Würzburg Radiotelescope Description and User Manual
Contents
1. 20 DB 20 40 60 1000 500 g 500 1000 Velocity km s To remove a noise spike such as shown to the left of the signal again type DRAW and use the mouse to place the cursor on the spike then type 1 9 74 00 HI WURZBURG 0 09 FEB 2009 R 1 7 MAR 2011 RA 20 18 06 00 DEC 35 46 49 0 Eq 2000 0 Offs 0 0 0 0 Unknown tau 0 057 Tsys 30 Time 1 0 min El 51 4 N 2048 l0 1024 00 VO Q 2026 Dy 1 087 Ear FO 1420 535223 Df 5 1500E 03 Fi 1420 532253 1425 1420 20 0 20 40 60 1000 500 g 500 1000 Velocity km s 31 as many times as needed Again typing E exits the interactive mode Then when you next execute the PLOT command you obtain the last spectrum shown below 1 9 74 00 HI WURZBURG 0 09 FEB 2009 R 17 MAR 2011 RA 20 18 06 00 DEC 35 46 49 0 Eq 2000 0 Offs 90 0 0 0 Unknown tau 0 057 Tsys 30 Time 1 0 min El 51 4 N 2048 10 1024 00 YO 0 2026 Dy 1 087 Ear FO 1420 535223 Df 5 1500E 03 Fi 1420 532253 1425 1420 20 10 pey 1000 590 g 500 1000 Velocity km s To save the result as an output file called for example CleanedSpectrum Wurz first type FILE OUT CleanedSpectrum Wurz m followed by WRITE To re display the file with CLASS the command sequence is FILE IN CleanedSpectrum Wurz FIND LIS GET FIRST PLOT Alternatively you can save the plot as a postscript file HARD CleanedSpectrum eps DEV EPS FAST VIII W2. AFGL 2688 4 E Observations lar Reservations management 19 LP And observations management 20 gt th ole Cne Maintenance 2l Once the data acquisition is complete and your spectrum and been displayed on the screen you can screen capture or click on the CD to obtain a zip archive of your data files as for Beginner Mode mom A Observations list mo oo e i Mol 2937 Herpin 2014 09 03 04 00 00 08 00 00 test 2879 Herpin Fabrice 2014 07 10 16 00 00 20 00 00 pulsars Fabrice 2014 06 03 08 00 00 12 00 00 tests Fabrice 2014 04 04 12 00 00 16 00 00 OH Fabrice 2014 04 04 04 00 00 08 00 00 OH i 5 G 2014 04 03 04 00 00 08 00 00 OH 22 VI MAPPING THE GALAXY P le galactique Nord b latitude galactique 4 longitude galactique P le galactique Sud Figure 5 Left Galactic coordinate system Right The b 0 plane of our galaxy the Milky Way showing longitude and the spiral arms The Sun and Earth are at the orgin I Galactic coordinates The Sun is roughly 8 5 kpc from the center of the Milky Way Most of galaxy s stars and gas clouds lie in a thin disk rotating around the galactic center The Sun s tangential Fabrice c est crit radiale en V F c est une coquille non velocity is about 220 km s Thus it takes the Sun about 240 million years to make a complete tour Galactic coordinates l b conveniently describe the position of a star or clo
3. Lis alz E 14 15 16 ile 18 19 26 sal Zas Za 24 25 26 sane 28 29 36 Salt ert ale 34 355 36 one 38 395 46 41 42 43 44 45 46 475 48 49 56 51 52 533 54 55 56 57 58 59 68 LASo gt ff The number at far left 1s an index of your 74 00 observations taken at the HI frequency with the WURZBURG telescope SY eS RS m BE m BE a S m ES m BE m BE m BEA oa ES m E m BE m BE m BE o Y m BEY m BE m BE m BES m ES m BE m BE m BE a BS m EY SS m ES a ES m EY m E m ES m ES m ES m EY m BES m BES m ES m ES m E m ES m ES m ES a EY m E m ES m ES m ES a EY m EN m ES m ES m ES a BEY m ES a ES m BES a GEY a BES a 66 observations found 74_66 74_66 74_68 74_00 74_68 74_66 74_66 74_68 74_66 74_68 74_66 74_68 74_00 74_00 74_66 74_66 74_66 74_66 74_68 74_68 74_68 74_66 74_66 74_66 74_66 74_68 74_66 74_66 74_66 74_66 74_66 74_66 74_68 74_66 74_66 74_66 74_68 74_68 74_66 74_68 74_66 74_66 74_66 74_66 74_66 74_66 74_68 74_66 74_66 74_66 74_66 74_66 74_66 74_68 74_66 74_66 74_66 74_66 74_68 74_00 HI HI HI HI HI HI HI HI HI HI HI HI HI HI HI HI HI HI HI HI HI HI HI HI HI HI HI HI HI HI HI HI HI HI HI HI HI HI HI HI HI HI HI HI HI HI HI HI HI HI HI HI HI HI HI HI HI HI HI HI WURZBURG WURZBURG WURZBURG WURZBURG WURZBURG WURZBURG WURZBURG WURZBURG WURZBURG WURZBURG WURZBURG WUR
4. _ ae oe oe To reserve simply click on a date The different time slots then appear green indicating which are free You can reserve as many as you like Note that the reservation times are un UT Universal Time You then enter a few words to describe your observation s purpose examples 1 try for a beginner Elucidate the secrets of the Universe There s nothing good on TV etc Your reservation then appears on the calendar Your reservation as well as on the Observations list Warning Reservations and observations are made at telescope time TU 14 September 2014 00h00 04h00 04h00 08h00 08h00 12h00 12h00 16h00 16h00 20h00 20h00 00h00 2014 9 3 08 00 00 12 00 00 Delete this reservation Cancel 00h00 04h00 04h00 08h00 08h00 12h00 12h00 16h00 16h00 20h00 20h00 00h00 Obviously you are not allowed to click other people s reservations Selecting the Observation list tab in the Manage my observations menu shows you all of your observations Observations list 15 3 Observer en mode normal i e novice Normal beginner mode observations To start observing simply click on Observe in the menu on the left and choose either beginner or expert mode In Beginner Mode you choose only the target from a pre defined list and the gas species that you will observe X Home Beginer mode The gas species are atomic hydr
