{"id":346,"date":"2026-10-21T01:27:52","date_gmt":"2026-10-21T06:27:52","guid":{"rendered":"https:\/\/radio.cvastro.org\/index.php\/radio-astronomy\/"},"modified":"2026-10-21T01:27:52","modified_gmt":"2026-10-21T06:27:52","slug":"radio-astronomy","status":"publish","type":"page","link":"https:\/\/radio.cvastro.org\/","title":{"rendered":"Radio Astronomy at Hobbs Observatory"},"content":{"rendered":"\t<div class=\"cvas-site cvas-home\">\n\t\t<section class=\"hero\">\n\t\t\t<canvas class=\"hero-stars\" aria-hidden=\"true\"><\/canvas>\n\t\t\t<svg class=\"hero-ground\" viewBox=\"0 0 1600 170\" preserveAspectRatio=\"xMaxYMax slice\" aria-hidden=\"true\" focusable=\"false\"><defs><radialGradient id=\"ha-core\"><stop offset=\"0\" stop-color=\"#fff6d8\"\/><stop offset=\".35\" stop-color=\"#ffcf6b\" stop-opacity=\".9\"\/><stop offset=\"1\" stop-color=\"#ff8a3d\" stop-opacity=\"0\"\/><\/radialGradient><radialGradient id=\"ha-lobe\"><stop offset=\"0\" stop-color=\"#ffb070\" stop-opacity=\".85\"\/><stop offset=\".5\" stop-color=\"#e2509e\" stop-opacity=\".45\"\/><stop offset=\"1\" stop-color=\"#7a3cff\" stop-opacity=\"0\"\/><\/radialGradient><linearGradient id=\"ha-jet\" x1=\"0\" x2=\"1\"><stop offset=\"0\" stop-color=\"#ffb26b\" stop-opacity=\".1\"\/><stop offset=\".5\" stop-color=\"#ffe2a8\" stop-opacity=\".95\"\/><stop offset=\"1\" stop-color=\"#ffb26b\" stop-opacity=\".1\"\/><\/linearGradient><filter id=\"ha-glow\" x=\"-60%\" y=\"-60%\" width=\"220%\" height=\"220%\"><feGaussianBlur stdDeviation=\"5\"\/><\/filter><linearGradient id=\"ha-earth\" x1=\"0\" y1=\"0\" x2=\"0\" y2=\"1\"><stop offset=\"0\" stop-color=\"#0b1426\"\/><stop offset=\"1\" stop-color=\"#05080f\"\/><\/linearGradient><\/defs><g transform=\"translate(905 74) rotate(-14) scale(.78)\"><ellipse cx=\"-122\" cy=\"0\" rx=\"66\" ry=\"40\" fill=\"url(#ha-lobe)\" filter=\"url(#ha-glow)\"\/><ellipse cx=\"122\" cy=\"0\" rx=\"60\" ry=\"36\" fill=\"url(#ha-lobe)\" filter=\"url(#ha-glow)\"\/><ellipse cx=\"-122\" cy=\"0\" rx=\"30\" ry=\"17\" fill=\"#ffc48a\" opacity=\".4\" filter=\"url(#ha-glow)\"\/><ellipse cx=\"122\" cy=\"0\" rx=\"27\" ry=\"15\" fill=\"#ffc48a\" opacity=\".4\" filter=\"url(#ha-glow)\"\/><rect x=\"-112\" y=\"-1.6\" width=\"224\" height=\"3.2\" rx=\"1.6\" fill=\"url(#ha-jet)\"\/><circle r=\"15\" fill=\"url(#ha-core)\"\/><circle r=\"2.6\" fill=\"#fffbe8\"\/><\/g><text x=\"905\" y=\"128\" class=\"ha-cap\" text-anchor=\"middle\">a radio galaxy: twin jets feeding two radio lobes<\/text><g class=\"ha-path\"><path d=\"M1040 64 C1110 50 1170 48 1240 66\"\/><path d=\"M1040 80 C1150 70 1300 60 1420 74\"\/><\/g><g class=\"ha-waves\" transform=\"translate(1290 52) rotate(-24)\"><path d=\"M-30 -8 Q0 -22 30 -8\"\/><path d=\"M-46 -24 Q0 -44 46 -24\"\/><path d=\"M-62 -40 Q0 -66 62 -40\"\/><\/g><g class=\"ha-waves\" transform=\"translate(1468 60) rotate(-24)\"><path d=\"M-30 -8 Q0 -22 30 -8\"\/><path d=\"M-46 -24 Q0 -44 46 -24\"\/><path d=\"M-62 -40 Q0 -66 62 -40\"\/><\/g><g transform=\"translate(1290 158) scale(1)\"><g transform=\"translate(0 -74)\"><path d=\"M-8 4 L-20 74 L20 74 L8 4Z\" class=\"ha-mount\"\/><rect x=\"-6\" y=\"-2\" width=\"12\" height=\"10\" rx=\"2\" class=\"ha-mount\"\/><g transform=\"rotate(-24)\"><path d=\"M-62 0 Q0 38 62 0 Q0 27 -62 0Z\" class=\"ha-refl\"\/><path d=\"M-62 0 Q0 38 62 0\" class=\"ha-rim\"\/><line