Docstoc

MONET

Document Sample
MONET Powered By Docstoc
					Introduction to Astronomical Image Processing with ImageJ : Observing with the MONET Telescopes                                        05/02/2007 04:37 PM




           Observing with the MONET Telescopes



           NOTE: THIS IS A PRELIMINARY MANUAL FOR POST-COMMISSIONING OBSERVATIONS; AS SOON AS THE NEXT
           SOFTWARE PHASE IS REACHED, ALL OF THE ADMINISTRATIVE AND SOME OF THE OBSERVING PROCEDURES
           WILL CHANGE DRAMATICALLY.



           This document is available in PDF format or as a zip-archive containing both the HTML and PDF documentation.



           Topics:

                  Introduction
                  Signing up for Time in the On-Line Calendar
                  Checking the Weather
                  Entering the Virtual Observatory
                  Opening the Enclosure
                  Initializing the Telescope
                  Pointing the Telescope
                  Making an Observation
                  Downloading the Images
                  Focusing the Telescope
                  Making Flatfield Images
                  Parking the Telescope
                  Closing the Enclosure
                  Maintaining the On-Line Logbook
                  The Engineering Web Interface
                  Links




           Introduction
           The MONET/North telescope was erected at McDonald Observatory in West Texas in December 2005. Since then, it has
           been operated mostly remotely from Göttingen using multiple VNC connections which give the operator immediate access to
           the computers controlling the telescope and camera at the observatory. During this commissioning phase, considerable work
           has been put into a browser-based software interface geared mainly towards the high school users that are supposed to use
           up to 40% of the total observing time.

           The browser-based interface (referred to hereafter simply as the "UI", the "user interface") is now available in its initial, still
           primitive, form. The basic philosophy of the UI is to present a realistic simulation of an observing experience.

                  First, one selects which observatory one wants to use (currently only MONET/North, but soon to include MONET/South
                  and potentially other telescopes, e.g. the 50-cm telescope in Göttingen). This is done by selecting a telescope from a
                  global view that also shows the observer where it is night or day, and roughly what weather conditions exist.
                  After selecting an observatory, one enters a virtual control room where one can immediately see what systems are
                  active (when no systems are active, the room is empty).
                  Clicking on an icon in the control room gives the observer (and any guest) a summary of the status of that sub-system,
                  be it weather, enclosure, telescope, camera, or current observer.
                  Immediate control of the observatory is made from the "OBSERVER" chair, where one has single interface which gives
                  the observer sufficient control over all systems to perform basic observations. In this UI window, blue or green lights on
                  various fields indicate that everything is OK (yellow or red weather lights indicate difficult or forbidden conditions, grey
                  lights indicate no connection is available to the sub-system, blue lights mean the connections are OK, green lights
                  mean that the status of the subsystem is OK.

           Until the next phase of the portal software is finished - the integration of telescope operations with user and project
           administration - all activities should be organized via an on-line "Twiki", a very simple internet content management system:
           http://monet.uni-goettingen.de/twiki/bin/view/MONET/OnlineLog . The details of how to use the Twiki are given
           below, along with screen-shots. Observers can use either the institutional or private Twiki accounts (accounts and help filling


http://www.astro.physik.uni-goettingen.de/~hessman/ImageJ/Book/…20ImageJ/Observing%20with%20the%20MONET%20Telescopes/index.html                  Page 1 of 10
Introduction to Astronomical Image Processing with ImageJ : Observing with the MONET Telescopes                                                      05/02/2007 04:37 PM


           out the twiki available from your local MONET admin).

           Note that we strongly recommend using a mozilla-based browser like FireFox (Windows, Solaris, Linux, OSX, ...) or some
           other standards-compatible browser like Konqueror (Linux), Opera (Windows, Solaris, Linux, OSX, ...), or Safari (OSX).
           Internet Explorer (Windows) may be the most commonly used browser, but it is the least compatible with formal standards,
           resulting in much too much work for the portal programmers in this initial phase.




           Signing up for Time in the On-Line Calendar
           Currently, observation requests are simply handled by the observers entering their wishes in the on-line Calendar - collisions
           or problems are handled collegially or by contacting FVH.




                  Example reservation calendar showing two reserved nights (evenings?) - 2007-06-14 and 15 - have been reserved for McDonald Observatory.

           Reservations are added to the appropriate calendar by editing the page (click on the "Edit" link at the bottom of every Twiki
           page), placing a short signature and UT time-range in the appropriate day (see below), and then saving the results (click on
           the "Save" link at the bottom of the page). PLEASE don't forget the UT times, even if you want to reserve the entire night (as
           above!) : few observers will want to reserve an entire night and many will be happy to share a night (serially, of course).
           Suggested short signatures are "Goe" for Göttingen, "McD" or "TX" for Texas, "SA" for SAAO, and "Ruhr" for Bochum/Essen
           or similarly short initials for individual users.




                                                              Example of what an editable calendar looks like.




           Checking the Weather




           Always check the satellite weather animation (also available in the
           MONET "Engineering Web Interface", EWI, available from your local
           MONET admin), since this is the best way to see what the trends for the
           night might be (the observatory is located at the middle of the diamond-
           shaped county just south of the line connecting El Paso and Odessa).

http://www.astro.physik.uni-goettingen.de/~hessman/ImageJ/Book/…20ImageJ/Observing%20with%20the%20MONET%20Telescopes/index.html                              Page 2 of 10
Introduction to Astronomical Image Processing with ImageJ : Observing with the MONET Telescopes                                     05/02/2007 04:37 PM


           Here's an example of a night which might look fine judging from the
           instantaneous weather data but definitely deserves close watching!




