Radio Telescope User Manual STANDARD OPERATING
Contents
1. Clicking on the Stow button will return the telescope to the normal stow position in the eastern most low elevation position of the main Az El travel zone The travel zone is established by the AZLIMIT and ELLIMIT commands in the srt cat file track The track button enables the antenna to slew to the selected source from clicking on the map selecting from the source list or after typing the source information on the command entry text box The track sequence will work automatically when a source is selected from a command cmd file azel Action on the Azel button allows the user to enter a fixed azimuth elevation position in the command entry text box assuming the entered coordinates are within the Az El limits of travel of the SRT as set in the srt cat file npoint Initiates a 25 point scan map of the source selected The map is 1 2 beamwidth spaced and when finished displays a false color Gaussian plot to the left of the accumulated spectrum plot This plot will clear when the clear button is enabled The resulting maximum T ant with associated offset is displayed under scan results in the information sidebar The color plot will NOT refresh if the SRT window is reduced then refreshed bmsw Initiates a continuous off on off beamswitched comparison observation of the selected source at the frequency settings entered with freq The off on off measurements are a set and are complimentary meaning that the two off so2. and begins data recording The current line number and text being read is echoed on the message board above the text entry box To start automatic recording and reading of a file other than the default srt cmd enter the desired command file name with the cmd suffix in the command text entry box cal Starts an automatic calibration sequence during which a noise source located at the apex of the antenna surface is enabled for 1 second The system then takes a data sample without the noise source enabled The resulting system noise temperature is reported in the information side bar as Tsys Vane Not applicable to this telescope B MESSAGE BOARD AND TEXT INPUT The command text input box and the system message board are located at the bottom of the SRT controlpanel window Many of the actions initiated by clicking the command toolbar are implemented by entry of parameter settings in the text box Information regarding the correct entry is printed in a message board above the text entry area when the mouse pointer is moved over the desired command button Some of the buttons source and Rcmdfl will display more than one set of instructions if the pointer is moved away then returned to the button area In the case of the source button continuous clicking of the left mouse button will scroll through the source list on file and each source name will display in the message board The message board will also display the current active
3. 4 MHz the number of steps to 25 and the step spacing to 40 kHz This observation would have a span of 25 times 40kHz from 1419 9 to 1420 9 MHz with a center frequency of 1420 4 MHz the syntax is center frequency space no of steps space step size then click on freq if there is no input for step size the default is 40kHz Offset Typing an azel type command into the text box and clicking on offset will move the telescope the appropriate offset distance from its previous position This is useful when tracking an object and the user wishes to check if the object is centered on the SRT The syntax for the command is identical to the azel command e g 10 10 will offset the position of the SRT by 10 degrees in azimuth and elevation The default is positive so the user must enter a minus sign to offset in the opposite direction Record Starts recording a command file appropriate to the settings immediately previous to its execution The recorded file has the extension rad and is saved in the telescope srt java directory To operate click on the record button in the command toolbar to start and again to stop This will default the name of the command file to yydddhh rad i e year date and time of recording To record to a suitable filename type the filename e g stellar rad in the text box and click on record Cal Initiates the electronic noise calibrator for one second to calibrate the system and calculate the system tempe
4. U I is an interactive Java generated window that allows command and control functions of the telescope as well as acquisition of data see picture above The G U I consists of A 15 button tool bar B Text entry command bar C Information side bar D Sky map E Spectral line and continuum display Each of these will be described in turn A THE COMMAND TOOL BAR The main input device on the SRT G U I is the command tool bar It consists of 15 buttons arranged horizontally along the top of the screen Pointing and clicking the left mouse button on any of these will initiate an automatic sequence such as cal calibrate or track or wait on further input from the user freq offset The following is a list of command functions and their description clear As the label implies the clear button will clear the control console display of accumulated spectral line data 25 point scan data This function is useful if the user is accumulating multiple spectra from different sources or galactic coordinates The system will treat new source spectra as additions to the accumulated spectrum atten Enabling the atten attenuation button adds or removes a 10dB attenuation to the receiver with successive left button mouse clicks The atten will illuminate red while the 10dB attenuation is active The attenuation value can also be read just above the center of the message board area to the right of the power temperature information stow