x1=\"-52\" y1=\"7\" x2=\"0\" y2=\"-52\" class=\"ha-leg\"\/><line x1=\"52\" y1=\"7\" x2=\"0\" y2=\"-52\" class=\"ha-leg\"\/><line x1=\"0\" y1=\"19\" x2=\"0\" y2=\"-52\" class=\"ha-leg\"\/><rect x=\"-6\" y=\"-60\" width=\"12\" height=\"11\" rx=\"2\" class=\"ha-feed\"\/><\/g><\/g><\/g><g transform=\"translate(1468 160) scale(0.92)\"><g transform=\"translate(0 -74)\"><path d=\"M-8 4 L-20 74 L20 74 L8 4Z\" class=\"ha-mount\"\/><rect x=\"-6\" y=\"-2\" width=\"12\" height=\"10\" rx=\"2\" class=\"ha-mount\"\/><g transform=\"rotate(-24)\"><path d=\"M-62 0 Q0 38 62 0 Q0 27 -62 0Z\" class=\"ha-refl\"\/><path d=\"M-62 0 Q0 38 62 0\" class=\"ha-rim\"\/><line x1=\"-52\" y1=\"7\" x2=\"0\" y2=\"-52\" class=\"ha-leg\"\/><line x1=\"52\" y1=\"7\" x2=\"0\" y2=\"-52\" class=\"ha-leg\"\/><line x1=\"0\" y1=\"19\" x2=\"0\" y2=\"-52\" class=\"ha-leg\"\/><rect x=\"-6\" y=\"-60\" width=\"12\" height=\"11\" rx=\"2\" class=\"ha-feed\"\/><\/g><\/g><\/g><path d=\"M0 150 C60 142 110 148 160 140 C220 131 260 146 330 139 C400 132 440 147 510 141 C590 134 630 148 700 142 C780 135 820 147 900 141 C980 134 1020 148 1100 142 C1170 136 1200 146 1260 143 C1330 139 1380 147 1450 142 C1510 138 1560 145 1600 141 L1600 170 L0 170 Z\" fill=\"url(#ha-earth)\"\/><\/svg>\t\t\t<div class=\"wrap hero-in\">\n\t\t\t\t<div class=\"hero-copy\">\n\t\t\t\t\t<p class=\"eyebrow\">Chippewa Valley Astronomical Society \u00b7 Radio Astronomy<\/p>\n\t\t\t\t\t<h1>Hear the universe.<\/h1>\n\t\t\t\t\t<p class=\"lead\">The Sun, the hydrogen gas between the stars, and distant galaxies all give off radio waves. At Hobbs Observatory our members listen with two 20-foot dishes, and anyone can learn how, even by building a Sun detector from a used satellite TV dish.<\/p>\n\t\t\t\t\t<div class=\"hero-btns\">\n\t\t\t\t\t\t<a class=\"cvas-btn cvas-btn-primary\" href=\"https:\/\/radio.cvastro.org\/index.php\/radio-telescope\/\">Watch the telescope live<\/a>\t\t\t\t\t\t<a class=\"cvas-btn\" href=\"https:\/\/radio.cvastro.org\/index.php\/build-a-radio-telescope\/\">Build your own<\/a>\t\t\t\t\t\t<a class=\"cvas-btn cvas-btn-ghost\" href=\"#join\">Join us<\/a>\n\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t<aside class=\"live-card\" data-live>\n\t\t\t\t\t<div class=\"lc-head\"><span class=\"lc-dot\"><\/span><span class=\"lc-state\">Connecting\u2026<\/span><span class=\"lc-age\"><\/span><\/div>\n\t\t\t\t\t<div class=\"lc-title\">Our radio telescope right now<\/div>\n\t\t\t\t\t<p class=\"lc-wait\">No reading in the last hour. This fills in by itself as soon as the observatory PC sends data.<\/p>\n\t\t\t\t\t<canvas class=\"lc-spark\" aria-label=\"Radio signal, last 60 minutes\"><\/canvas>\n\t\t\t\t\t<div class=\"lc-grid\">\n\t\t\t\t\t\t<div><span>Signal<\/span><b class=\"lc-sig\">\u2014<\/b><\/div>\n\t\t\t\t\t\t<div><span>Dish elevation<\/span><b class=\"lc-el\">\u2014<\/b><\/div>\n\t\t\t\t\t\t<div><span>Beam pointing at<\/span><b class=\"lc-dec\">\u2014<\/b><\/div>\n\t\t\t\t\t\t<div><span>At the observatory<\/span><b class=\"lc-wx\">\u2014<\/b><\/div>\n\t\t\t\t\t<\/div>\n\t\t\t\t\t<a class=\"lc-link\" href=\"https:\/\/radio.cvastro.org\/index.php\/radio-telescope\/\">Open the live telescope page \u2192<\/a>\t\t\t\t<\/aside>\n\t\t\t<\/div>\n\t\t<\/section>\n\n\t\t<section class=\"tonight\" data-tonight>\n\t\t\t<div class=\"wrap\">\n\t\t\t\t<div class=\"sec-head\"><h2>Tonight