5. s radial speed relative to the LSR Local Standard of Reference which is roughly the Sun If you don t know it simply use zero your source s peak in the spectrum will not be centered which is generally not a problem You then choose an integration time that is how long the observation will last For most HI sources a few minutes are enough Finally if needed you can change the OFF reference frequency In most cases this is unnecessary and is not recommended But if you suspect that the reference frequency is suffering from interference noise from the local environment you can try other frequencies starting with the range 1450 to 1460 MHz You then accept your parameters and to start the observation The telescope time to pointing is indicated l Home Observation in progress Public EJ mome Observation parameters create account Source W30H Molecule HI antenna specifications Z Documentation a a STATUS Spectrum Skychart Pointing 8 mn Sky Chart Fabrice Herpin i SJ User account System temperature 130K change password S External temperature 20 0 C J Manage my observations Hygrometry 7 5 E observations list Sky chart Legend oe 1 M33 4 Observe 2 W30H 3 CygA NEw Webcam 4 G343 5 039 9 00 0 E meteo 6 Gal70 0 Beginer mode 7 Gal100 0 8 BD 61 339 advanced mode 9 B44 1018 10 Orion A Administration 11 AFGL 618 Users list 14 V Hya i 15 V Cyg Email users 16
6. C 7 5 The time to reach the target depends on how far it is from where the telescope was initially pointed In the example shown it took 11 minutes The maxium time is roughly 30 minutes You can stop the telescope at any time by clicking on the red button x Home Observation in progress Observation parameters STATUS Pointing 8 mn System temperature 130K External temperature 20 0 C Hygrometry 7 5 Sky chart Legend M33 W30H Cyg A G34 3 039 9 00 0 Gal70 0 Gall00 0 BD 61 339 9 BD 44 1018 10 Orion A 11 AFGL 618 12 IRC 10216 13 RWLmi 14 V Hya 15 V Cyg 16 AFGL 2688 17 NGC 7027 18 S Cep 19 LP And 20 Noth Pole Galactic oOonwonuwm bd Wh Pr E EN Seay Suet Care amar egy Source W30H Molecule HI ae Spectrum Skychart Sky Chart N Stop antenna x Pointing imi Are you sure to want to sopt this observation Confirm 18 After reaching the target the telescope automatically switches to tracking mode moving slowly to compensate for the Earth s rotation The telescope thus remains accurately oriented in spite of the apparent motion of the stars across the sky The observation then begins lasting for 30 seconds in beginner mode The resulting plot of the spectrum is updated in real time and appear on the Spectrum tab A message alerts you that the observation has ended 19 A screen capture allows you to keep a copy o
7. Galactic Rotation Curve Several clouds can lie along a single line of sight The cloud with the greatest radial velocity lies at the tangent point T where we see the velocity vector parallel to the line of sight We then have R Ro sin l 7 V Vimax Vo sin I 8 By measuring V max over a range of longitudes we can calculate R and V for each measurement to obtain an observed rotation curve V R as in Figure 7 v d Figure 7 Observed Galactic rotation curve solid blue and the expected curve red dashed if the Galaxy s mass were only that of the visible stars 2 In the scientific jargon V constant with R is called a flat rotation curve The discovery in the 1920 s that most galaxies have flat rotation curves was the first major step towards the discovery of the existence of Dark Matter 25 5 Distance R between a cloud and the Galactic center To find the distance R to a given detected gas cloud we use all the radial speeds measured along that line of sight and not just the maximum value as above We substitute V R Vo in Eq 6 that is we approximate the blue solid curve in Figure 7 as being perfectly flat This gives V Ro R 1 Vo sinl 9 which we invert to obtain R Vo Ro sin l Vo sin L V 10 6 The cloud s position in polar coordinates r l The simplest way to map the Galaxy and see the spiral arms is to express each cloud each peak in the spectrum of radio intens
8. Our Galaxie f 180 seater rotation i Perseus arm 90 10 kpe Figure 3 View of our Galaxy picture Onsala observatory Sweden GO stands for the Galactic center The position of the Earth coincides with that of the Sun In the galactic coordinates system see Section VI the longitude 1s counted from zero the sun to the galactic center axis and increases counterclockwise Latitude b gives the angle relative to the plane of the Galaxy so b 0 being the galactic plane On a given position on the Earth only part of the Milky Way can be observed The HI emission The figure below shows a series of HI spectra of our Galaxy obtained at different longitudes by the Onsala telescope SALSA roughly equivalent to our instrument If the gas has a velocity v relative to the observer then the wavelength i of the observed signal changes from a factor AA v A c where c is the speed of light This phenomenon is called Doppler effect and Ad is the Doppler shift Thus from the measured frequency for each peak of the HI signal can be inferred the gas velocities for each spectrum the peak position of the observed line gives a frequency which thanks to the Doppler effect can be converted into speed on the line of sight Assuming that the total velocity is constant with the radius differential rotation characteristic of spirals the distance of the gas cloud can be calculated This is detailed in Sect
9. source of pollution for astronomical observation Hence in the visible range the observation is made difficult because of light pollution The presence of interferences in the radio domain is less known not visible and having less impact on the environment but also disturbing for astrophysics While some bands are legally reserved for radio astronomy it is common to find parasites in these bands due to non compliance or improper adjustment facilities presence of harmonics of a signal in reserved bands The tests showed that for HI the area around El 20 and Az 240 is very noisy More generally any observation below El 20 should be avoided Regarding OH the 2 1 transition is not observable In addition these tests were used to determine the off frequency used in the observation frequency switch mode Indeed as the spectrum is subtracted off from the raw spectrum it has to be free of emission lines parasite or astronomical source 5 Reference sources To validate the calibration of the observations we observed reference sources whose spectrum is known and present in the Leiden Argentine Bonn Galactic HI Survey database http www astro uni bonn de hisurvey profile Source Bd 61_339 0 2 ee es ee ee ee ee ee ee ee ee ee 100 Wurzburg R f rence 0 15 T K 0 1 40 0 05 Vr km s Figure 4 Comparison between W rzburg spectrum black and reference spectrum red for an observation o