5. left of the control console display shows the station name latitude and longitude as read from the srt cat file The second line lists the current antenna drive status such as moving simulate stopped SRT OPERATION The following section is intended to familiarize the reader with the operation of the SRT It is intended as a guide and not as a full working technical manual For more information on the workings of the SRT consult the website http web haystack mit edu SRT Starting the GUI Log on to the computer as normal Go to programs msdos prompt When you are in the msdos window type cd to get to the root directory Type cd telescope srt java to get to the srt directory To get to the G U I type java srt 0 N B There are in fact six modes of executable including java srt 0 these are as follows Run the SRT java srt 0 Simulate SRT java srt 1 1 Simulate Antenna java srt 0 1 Simulate Radio java srt 1 Simulate speed time x 10 java srt 1 10 Simulate with 1 hour advance java srt 1 1 Using the G U I Manual operation For most purposes it is sufficient to enter commands such as azel record etc manually To do this the SRT software contains a text input section section 2 B to facilitate manual control Entering commands is simply a case of clicking in the text box at the bottom of the screen and typing your text Next click on the appropriate command button in the command tool bar section 2 A and the SRT
6. line command from a command file and the line number This text will appear green in the form filename cmd line nn text command To the right of the message board text area is another space used to echo information after a text command is entered Printed in blue it will repeat the issued command or advise the user that the issued command is waiting on some other action of the telescope Receiver output and telescope status can be read in two small text boxes just above the message board and below the map azimuth scale In the left box reading from the left is the current frequency sweep set in freq receiver counts uncorrected power level detected by the receiver the real time system temperature and the attenuation setting In the right box the user can reading the current status of the telescope as a whole Stowed slewing or tracking C INFORMATION SIDEBAR The information sidebar lists nearly all of the pertinent information the user needs to monitor real time observing with the telescope The sidebar displays from top to bottom Antenna Coordinates Command computer command Azel actual position Total Offsets User input mapping etc Pointing Corrections degrees Axis Corrections mechanical user set Galactic Coordinates RA and DEC Hrs and Deg Time Universal Time UT Local Sidereal Time LST Source Source Name RA and DEC Azimuth and Elevation Center Frequency Input Frequency MH
7. 80 90 calibration position freq 1415 5 0 0 scan frequency 5 bins samples no frequency step noisecal calibration Sun Source command Azimuth Scan Comment offset 30 0 start offset commands for scan 30 to 30 degrees offset 29 O offset 28 0 offset 27 O offset 26 0 offset 25 0 through to offset 30 0 Elevation Scan Comment offset 0 30 Start elevation scan if sun El is lt 60 degrees offset 0 29 offset 0 28 offset 0 27 offset 0 26 offset 0 25 through to 0 30 roff End recording Galactic rotation curve LST 18 00 00 wait until 1800 LST when Galactic center is above telescope limits 1420 4 50 set radiometer center frequency and a number of frequency bins azel 180 90 point south at 45 degrees noisecal calibrate radiometer galactic 0 0 move telescope to Galactic center record g00 rad start data file 600 take data for 600 seconds Note no space after colon roff turn off data recording galactic 10 0 move telescope to Galactic longitude of 10 degrees record g10 rad repeat Bibliography Undergraduate Research Educational Initiative website http web haystack mit edu urei tut4 html Astrophys Assist Educational Resources website www astrophys assist com educate sngldish dishO3 htm Die kosmische A Klasse Beobachtung historischer Radioquellen website www klima luft de steinicke Artikel aklasse aklasse htm Kra
8. Radio Telescope User Manual Richard Baker 2 Message boardtext ees entry window Serinna seeds teh 5 Spectral line Pe 6 Total power chat recorder Fig 25 A picture of the command window The numbers in this figure correspond to the numbers immediately above Picture taken from pdf file on SRT wehsite STANDARD OPERATING PROCEDURES All users of the telescope MUST obey the following rules Remaining in designated areas Do not approach the edge of the roof Beware of tripping hazards loose cables etc Do not drop items over the side of the roof Always fasten down equipment to avoid it blowing off the roof Weather conditions There will be no roof access if the weather conditions are too fierce e g too icy windy etc Proper precautions to be taken when if working in the dark and or rainy Apparatus Take care of equipment at all times Be aware of electrocution aspect of equipment Make sure all cables are weatherproof to prevent short circuits etc DO NOT attempt to touch any exposed wires or cables whilst power is supplied to the telescope Follow standard operating procedures when using computers backrests breaks etc Follow procedures for lifting heavy equipment Telescope operating procedures Park SRT telescope at zenith to ensure minimal surface aspect to wind Shut roof doors when not in use THERE WILL BE NO ROOF ACCESS WITHOUT SUPERVISION G U I OVERVIEW The SRT Graphical User Interface G
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10. cord space filename rad Integrates a source for a set period of time assuming the time instruction is the next command or until the roff command is given e g record scan1 rad 60 roff Typing noisecal will initiate the electronic noise calibrator in exactly the same way as the manual command space freq space center frequency MHz space number of steps space step size MHz This is identical to the manual instruction e g freq 1420 4 51 0 04 It is also possible to track objects in the command file Entering the source name after the colon sourcename will achieve this e g Sun Note that this is case sensitive Reading data files As stated above the data files are recorded to the telescope srt java directory The format of these files is confusing especially where many frequency spacings are used The format of this data is in the form of columns which include commands from the user frequency information as well as intensity information in tabular form These files are readily interpreted by Microsoft Excel With carefully manipulation upon opening the file in Excel the user can process the raw data creating graphs and tables that are more easily understood Command file examples In order to familiarize the user with the syntax of commands this manual includes some basic command files Measuring antenna beamwidth record filename Start recording output filename is optional azel 1