over Hobbs<\/h2><a href=\"https:\/\/radio.cvastro.org\/index.php\/night-sky\/\">Full night sky forecast \u2192<\/a><\/div>\n\t\t\t\t<div class=\"tn-grid\">\n\t\t\t\t\t<div class=\"tn-card tn-facts\">\n\t\t\t\t\t\t<div class=\"tn-f\"><span class=\"tn-k\">Fully dark<\/span><b class=\"tn-dark\">\u2014<\/b><small class=\"tn-dark-s\"><\/small><\/div>\n\t\t\t\t\t\t<div class=\"tn-f\"><span class=\"tn-k\">Moon<\/span><b class=\"tn-moon\">\u2014<\/b><small class=\"tn-moon-s\"><\/small><\/div>\n\t\t\t\t\t\t<div class=\"tn-f\"><span class=\"tn-k\">Sun today<\/span><b class=\"tn-sun\">\u2014<\/b><small class=\"tn-sun-s\"><\/small><\/div>\n\t\t\t\t\t<\/div>\n\t\t\t\t\t<div class=\"tn-card tn-wide\">\n\t\t\t\t\t\t<div class=\"cc-top\"><span class=\"tn-k\">Clouds, hour by hour<\/span><span class=\"cc-verdict\"><\/span><\/div>\n\t\t\t\t\t\t<p class=\"cc-say\">Loading the forecast\u2026<\/p>\n\t\t\t\t\t\t<div class=\"cc-row\" role=\"list\" aria-label=\"Cloud forecast for the next 12 hours\"><\/div>\n\t\t\t\t\t\t<small class=\"cc-note\"><\/small>\n\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t<\/div>\n\t\t<\/section>\n\n\t\t<section class=\"workdays\" id=\"work-days\">\n\t\t\t<div class=\"wrap two\">\n\t\t\t\t<div>\n\t\t\t\t\t<p class=\"eyebrow\">Get involved<\/p>\n\t\t\t\t\t<h2>Come out to a work day<\/h2>\n\t\t\t\t\t<p>Work days are when members build, fix and improve the dishes, feeds and receivers at Hobbs Observatory. You do not need any experience; it is the best way to learn how a radio telescope really works.<\/p>\n\t\t\t\t\t<p><a class=\"cvas-btn\" href=\"https:\/\/radio.cvastro.org\/index.php\/work-days\/\">All work days<\/a><\/p>\t\t\t\t<\/div>\n\t\t\t\t<div><div class=\"cvas-site-block cvas-wd\"><ol class=\"wd-list\"><li class=\"wd-item\" data-id=\"1\"><div class=\"wd-date\"><span class=\"wd-dow\">Sat<\/span><span class=\"wd-d\">24<\/span><span class=\"wd-m\">Oct<\/span><\/div><div class=\"wd-body\"><div class=\"wd-title\">RA Workday<\/div><div class=\"wd-when\">Saturday, October 24, 2026 \u00b7 9:00 am\u201312:00 pm CDT<\/div><div class=\"wd-loc\">Hobbs Observatory, S1 County Hwy K, Fall Creek, WI 54742<\/div><div class=\"wd-note\">Come on out. We arrive between 9:00 and 9:45 am.<\/div><a class=\"wd-ics\" href=\"https:\/\/radio.cvastro.org\/index.php\/wp-json\/cvas-ra\/v1\/workdays\/1.ics\">Add to my calendar<\/a><\/div><\/li><li class=\"wd-item\" data-id=\"2\"><div class=\"wd-date\"><span class=\"wd-dow\">Sun<\/span><span class=\"wd-d\">1<\/span><span class=\"wd-m\">Nov<\/span><\/div><div class=\"wd-body\"><div class=\"wd-title\">Daylight Savings Time ENDS<\/div><div class=\"wd-when\">Sunday, November 1, 2026 \u00b7 2:00 am\u20132:00 pm CST<\/div><div class=\"wd-note\">Turn your clocks back 1 hour! Daylight Savings Time ENDS<\/div><a class=\"wd-ics\" href=\"https:\/\/radio.cvastro.org\/index.php\/wp-json\/cvas-ra\/v1\/workdays\/2.ics\">Add to my calendar<\/a><\/div><\/li><\/ol><div class=\"wd-sub\"><strong>Keep work days on your phone.