Subject: Vermont Astronomical Society Newsletter From: "Paul Walker" Date: Wed, 4 Jan 2006 21:19:11 -0500 To: "WILLIAM CHARASH" , "WALLY MICK" , "TY DANCO" , "TINA CENTOFANTE" , "THOMAS HORN" , "THOMAS HASELTON" , "THOMAS BEARDSLEY" , "THEODORE M MARCY" , "STACEY & JUSTIN KING" , "SHARON PROVOST" , "SCOTT PENNINGTON" , "SARA BURKE" , "SANDRA TUMOSA" , "SANDRA PAUL" , "RUSSEL CHMELA" , "ROSS PERRY" , "RONALD LEWIS" , "RONALD ANSTEY" , "RODNEY MONTAGUE" , "ROBERT WILLIAMS" , "ROBERT MURPHY" , "ROBERT CLAWSON" , "Richard Torde" , "RICHARD FISHER" , "RICH GRAHAM" , "RANDY WOLF" , "PETER WILLIAMS" , "PETER TOSHEV" , "PETER GILLETTE" , "Paul W" , "PATRICK PORCH" , "PATRICIA BUNT" , "NANETTE SMITH" , "MONTY MARKOW" , "MOE CLOUTIER" , "MIRSAD SKOPLJAK" , "MIKE ENDRUSICK" , "MICHAEL TOBIN" , "MICHAEL HEINEMANN" , "MICHAEL FORTNEY" , "MICHAEL DUNPHY" , "Mark Pendergrast" , "MARK FREDERICK" , "MARC & DARLENE SCARANO" , "LYN ELDER" , "LOUIS VARRICCHIO" , "LINDA GOODMAN" , "LEONARD BOSTWICK" , "LAWRENCE GARRETT" , "LAURA WILLIAMS" , "KEVIN CORRIGAN" , "KERRY BERNSTEIN" , "KAREN PREISSLER #2" , "KAREN PREISSLER" , "JUSTIN BERMAN" , "JUNE T. GIROUX" , "JUDIT FABIAN" , "JONATHAN CHAPPLE-SOKOL" , "John St.Louis" , "JOHN COHN" , "JOE JOHNSTON" , "JESSICA KAUFMAN" , "Jeremy Segeer" , "JEFFREY KAUFMAN" , "JANE OLESEN" , "JAMES M. JOHNSON" , "HOWARD DRUCKERMAN" , "GEORGE KOSTOPOULOS" , "GARY NOWAK" , "Frank Vanecek" , "FRANK PAKULSKI" , "FLOYD GLICK" , "Ewan Douglas" , "DOUG WILLIAMSON" , "DONNA LESCOE" , "Don Manley" , "Dennis Woos" , "DENNIS WAITE" , "DENNIS NAUGHTON" , "DELBERT O. MARTIN" , "Dean Adams" , "DAVID JOHNSON" , "DAVID HERREN" , "DAVE HARMON" , "DANNY LANDRY" , "CONRAD BREMER" , "CONRAD \(C. J.\) AUBE" , "CHUCK MUSANTE" , "CHRIS BROWN" , "CHRIS & CYNTHIA HENDEL" , "Charles Jakiela" , "C. J. PARK" , "Bruce Douglas" , "Brad Vietje" , "Bob Szczerbak" , "BOB PEACOCK" , "Bob Horton" , "BILL BYRNE" , "Bill Banke Jr" , "BENJAMIN McCARTY" , "Ben Moger-Williams" , "BEN GREENFIELD" , "BECCA RAYMON" , "ARIEL E MARCY" , "ALLON WILDGUST" , "ALLISON CARROLL" , "JO-ANN DOYLE" The Morning Star Winter 2006 Contents President’s Page _____________________________Page 1 New Members ______________________________ Page 1 Meetings __________________________________ Page 1 Jan 9, History and Fate of the Universe ... In Brief. Feb 6, Observing Double Stars and The Lunar 100. Mar 6, California Astronomy Club. Articles- Radio Meteors _______________________ Page 2 Observer’s Page ____________________________ Page 4 Equipment Corner ___________________________ Page 4 Announcements _____________________________ Page 4 Loaner items available, VAS Decals & Patches, Subscription discounts. Dues, Moving?, Email, Web Site _______________ Page 4 President’s Page Hello Vermont Astronomers! As we begin a new year, I have hopes for an active year for Vermont astronomers. Mars is still shining brightly overhead as it draws further away from us and continues its visible shrinking act, making it harder to see any details. Venus is growing in size as it gets closer to us in its trip around the Sun, but sliming to an ever thinning crescent until lost in the solar glare. Saturn is visible in the East early in the evening, and although its rings are closing to the eventual point of disappearing, still tends to be a favorite of many observers. Weather permitting, I hope for an astronomically active 2006 for myself as well. For now, I have "The PLAN"! No, really...it's true! It's my PLAN for successful and enjoyable observing of the night sky, as proclaimed (by me) at the December monthly meeting. Some of you are thinking "what is Jack going on about this time?". The answer is - my PLAN to prevent the usual "go out and find the same few things and nothing else and get frustrated and go inside" syndrome. My typical method for astronomical failure of rolling of the roof of my observa-shed and THEN try to think of deep sky things to see. Backwards, Jack! My PLAN: I listed 20+ things to look for, based on what