10. spectrum 2 d column radial velocity V in km s x axis of the spectrum 3 column radio frequency in MHz before Doppler calculation yielding V Any plotting software such as Excel or gnuplot allows you to reproduce the spectral plot 3 Using CLASS Here we explain how to improve the data analysis using professional software called CLASS part of the GILDAS package downloadable from _http Avww iram fr IRAMFR GILDAS CLASS runs in a unix like line command environment linux or mac Consider the contents of the directory where you have stored your data A 60 second observation yields 60 files that integrate 1 second each The source shown is called 74 00 observed 9 March 2011 beginning at 10 32 and 31 seconds A screen shot of the directory contents is shown and contains 74_86_26116369_16h32mn31s class data_74_66_26116389_16h32mn31s_28 class data_74_66_26118389_16h32mn31s_47 c lass data_74_66_26116389_16h32mn31is_1 class data_74_66_26116389_16h32mn31s_29 class data_74_66_26116389_16h32mn31s_48 class data_74_66_26116369_16h32mn31s_18 class data_74_66_26116389_16h32mn31s_3 class data_74_86_26116369_16h32mn31s_49 class data_74_66_26116369_16h32mn31s_11 class data_74_66_26116389_16h32mn31s_38 class data_74_66_26116389_16h32mn31is_5 class data_74_66_26116369_16h32mn31s_12 class data_74_66_26116389_16h32mn31s_31 class data_74_86_26116389_16h32mn31s_56 class data_74_66_26116369_16h32mn31s_13 class data_74_66_26116389_16h32mn31s_
11. 1s_8 c lass data_74_66_26116369_16h32mn31s_25 class data_74_66_26116389_16h32mn31s_44 class data_74_00_20110309_10h32mn31s_9 c lass data_74_66_26116369_16h32mn31s_26 class data_74_66_26116389_16h32mn31s_45 class new s m data_74_66_26116369_18h32mn31s_27 class data_74_66_26116369_16h32mn31s_46 c lass Sixty G 1 to 60 files called data sourcename date hour i class of one second observations in X Y Z text format a file sourcename date hour class which is a short CLASS script to convert your files from text to CLASS format The CLASS initialization file new class called by the above script Type CLASS at the command line presuming you have installed it and that your paths are well defined from the directory containing your data Run the script sourcename date hour class by typing the command shown that is script file name followed by enter LAS9B gt 74_86_26116389_18h32mn31s_ 28 When the script has finished executing a new file called sourcename date hour wurz will have been created here 74 00 20110309 10h32mn31s60 wurz containing your data in the CLASS format To read the file type file in sourcename_date_hour wurz then find LA4S96 gt file in 74_66_26116369_16h32mn31s66 wurz I CONVERT I INPUT LAS90 gt find I FIND Lasoa gt f File is Native and lis Your sixty observations are listed on the screen LAS90 gt lis Current index contains 1 2 4 9 16
12. 32 class data_74_66_26116389_16h32mn31s_51 c lass data_74_66_26116369_16h32mn31s_14 class data_74_66_26116389_16h32mn31s_33 class data_74_86_26116389_16h32mn31s_52 class data_74_66_26116389_16h32mn31s_15 class data_74_66_26116389_16h32mn31s_34 class data_74_86_26116369_16h32mn31s_53 class data_74_66_26116369_16h32mn31s_16 class data_74_66_26116389_16h32mn31s_35 class data_74_86_26116389_16h32mn31s_54 class data_74_66_26116369_16h32mn31s_17 class data_74_66_26116369_16h32mn31s_36 class data_74_86_26116389_16h32mn31s_55 class data_74_66_26116369_16h32mn31s_18 class data_74_66_26116389_16h32mn31s_37 class data_74_86_26116389_16h32mn31s_56 class data_74_66_26116369_16h32mn31s_19 class data_74_66_26116389_16h32mn31s_38 class data_74_86_26116389_16h32mn31s_57 class data_74_66_26116369_16h32mn31s_2 class data_74_66_26116309_16h32mn31s_39 class data_74_86_26116389_16h32mn31s_58 class data_74_66_26116369_16h32mn31s_28 class data_74_66_26116389_16h32mn31s_4 class data_74_86_26116389_16h32mn31s_59 class data_74_66_26116369_16h32mn31s_21 class data_74_66_26116389_16h32mn31s_48 class data_74_66_26116389_16h32mn31s_6 class data_74_66_26116369_16h32mn31s_22 class data_74_66_26116389_16h32mn31s_41 class data_74_66_26116389_16h32mn31s_68 class data_74_66_26116369_16h32mn31s_23 class data_74_66_26116389_16h32mn31s_42 class data_74_00_20110309_10h32mn31s_7 c lass data_74_66_26116369_16h32mn31s_24 class data _74_00_20110309_10h32mn31s_43 class data _74_00_20110309_10h32mn3
13. North Galactic pole 17 You can also use ephemeris software to see where sources will be in the sky at various times XEphem http www clearskyinstitute com xephem runs on Mac and linux whereas Carte du ciel http www ap i net skychart fr start and Stellarium http www stellarium org run on all platforms Once you confirm your choice the radio telescope will start moving towards the target source Public Home Create account Antenna specifications Documentation Team Contact Fabrice Herpin 4 User account Change password Delete account pis Manage my observations Observations list Observations planning 4 Observe NEW webcam Meteo Beginer mode Advanced mode Administration 4 Users accounts users list Email users Observations Reservations management Observations management 4 _J Maintenance Ghan antanna eI _ STATUS Pointing 8 mn System temperature External temperature Hygrometry Sky chart Legend 1 M33 2 W30H 3 CygA 4 G34 3 5 039 9 00 0 6 Gal700 7 Gal100 0 8 BD 61 339 9 BD 44 1018 10 Orion A 11 AFGL 618 12 IRC 10216 13 RWLmi 14 V Hya 15 V Cyg 16 AFGL 2688 17 NGC 7027 18 S Cep 19 LP And 20 Noth Pole Galactic Observation in progress Observation parameters Source W30H Molecule HI In progress Spectrum Skychart Sky Chart N 130K 20 0