<\/strong> Subscribe once and changes and cancellations appear automatically. <a href=\"webcal:\/\/radio.cvastro.org\/index.php\/wp-json\/cvas-ra\/v1\/workdays.ics\">iPhone, Mac or Outlook<\/a> \u00b7 <a href=\"https:\/\/calendar.google.com\/calendar\/r?cid=webcal%3A%2F%2Fradio.cvastro.org%2Findex.php%2Fwp-json%2Fcvas-ra%2Fv1%2Fworkdays.ics\" target=\"_blank\" rel=\"noopener\">Google Calendar<\/a> \u00b7 <a href=\"https:\/\/radio.cvastro.org\/index.php\/wp-json\/cvas-ra\/v1\/workdays.ics\">Calendar file link<\/a><\/div><\/div><\/div>\n\t\t\t<\/div>\n\t\t<\/section>\n\n\t\t<section class=\"learn\" id=\"learn\">\n\t\t\t<div class=\"wrap\">\n\t\t\t\t<p class=\"eyebrow\">Learn<\/p>\n\t\t\t\t<h2>What is radio astronomy?<\/h2>\n\t\t\t\t<div class=\"two\">\n\t\t\t\t\t<p class=\"big-p\">Light is only a thin slice of the electromagnetic spectrum. Radio waves are the same kind of wave, but with wavelengths from millimetres to many metres. Radio telescopes collect this faint energy to study things light cannot show us: the cold hydrogen gas that fills our galaxy, the active Sun, the remains of exploded stars and galaxies billions of light-years away.<\/p>\n\t\t\t\t\t<p>Earth's atmosphere lets two kinds of waves reach the ground: visible light and a wide band of radio. That is why amateurs can do real radio astronomy from a backyard, day or night, and often through clouds. The <a href=\"https:\/\/public.nrao.edu\/radio-astronomy\/\">National Radio Astronomy Observatory<\/a> has a good introduction.<\/p>\n\t\t\t\t<\/div>\n\t\t\t\t<svg class=\"cvas-spectrum\" viewBox=\"0 0 960 230\" role=\"img\" aria-label=\"The electromagnetic spectrum from gamma rays to radio, with the wavelengths used by radio astronomers marked\"><defs><linearGradient id=\"vis\" x1=\"0\" x2=\"1\"><stop offset=\"0\" stop-color=\"#8b5cf6\"\/><stop offset=\".25\" stop-color=\"#3b82f6\"\/><stop offset=\".5\" stop-color=\"#22c55e\"\/><stop offset=\".72\" stop-color=\"#facc15\"\/><stop offset=\"1\" stop-color=\"#ef4444\"\/><\/linearGradient><linearGradient id=\"win\" x1=\"0\" x2=\"1\"><stop offset=\"0\" stop-color=\"#5ce1ff\" stop-opacity=\"0\"\/><stop offset=\".2\" stop-color=\"#5ce1ff\" stop-opacity=\".35\"\/><stop offset=\".8\" stop-color=\"#5ce1ff\" stop-opacity=\".35\"\/><stop offset=\"1\" stop-color=\"#5ce1ff\" stop-opacity=\"0\"\/><\/linearGradient><\/defs><rect x=\"40\" y=\"70\" width=\"62.9\" height=\"44\" fill=\"#5b3b8c\"\/><text x=\"71.4\" y=\"97\" class=\"sp-band\">Gamma<\/text><rect x=\"102.9\" y=\"70\" width=\"188.6\" height=\"44\" fill=\"#6a47a8\"\/><text x=\"197.1\" y=\"97\" class=\"sp-band\">X-ray<\/text><rect x=\"291.4\" y=\"70\" width=\"99.3\" height=\"44\" fill=\"#7b5cd6\"\/><text x=\"341.1\" y=\"97\" class=\"sp-band\">UV<\/text><rect x=\"390.7\" y=\"70\" width=\"18.6\" height=\"44\" fill=\"url(#vis)\"\/><rect x=\"409.3\" y=\"70\" width=\"196.4\" height=\"44\" fill=\"#8a3a3a\"\/><text x=\"507.5\" y=\"97\" class=\"sp-band\">Infrared<\/text><rect x=\"605.7\" y=\"70\" width=\"314.3\" height=\"44\" fill=\"#13607a\"\/><text x=\"762.9\" y=\"97\" class=\"sp-band\">Radio and microwave<\/text><text x=\"400\" y=\"62\" class=\"sp-vis\">Visible light<\/text><rect x=\"384.3\" y=\"128\" width=\"35.5\" height=\"10\" fill=\"url(#win)\"\/><rect x=\"605.7\" y=\"128\" width=\"281.4\" height=\"10\" fill=\"url(#win)\"\/><text x=\"40\" y=\"156\" class=\"sp-note\">Blue bars: where Earth's atmosphere lets waves through to the ground. Everything else is studied from space.