/career/nonacademic/ AAS Non-Academic Astronomy Network]

[[Category:{{PAGENAME}}|Astronomy]]
[[Category:Wikiversity schools|Physics and Astronomy]]

Astronomy

2007-03-03T23:45:35Z

88.104.153.253: Added some course names

{{nav|School:Physics and Astronomy}}

[[Image:Cellarius ptolemaic system.jpg|thumb|right|200px]]
'''Welcome to the Department of Astronomy!'''

Astronomy is the science of celestial objects and phenomena that originate outside the Earth's atmosphere, such as stars, planets, comets, aurorae, galaxies, and the cosmic background radiation. It is concerned with the formation and development of the universe, the evolution and physical and chemical properties of celestial objects and the calculation of their motions.

==Welcome==

Astronomy is a new Department at Wikiversity, and it's growth depends on participation from everyone who seeks to learn here. The basic philosophy is to learn by doing. This is reflected in the content of lessons and activities. But this means more than just reading a lesson and following the directions. We also hope that you will participate in the process of creating lessons.

To get started try the lesson on [[Stellar Evolution]] or the activity on [[Observational astronomy]].

For a glimpse of some of the topics that we hope to cover in the future see the [[Topic:Astronomy/Courses]].

If you have any questions about astronomy or requests for topics that you would like to learn, post them to the [[Topic:Astronomy/Help_desk|astronomy help desk]].

==Things to do==
* Cleanup all astronomy related pages and organize
* Link to information about supernova/asteroid online searches
** [[Portal:Asteroid Surveys]]
* Link to data sources
* Link to amateur astronomers societies (and get amateur astronomers to this page)
* Load in the astrophysics source code library
* Create links at Wikipedia to related pages here.

== Courses ==
Get to work writing courses! Simply make a link to the name of the course and start writing!
== Level 1 ==
*[[Introduction to the Planets]]
*[[Observational astronomy]]

== Level 2 ==
*[[Topic:Introduction to Astrophysics|Introduction to Astrophysics]]
*[[Special Relativity]]

== Level 3 ==
*[[Topic:Stellar Evolution|Stellar Evolution]]
*[[High Energy Astrophysics]]
*[[Introduction to General Relativity]]
*[[Topic:Cosmology|Cosmology]]

==Active participants==
The histories of Wikiversity pages indicate who the active participants are. If you are an active participant in this school, you can list your name here (this can help small schools grow and the participants communicate better; for large schools it is not needed).

*[[User:Roadrunner]]
*[[User:Suto]]
*[[User:Mu301]]

Are you interested in Astronomy? Would you like to create instruction material and help out with people studying this topic? Sign up to be a participant by adding your username to this list!

==School news==
* '''August 17, 2006''' - School founded!

==Research projects==

[[Learning project]]: [[Astronomy Project]] - students access public astronomy databases and explore outer space.

[[Astrophysics Source Code Library]] = ASCL

[[BoomCode]] - GPL Type II supernova collapse code

==Resources==
Know any good resources for scholars of this topic? Add them here!

===Wikiresources===
*[[Topic:Astronomy/Wikiresources]]

===External Resources===
*[http://adswww.harvard.edu/ Journal article database]
*[http://www.arxiv.org/ Preprints database]
*[http://ascl.net/ Astrophysics source code library]
*[http://cosmos.colorado.edu/stem/courses/common/documents/hypertext.html Dick McCray's Astronomy Hypertext]
*[http://webcast.berkeley.edu/courses/archive.php?seriesid=1906978334 Introduction to General Astronomy, Webcast from Berkeley]
*[http://academia.wikia.com/wiki/Amateur_Astronomy Amateur Astronomy] - wiki journal

== Related news ==
[http://www.universetoday.com/2007/02/21/exoplanet-is-hot-and-dry/ February 21, 2007 - Astronomers are finally able to analyze the atmosphere of exoplanets]

==Careers==
* [http://www.hp-h.com/b/astromill/ Astrophysics job rumor mill]
* [http://members.aas.org/JobReg/JobRegister.cfm AAS Job Register]
* [http://www.aas.org/career/nonacademic/ AAS Non-Academic Astronomy Network]

[[Category:{{PAGENAME}}|Astronomy]]
[[Category:Wikiversity schools|Physics and Astronomy]]

About observational astronomy

2007-02-17T09:39:37Z

88.104.186.121: corrected spelling

[[Image:Barnard33.jpg|thumb|right|300px|The [[w:Horsehead Nebula|Horsehead Nebula]]]]

Astronomers can gain an understanding of objects in the universe by studying them with a telescope. Observational astronomy is the process of collecting and analyzing data to learn about these objects. In this learning project a computer program will be used to view and study images taken with a telescope to learn basic concepts in astronomy.