constellations would be visible to me in the next couple of months. Then I listed a few of each kind of object I want to see - planets, star clusters, nebulae and galaxies. I did make the attempt one evening but was clouded out soon after getting set up. But - when the next clear night comes along, and I'm home, I'll make another attempt. I know many newbies to amateur astronomy give it up because they don't know what to look for, or even what they can see, or where to look. VAS members can't always be available to help them, but maybe if they knew how to plan for a night of observation, and were successful, and actually enjoyed it, they would give it another go. That was my goal in revealing my master PLAN in December, but sadly very few newbies attended that meeting. Well, at least I have a PLAN. All I need to do now is stick to it. Then I need to finish my 12.5 inch mirror. Share the skies with someone you don't know in 2006. Jack New Members VAS welcomes the following new member who joined us within the last three months: Jo-Ann Doyle Meetings/Presentations: Meetings are held the first (non-holiday) Monday of the month, at 7:30 P.M. in the UVM Waterman Building, room 413. For inclement weather call Jack St. Louis (802-658-0184) to confirm. Jan 9 - History and Fate of the Universe ... In Brief by Scott Pennington. All levels. Feb 6 - Two talks- Observing Double Stars by Doug Woos and The Lunar 100 by Tim Woos. All levels. Mar 6 - Experiences in a California Astronomy Club by Lyn Elder. All levels. Members are needed to provide Mini-Talks (15 min) or full 1-hour presentations. If you have a topic you'd like to share, please contact Jack St. Louis. Board meetings are usually held on Monday one week after each member meeting at 7:30 - 9:00 PM. All are welcome-Contact Jack St. Louis for details. Articles Radio Meteors: Ion Trail Detection Using FM Radio and TV signals By Chris R. Brown chrisrbrown@verizon.net It is not hard to detect meteors by observing a remote, over-the-horizon signal source. When a meteor comes into the atmosphere, it leaves an ion trail which can reflect some radio energy towards an observer. These trails can last from a fraction of a second to as much as a minute. Figure 1. Distant FM radio or TV signal reflected from the ion trail of a meteor. Here is a description of the apparatus and software used to detect "radio meteors". For over-the-horizon beacons, one can use distant FM stations, but a better signal-to-noise ratio and interesting audio sounds are heard using a TV video carrier. Channel 2 in Boston (55.25 MHz) is a good source in the early morning when it is not transmitting digital TV signals. It is 160 miles away from Montpelier. Any of the lower VHF channels 2 through 6 is fine, but not a local station. Figure 2. Block diagram of apparatus used to detect trails of ions caused by meteors. The VHF radio I use is a Watkins-Johnson type 906A-6 which was made around 1960, but is still useful for this purpose. Any VHF receiver that will tune from 50 to 150 MHz and has an IF output should work fine. Commercial products like the Icom R-7000 or a similar VHF receiver is ideal for the purpose. My receiver has a 21.4 MHz IF output maximum of about 2 V p-p. The bandwidth is switchable, and 20 KHz seems to work best. This signal is fed to a simple demodulator and low pass filter, shown below in figure 3. In my apparatus, the output of the filter is then sent to a Metrabyte DAS-16 data acquisition card in a PC, and processed for display and data storage with the QBASIC software listed in Appendix 1. The data sample rate is 10 per second. The microphone input of a sound card can be used for analog to digital conversion if sufficient documentation makes it possible, but as these cards sample at around 44 KHz, the resulting files will be large. Figure 3. Demodulator and lo-pass circuit When this system was first connected with the QBASIC code running and a dipole antenna outside, a distant FM station was tuned, and almost immediately generated presentable