PMT Star Tracker

<body topmargin=0 leftmargin=0 marginheight=0 marginwidth=0> <table cellpadding=0 cellspacing=0 border=0><tr> <td valign="top" height=90 BGCOLOR="#006699" TEXT="#080000" background="1fcfd5a3.jpg"> <div> <FONT SIZE="5" COLOR="#000000" FACE="Arial" ><B>BIT Company</B></FONT><B>    </B><B> |    </B><A HREF="id83.htm" TARGET="_top" TITLE="Nuclear/Photometric Instruments"><U><B> </B></U></A><A HREF="id83.htm" TARGET="_top" TITLE="Nuclear/Photometric Instruments"><U><B>Index</B></U></A></div> <bR> <div> </div> </td> </tr><tr> <td valign="top" height=390 BGCOLOR="#FFFFFF" TEXT="#080000"> <div> <B>PMT Star Tracker</B></div> <div> <IMG SRC="2ae90cd0.jpg" border=0 width="400" height="205" ALIGN="BOTTOM" HSPACE="0" VSPACE="0"></div> <bR> <div> <B>Automatic optical tracking of stellar objects, satellites, and planets has classically been available to the military and well endowed research institutions. In the case of astronomy, tracking for the "low priced spread" still consists of synchronous drives and an accurate orientation of the telescope's equatorial mounting. This is basically OK for a fixed assembly if one is willing to manually correct for the perturbations of the atmosphere, planetary axis wobble, and imperfect equipment alignment.</B></div> <bR> <div> <B>Amateur astronomers, high schools, and smaller colleges do not have big budjets for the more sophisticated hardware, and in many cases rely on field trips to get out of city lights for special events. Setting up field portable telescopes is a bit tedious so the approach with this device was to provide ease of precise tracking for time exposures, be inexpensive to construct, and operate with 12 Volt field power.</B></div> <bR> <DIV ALIGN="LEFT"></DIV> <div> <B>DESCRIPTION</B></div> <bR> <div> <B>The Star Tracker utilizes a trio of low cost photomultipliers, a four-way beam splitter, an integral high voltage power supply, and a two dimensional processing matrix to generate X and Y error signals to steer small servo motors on the telescope. In addition, LED displays are provided for quadrant lock information and signal strength. The operating procedure is very simple: locate the object to be tracked through the viewfinder eyepiece with the vernier controls, then switch the servos to Track. Special effort was put into assuring that the components required to construct this device are low cost and easily available. With the exception of the photomultiplier beam splitter, all parts are available through conventional component houses. The use of the triad rather than the more usual quad of sensors resulted in cost and size reduction with no loss of signal-to-noise due to the additional light available.The viewfinder beam splitting mirror has an elliptical center section to reflect a portion of the incoming light to the eyepiece and the majority to the PMT beam splitter. Information on construction of the beam splitters is available on request.</B></div> <bR> <div> <B><IMG SRC="2df58b50.jpg" border=0 width="600" height="437" ALIGN="BOTTOM" HSPACE="0" VSPACE="0"></B></div> <bR> <div> <A HREF="id17.htm" TARGET="_top" TITLE="Contact Us"><U><B>Contact us</B></U></A></div> <bR> <div> <B>Back to </B><FONT SIZE="3" COLOR="#0000FF" FACE="Arial" ><A HREF="id83.htm" TARGET="_top" TITLE="Nuclear/Photometric Instruments"><U><B>index</B></U></A></FONT></div> <bR> </td> </tr></table></body>