14. Observatoire Aquitain Universite BORDEAUX des Sciences de l Univers W rzburg Radiotelescope Description and User Manual Fabrice Herpin David Smith wurzburg obs u bordeaux1 fr Version 2 1 Longitude 0 31732 O Latitude 44 50 6 N Altitude 73m Summary In the Fall of 2007 at the LAB OASU in Floirac near Bordeaux we began the renovation of a Wurzburg radio telescope to convert it into a powerful tool for teaching and outreach Teachers all levels of education students and amateur astronomers can now use it to study galactic HI and OH emission One can use it via a web interface or locally individually or through mini courses on site supervised by the research staff This tool 1s now part of the Hands On Universe project Note especially that the telescope is open to all for free This manual covers the version 2 interface Table of Contents Introduction to radio astronomy ll Presentation of the radiotelescope Ill What can we observe with this antenna IV Constraints of the radiotelescope V How to use the radio telescope VI Mapping the Galaxy Vil Data Analysis VIII Wurzburg Team O OD OI QO 26 31 l INTRODUCTION TO RADIO ASTRONOMY Less known to the general public than optical astronomy radio astronomy has made many major discoveries since the middle of the 20 century Examples are the discovery of the cosmic background radiation quasars and pulsars The advantage of usi
15. RZBURG TEAM The W rzburg project is a team effort Key contributors include Organisation amp coordination F Herpin and H Souli with lots of help from P Cais and in particular from A Cap ran for the financial dealings Mechanical J C Bouquier F Glize M Soulette A Triffaux P Truchelut Electronics W D Anna B Quertier P Ca s P Camino J M Desbats S Gauffre Z Salim Programming S Lopez N Autin A Caillo W D Anna B Quertier S Rousseau 32 We thank David Denis Petit and David Smith for their contributions to this manual We thank Ugo Hincelin for the section on Galactic Observations as well as Cathy Horellou amp Daniel Johansson of Onsala Space Observatory for their advice and for their work on the SALSA antennan Their document Mapping the Milky Way was a starting point for the present work Finally we thank P Charlot director of the LAB and F Grousset and E Villenave former director and director respectively of the OASU The following institutions provided financial support LAB OASU Universit de Bordeaux Ecole doctorale de Physique de Bordeaux SF2A et Sciences a l cole Sciences l cole S DN gt SOCI T FRAN AISE D ASTRONOMIE amp D ASTROPHYSIQUE
16. ZBURG WURZBURG WURZBURG WURZBURG WURZBURG WURZBURG WURZBURG WURZBURG WURZBURG WURZBURG WURZBURG WURZBURG WURZBURG WURZBURG WURZBURG WURZBURG WURZBURG WURZBURG WURZBURG WURZBURG WURZBURG WURZBURG WURZBURG WURZBURG WURZBURG WURZBURG WURZBURG WURZBURG WURZBURG WURZBURG WURZBURG WURZBURG WURZBURG WURZBURG WURZBURG WURZBURG WURZBURG WURZBURG WURZBURG WURZBURG WURZBURG WURZBURG WURZBURG WURZBURG WURZBURG WURZBURG WURZBURG WURZBURG WURZBURG 8 8 8 8 8 8 8 8 4 8 8 8 8 8 8 8 8 8 8 8 4 8 4 8 8 8 8 8 8 8 8 8 8 48 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 4 8 8 8 8 8 8 8 cies ae T ade el SS a eS ne oe ee eee we s es Lene mee ee eo eee evn foe ee odo jae iam en CN ce NaS Ges ee Gy eee ene Vim eo ene ee ee ene ase SOTO O90 STOTT TTSWUGUUMMMMUDPUIIUVIWUMMWMMUGP E ma E ma BE mn E a VIMO OMWMOMIMPEPD DPI WVIWIVOWMWOPqaaqaqrqqoococg 74_66_26116369_16h32mn31s68 wurz successfully opened 8 8 8 8 8 8 8 8 0 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 68 8 8 8 8 8 8 8 8 68 8 8 8 8 0 8 8 8 8 SOOO OT TTT TTT TSTTSSTT TST STTSSTSTSTTTOTTTOSFITITVAVAIAVAISOSFSFSSSSSSSSISITISFTOOOOSOS mmmmmmmmmmmmmmmmMmmMmMmMMM MMMM MMMM MMMM MMMM MMMM eee fay fs fs ds tej fay fej ef tej fay tay fay t
17. e the radial velocity to a distance 3 Geometry of the Galaxy When pointing the radio telescope towards a given gas cloud within the Galaxy we see not its total velocity V but only the radial component V along the line of sight In Figure 6 SM is the line of sight Vo is the Sun s velocity tangent to the circular movement of the Galaxy V is the projection on V on SM minus the projection of Vo on SM that is the component of the Sun s motion along the line of sight Figure 6 Galactic geometry S is the Sun you are here C is the Galactic center and M is the source being observed Summarizing Vo Sun s tangential velocity around the Galactic center 220 km s Ro CS distance from the Sun to the Galactic center 8 5 kpc Galactic longitude V Gas cloud s total velocity R CM distance between the cloud and the Galactic center r MS distance between the cloud and the Sun We have V V cos a Vo sin c 1 Inspection of Figure 6 shows 90 1 90 c 180 c l 2 So that we can re write Eq 1 as V V cos a Vo sin l 3 Since the line CM is at a right angle to V we have b 90 a 90 a gt a a 4 24 The distance CT can be expressed in two ways CT Ro sin l R cos a cos a R R sin l 5 Hence V becomes V V Ro R Vo sinl 6 This equation has two unknowns R and V To obtain R we assume from here on that V is a constant independent of R 4