<\/text><line x1=\"40\" x2=\"40\" y1=\"114\" y2=\"120\" class=\"sp-tick\"\/><text x=\"40\" y=\"176\" class=\"sp-tl\">1 pm<\/text><line x1=\"228.6\" x2=\"228.6\" y1=\"114\" y2=\"120\" class=\"sp-tick\"\/><text x=\"228.6\" y=\"176\" class=\"sp-tl\">1 nm<\/text><line x1=\"417.1\" x2=\"417.1\" y1=\"114\" y2=\"120\" class=\"sp-tick\"\/><text x=\"417.1\" y=\"176\" class=\"sp-tl\">1 \u00b5m<\/text><line x1=\"605.7\" x2=\"605.7\" y1=\"114\" y2=\"120\" class=\"sp-tick\"\/><text x=\"605.7\" y=\"176\" class=\"sp-tl\">1 mm<\/text><line x1=\"668.6\" x2=\"668.6\" y1=\"114\" y2=\"120\" class=\"sp-tick\"\/><text x=\"668.6\" y=\"176\" class=\"sp-tl\">1 cm<\/text><line x1=\"794.3\" x2=\"794.3\" y1=\"114\" y2=\"120\" class=\"sp-tick\"\/><text x=\"794.3\" y=\"176\" class=\"sp-tl\">1 m<\/text><line x1=\"920\" x2=\"920\" y1=\"114\" y2=\"120\" class=\"sp-tick\"\/><text x=\"920\" y=\"176\" class=\"sp-tl\">100 m<\/text><line x1=\"692.6\" x2=\"692.6\" y1=\"30\" y2=\"70\" class=\"sp-mark\"\/><circle cx=\"692.6\" cy=\"70\" r=\"3.5\" class=\"sp-dot\"\/><line x1=\"751.8\" x2=\"751.8\" y1=\"30\" y2=\"70\" class=\"sp-mark\"\/><circle cx=\"751.8\" cy=\"70\" r=\"3.5\" class=\"sp-dot\"\/><line x1=\"867.5\" x2=\"867.5\" y1=\"2\" y2=\"70\" class=\"sp-mark\"\/><circle cx=\"867.5\" cy=\"70\" r=\"3.5\" class=\"sp-dot\"\/><rect x=\"564\" y=\"29\" width=\"124.6\" height=\"13\" class=\"sp-vbg\"\/><text x=\"686.6\" y=\"52\" class=\"sp-ml\" text-anchor=\"end\">Sun detector<\/text><text x=\"686.6\" y=\"39\" class=\"sp-mv\" text-anchor=\"end\">2.4 cm \u00b7 12.45 GHz<\/text><rect x=\"755.8\" y=\"29\" width=\"138\" height=\"13\" class=\"sp-vbg\"\/><text x=\"757.8\" y=\"52\" class=\"sp-ml\" text-anchor=\"start\">Hydrogen line<\/text><text x=\"757.8\" y=\"39\" class=\"sp-mv\" text-anchor=\"start\">21.1 cm \u00b7 1420.4 MHz<\/text><rect x=\"745.6\" y=\"1\" width=\"117.9\" height=\"13\" class=\"sp-vbg\"\/><text x=\"861.5\" y=\"24\" class=\"sp-ml\" text-anchor=\"end\">Jansky 1933<\/text><text x=\"861.5\" y=\"11\" class=\"sp-mv\" text-anchor=\"end\">14.6 m \u00b7 20.5 MHz<\/text><text x=\"480\" y=\"210\" class=\"sp-axis\">Wavelength (each step is ten times longer) \u2192<\/text><\/svg>\n\t\t\t\t<div class=\"cards3\">\n\t\t\t\t\t<article class=\"card\"><span class=\"card-k\">12 GHz \u00b7 2.4 cm<\/span><h3>The Sun<\/h3><p>The Sun is the easiest radio source to detect. An 18-inch satellite TV dish and a $38 USB radio will find it.<\/p><a href=\"https:\/\/radio.cvastro.org\/index.php\/build-a-radio-telescope\/\">Build one \u2192<\/a><\/article>\n\t\t\t\t\t<article class=\"card\"><span class=\"card-k\">1420.4 MHz \u00b7 21.1 cm<\/span><h3>Hydrogen in the Milky Way<\/h3><p>Hydrogen atoms between the stars give off radio waves at exactly 1420.405752 MHz. With a horn antenna and a small software-defined radio you can map the spiral arms for about $100.<\/p><a href=\"https:\/\/radio.cvastro.org\/index.php\/2020\/03\/03\/newer-and-cheaper-amateur-radio-telescope\/\">Our horn parts list \u2192<\/a><\/article>\n\t\t\t\t\t<article class=\"card\"><span class=\"card-k\">Big dishes<\/span><h3>Radio galaxies and dead stars<\/h3><p>Cygnus A, a distant galaxy with giant radio jets, and Cassiopeia A, the remains of an exploded star, are among the brightest radio sources in the sky. Our 20-foot dishes see them drift through the beam.