data. Some results are shown in figures 4 through 6 below. The signal to noise ratio is good, and even better with the TV carrier than with the FM stations. A thousand signal strength units is about a quarter of a volt of signal out of the demodulator and low-pass filter Figure 4. First light! The noise floor is mostly from FM station modulation. On the web are many sites describing radio meteors and their detection. (see References) Some of these mention "overdense" and "underdense" events, referring to the number of ions produced. Bigger meteors produce overdense events. The ion trails last longer. During some overdense events like the one shown in Figure 5. below, the audio output of the receiver produces a rapid chirping sound, like little birds. It is possible that the TV sidebands are being Doppler shifted into the video carrier frequency, where an audible hetrodyne note is heard. The mechanism for this may be the ion trail decelerating, resulting in a changing Doppler shift . Figure 5. Long duration overdense event with prominent Doppler birdies in the audio. When underdense events occur, sometimes a tone is heard in the audio range, lasting as long as the spike lasts. This may also be a Doppler effect. The pitch of the tone is most often unchanging, but occasionally it will vary. It is not like the fast chirping birdies in an overdense event. Figure 6. Overdense and underdense events in the same 30 second time frame. Note the improved noise floor using the TV carrier. Though radio meteors can be detected at any time of day, midnight to noon is the peak period for meteors, and airplane traffic becomes noticeable after 6 AM because of multi-path interference effects. See Fig. 7. The atmosphere is most stable before dawn, so the best times for observing are in the early morning. For those who do not like to be awake in those hours, computer controlled automation is an option. Figure 7. Multi-path interference from an airplane. Another interesting feature of these traces is the exponential tail associated with overdense events, for example, from 9-30 seconds in figure 5 and 12-14 seconds in figure 6. This tail is usually noisy. Many sources on the web say that this is due to multi-path interference effects. Ok, maybe, but the spike at 25 seconds on figure 5 is probably a separate underdense event. One of my friends saw these traces and asked if I was sure these events were due to meteors. this is a really good question and one to be answered carefully. I have not answered her question yet. I have three ways of thinking about this. First, everybody else thinks they are meteors, but that's really not much of an answer. Secondly, compare the kinetic energy of incoming sand grains with the energy of a typical cosmic ray. No contest, the sand grain, at 40 km/s, has much more energy. Third, I have been keeping track of hourly rates for different dates of observation, so as to correlate hourly rates with known meteor showers. so far, the results are inconclusive, as I have unfortunately slept through the shower peaks! I'm pretty sure they are meteors, but not certain. In any event, it is fun to try to interpret what is seen. References: Google on "radio meteors", and these sites will appear, along with many more! http://www.spaceweather.com/glossary/nasameteorradar.html http://www.imo.net/radio/ http://www.amsmeteors.org/radmet.html http://www.net4you.co.at/user/kuneth/gallery.html Appendix 1. QBASIC code to read data from DAS-16 card CLS PRINT : PRINT : PRINT : PRINT PRINT " DAS16 single channel free running data acquisition routine." PRINT " Samples are taken at a rate depending on the initial " PRINT " setting of the variable Slower% and MuchSlower% in" PRINT " in the main loop." PRINT : PRINT : PRINT BaseAdr% = &H300 'base I/O address for DAS16 card OUT (BaseAdr% + 2), 0 'mux scan register set to ch. 0 PRINT INPUT " Number of data points to be collected = ", ArraySize% PRINT DIM Dater%(ArraySize%) INPUT " Filename prefix? > ", L$ I% = 1 'filename index