<story><title>How to Discover a Galaxy with a Telephoto Lens</title><url>http://nautil.us/issue/32/space/how-to-discover-a-galaxy-with-a-telephoto-lens</url></story><parent_chain></parent_chain><comment><author>antognini</author><text>Ultimately the reason these small telescopes are so useful for finding these faint, diffuse galaxies is because the surface brightness of an object is independent of the collecting area.  Larger optical telescopes have much better resolution, so the amount of light detected from a diffuse galaxy is fairly similar per pixel to a little telescope like Dragonfly.  But a little telescope costs probably about three orders of magnitude less than a big telescope and you can afford to hammer a particular target night after night, whereas you&amp;#x27;d be lucky to have an hour of time on a large telescope.&lt;p&gt;There are a number of other great small-telescope projects in different areas of astronomy.  The one closest to my heart is ASAS-SN (pronounced &amp;quot;Assassin&amp;quot;) since it was the idea of the professor across the hall from me when I was at Ohio State and an officemate of mine was the one who spent much of his graduate career building it.  The idea was to get a little telescope (like Dragonfly it&amp;#x27;s pretty much just a telephoto lens with a detector attached) and then have it look at ~1&amp;#x2F;3 of the sky every night.  That way if a supernova goes off in a nearby galaxy (or there is some other transient) it&amp;#x27;s discovered within a few days.  Just this month they published a paper on the discovery of the brightest supernova ever observed [1].  They currently discover more supernovae than all other groups combined (including amateur astronomers, who are a formidable force!).&lt;p&gt;There&amp;#x27;s another small-telescope project built to search for exoplanets called KELT (the Kilodegree Extremely Little Telescope).  Since transiting planets are generally detected around bright stars (at least in apparent magnitude), telescope size is not so important for their discovery.  In fact, having too big a telescope can be an issue because the host star is so bright that it saturates the detector.  So far they&amp;#x27;ve discovered (I think) somewhere around a dozen planets, though my favorite is Kelt-4Ab because it&amp;#x27;s in a triple star system (and also because I&amp;#x27;m on the paper) [2].&lt;p&gt;[1]: &lt;a href=&quot;https:&amp;#x2F;&amp;#x2F;en.wikipedia.org&amp;#x2F;wiki&amp;#x2F;ASASSN-15lh&quot; rel=&quot;nofollow&quot;&gt;https:&amp;#x2F;&amp;#x2F;en.wikipedia.org&amp;#x2F;wiki&amp;#x2F;ASASSN-15lh&lt;/a&gt;&lt;p&gt;[2]: &lt;a href=&quot;http:&amp;#x2F;&amp;#x2F;arxiv.org&amp;#x2F;abs&amp;#x2F;1510.00015&quot; rel=&quot;nofollow&quot;&gt;http:&amp;#x2F;&amp;#x2F;arxiv.org&amp;#x2F;abs&amp;#x2F;1510.00015&lt;/a&gt;</text></comment>
<story><title>How to Discover a Galaxy with a Telephoto Lens</title><url>http://nautil.us/issue/32/space/how-to-discover-a-galaxy-with-a-telephoto-lens</url></story><parent_chain></parent_chain><comment><author>acqq</author><text>The paper by Dragonfly designers:&lt;p&gt;&lt;a href=&quot;http:&amp;#x2F;&amp;#x2F;arxiv.org&amp;#x2F;abs&amp;#x2F;1401.5473&quot; rel=&quot;nofollow&quot;&gt;http:&amp;#x2F;&amp;#x2F;arxiv.org&amp;#x2F;abs&amp;#x2F;1401.5473&lt;/a&gt;&lt;p&gt;It&amp;#x27;s not &amp;quot;just&amp;quot; the off-the shelf lenses and cameras, although the lenses are really the crucial part and they are very cleverly used, achieving up to then never achieved low light scattering. At the time it used only 8 lenses, the telescope had weight of more than 100 kg.&lt;p&gt;Here&amp;#x27;s the robotic mount they used then:&lt;p&gt;&lt;a href=&quot;http:&amp;#x2F;&amp;#x2F;www.bisque.com&amp;#x2F;sc&amp;#x2F;pages&amp;#x2F;ParamountMEII.aspx&quot; rel=&quot;nofollow&quot;&gt;http:&amp;#x2F;&amp;#x2F;www.bisque.com&amp;#x2F;sc&amp;#x2F;pages&amp;#x2F;ParamountMEII.aspx&lt;/a&gt;&lt;p&gt;The paper with the first results from the Dragonfly:&lt;p&gt;&lt;a href=&quot;http:&amp;#x2F;&amp;#x2F;iopscience.iop.org&amp;#x2F;article&amp;#x2F;10.1088&amp;#x2F;2041-8205&amp;#x2F;782&amp;#x2F;2&amp;#x2F;L24&amp;#x2F;meta&quot; rel=&quot;nofollow&quot;&gt;http:&amp;#x2F;&amp;#x2F;iopscience.iop.org&amp;#x2F;article&amp;#x2F;10.1088&amp;#x2F;2041-8205&amp;#x2F;782&amp;#x2F;2&amp;#x2F;L2...&lt;/a&gt;</text></comment>