<\/p><a href=\"https:\/\/radio.cvastro.org\/index.php\/radio-telescope\/\">When they pass over \u2192<\/a><\/article>\n\t\t\t\t<\/div>\n\n\t\t\t\t<h3 class=\"tl-title\">A short history<\/h3>\n\t\t\t\t<ol class=\"timeline\">\n\t\t\t\t\t<li><b>1933<\/b><span>Karl Jansky, an engineer at Bell Laboratories, finds radio waves coming from the centre of the Milky Way at 20.5 MHz. <a href=\"https:\/\/public.nrao.edu\/gallery\/karl-jansky-and-his-merrygoround\/\">NRAO<\/a><\/span><\/li>\n\t\t\t\t\t<li><b>1937<\/b><span>Grote Reber builds a 31.4-foot dish in his backyard in Wheaton, Illinois. He maps the radio Milky Way and finds bright sources in Cygnus and Cassiopeia. <a href=\"https:\/\/greenbankobservatory.org\/about\/telescopes\/reber-telelescope\/\">Green Bank Observatory<\/a><\/span><\/li>\n\t\t\t\t\t<li><b>1942<\/b><span>Radio waves from the Sun are detected, first by British radar stations in February, then as microwaves by G. C. Southworth at Bell Labs. <a href=\"https:\/\/cdaweb.gsfc.nasa.gov\/pub\/data\/stereo\/documents\/websites\/swaves\/History%20of%20Radio%20Astronomy.html\">NASA STEREO<\/a><\/span><\/li>\n\t\t\t\t\t<li><b>1951<\/b><span>Harold Ewen and Edward Purcell at Harvard detect the 21-cm hydrogen line on March 25, six years after H. C. van de Hulst predicted it. <a href=\"https:\/\/www.nature.com\/articles\/168356a0\">Nature 168, 356<\/a><\/span><\/li>\n\t\t\t\t\t<li><b>2021<\/b><span>CVAS gives both 20-foot dishes at Hobbs matching feeds, the first step toward combining them as an interferometer. <a href=\"https:\/\/radio.cvastro.org\/index.php\/2021\/12\/08\/radio-astronomy-interferometer-coming-soon\/\">Club news<\/a><\/span><\/li>\n\t\t\t\t\t<li><b>Today<\/b><span>Our dish data goes on the web as it is recorded. <a href=\"https:\/\/radio.cvastro.org\/index.php\/radio-telescope\/\">Watch it live<\/a><\/span><\/li>\n\t\t\t\t<\/ol>\n\t\t\t<\/div>\n\t\t<\/section>\n\n\t\t<section class=\"build\" id=\"build\">\n\t\t\t<div class=\"wrap\">\n\t\t\t\t<p class=\"eyebrow\">Build your own<\/p>\n\t\t\t\t<h2>A radio telescope on the cheap<\/h2>\n\t\t\t\t<div class=\"cards2\">\n\t\t\t\t\t<article class=\"card build-card\">\n\t\t\t\t\t\t<div class=\"bc-top\"><h3>Sun Detector 2.0<\/h3><span class=\"bc-cost\">About $38 + used dish<\/span><\/div>\n\t\t\t\t\t\t<p>A used 18-inch satellite TV dish and a $38 USB radio on a laptop. Point it at the Sun and watch the power climb, then let the Earth turn and record the Sun drifting through the beam.<\/p>\n\t\t\t\t\t\t<ul class=\"ticks\"><li>One afternoon to build; works in daylight<\/li><li>Great for families and classrooms<\/li><li>Based on the Itty Bitty Telescope by the late Chuck Forster, CVAS and SARA member<\/li><\/ul>\n\t\t\t\t\t\t<a class=\"cvas-btn cvas-btn-primary\" href=\"https:\/\/radio.cvastro.org\/index.php\/build-a-radio-telescope\/#sun\">Step-by-step guide<\/a>\t\t\t\t\t<\/article>\n\t\t\t\t\t<article class=\"card build-card\">\n\t\t\t\t\t\t<div class=\"bc-top\"><h3>Hear the Milky Way<\/h3><span class=\"bc-cost\">$88 to $375<\/span><\/div>\n\t\t\t\t\t\t<p>Pick up the 21-cm hydrogen line of our galaxy at 1420.4 MHz: the same science our 20-foot dishes do. Buy the ready-made Discovery Dish kit, or build a horn, a Wi-Fi grid dish or your own dish, with a $50 amplifier.<\/p>\n\t\t\t\t\t\t<ul class=\"ticks\"><li>A weekend project<\/li><li>Free software: SDR#, Virgo, ezRA<\/li><li>Bring it to a work day and we will help you test it<\/li><\/ul>\n\t\t\t\t\t\t<a class=\"cvas-btn\" href=\"https:\/\/radio.cvastro.org\/index.php\/build-a-radio-telescope\/#hydrogen\">Compare the options<\/a>\t\t\t\t\t\t<p class=\"fine\">Prices checked October 20, 2026.