Experiment with CCD Camera Images - Revision history

WikiSysop at 02:12, 3 October 2015

2015-10-03T02:12:17Z

← Older revision		Revision as of 02:12, 3 October 2015
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	<center>		<center>
	http://www.astro.louisville.edu/~~js9~~/js9_ngc2070_tarantula_rgb.html		http://www.astro.louisville.edu/js9_examples/js9_ngc2070_tarantula_rgb.html
	</center>		</center>

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	http://www.astro.louisville.edu/~~js9~~/js9_orion_rgb.html		http://www.astro.louisville.edu/js9_examples/js9_orion_rgb.html
	</center>		</center>

WikiSysop at 03:45, 5 November 2014

2014-11-05T03:45:04Z

← Older revision		Revision as of 03:45, 5 November 2014
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	For an astronomer, an image is not necessarily a pretty picture. Indeed the information in each image usually goes far beyond what you can see at first look. Image processing is the technique by which an image can be transformed to reveal (or suppress) selected features, or to extract quantitative information in other forms.		For an astronomer, an image is not necessarily a pretty picture. Indeed the information in each image usually goes far beyond what you can see at first look. Image processing is the technique by which an image can be transformed to reveal (or suppress) selected features, or to extract quantitative information in other forms.

	Often we need specially designed programs in astronomy to acquire, analyze, and modify images. In this activity you will use a web-based Java version of a program called "DS9", which may be a familiar name for Star Trek fans. For more information, and a version you can install on most computers, visit the ~~website~~ of the research group that maintains the software.		Often we need specially designed programs in astronomy to acquire, analyze, and modify images. In this activity you will use a web-based Java version of a program called "DS9", which may be a familiar name for Star Trek fans. For more information, and a version you can install on most computers, visit the websites of the research group that maintains the software.

	<center>		<center>
	[http://hea-www.harvard.edu/RD/ds9/ SAOImage ds9]		[http://hea-www.harvard.edu/RD/ds9/ SAOImage ds9 software to run on your computer]

			[http://js9.si.edu/ SAOImage js9 runs in your browser]
	</center>		</center>

	For our purposes we will provide a website ~~that provide the software running in a browser~~ so that you do not have to install anything. You will need a fairly modern ~~brower~~ for this, ~~preferrably~~ Firefox or Chrome, but it should work even on or phone or tablet running IoS or Android. Your comments and suggestions ~~in the discussion group~~ would be appreciated~~, but this~~ is a new way of doing this for us to.		For our purposes we will provide a website so that you do not have to install anything. You will need a fairly modern browser for this, preferably Firefox or Chrome, but it should work even on or phone or tablet running IoS or Android. Your comments and suggestions would be appreciated because is a new way of doing this for us to.

WikiSysop: /* Orion */

2014-03-31T06:29:58Z

Orion

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	''8. What is the NGC number of the nebula centered approximately on RA 05:25:15 Declination -04:53:12?''		''8. What is the NGC number of the nebula centered approximately on RA 05:35:15 Declination -04:53:12?''

WikiSysop: /* Make a Color Composite */

2014-02-18T10:07:49Z

Make a Color Composite

← Older revision		Revision as of 10:07, 18 February 2014
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	''1. What are the x and y coordinates of the red star that is close to the center of the Tarantula? "		''1. What are the x and y coordinates of the red star that is close to the center of the Tarantula?''

WikiSysop: /* Make a Color Composite */

2014-02-18T10:07:18Z

Make a Color Composite

← Older revision		Revision as of 10:07, 18 February 2014
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	Look around this image and you should be able to find a few stars at are much redder than the others. These are stars that are brighter in the "R" filter than they are in the B and V filters. Stars of this type, that are red and very luminous, are typically red giant stars that have aged off the main sequence, that is, these are dying stars. You can see now that by using different filters, and managing how data are displayed, you can study the properties of individual stars in a cluster like the one at the center of the Tarantula nebula.		Look around this image and you should be able to find a few stars at are much redder than the others. These are stars that are brighter in the "R" filter than they are in the B and V filters. Stars of this type, that are red and very luminous, are typically red giant stars that have aged off the main sequence, that is, these are dying stars. You can see now that by using different filters, and managing how data are displayed, you can study the properties of individual stars in a cluster like the one at the center of the Tarantula nebula.


