VLA Radio telescope

<body topmargin=0 leftmargin=0 marginheight=0 marginwidth=0> <table cellpadding=0 cellspacing=0 border=0><tr> <td valign="top" colspan=2 height=22 BGCOLOR="#330099" TEXT="#080000" bgproperties="fixed" background="040000d2erkqrf.gif"> <div> Derby and District Astronomical Society - Aries Magazine</div> <div> </div> </td> </tr><tr> <td valign="top" width=145 BGCOLOR="#333399" TEXT="#080000" background="03fa2c00erkjzj.gif"> <div> <A HREF="index.htm" TARGET="_top" TITLE="Aries Astronomy magazine on line Derby a"><U>HOME</U></A></div> <bR> <div> <A HREF="editorial.htm" TARGET="_top" TITLE="Aries on line Autumn 2000 editorial"><U>Aries on line - Autumn 2000 editorial</U></A></div> <div> <A HREF="double_stars.htm" TARGET="_top" TITLE="Double Stars"><U>Double Stars</U></A></div> <div> <A HREF="id25.htm" TARGET="_top" TITLE="Pluto and Back for bed"><U>Pluto and Back for bed</U></A></div> <div> <B>VLA Radio telescope</B></div> <div> <A HREF="id27.htm" TARGET="_top" TITLE="Beginners nebulae"><U>Beginners - nebulae</U></A></div> <div> <A HREF="id28.htm" TARGET="_top" TITLE="Forgotten Astronauts"><U>Forgotten Astronauts</U></A></div> <div> <A HREF="id29.htm" TARGET="_top" TITLE="Sky Scene Oct Dec 2000"><U>Sky Scene Oct - Dec 2000</U></A></div> <bR> </td> <td valign="top" height=458 BGCOLOR="#FFFFFF" TEXT="#080000" background="06a92963.gif"> <div> <I>Aries Astronomy magazine on line- Derby and District Astronomical Society</I></div> <div> <IMG SRC="04107040.gif" border=0 width="263" height="4" ALIGN="BOTTOM" HSPACE="0" VSPACE="0"></div> <bR> <div> Observatories of the world:</div> <div> 1. The VLA radiotelescope in New Mexico.</div> <div> <I><B>Author: Steve Parkins</B></I></div> <bR> <div> No. 1 in a series of I don't know how many!</div> <bR> <div> This first article concerns one of the most remarkable radio telescopes yet built, (no-one said we have to start the series with a big mirror), the V.L.A. or Very Large Array radio telescope. This was one of the most ambitious ventures in astronomy when it was designed and built in the late 70`s.</div> <DIV ALIGN="LEFT"></DIV> <div> <TABLE BORDER="2" CELLPADDING="2" CELLSPACING="1" WIDTH="426" BORDERCOLORLIGHT="#C0C0C0" BORDERCOLORDARK="#808080" FRAME="BOX" RULES="ALL" ALIGN="BOTTOM" HSPACE="0" VSPACE="0" > <tR> <tD VALIGN=TOP HEIGHT= 16 ><NOBR><div> <A HREF="http://www.nrao.edu)" TARGET="_top" TITLE="http://www.nrao.edu)"><U>For images, visit the NRAO site. Click anywhere on this text to go there.</U></A></div> </NOBR></tD> </tR> </TABLE></div> <div> It is located on an open area called the Plains of St. Augustin near the small town of Magdalena in the depths of New Mexico. The nearest town of any size is Socorro who's other claim to fame is it's high degree of U.F.O activity, ( we try to cater for all sorts here in Aries). Anyone who as seen the film 2010 or Contact will have seen plenty of the VLA as the opening scenes were filmed there.</div> <bR> <div> The whole telescope consists of 27 dishes, 81 feet in diameter mounted on 3 rail tracks in a `Y shape configuration a total of about 22 miles across on the flat plain. This allows the dishes to be spread far apart or bunched close together depending on the type of observation required.</div> <bR> <DIV ALIGN="LEFT"></DIV> <div> <IMG SRC="07f10a00.gif" border=0 width="272" height="160" ALIGN="BOTTOM" HSPACE="0" VSPACE="0"></div> <bR> <div> The dishes are not re-positioned regularly, they stay in one of 4 configurations for about 4 months and then take a couple of days to re-arrange. Since each dish weighs 230 tons a heavy duty transporter is required to do the job.</div> <bR> <div> The maximum resolution of the system is an impressive 0.04 arcseconds, equivalent to a golf ball at a distance of 100 miles. The bandwidth of the system is between 300 and 50 000 Mhz although this is due to be increased in the near future. The VLA works on the principle of the interferometer similar to the Jodrell Bank ‘MERLIN’ system which covers a large part of England. </div> <bR> <div> It was originally built using what is known as a ‘waveguide‘. This is a hollow steel tube with an inner surface of copper wire which conducted the information received by the dishes to the equipment at the control centre. It was buried underground and ran alongside the railway tracks but as part of the current expansion plans, it is to be replaced by an up to date fibre optic data transfer system. There are also plans to increase the number of dishes themselves to 40. The upgrade of the VLA is one of the recommendations of the American National Research Council to the U.S. government that they produce every ten years, others being the suggested go-ahead of a Hubble Space telescope replacement in solar orbit and a massive 30 metre segmented mirror ground based telescope.</div> <bR> </td> </tr></table></body>