18. f a region of our Galaxy The details of the spectrum are the same the velocity and intensity scales too 1 CLASS software is developped by IRAM hitp Avww iram fr IRAMFR GILDAS 11 V HOW TO USE THE RADIO TELESCOPE I Logging on Use any internet brower n access the mnrevUne web Page ou below Firefox and Google Caron are er Neat Mac vs PC vs Linux makes no difference Login Create account forgot password Home ee Introduction Create account In fall 2007 at the Bordeaux Observatory now LAB OASU we have started the renovation of the W rzburg radio telescope in order Antenna specifications to convert it into an outreach and learning facility Documentation From now on the HI and OH emissions from our Galaxy are observable by anyone from home The radio telescope is available for Team teachers any levels for students and for non professional astronomers through a web interface or on site Contact More precisely we offer the possibility to observe remotely via internet and or during training sessions on site managed by our local staff We stress that the radio telescope is open for all If you are already signed up log in using your username and password and go to Step 2 For new users click on Create an account Fill in the sign up form shown in the figure and click on sign up ZBU Home Documentation Create account ee Password Login Create account
19. f your observation You can also obtain a collection of files from your observation by clicking on the CD The files include the spectral graph text files where three columns correspond to the radio intensity as a function of radio frequency or of the radial velocity of the source along the line of sight this is explained further below and some files containing other information related to the data acquisition The data can also be obtained by clicking on the CD in the Your Observations list as shown X Home Observation in progress Observations list 2014 04 03 in the figure The data is thus saved onto your own computer 4 Observations in Expert Mode When you choose Expert Mode more parameters can be set than in Beginner s mode Home Observations list Advanced mode wAn NANN Fabrice Herpin SEMS EAS 21 ete Instead of a pre defined list of targets you must now indicate the object s celestial coordinates yourself You can choose between equatorial coordinates right ascension and declination or Galactic longitude and latitude b You should also indicate a name for your target Home Observations list Advanced mode We suggest using names that will help identify the observation later such as 1 100 b 0 for an observation of the Galaxy at 1 b 100 0 degrees The name is used for the data files that will be produced You can specify the target
20. forgot password Home amp Create account Public Home A T T Create account Antenna specifications Documentation Team Fields with are mandatory Contact Last Name First Name Phone number Email adress Function Society Create account Cancel 12 Within a few minutes you will receive automatic e mail with your password Note that you must then validate your account by logging in as per the instructions in the e mail message Anyone can use the radio telescope no restrictions apply We ask for your e mail address only in case there is some problem and thus a valid e mail address is required You can change your password at any time ZBU 7 Total connections 521 i me a Today connections 1 al B Logout L Change password Delete account El Home Public Introduction Create account In fall 2007 at the Bordeaux Observatory now LAB OASU we have started the renovation of the W rzburg radio telescope in order antenna specifications to convert it into an outreach and learning facility Documentation From now on the HI and OH emissions from our Galaxy are observable by anyone from home The radio telescope is available for Team teachers any levels for students and for non professional astronomers through a web interface or on site contact More precisely we offer the possibility to observe remotely via internet and or during training sessions on
21. g 500 10900 Velocity km s Next we clean the signal by removing the base line To define the velocity interval containing the signal region that we wish to explore type SET CURSOR ON SET WIN You can now use your mouse to move the cursor over the plot image Press the space bar once when the cursor is to the left of the signal region and again on the right and then type E to exit the interactive mode Typing DRAW WIN then redraws the window for the selected region LAS9B gt set cursor on LASSB gt set win LASSB gt draw win LAS9H gt 30 To model the baseline excluding the signal region use the command BASE 9 PL LAS9B gt base 9 pl I POLYNO Degree 2 would be even better I POLYNO degree 9 rms 6 194 area 995 v 14 27 width 6 666 LASoB gt This determines a 9 order polynomial resembling the wavy baseline in particular to allow an interpolation across the signal region You can iterate as many times as you please on the definition of the signal region and or on the order of your polynomial until the curve seems to match the data reasonably The PLOTcommand then displays the cleaned signal after baseline subtraction 1 9 74 00 HI WURZBURG 0 09 FEB 2009 R 17 MAR 2011 RA 20 18 06 00 DEC 35 46 49 0 Eq 2000 0 Offs 9 0 0 0 Unknown tau 0 057 Tsys 30 Time 1 0 min El 51 4 N 2048 10 1024 00 YO 0 2026 Dv 1 087 Ear FO 1420 532253 Df 5 1500E 03 Fi 1420 53223 1425 1420
