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	<title>90 MilliMeters &#187; Observation Notes</title>
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	<link>http://www.90mm.us</link>
	<description>Backyard Astronomy with Small Telescopes</description>
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		<title>Shadow of solar eclipse on planet earth</title>
		<link>http://www.90mm.us/2010/07/14/shadow-of-solar-eclipse-on-planet-earth/</link>
		<comments>http://www.90mm.us/2010/07/14/shadow-of-solar-eclipse-on-planet-earth/#comments</comments>
		<pubDate>Thu, 15 Jul 2010 00:36:32 +0000</pubDate>
		<dc:creator>Dan</dc:creator>
				<category><![CDATA[Observation Notes]]></category>

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		<title>Amateur Astronomy Sky This Week for June 13 to 19, 2010</title>
		<link>http://www.90mm.us/2010/07/10/amateur-astronomy-sky-this-week-for-june-13-to-19-2010/</link>
		<comments>http://www.90mm.us/2010/07/10/amateur-astronomy-sky-this-week-for-june-13-to-19-2010/#comments</comments>
		<pubDate>Sat, 10 Jul 2010 22:09:15 +0000</pubDate>
		<dc:creator>Dan</dc:creator>
				<category><![CDATA[Observation Notes]]></category>

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		<title>April 2010 is Global Astronomy Month</title>
		<link>http://www.90mm.us/2010/04/08/april-2010-is-global-astronomy-month/</link>
		<comments>http://www.90mm.us/2010/04/08/april-2010-is-global-astronomy-month/#comments</comments>
		<pubDate>Thu, 08 Apr 2010 12:45:48 +0000</pubDate>
		<dc:creator>Dan</dc:creator>
				<category><![CDATA[Observation Notes]]></category>

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		<title>Bode’s Nebulae</title>
		<link>http://www.90mm.us/2010/03/14/bode%e2%80%99s-nebulae/</link>
		<comments>http://www.90mm.us/2010/03/14/bode%e2%80%99s-nebulae/#comments</comments>
		<pubDate>Sun, 14 Mar 2010 21:14:00 +0000</pubDate>
		<dc:creator>Dan</dc:creator>
				<category><![CDATA[Observation Notes]]></category>
		<category><![CDATA[Astronomy]]></category>
		<category><![CDATA[Deep Sky]]></category>
		<category><![CDATA[M81]]></category>
		<category><![CDATA[M82]]></category>
		<category><![CDATA[telescopes]]></category>
		<category><![CDATA[Ursa Major]]></category>