Start: CLS SCREEN 12 'VGA option WINDOW (0, 2500)-(ArraySize%, -100) 'limits of display LINE (0, 0)-(ArraySize%, 0) 'x axis LINE (0, 0)-(0, 2500) 'y axis PSET (0, Dater%(0)) COLOR 14 'yellow FOR j% = 0 TO ArraySize% - 1 OUT BaseAdr%, 0 'this triggers data acquisition LoByte% = INP(BaseAdr%) HiByte% = INP(BaseAdr% + 1) DIO% = 16 * HiByte% + LoByte% /16 Dater%(j%) = DIO% LINE -(j% + 2, Dater%(j%)) Slower% = 440 'nested delay loops WHILE Slower% > 1 Slower% = Slower% - 1 MuchSlower% = 100 WHILE MuchSlower% > 1 MuchSlower% = MuchSlower% - 1 WEND WEND IF INKEY$ = CHR$(27) THEN END NEXT j% COLOR 15 'white PRINT INPUT "Save this data"; yn$ IF yn$ = "n" THEN GOTO Start P$ = L$ + LTRIM$(STR$(I%)) + ".dat" 'construct filename OPEN P$ FOR OUTPUT AS #1 FOR j% = 0 TO ArraySize% - 1 'write to file WRITE #1, .1 * j%, Dater%(j%) NEXT j% CLOSE #1 I% = I% + 1 'filename number GOTO Start END Observers Page Photo by Floyd Glick Date: 24 Oct 2005 Time: 4:43 AM Telescope: 8"Dia - F# 4 (homemade); equatorial mount with 120vac 60Hz motor drive. Camera data: ISO=125; exposure=1/39 sec.; F#=9; Width=1280 pixels; Height=960 pixels (original image); Final image reduced to 320x324. Mars, 10/30/05, Paul Walker, 10" f/5.6 reflector, Cannon digital camcorder. Top image is a stack of 30 video frames taken at 2:04 AM EST. The bottom is a stack of 40 video frames taken about 3:16 AM EST. Several features are visible including a dust storm. Images are 720x480 pixels. Equipment Corner Meade model "Jupiter" DS-114EC Reflector, diameter 114 mm, focal length 910mm, F/8 with Autostar and star locator, compatible with Windows 95, dual axis motors, 5 power x 24mm viewfinder, also has a tripod, 3 eyepieces and 3x Barlow lens. Stephen Greenfield, 879-3132, spgreenfield@adelphia.net As some of you folks know, I had a 16" Pyrex mirror blank from United Lens – a very high quality blank. I found a place (www.glassfab.com in Rochester, NY) to diamond bandsaw this blank into two pieces. One piece is 1" thick, and the other is 1.75" thick, and both are 16" diameter. I would like to sell one or the other of them, but not both. If anybody wants one of these blanks, let me know. I will sell the 1" blank for $400, or the 1.75" blank for $500. Dennis Woos. Call 453-2360. If anyone has astronomy equipment for sale or looking to buy, let Paul Walker know and we'll put it in the next Morning Star (due out the end of March). Announcements Items available for loaning from VAS or individual members (telescopes, manuals, observing aids, computers, electronics, etc.), for a list, contact C.J. Park, VAS Resource Manager, parkite@sover.net or phone 862-4027. Also let him know of items you have that you would like put on the list. VAS decals 4 / $1 are available. See Moe anytime or contact him at the next meeting. There are still a few VAS 40th Anniversary patches available for $3. Contact Bob Peacock to get a club discount on your Sky & Telescope or Astronomy subscription. To get on VAS’s Astro Net (vtastronmoy@list) visit our web site and follow the link at the bottom of the home page (www.uvm.org/vas/). Don’t forget to visit the Green Mountain Alliance of Amateur Astronomers web site at www.uvm.org/gmaaa . Dues Please check your dues date. Look next to your address on the newsletter. Those with email I will notify by email. No date is shown for Life or Honorary members. If you believe the date is incorrect please let Paul Walker or Bob Peacock know, the data base may not be up to date. We apologize for any inaccuracies in our record keeping. Send dues to VAS, PO Box 782, Williston, VT 05495 Moving? Please send your new mailing address to Paul Walker, 53 Valley View, Middlebury, VT 05753. Email If you don’t receive this newsletter by email and would like to or your email address has changed please send it Paul’s way, thanks. (paulwaav@together.net). This will save a lot on postage and time (not to mention make it easier to inform you of last minute events). Web Site www.uvm.org/vas Web master: Jack St. Louis (vas@list.uvm.edu)