	''1. What are the x and y coordinates of the red star that is close to the center of the Tarantula? "		''1. What are the x and y coordinates of the red star that is close to the center of the Tarantula? "


	''2. There are also some other somewhat fainter red stars off center that you may need to use the panner to find. Where are they? Some stars are a little more blue than white too, but they are harder to identify by eye.''		''2. There are also some other somewhat fainter red stars off center that you may need to use the panner to find. Where are they? Some stars are a little more blue than white too, but they are harder to identify by eye.''

WikiSysop: /* Compare to the Sky */

2014-02-18T10:06:48Z

Compare to the Sky

← Older revision		Revision as of 10:06, 18 February 2014
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	We need to see what this nebula looks like in the Digital Sky Survey that is a reference archive of the whole sky. One way you can access this through Sky-Map with the web site		We need to see what this nebula looks like in the Digital Sky Survey that is a reference archive of the whole sky. One way you can access this through Sky-Map with the web site


	<center>		<center>

WikiSysop: /* Compare to the Sky */

2014-02-18T10:06:33Z

Compare to the Sky

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	Once you are in that site, enter ''Tarantula'' in the search box and you'll see an image of the nebula in the Large Magellanic Cloud. Compare that with your image and see if you can figure out how your image must be transformed to match the north up and west to the right standard. This is the sky as you would see it by eye, looking up and facing south in the southern hemisphere. West would be on your right, east on your left, north up and behind you, south (and the south celestial pole) down in front of you. Images taken with telescopes can have an aribitrary orientation, and even be flipped up-down or left-right.		Once you are in that site, enter ''Tarantula'' in the search box and you'll see an image of the nebula in the Large Magellanic Cloud. Compare that with your image and see if you can figure out how your image must be transformed to match the north up and west to the right standard. This is the sky as you would see it by eye, looking up and facing south in the southern hemisphere. West would be on your right, east on your left, north up and behind you, south (and the south celestial pole) down in front of you. Images taken with telescopes can have an aribitrary orientation, and even be flipped up-down or left-right.


	''3. Which way is north and which way is west in these images?''		''3. Which way is north and which way is west in these images?''


	The Tarantula Nebula is about 170,000 light years away, in another galaxy. It's as far as our telescopes can pick out individual stars at birth, and at that mostly the brightest ones. You'll notice some stars in the image are very red. These are most likely red giants, massive stars that have already used their supply of hydrogen in their core, and are evolving toward becoming a supernova.		The Tarantula Nebula is about 170,000 light years away, in another galaxy. It's as far as our telescopes can pick out individual stars at birth, and at that mostly the brightest ones. You'll notice some stars in the image are very red. These are most likely red giants, massive stars that have already used their supply of hydrogen in their core, and are evolving toward becoming a supernova.

WikiSysop: /* Orion */

2014-02-18T10:06:11Z

Orion

← Older revision		Revision as of 10:06, 18 February 2014
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	Repeat what we did with the Tarantula, assigning R to red, V to green, and B to blue but using a log scale rather than a linear scale. Adjust the display so that the background is black and the stars are largely white. Part of the Orion Nebula will be white where dust is scattering starlight. However much of it will be another color from the hydrogen gas excited by a hot star at the center.		Repeat what we did with the Tarantula, assigning R to red, V to green, and B to blue but using a log scale rather than a linear scale. Adjust the display so that the background is black and the stars are largely white. Part of the Orion Nebula will be white where dust is scattering starlight. However much of it will be another color from the hydrogen gas excited by a hot star at the center.


	''6. What color is the emitted by this gas?''		''6. What color is the emitted by this gas?''