22. half the signal intensity when viewed 0 radians away from the source direction This description of the blurred image is called the approximation of a Gaussian beam Determined experimentally the antenna beam is 0 2 8 For its focal length this means that the horn only sees an antenna diameter of 4 9 m IIl WHAT CAN WE OBSERVE WITH THIS ANTENNA The range of frequencies available allows observations of the galactic HI hydrogen H in emission absorption at a wavelength of 21 cm 1 e at a frequency of 1420 4 MHz the OH maser emissions at 1 6 1 7GHz see below The OH frequencies are being tested and will be available shortly Why these HI and OH transitions Most of the gas in our Galaxy is in hydrogen HI atomic form which emits radiation at a radio wavelength of 21 cm that is to say a frequency of 1420 MHz The 21 cm line was theoretically predicted in 1945 by van de Hulst and has been observed for the first time in 1951 Most of the stars and gas in our Galaxy is located in a thin disk The sun is located at a distance of about 8 5 kpc 25 000 light years from the galactic center Because of our position in the Galaxy it is quite difficult to study the three dimensional structure thereof Radio astronomy observations of the hydrogen atom helped to reveal the properties of the Galaxy mainly because this type of radiation is not quenched by the dust and the gas expands unlike stars beyond the galactic disk
23. ion VI The OH emission OH was the first astronomical molecule detected 1963 in the radio part of the electromagnetic spectrum The spectral lines of OH are at wavelengths 2 2 3 7 5 0 6 3 and Notation Frequency MHz OH 1 2 1612 2 OH 1 1 1665 4 OH 2 2 1667 4 OH 2 1 1720 5 18 cm This molecule is observed in the Earth s atmosphere planetary atmospheres in comets in molecular clouds galaxies but especially in evolved stars stars older than our Sun with equivalent mass as maser radiation OH Maser radiation at 18 cm emitted by evolved stars is actually composed of three lines the main ones at 1665 and 1667 MHz lines and a satellite line at 1612 MHz Depending on the intensity of the OH maser lines at 1 7 GHz evolved stars can be classified into different groups Type I or II One can also study the frequency of the radiation relative to the change in brightness of the star the light curve of most of these stars is known The classic OH maser emission spectrum is characterized by a double peak profile From the separation in velocity of the 2 peaks one can infer the expansion velocity of the OH envelope while the middle velocity gives the velocity of the central star IV CONSTRAINTS OF THE RADIOTELESCOPE 1 Instrument field of view Because of his mount the antenna can only observe part of the sky basically anything that is too far north is unobservable Whenever you select a source to obse
24. ity versus radial velocity in polar coordinates 7l As before r is the distance between the Sun and the cloud and is the cloud s longitude galactique From Figure 6 R Ro 77 2 Ro r cosl 11 This quadratic equation has two solutions r R Ro sin 1 Ro cos l 12 In quadrants II and III only one solution is physical r positive and the position of the emitting cloud is uniquely determined For quadrants I and IV two solutions are possible corresponding to the two intersections of the line of sight MS with the solar circle red dashed in Figure 6 26 VII DATA ANALYSIS I Using the spectral plot Frequency Switch On Off 20 Brightness temperature K a S amaii i ii eee Puede hit atate ged EEA ere E OEE LARA RARE arqg AE eee Secreta STOOD k 1000 500 0 500 1000 LSR radial velocity km s The image file obtained from the observation is a spectrum the intensity of the signal picked up by the antenna for the molecule chosen by the user HI in this example as a function of the radial velocity V Recall that we obtain V for a given measured radio frequency by assuming that the signal occurred at the HI relaxation frequency 1420 MHz but that the frequency was Doppler shifted due to the movement of the emitter relative to the Earth More precisely not the Earth but a point near the Sun that takes into account the sun s movement relative to the general Galactic
25. lete account Correlators 2 4 Manage my observations 2048 channels per subband Observations list spectral resolution 5kHz Observations planning Note that the column of tabs on the left is accessible even without an account They allow potential users to contact us to consult the antenna characteristics and so forth 13 2 Reserving an Observation Session Once logged in the Manage my observations tab gives you access to Reserve an observation as well as the list of your reservations and past observations Fabrice Herpin e Total connections 521 ha Today connections 1 A Logout L Change password Delete account El Home Public Slime Introduction Create account In fall 2007 at the Bordeaux Observatory now LAB OASU we have started the renovation of the W rzburg radio telescope in order antenna specifications to convert it into an outreach and learning facility Documentation From now on the HI and OH emissions from our Galaxy are observable by anyone from home The radio telescope is available for Team teachers any levels for students and for non professional astronomers through a web interface or on site Contact More precisely we offer the possibility to observe remotely via internet and or during training sessions on site managed by our local Fabrice Herpin a Sie aire eet Eha racic Selene S Opati Tor ail 4 User account Radioastronomy for all Change passwo
26. lux K sol all AT ih Mall ALD a Mt lh VAAL ITI Halt AN col Hl TTY wali j itl 691 15 691 20 691 25 691 30 691 35 691 40 691 45 691 50 691 55 691 60 usb frequency GHz Figure 1 Example of CO molecule radio signal detected with an antenna other than the Wurzburg The signal is observed over a given frequency and the strength is measured by a quantity called the flux or intensity in Kelvins Il PRESENTATION OF THE RADIOTELESCOPE The W rzburg radiotelescope is a former German army radar moved to the observatory in 1962 It was used to observe the Sun continuously from 1966 to 1987 Its renovation began in 2007 Figure 2 W rzburg radiotelescope left and horn right To observe solar bursts the receiver was set to 930 MHz Since renovation the bands of observing frequencies are now between 1 35 GHz and 2 7 GHz The Wurzburg consists of a 7 5 meter diameter collecting parabolic antenna a horn Figure 2 that receives the signal focussed on it by the antenna and transmits the radio signal to the electronics an electronics systems with a computer to process the signal and to steer the antenna Diffraction limits a telescope to a minimum angular size 0 of an object that can be resolved 0 1 22 A D where is the wavelength used for observations D is the antenna diameter 0 is taken as the width of the main beam at mid height 0 HPBW That is a point like source at infinity will have