<\/p>\n\t\t\t\t\t<\/article>\n\t\t\t\t<\/div>\n\t\t\t<\/div>\n\t\t<\/section>\n\n\t\t<section class=\"news\">\n\t\t\t<div class=\"wrap two\">\n\t\t\t\t<div>\n\t\t\t\t\t<p class=\"eyebrow\">From the club<\/p>\n\t\t\t\t\t<h2>News and projects<\/h2>\n\t\t\t\t\t<div class=\"cvas-posts\"><a class=\"cvas-post\" href=\"https:\/\/radio.cvastro.org\/index.php\/2021\/12\/08\/radio-astronomy-interferometer-coming-soon\/\"><span class=\"cvas-post-date\">December 8, 2021<\/span><span class=\"cvas-post-title\">Radio Astronomy Interferometer COMING SOON&#8230;<\/span><span class=\"cvas-post-ex\">EXCITING NEWS!After getting up the East Dish and verifying the signals were good, we went ahead and took down the \u00a0cantenna on&hellip;<\/span><\/a><a class=\"cvas-post\" href=\"https:\/\/radio.cvastro.org\/index.php\/2020\/03\/03\/newer-and-cheaper-amateur-radio-telescope\/\"><span class=\"cvas-post-date\">March 3, 2020<\/span><span class=\"cvas-post-title\">Newer and Cheaper Amateur Radio Telescope<\/span><span class=\"cvas-post-ex\">The Horn Antenna seems to be a favorite goto and for good reason. All you need is Aluminum flashing 20&#8243;x10, a empty&hellip;<\/span><\/a><a class=\"cvas-post\" href=\"https:\/\/radio.cvastro.org\/index.php\/2019\/05\/11\/the-amateur-radio-telescope\/\"><span class=\"cvas-post-date\">May 11, 2019<\/span><span class=\"cvas-post-title\">The Amateur Radio Telescope<\/span><span class=\"cvas-post-ex\">To build your own Amateur Radio Telescope, you will need a few item to get started. You will need: Antenna --&gt; LNA&hellip;<\/span><\/a><\/div>\t\t\t\t<\/div>\n\t\t\t\t<div>\n\t\t\t\t\t<p class=\"eyebrow\">Resources<\/p>\n\t\t\t\t\t<h2>Where to learn more<\/h2>\n\t\t\t\t\t<div class=\"res\">\n\t\t\t\t\t\t<h4>Learn<\/h4>\n\t\t\t\t\t\t<a href=\"https:\/\/public.nrao.edu\/radio-astronomy\/\">NRAO: what is radio astronomy?<\/a>\n\t\t\t\t\t\t<a href=\"http:\/\/www.radio-astronomy.org\/pdf\/sara-beginner-booklet.pdf\">SARA beginner's booklet (PDF)<\/a>\n\t\t\t\t\t\t<a href=\"https:\/\/www.radio-astronomy.org\/\">Society of Amateur Radio Astronomers (SARA)<\/a>\n\t\t\t\t\t\t<a href=\"https:\/\/groups.google.com\/g\/sara-list\">SARA discussion list<\/a>\n\t\t\t\t\t\t<a href=\"http:\/\/www.setileague.org\/general\/index.html\">The SETI League<\/a>\n\t\t\t\t\t\t<h4>Software<\/h4>\n\t\t\t\t\t\t<a href=\"https:\/\/www.radiosky.com\/softwarehome.html\">Radio-SkyPipe and Radio Eyes (Radio-Sky Publishing)<\/a>\n\t\t\t\t\t\t<a href=\"https:\/\/airspy.com\/download\/\">SDR# software-defined radio<\/a>\n\t\t\t\t\t\t<a href=\"https:\/\/www.rtl-sdr.com\/big-list-rtl-sdr-supported-software\/\">RTL-SDR software list<\/a>\n\t\t\t\t\t\t<a href=\"https:\/\/github.com\/0xCoto\/Virgo\">Virgo spectrometer<\/a>\n\t\t\t\t\t\t<a href=\"https:\/\/github.com\/tedcline\/ezRA\">ezRA, easy radio astronomy<\/a>\n\t\t\t\t\t\t<a href=\"https:\/\/pictortelescope.com\/\">PICTOR, a free online radio telescope<\/a>\n\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t<\/div>\n\t\t<\/section>\n\n\t\t<section class=\"join\" id=\"join\">\n\t\t\t<div class=\"wrap two\">\n\t\t\t\t<div>\n\t\t\t\t\t<p class=\"eyebrow\">Join us<\/p>\n\t\t\t\t\t<h2>Become part of the group<\/h2>\n\t\t\t\t\t<p>The radio group is part of the Chippewa Valley Astronomical Society. CVAS membership is open to anyone with an interest in astronomy, from beginners to engineers.