	For the Orion images we have added celestial coordinates to the data, and as you move the cursor around the image you will see the coordinates change. There are (x,y) values indicating which pixel is selected, and (right ascension, declination) values indicating where in the sky that pixel is looking. You'll see numbers like FK5(05:36:40, -05:19:26). "FK5" is a standard way of calibrating astronomical coordinates, the first set of numbers is the right ascension in hours, minutes and seconds of time, and the second set of numbers is the declination in degrees, minutes and seconds of arc.		For the Orion images we have added celestial coordinates to the data, and as you move the cursor around the image you will see the coordinates change. There are (x,y) values indicating which pixel is selected, and (right ascension, declination) values indicating where in the sky that pixel is looking. You'll see numbers like FK5(05:36:40, -05:19:26). "FK5" is a standard way of calibrating astronomical coordinates, the first set of numbers is the right ascension in hours, minutes and seconds of time, and the second set of numbers is the declination in degrees, minutes and seconds of arc.
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	''7. Identify this star by name and location.''		''7. Identify this star by name and location.''


	The easiest way is to use the on-line sky map:		The easiest way is to use the on-line sky map:

WikiSysop: /* Orion */

2014-02-18T10:05:37Z

Orion

← Older revision		Revision as of 10:05, 18 February 2014
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	The easiest way is to use the on-line sky map:		The easiest way is to use the on-line sky map:

			<center>
	http://www.sky-map.org/		http://www.sky-map.org/
			</center>

	When the page of this map service opens, put "M42" in the search box and you'll be taken to the Orion Nebula. Use the zoom, and move the cursor around to see how the right ascension and declination change across this map. Find the the star that has the same coordinates as the one our image. You'll notice the pattern of stars too. The image of Orion on the web is much "deeper", that is, it shows more of the nebula, but the longer exposure also obscures the fainter stars within the nebula and hides their colors.		When the page of this map service opens, put "M42" in the search box and you'll be taken to the Orion Nebula. Use the zoom, and move the cursor around to see how the right ascension and declination change across this map. Find the the star that has the same coordinates as the one our image. You'll notice the pattern of stars too. The image of Orion on the web is much "deeper", that is, it shows more of the nebula, but the longer exposure also obscures the fainter stars within the nebula and hides their colors.

	Just north of M42, the bright part of the Orion Nebula, there is a fainter nebula surrounding some stars. Use Sky-Map to find the NGC designation of this nebula.		Just north of M42, the bright part of the Orion Nebula, there is a fainter nebula surrounding some stars. Use Sky-Map to find the NGC designation of this nebula.


	''8. What is the NGC number of the nebula centered approximately on RA 05:25:15 Declination -04:53:12?''		''8. What is the NGC number of the nebula centered approximately on RA 05:25:15 Declination -04:53:12?''
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	Looking at our image of Orion, run the cursor up and down and notice how the declination changes. It is around -05:20 at the center, that is -5 degrees and 20 minutes of arc. There are 60 minutes of arc in a degree, so 20 minutes is 20/60 or 0.33 degrees. That is, close to the center the declination is -5.33 degrees. Now move the cursor up and down and look at the range of angles from the northernmost to the southermost part of the bright nebula at the center.		Looking at our image of Orion, run the cursor up and down and notice how the declination changes. It is around -05:20 at the center, that is -5 degrees and 20 minutes of arc. There are 60 minutes of arc in a degree, so 20 minutes is 20/60 or 0.33 degrees. That is, close to the center the declination is -5.33 degrees. Now move the cursor up and down and look at the range of angles from the northernmost to the southermost part of the bright nebula at the center.


	''9. How many minutes of arc from top to bottom is the angle in the sky covered by the Orion nebula? Convert that to degrees too by dividing by 60. Compare it to the full Moon, which is nearly 0.5 degrees across.''		''9. How many minutes of arc from top to bottom is the angle in the sky covered by the Orion nebula? Convert that to degrees too by dividing by 60. Compare it to the full Moon, which is nearly 0.5 degrees across.''


	Now do the same thing for the entire image.		Now do the same thing for the entire image.


	''10. From top to bottom, how large an angle on the sky does this image of Orion cover?''		''10. From top to bottom, how large an angle on the sky does this image of Orion cover?''

WikiSysop: /* Compare the Infrared */

2014-02-18T10:04:46Z

Compare the Infrared

← Older revision		Revision as of 10:04, 18 February 2014
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	''4. What are the coordinates of the star that stands out as bright red now? Make a note of the "image(x,y)" location which you'll use when you report your results.''		''4. What are the coordinates of the star that stands out as bright red now? Make a note of the "image(x,y)" location which you'll use when you report your results.''


	Let's compare the two images you have made.		Let's compare the two images you have made.