27. motion called the Local Standard of Rest or LSR In the spectral figure a peak appears near 20 km s This is interpretated as an HI emitter with that velocity component along the lin of sight to the LSR The y axis of the spectral plot is the signal power expressed as a brightness temperature in Kelvins degrees above absolute zero A bigger peak indicates a larger number of hydrogen atoms The overall signal shape away from the double HI peaks is called the baseline It is a combination of the total radio emission from various types of gas along that line of sight the emission of the Earth s atmosphere at these radio frequencies and of the radio telescope itself and its electronics For our purposes we can consider the baseline to indicate the noise level Fabrice on dit qq chose a propos du gros spike negative a 490 km s Pour la version anglaise je propose de remplacer par un truc plus clean non 2 Using the X Y Z text file 3 http en wikipedia org wiki Local_standard_ of rest 2d For each of your observations for each second of observations a file called data sourcename date hour x class is generated containing une 1 colonne avec l intensit du signal axe des Y sur la pr c dente image une 2 e colonne avec les vitesses axe des X sur la pr c dente image une 3 colonne avec les fr quences quivalent de la 2 colonne par effet Doppler lst column signal intensity Tb y axis of the
28. ng radio telescopes is the possibility of observations in daylight from the city of objects in our Galaxy and far beyond 2 sis radio o tid S a U LA aa 10 lt i EE i 1 10 Longueur d onde en m Radio astronomy is the science that studies the electromagnetic radiation from astronomical sources emitted at frequencies from a few MHz to 2 THz or wavelengths of a few tens of meters to a few tenths of a millimeter Radio wavelengths are longer than optical wavelengths The millimeter A gt 1 mm and submillimeter A lt 1 mm domains allow the exploration of regions inaccessible at optical and UV wavelengths for example young star forming regions These areas are relatively cold and emit mainly radio frequencies The signals picked up by radio telescopes are electromagnetic waves emitted by molecules atoms or ions in space around stars in molecular clouds etc These species have been excited by a heating source e g star or gas shocks then emit photons by relaxing to their normal state The emission of each molecule is very weak but given the vastness of interstellar space the total emission is perfectly detectable The signal emission occurs only at very specific and known frequencies In the same way that turning the knob of a classical radio receiver selects your favorite music channel the radio telescope is tuned to the frequencies emitted by the molecules which facilitates their identification f
29. ogen called HI H one at a radio frequency of 1420 MHz and hydroxyl molecules OH near 1600 MHz The other telescope settings such as integration time are Set l Home Beginer mode As an example one can pick the galaxy M33 Clicking OK starts the observation that is points the telescope in the right direction and then acquires some data 16 If the source is not currently in a part of the sky that the telescope can point to a message appears and you must pick a different target u H Observation in progress Observation parameters Source LP_And Molecule HI STATUS Spectrum Source non pointable too far west System temperature 130K Observation failed x External temperature 19 7 C xX Hygrometry 7 5 OK Use the sky chart to identify HI sources blue squares or OH sources pink squares that are within the faint red dashed curve that indicates the sky zone accessible by the telescope The green triangle shows where the telescope is currently pointing The symbol numbers correspond to the objects list in the legend namely Sky Chart N 1 M33 HI 2 W30H HI 3 Cyg A HI 4 G34 3 HI 5 OH 039 9 00 0 HI 6 GAL70 0 0 0 HI 7 GAL100 0 0 0 HI 8 BD 61 339 HI 9 BD 44 1018 HI 10 Orion A HI 11 AFGL618 OH 12 IRC 10216 OH 13 RW LMi OH 14 V Hya OH 15 V Cyg OH 16 AFGL2588 OH 17 NGC7027 OH 18 S Cep OH 19 LP And OH 20
30. rd Less known than optical astronomy radioastronomy is on the origin of major scientific discoveries such as the cosmological background emission pulsars radio sources associated to black holes and organic molecules in space Delete account Moreover although a large fraction of the LAB staff is involved in radioastronomy so far none instrument was available on site to show our activity Now for the first time we make possible observations with radio telescope for everyone the understanding of our daily research activities the understanding of the radioastronomy This work has been supported by To make an observation click on the Observations calendar tab The following page appears Observations calendar Observations calendar 4 September 2014 gt S M T Ww T F S 3 4 5 7 8 9 10 11 12 13 14 Confirm a reservation x 21 28 3 Reserv this date 2014 9 3 08 00 00 12 00 00 Description test Availabilities for the Ava 2014 9 2 Confirm Cancel Click on an available hour range Warning Reservations and observations are made at telescope time TU Think about it before to reserve and abserve Click on an available hour range Think about it before to reserve and abserve 00h00 04h00 04h00 08h00 08h00 12h00 12h00 16h00 16h00 20h00 20h00 00h00 renos one 00h00 04h00 04h00 08h00 08h00 12h00 12h00 16h00 16h00 20h00 20h00 00h00