== Introduction ==

The activities in this learning project are based on the idea of learning by doing. You will learn about astronomy by going through the same process that an astronomer does to analyze data. As you follow the instructions in the activity you should also follow the links to related reading materials.

A [[Wikiversity:learning projects|learning project]] is a collection of pages devoted to the Learning of a specific topic or family of topics; and, simultaneously, a group of people that use said pages to collaborate on a learning goal.

This page is the start of a series of related activities that will be created here during the first half of 2007. Visit the [[/Planning|planning page]] to see some ideas on how this project might develop, and check back often to see the progress. There new also new projects to [[/Supernova|observe supernova]] and study [[/Extrasolar planet|extrasolar planets]] which have just started.

== Activities ==

A CCD imaging system is a type of digital camera that is very sensitive to the dim light from distant objects. The CCD camera is attached to a telescope and the images are stored on a computer where they can later be analyzed. Astronomical images are stored in a computer file format called [[w:FITS|FITS]]. These images can be opened and viewed by using computer software that understands this file format.

=== Browsing the sky ===

We will start by using a program called the [[w:Aladin Sky Atlas|Aladin Sky Atlas]] to retrieve images taken with a telescope and study them.

*Open another window in your web browser by clicking on this link to the [http://aladin.u-strasbg.fr/AladinPreview Aladin previewer] program.
*In the text box enter the name of the object that we are interested in studying. Type '''M101''' and then click the '''Plate view''' button.

This image shows an area of the sky that includes a [[w:galaxy|galaxy]]. Where did this image come from? Aladin allows you to retrieve images from a number of different sources. This particular image was taken as part of the [[w:Palomar Sky Survey|Palomar Sky Survey]]. The galaxy is the small spiral shape near the upper left. The galaxy is much more distant than the individual bright stars in this view. To get a closer look at the galaxy lets take a look at a more magnified view.

*In the Aladin window click on the '''back''' button to return to the search page. Then click on the '''Default image''' button to retrieve a closeup image of M101.

A galaxy is composed of [[w:star|stars]] and the brighter parts of the image indicate places within the galaxy where there is a greater concentration of stars, for instance in the [[w:spiral galaxy|spiral arms]]. The common name for this object is the [[w:Pinwheel Galaxy|Pinwheel Galaxy]]. Astronomers also refer to it using a designation in an [[w:astronomical catalog|astronomical catalog]]. The Pinwheel Galaxy is number 101 in a [[w:Messier object|list of objects]] catalogued by astronomer [[w:Charles Messier|Charles Messier]].

*Now use Aladin to retrieve a color image of M101 by clicking on the '''RGB image''' button.

The cameras used by astronomers only capture [[w:greyscale|greyscale]] images. To produce a color composite image requires taking seperate exposures through color filters - usually red, green and blue. The three exposures are then combined to produce a final color image. In the color image of M101 you can see that the three seperate exposures are not perfectly lined up which is why there is a purple border around the edge.

*Click on the '''New query''' button in Aladin. Just below the search text box there is a list of examples. Retrieve images of some of the other galaxies listed such as the [[w:Triangulum Galaxy|Triangulum Pinwheel]] by clicking on '''M33'''.

Take a look at [[b:Astronomy/Types of Galaxies|types of galaxies]] and [[w:Galaxy classification|galaxy classification]] as you look at the images. Try to classify each galaxy. Is it [[w:spiral galaxy|spiral]], [[w:elliptical galaxy|elliptical]], or [[w:Irregular galaxy|another type]]?

=== Creating color images ===

*Open another window in your web browser by clicking on this link to the [http://aladin.u-strasbg.fr/ Aladin Sky Atlas home page].

There are three different versions of the Aladin program. The version used in the first activity is the Aladin Previewer. The Previewer is a convenient tool for browsing images but it does not allow for editing the images. For this activity we will need to use the full version of Aladin.