<\/p>\n\t\t\t\t\t<ul class=\"dues\">\n\t\t\t\t\t\t<li><b>$20<\/b><span>Individual<\/span><\/li>\n\t\t\t\t\t\t<li><b>$25<\/b><span>Family<\/span><\/li>\n\t\t\t\t\t\t<li><b>$10<\/b><span>Full-time student<\/span><\/li>\n\t\t\t\t\t<\/ul>\n\t\t\t\t\t<p class=\"fine\">Yearly dues, January to December, as listed on the CVAS membership page in October 2026. Join online or by mail there.<\/p>\n\t\t\t\t\t<p><a class=\"cvas-btn cvas-btn-primary\" href=\"https:\/\/www.cvastro.org\/membership\/\">Join CVAS<\/a><\/p>\n\t\t\t\t\t<p>Not ready to join? Come to a work day, or send us a message: questions about building your own telescope are always welcome.<\/p>\n\t\t\t\t<\/div>\n\t\t\t\t<div class=\"card\"><h3 style=\"margin-top:0\">Send us a message<\/h3><form class=\"cvas-contact\" data-rest=\"https:\/\/radio.cvastro.org\/index.php\/wp-json\/cvas-ra\/v1\/\" novalidate><div class=\"cf-row\"><label>Your name<input type=\"text\" name=\"name\" autocomplete=\"name\" maxlength=\"100\" required><\/label><label>Email<input type=\"email\" name=\"email\" autocomplete=\"email\" maxlength=\"190\" required><\/label><\/div><label>What is it about?<select name=\"topic\"><option value=\"join\">Joining CVAS and the radio group<\/option><option value=\"workday\">Coming out to a work day<\/option><option value=\"build\">Building my own radio telescope<\/option><option value=\"visit\">A visit, talk or school group<\/option><option value=\"other\">Something else<\/option><\/select><\/label><label>Message<textarea name=\"message\" rows=\"5\" maxlength=\"4000\" required placeholder=\"Tell us a little about your interest. No experience needed.\"><\/textarea><\/label><label class=\"cf-hp\" aria-hidden=\"true\">Leave this empty<input type=\"text\" name=\"website\" tabindex=\"-1\" autocomplete=\"off\"><\/label><div class=\"cf-foot\"><button type=\"submit\" class=\"cvas-btn cvas-btn-primary\">Send message<\/button><span class=\"cf-status\" role=\"status\" aria-live=\"polite\"><\/span><\/div><p class=\"cf-privacy\">We use your name and email only to reply to you.<\/p><noscript><p>This form needs JavaScript. You can also write to contact@cvastro.org.<\/p><\/noscript><\/form><\/div>\n\t\t\t<\/div>\n\t\t<\/section>\n\t<\/div>\n\t\n","protected":false},"excerpt":{"rendered":"","protected":false},"author":1,"featured_media":0,"parent":0,"menu_order":0,"comment_status":"closed","ping_status":"closed","template":"cvas-full","meta":{"footnotes":""},"class_list":["post-346","page","type-page","status-publish","hentry"],"_links":{"self":[{"href":"https:\/\/radio.cvastro.org\/index.php\/wp-json\/wp\/v2\/pages\/346","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/radio.cvastro.org\/index.php\/wp-json\/wp\/v2\/pages"}],"about":[{"href":"https:\/\/radio.cvastro.org\/index.php\/wp-json\/wp\/v2\/types\/page"}],"author":[{"embeddable":true,"href":"https:\/\/radio.cvastro.org\/index.php\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/radio.cvastro.org\/index.php\/wp-json\/wp\/v2\/comments?post=346"}],"version-history":[{"count":0,"href":"https:\/\/radio.cvastro.org\/index.php\/wp-json\/wp\/v2\/pages\/346\/revisions"}],"wp:attachment":[{"href":"https:\/\/radio.cvastro.org\/index.php\/wp-json\/wp\/v2\/media?parent=346"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}