Difference between revisions of "October 22, 2004"
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| − | <tr><td><div align="center" class="main_sm">Image Credit: [mailto:frankb@celestialwonders.com Frank Barrett]</p> | + | <tr><td><div align="center" class="main_sm"><p>Image Credit: [mailto:frankb@celestialwonders.com Frank Barrett]</p> |
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<p align="left">Most images of the Moon are taken in visible light, which is where human eyes are most sensitive. But here (right) is one taken through a hydrogen-alpha filter which is normally used to image the Sun in a narrow red part (656.3 nm) of the visible spectrum. I compare this image to Frank's previous [[February_16,_2004|LPOD]] (and [http://antwrp.gsfc.nasa.gov/apod/ap031212.html APOD]!) image on the left which was taken in visible light. I enhanced both images, making comparison a little uncertain. Nevertheless, there are a few interesting comparisons. first, the two images look quite similar - probably because the Sun is quite bright at H-alpha wavelengths, contributing significantly to its total visible brightness. Second, there are some differences. In H-alpha, Mare Nectaris is more muted - the rays that cross it are more strongly depicted. The same seems true for maria Fecunditatis and Crisium - both are low in titanium. Additionally, the dark mare patches south of Mare Serenitatis have more contrast on the H-alpha image. Frank's image suggests that amateurs may want to experiment imaging the Moon thru different color filters to explore compositional differences in the maria. </p> | <p align="left">Most images of the Moon are taken in visible light, which is where human eyes are most sensitive. But here (right) is one taken through a hydrogen-alpha filter which is normally used to image the Sun in a narrow red part (656.3 nm) of the visible spectrum. I compare this image to Frank's previous [[February_16,_2004|LPOD]] (and [http://antwrp.gsfc.nasa.gov/apod/ap031212.html APOD]!) image on the left which was taken in visible light. I enhanced both images, making comparison a little uncertain. Nevertheless, there are a few interesting comparisons. first, the two images look quite similar - probably because the Sun is quite bright at H-alpha wavelengths, contributing significantly to its total visible brightness. Second, there are some differences. In H-alpha, Mare Nectaris is more muted - the rays that cross it are more strongly depicted. The same seems true for maria Fecunditatis and Crisium - both are low in titanium. Additionally, the dark mare patches south of Mare Serenitatis have more contrast on the H-alpha image. Frank's image suggests that amateurs may want to experiment imaging the Moon thru different color filters to explore compositional differences in the maria. </p> | ||
<blockquote> | <blockquote> | ||
| − | <p align="right">— [mailto:tychocrater@yahoo.com Chuck Wood]</blockquote> | + | <p align="right">— [mailto:tychocrater@yahoo.com Chuck Wood]</p></blockquote> |
<p align="left"><b>Technical Details:</b><br> | <p align="left"><b>Technical Details:</b><br> | ||
Right image: Sept 25, 2004. Orion 80 mm ED + SBIG ST7E camera + Schuler 10nm H-alpha filter. Mosaic of two 110 ms exposures. CAW ehhanced with unsharp mask. Left image: Dec 9, 2003. Celestron C8 SCT with a SBIG ST-7E ccd camera and an Orion Moon Filter to capture 18 frames at 110 ms each which were mosaicked into this image.</p> | Right image: Sept 25, 2004. Orion 80 mm ED + SBIG ST7E camera + Schuler 10nm H-alpha filter. Mosaic of two 110 ms exposures. CAW ehhanced with unsharp mask. Left image: Dec 9, 2003. Celestron C8 SCT with a SBIG ST-7E ccd camera and an Orion Moon Filter to capture 18 frames at 110 ms each which were mosaicked into this image.</p> | ||
<p><b>Related Links:</b><br> | <p><b>Related Links:</b><br> | ||
[http://www.celestialwonders.com/Latest.html Frank's Celestial Wonders] | [http://www.celestialwonders.com/Latest.html Frank's Celestial Wonders] | ||
| + | </p> | ||
<p align="left"><b>Tomorrow's LPOD: </b> Imaging the First Lunar Photographer</p> | <p align="left"><b>Tomorrow's LPOD: </b> Imaging the First Lunar Photographer</p> | ||
</tr> | </tr> | ||
Revision as of 19:50, 17 January 2015
H-Alpha Moon
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Image Credit: Frank Barrett |
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H-Alpha Moon Most images of the Moon are taken in visible light, which is where human eyes are most sensitive. But here (right) is one taken through a hydrogen-alpha filter which is normally used to image the Sun in a narrow red part (656.3 nm) of the visible spectrum. I compare this image to Frank's previous LPOD (and APOD!) image on the left which was taken in visible light. I enhanced both images, making comparison a little uncertain. Nevertheless, there are a few interesting comparisons. first, the two images look quite similar - probably because the Sun is quite bright at H-alpha wavelengths, contributing significantly to its total visible brightness. Second, there are some differences. In H-alpha, Mare Nectaris is more muted - the rays that cross it are more strongly depicted. The same seems true for maria Fecunditatis and Crisium - both are low in titanium. Additionally, the dark mare patches south of Mare Serenitatis have more contrast on the H-alpha image. Frank's image suggests that amateurs may want to experiment imaging the Moon thru different color filters to explore compositional differences in the maria. Technical Details: Related Links: Tomorrow's LPOD: Imaging the First Lunar Photographer |
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