		<guid isPermaLink="false">http://www.90mm.us/?p=219</guid>
		<description><![CDATA[Ursa Major holds a few deep sky objects for observers with small telescopes that are visible even under moderately light polluted skies. Bode’s Nebulae, better known as M81 and M82, are two such objects and both are readily visible in a low power eyepiece. Messier 81 was first discovered by Johann Elert Bode in 1774. [...]]]></description>
			<content:encoded><![CDATA[<p><a href="http://www.90mm.us/wp-content/uploads/2010/03/heic0801i.jpg"><img class="alignleft size-medium wp-image-237" title="heic0801i" src="http://www.90mm.us/wp-content/uploads/2010/03/heic0801i-300x206.jpg" alt="" width="300" height="206" /></a>Ursa Major holds a few deep sky objects for observers with small telescopes that are visible even under moderately light polluted skies. Bode’s Nebulae, better known as M81 and M82, are two such objects and both are readily visible in a low power eyepiece. Messier 81 was first discovered by Johann Elert Bode in 1774. Consequently, the pair of galaxies (M81 &amp; M82) is sometimes referred to as &#8220;Bode&#8217;s Nebulae&#8221;. In 1779, Pierre Méchain and Charles Messier re-identified Bode&#8217;s object, which was subsequently listed in the Messier Catalogue. M81 &amp; M82 are located approximately 10° northwest of Alpha Ursae Majoris making this an easy target to locate. You can download a <a href="http://www.90mm.us/PDF/M81_M82_finder.pdf">Telrad finder chart here</a> or a more <a href="http://www.90mm.us/PDF/m81_m82_detail.pdf" target="_blank">detailed finder chart here.</a></p>
<p>As with any telescope at low power, the <a href="http://www.mydeepsky.net/orion-astroview-90mm-eq-refractor-telescope/" target="_blank">90mm</a> at 40x shows these two galaxies at either edge of the field of view. M81 looks like an oval of defused light radiating out from the bright center while M82 appears as a thin, elongated, evenly distributed silver of light. Increasing the power to 71x improves the contrast and I can detect a dark dust lane in M81 about half way from the center to the faint outer edge. Stepping up to the 150mm at 54x the spiral nature of M81 becomes evident. Since this object can handle higher magnifications, I dropped in my <a href="http://www.mydeepsky.net/meade-20mm-series-4000-qx-1-25-wide-angle-eyepiece-with-70-degree-field-of-view/" target="_blank">20mm eyepiece</a> coupled with a 2x Barlow for 76x. Now I can see greater detail in the spiral arms of this grand galaxy. Amazing how just a small amount of magnification can improve the view.</p>
<p>In the <a href="http://www.mydeepsky.net/celestron-advanced-series-c6-r-gt-354-x-150mm-telescope/" target="_blank">150mm</a> at 38x, M82 is an elongated glow that is brighter toward the western edge. I bumped the power up to 76x for a better view but was unable to detect any detail. The light is more evenly distributed across the surface at this power and the galaxy fills the eyepiece.</p>
<p>If you observe from an urban location where light pollution is an issue, such as here at the 90mm observatory, these objects will benefit from using a narrow-band filter. Narrow-band filters pass the critical hydrogen-beta and ionized oxygen wavelengths, while blocking out the remainder of the visual spectrum. They also increase the contrast of emission and planetary nebulae, revealing detail that is often washed out by background sky glow.</p>
<p>When observing M81 &amp; M82, as with any deep sky object, try using different eyepieces and eyepiece/Barlow combinations to see which gives the best view. Take time to study the object for a few minutes, you’ll be surprised at the amount of detail you’ll start to see. Don’t forget about<a href="http://en.wikipedia.org/wiki/Averted_vision" target="_blank"> averted vision</a>. A good amount of detail can be seen with this observing technique.</p>
<p>Until next time, clear skies.<br />
-Dan</p>
<p>[<a href="http://cmp.ly/5/mqf4ye" target="_blank">Disclosure</a>]</p>
<address>I have a marketing connection to a brand, topic or product herein. Through the use of affiliate links contained herein, I may collect fees from purchases made.</address>
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		<title>Jupiter and the Great Red Spot</title>
		<link>http://www.90mm.us/2009/09/29/jupiter-and-the-great-red-spot/</link>
		<comments>http://www.90mm.us/2009/09/29/jupiter-and-the-great-red-spot/#comments</comments>
		<pubDate>Wed, 30 Sep 2009 02:39:24 +0000</pubDate>
		<dc:creator>Dan</dc:creator>
				<category><![CDATA[Observation Notes]]></category>
		<category><![CDATA[Great Red Spot]]></category>
		<category><![CDATA[Jupiter]]></category>
		<category><![CDATA[seeing]]></category>
		<category><![CDATA[transit]]></category>
		<category><![CDATA[transparency]]></category>

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		<description><![CDATA[One of the interesting features about Jupiter is the Great Red Spot (GRS). The GRS is a vast storm, spinning like a cyclone. I learned that the GRS would transit on September 28, 2009 around 11:17 PM EDT (you can get that information here) so I setup my DS-90 and got ready to watch. I know that [...]]]></description>
			<content:encoded><![CDATA[<p>One of the interesting features about Jupiter is the <a href="http://en.wikipedia.org/wiki/Great_Red_Spot#Great_Red_Spot" target="_blank">Great Red Spot (GRS).</a> The GRS is a vast storm, spinning like a cyclone. I learned that the GRS would transit on September 28, 2009 around 11:17 PM EDT (<a href="http://www.skyandtelescope.com/observing/objects/planets/3304091.html" target="_blank">you can get that information here</a>) so I setup my DS-90 and got ready to watch. I know that this happens often enough that it shouldn&#8217;t be a big deal but, I never took tje time to really look at the event. The moon on this night was waxing gibbous and shining brightly just left of Jupiter.</p>
<p>I focused on Jupiter at x40 and then dropped in my 11mm Plossl for x90. Much to my disappointment, the planet seemed to boil. This is an effect of the atmosphere known as &#8220;Seeing&#8221;. While the sky was transparent, the view was poor. You can learn more about <a href="http://www.oneminuteastronomer.com/2008/08/18/clear/" target="_blank">Seeing and Transparency here</a>.</p>
<p>As I continued to look, waiting for breaks in the turbulent atmosphere, I caught a few glimpses of the GRS which appeared as a light grayish oval at x90. At x117 the seeing was just a nightmare so I stayed at x90 for the night. </p>
<p>I will try to watch this event again in the coming weeks.</p>
<p>Clear Skise,</p>
<p>-Dan</p>
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