11. formation box below the map will carry the message Status slewing The sky map will show the telescope crosshairs superimposed on the selected source and illuminated yellow until the SRT arrives at the source The SRT travel limits are also plotted as square boxes on the screen The azimuth travel limits are set in the srt cat file In the above illustration the limits are approximately 91 to 269 degrees Coverage of the 271 to 89 degrees azimuth is achieved by moving the elevation axis through the zenith to the desired elevation and thus a plus 180 azimuth position A total elevation travel of up to 179 degrees is possible by setting the ELLIMIT command in srt cat allowing full sky coverage Example AZLIMIT 91 269 ELLIMIT 0 179 E SPECTRAL LINE AND CONTINUUM DISPLAY The G U I displays the spectral line plotting area of the SRT control panel There are two spectral windows The area of the SRT control console above the Sky Map is a continuously running chart recorder showing relative power of the signal received vs time The plot will continually overwrite as it paints from left to right and will reset to the bottom of the chart when the plot value reaches the 400K vertical scale maximum To minimize confusion when the scale resets 400K steps the plot is color coded note the color dot icon to the right of the temperature indicator Discrete Spectrum The right side black is the plot of each individual spectrum as it finishe
12. rature To start point at a relatively empty free from signals patch of sky and click on the cal button Automatic operation Although manual commands are useful for simple operations of the SRT it is clear that this method is too cumbersome for long operations such as integrating the galactic plane The G U I therefore is equipped with a limited command file structure capable of reading a program written by the user in which embedded commands such as track record etc can be executed automatically Its also incorporates time commands such as integrating over a set period or waiting until a set LST to start operations This has obvious advantages over manual control but has distinct syntactical preferences which this manual will briefly describe The repeated functions are initiated by way of a command file given the extension cmd the file can be given any name but it is best restricting the name to something appropriate to the procedure No full stops should be used in the file name and try to stick to ordinary characters The file can be written in any text editor but remember to save to file with the extension cmd also the file must be saved in the telescope srt java directory in order for the software to find it To initiate a file enter the filename in the text box and click on the remdfl button in the command toolbar The filename must have the extension cmd in order to be recognized The following are a list of commands
13. s the user input span in MHz see freq in section 1 3 1 The top of the display lists the input center frequency and the frequency step The bottom line lists the difference of the maximum and minimum values measured during the frequency scan There is also an arrow indicator showing the direction of increasing frequency Accumulated Spectrum The left side red spectral line plot shows the accumulated spectra since the selected observation began Listed at the top of this window is the title av Spectrum as well as the total integration time The bottom script shows the same max min difference and increasing frequency direction A snapshot of the accumulated spectrum can be seen in a pull down window by moving the mouse pointer to the accumulated spectrum window and clicking the left mouse button A sample is seen here 25 Point Map Display The third window in the plot area far left square field is the output display for 25 point spectral and continuum maps When a 25 point scan is complete a false color image of the map area will automatically display Continuum Display The left side box reports information showing the number of observation cycles and the total integration time above the graphical output Below the graph the average temperature the RMS and vertical scale are reported Total Power Chart Recorder black 0 400 blue 400 800 green 800 1200 red 1200 1600 Antenna Drive Motion Status Display This box at the upper
14. to familiarize the reader with the general structure of the command file All commands have a colon to start followed by a space with the exception of the time commands Position commands There are several ways that the SRT can move in position azel radec and galactic coordinates The appropriate syntax for each is as follows space azel space azimuth position space elevation postion e g azel 180 90 space radec space ra position hh mm ss space dec position hh mm ss e g radec 23 00 00 06 50 00 space galactic space galactic coordinate in 1 space galactic coordinate in b e g galactic 05 Again all commands must be within the SRT physical software limits Time commands Time commands are used to integrate wait over a set period of time or for the SRT to perform a command at a set time This can be either LST or UT The commands for these are LST time hh mm ss note no space after the colon This causes the SRT to wait until a specified time in LST before continuing with the command file e g LST 06 00 00 yyyy ddd hh mm ss same as above but in UT e g 2002 074 06 00 00 time span in seconds waits for a specified amount of time before executing the next command in the file e g 60 wait 1 min Miscellaneous commands Instructions that are used frequently but do not come under the heading of time or position commands are record noisecal and freq these commands are written as re