*To get started quickly just click on the [http://aladin.u-strasbg.fr/java/nph-aladin.pl Start Aladin applet] link to run Aladin in a browser window. (You can also [http://aladin.u-strasbg.fr/java/nph-aladin.pl?frame=downloading Download Aladin on your machine] and run the program from your desktop.)

*Start Aladin and click on the '''Load...''' button. In the '''Server selector''' window click on '''DSS'''. Pick a server to retrieve the images from, for instance '''DSS from STScI'''. In the '''Target''' box enter '''M101''' and then choose '''POSS1 Red''' for the '''Survey'''. Click '''Submit'''.

The image of M101 will now download and open in the Aladin multiview window. Notice that the image is displayed as a negative, ie. the bright stars appear black and the dark sky appears white. This is an image taken through a red filter. Next we will download a second image taken through a blue filter.

*Go back to the '''Server selector''' window and choose '''POSS1 Blue''' for the '''Survey'''. Click '''Submit'''. You can now '''Close''' the '''Server selector''' window.

We will now combine these two images to create a color composite.

*In the Aladin multiview window click on the icon labeled '''rgb'''. In the '''RGB image generator''' window use the pulldown menu to select the images for each color. For '''Red''' choose the image name that includes '''POSS1_Red'''. For '''Green''' leave it set to '''none'''. For '''Blue''' choose the image name that begins '''POSS1_Blue'''. Click on the '''Create''' button.

A third image will now appear in the Aladin multiview window. This type of image is called [[w:False-color|False-color]] because the colors do not exactly match what the human eye would see when looking through a telescope.

*You can use the '''Zoom''' button below the thumbnail image to change the scale of the main image. A zoom setting of '''1X''' will give you the largest image that can be displayed, without loss of resolution. Clicking on the thumbnail will center that spot in the main window image.

=== Supernova ===

The [[Observational astronomy/Supernova]] page has images of galaxies where a supernova has been observed recently. In this activity we will retrieve images taken before the supernova occured, and compare them to the new images.

[[Image:UGC14.jpg|thumb|300px|right|Supernova 2006sr in the galaxy UGC 14 on 2007-01-02]]

*Start Aladin and click on the '''Load...''' button. In the '''Server selector''' window click on '''DSS''' and select an image server. In the '''Target''' box enter the name of the galaxy which is '''UGC14''' and then choose '''POSS1_Red''' for the '''Survey'''. Click '''Submit'''.

*In the Aladin multiview window click on the icon labeled '''pixel'''. In the '''Pixel mapping''' popup window click on the '''Reverse''' button to change the image from a negative to a positive.

*To find out when this image was taken click on the icon labeled '''prop''' and look for '''Date-Obs:''' which indicates that the image was taken Aug. 11, 1953.

*Compare the image displayed in Aladin to the image shown at right. Click [[:Image:UGC14.jpg|here]] (or on the image) to see a larger version and to find out when it was taken (the '''Date''' is '''2007-01-02T23:03Z'''.) This supernova was first seen on Dec. 12, 2006, so it will not be visible in the earlier image displayed by Aladin. Do you see the supernova in the recent image? If you are unsure, click [[:Image:06srMU C200701022303.jpg|here]] to see another version of this image that is marked to show which star the supernova is.

*More images of this supernova can be found in [[:Category:Supernova Images]] or at the [http://www.rochesterastronomy.org/sn2006/sn2006sr.html Supernova 2006sr in UGC 14] webpage. Compare images taken on different dates to see if the supernova has changed brightness. The difference will be very subtle in images taken a week apart. It is more [[:Image:06srMU C200701262343.jpg|obvious]] after about a month.

==Readings==

Background information:
* [[w:Observational astronomy]]
* [[w:Telescope]]

==References==

Additional helpful readings include:
*[http://www.spacetelescope.org/projects/fits_liberator/improc.html Image processing introduction]
*[http://hubblesite.org/gallery/behind_the_pictures/meaning_of_color/index.shtml Color in Hubble images]
*[http://www.astro.ufl.edu/~oliver/ast3722/ast3722.htm Techniques of Observational Astronomy]

[[Category:Astronomy]]
[[Category:Astronomy Project]]
[[Category:Learning activities]]