31. rve a chart is displayed on the screen with the observable part of the sky On the image below the portion of the sky available is bounded by the dotted red below When selecting a source outside the field of view of the telescope a message will warn you Sky Chart N OH Source s lt wunpeintable HI lt unpointable O 2 Observing mode There are several observing modes for a telescope The one used with the W rzburg is the frequency switch mode This mode consists in observing integrating a source for some time at the requested frequency then in observing the same source same spatial position but at a frequency where the source does not emit off frequency To obtain the spectrum of the source without the defects inherent to the antenna and the environment we then just make the difference between the two observations The W rzburg provides spectra whose bandwidth is 10 MHz with a resolution of 5 kHz 3 Integration time The more we integrate on a source the better the signal to noise ratio and the easier it is to detect faint sources The electronics of the antenna allows for the moment to integrate a maximum of one second in order to ensure system stability Thus 1f you enter as integration 10 time 100 seconds the observations will therefore consist of 100 spectra of 1 each that you will add later with a software such as Class see section VII 4 Interferences and off frequency Cities represent a major
32. site managed by our local Fabrice Herpin staff We stress that the radio telescope is open for all 4 User account Radioastronomy for all Sa aaa Less known than optical astronomy radioastronomy is on the origin of major scientific discoveries such as the cosmological background emission pulsars radio sources associated to black holes and organic molecules in space 4 Manage my observations Observations list Moreover although a large fraction of the LAB staff is involved in radioastronomy so far none instrument was available on site to show Observations planning our activity Now for the first time we make possible 4 Observe observations with radio telescope for everyone NEW webcam the understanding of our daily research activities ory the understanding of the radioastronomy are sana This work has been supported by Having created your account you can log in The following page appears ZBU Fabrice Herpin 3 om t Total connections 521 Pes Today connections 1 lie B Logout Change password amp amp _ Delete account w Home Observations planning Antenna specifications Public Home Create account Antenna specifications antenna specifications Documentation Van Team x Longitude 0 31 32 Latitude 44 50 6 Altitude 73m Fabrice Herpin Diameter 7 5m 4 User account Observable frequency range 1 4 1 7GHz Change password Bandwidth 9 2MHz De
33. sp ts taj fey fay fe fej fap fey fap ts fay fay fe fs tej taj taj fay is fey fay bey fe te fey fa fej day fe fal fay fey te tel fay fay fal ts fej fap fey fey fey fay fs fay ts 79 79 79 79 79 79 79 79 79 79 79 79 79 79 79 79 79 79 79 79 79 79 79 79 79 79 79 79 79 79 79 79 79 79 79 79 79 79 T9 79 79 79 79 79 79 T9 79 79 79 79 79 79 79 79 79 79 79 79 79 79 ee To improve the signal to noise ratio we add all the observations together using the average command LASoB average 29 The command plot posts the data to the screen Typing SET FORMAT LONG followed by PLOT adds additional information to the plot giving this LAS9B gt pl LASSH gt set format long LAS9B gt pl LAS9O gt The figure header lists the source name the gas species HI or CO the telescope name observation date the pointing coordinates in Right Ascension and Declination the total integration time used in the plot 1 minute in this case the source speed that you may have entered here 0 2 km s and so forth 1 9 74 90 HI WURZBURG 0 09 FEB 2009 R 17 MAR 2011 RA 20 18 06 00 DEC 35 46 49 0 Eq 2000 0 Offs 0 0 0 0 Unknown tau O 05 Tsys 30 Time 1 0 min El 51 4 N 2048 10 1024 00 YO 0 2026 Dy 1 087 Ear FO 1420 53223 Df 5 1500E O3 Fi 1420 53223 1425 1420 20 Q 20 40 60 1000 500
34. ud where is called galactic longitude and b is galactic latitude As shown in the figure the reference system is centered on the Sun Latitude b 0 corresponds to the Galactic plane the Milky Way s disk The galaxy is divided into four quadrants shown in Figure 5 I 0 lt lt 90 II 90 lt lt 180 III 180 lt I lt 270 IV 270 lt I lt 360 2 Hydrogen in the Galaxy 10 to 15 of the mass of our galaxy is gas and most of the gas is atomic hydrogen Collisions of an atom with other matter or light can excite its electron to a higher energy state When an atom relaxes that is its electron s spin flips to become anti parallel with the proton s attaining a lower energy state the electron radiates at a precise frequency near 21 cm 1420 MHz Relaxation takes about 10 million years to happen for a given atom But the huge number of atoms in interstellar space makes the combined signal from all the relaxing atoms detectable The spectra we measure with the Wurzburg antenna cover a frequency range above and below 1420 MHz if the emitting gas is moving towards us the frequency is shifted higher Doppler shift Similarly if the gas is receding the frequency is lower Thus 23 measuring the peak s position allows us to deduce the component of the gas s speed along the line of sight By assuming that the gas is rotating along with the rest of the Milky Way we can translat
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