15. urce positions switch sign within each set The off source measurements are spaced at 1 beamwidth in azimuth offset beamwidth cos EL BEAMWIDTH is set in the srt cat file A left mouse click on the bmsw button after the scan has started will abort the beamswitch operation Results of the bmsw observation appear in the left red spectral plot window freq Sets the center frequency number of frequency steps and the step width in MHz Clicking on the freq button prompts the user to enter the desired settings in the command entry window Example for the analog receiver To observe the hydrogen line at 1420 4 MHz move the mouse pointer to the freq button Left click the button then move the cursor to the lower text input section and enter 1420 4 25 0 04 0 04 MHz is the default Where 1420 4 is the center frequency of an observation that is 25 times 0 04 MHz wide or spanning from 1419 9 to 1420 9 MHz offset Enables the user to enter any az el offset pair desired Left click the offset button and enter the offsets in the command entry box drift A left mouse click on Drift will offset the SRT in Right Ascension and Declination to allow the selected source to drift through the 7 degree beam of the telescope record Toggles output file recording on and off Output data files are labeled in the form yydddhh rad Record also allows the user to enter a filename rcmdfl Initiates reading of the default command file srt cmd
16. us J D 1986 Radio Astronomy 2nd Ed sec 1 13 APS news online website www aps org apsnews 1198 119807 html Undergraduate Research Educational Initiative website http web haystack mit edu urei tut5 html Astronomy 123 website zebu uoregon edu imamura 123 lecture 4 lecture 4 html The Milky Way a grand design website http blueox uoregon edu courses BrauImages Chap 18 FG18_016 jpg Radio Astronomy and Interference website http www aoc nrao edu intro rfi spillover html Radio Astronomy and Interference website http www aoc nrao edu intro rfi goodbad html Undergraduate Research Educational Initiative website http web haystack mit edu urei tut3 html Undergraduate Research Educational Initiative website http web haystack mit edu urei tut6 html Schematic designed by Glynn Summers Montez Jr Rodolfo Electronic Noise Calibrator for the Small Radio Telescope University of Texas at Austin Department of Astronomy Program created by Hugh Lang SRT website http web haystack mit edu SRT orien pdf Schematics designed by Glynn Summers and Luke Woofenden Burton W B 1985 Astronomy amp Astrophysics Supplement Series 62 365 Young J S Scoville N On the origin of molecular cloud rings in spiral galaxies CO observations of NGC 7331 and NGC 2841 Astrophysical Journal Part 2 Letters to the Editor vol 260 Sept 15 1982 p L41 L44 SRT software website page http web haystack mit edu SRT SRTManu
17. will execute the proper command For full instructions on the uses of the command tool bar see section 2 This section will give a brief overview on the basic commands along with syntactical instructions to familiarize the user with the basics of the SRT software Stow Instructs the SRT to move to its easterly limit whereupon it hits its mechanical limit switches This provides the telescope with a point of reference from which to calculate all further coordinates Clicking on stow in the command toolbar will cause the SRT to go to this position Track Clicking on an object in the Sky Map will cause that object to turn red Clicking on track instruct the SRT to track that object as long as it is within the software hardware limits of the telescope It is primarily used in conjunction with the record button to continuously integrate a signal Azel Entering the azimuth value followed by the elevation value will cause the SRT to move to that position on the Sky Map provided that the position entered is within the limits of the telescope If the command is out of limits it will be indicated in the top left corner of the screen in red The syntax for the command is azimuth space elevation e g 180 90 Freq Typing the frequency command into the text input box sets the center frequency number of frequency steps and size of steps at which the SRT will observe For example typing 1420 4 25 0 04 sets the center frequency to 1420
18. z Spacing Bin spacing MHz number of bins From input Integer tsys degrees K calcons trec degrees K Scan Results Max K offset Az El Widths Information Sidebar VLSR Velocity Local Standard of Rest Vcenter Center velocity of the current observation Vpeak Velocity of peak signal Fpeak Frequency bin of peak signal D SKY MAP The most obvious feature of the SRT control panel window is the sky map The map shows full sky coverage in azimuth and elevation with 10 degree tick marks in both axes The azimuth axis is labeled every 20 degrees the elevation every 10 degrees The elevation scale is exaggerated 33 from the azimuth scale Plotted automatically and labeled are the sources listed in the srt cat file Geo synchronous communications satellites in the catalog are indicated by blue dots The galactic equator is plotted The north galactic pole and the 0 90 180 and 270 galactic longitude quadrants are also plotted since they have been placed in the catalog The user can move the pointer to any plotted source and click on that source to select it from the source list When the source is selected the source plot label and the telescope crosshairs will be colored red Selecting a source in this manner does not initiate telescope motion to the source however only an additional action such as clicking the track button will engage the telescope controls While the SRT is slewing the right side in
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