                                                                                    If the satellite map looks fine, check the last hour's
                                                                                    weather from the Mt. Locke weather station (also in
                                                                                    EWI). For reference: T(C) = 0.56*[T(F)-32] and
                                                                                    V(kmh) = 0.62*V(mph) .




           The Mt. Locke weather station also measures the amount of dust in the air - often a problem during the windy season, when
           lots of dust from Mexican salt flats can make things so bad, that one cannot observe even when it it otherwise clear. The
           amount of dust is measured in units of "ppcf" or "particles per cubic foot" (= 3.5x10 -9 particles per cubic furlong ;-) : values
           higher than about 50,000 are dangerous for the telescope optics and no telescope at the observatory should open for values
           of 100,000 or more. In the above report, the dust sensor has been turned off due to high humidity (> 80%).

           There are two means of finding out whether it's cloudy (other than from the rough satellite images): the CTI cloud sensor
           (also in EWI) measures the mean cloudiness by comparing the microwave emission of the warm ground with either warm
           clouds or the cold clear sky; and a low-tech possibility which works fine on moon-lit nights is to take a look at the web-cam
           on Mt. Fowlkes which shows whether the other domes on Mt. Locke are open or not.




           Entering the Virtual Observatory
           Since MONET / Astronomie & Internet will soon consist of two telescopes, access to the observatories is first down via a
           global map of the world, showing not only the locations of the telescopes, but also the current night-day boundaries and
           weather.




           When you select a telescope from the live global view, you are taken to a virtual control room where all of the active
           observatory systems are represented by lifelike icon images that can be clicked on (if present) to determine their status
           (shown in the left info panel).




http://www.astro.physik.uni-goettingen.de/~hessman/ImageJ/Book/…20ImageJ/Observing%20with%20the%20MONET%20Telescopes/index.html                Page 3 of 10
Introduction to Astronomical Image Processing with ImageJ : Observing with the MONET Telescopes                                                              05/02/2007 04:37 PM




                  the TELESCOPE is represented by a computer screen in the lower left corner of the room showing an image of the
                  telescope;
                  the CAMERA is represented by a neighboring computer screen showing an astronomical image;
                  the STATUS light in the upper left corner, if on, indicates that the telescope is currently not available due to technicians
                  working at the telescope (no remote/robotic operations due to safety considerations);
                  the enclosure UPS ("uninterruptable power supply", a gigantic battery) is the tall cabinet in the left background;
                  clicking on the OBSERVER's chair in the middle tells you who is currently observing or gives you access to the
                  telescope (see below);
                  the status of the telescope enclosure (whether a ROOF is open or not) is available at the switch icon at the back of the
                  room;
                  the current WEATHER is available by clicking on the old-fashioned hygrometer on the first table to the right; and
                  the DOCS and PLANNING links are not yet useful.

           These icons do not have any other functionality beyond giving the virtual guest some information about the status of the
           observatory.

           To proceed and obtain control of the telescope and camera, you must

              1. log into the portal using one of the observing accounts (see your local MONET admin);
              2. click on the "OBSERVER" chair to make sure someone else doesn't have control of the observatory;
              3. click on the "More..." button which then appears in the left information panel, which will take you to the basic observing
                 page consisting of several panels containing control elements for all the systems needed to perform simple
                 observations (see image below).




           Part of the basic observing window showing the live web-cam image (here shown with the white lights turned on), an uninitialed telescope (the mirror covers are
             closed), a ready camera, closed roofs (visible both from the webcam image and from the blue status lights in the lower right-hand panel), an an active light
                                                                    switch (circled element in the lower right panel).



           The basic observing page also contains a weather summary box in the
           lower left corner of the UI window showing the main relevant data, both
           as text and as colored status lights: gray="unknown" (sensors not on-
           line); blue="available" (no data available); green="OK" (data available


http://www.astro.physik.uni-goettingen.de/~hessman/ImageJ/Book/…20ImageJ/Observing%20with%20the%20MONET%20Telescopes/index.html                                          Page 4 of 10
Introduction to Astronomical Image Processing with ImageJ : Observing with the MONET Telescopes                                  05/02/2007 04:37 PM


           and conditions are good); yellow="warning" (get ready to have the
           observatory shut down); and red="no observations possible" (the portal
           should refuse to open the roofs).




           Opening the Enclosure


           Open the roofs by pressing the "OPEN" button in the "ROOF and
           LIGHTS" panel. When both roof sections are open, the status lights will
           turn green.




           You can turn on the red viewing light and watch the roofs open in the web-cam image in the center panel (the refresh rate of
           the UI window is about 1 minute), however

                                      please do not use the white viewing light when the roof is open: we
                                      have neighbors who will definitely not like you shining a bright white
                                      light on their telescopes at night!

           When there is a visible half-to-full moon, you won't need any lights: the webcams are so sensitive that you will be able to see
           the telescope and the surrounding countryside as soon as the roofs are partically open.




           Initializing the Telescope




           Turn on the un-initialized telescope by pressing the "ON" button in the
           "TELESCOPE (next)" panel. When the telescope is ready (e.g. open
           mirror covers visible in the webcam images), you will see the panel
           change to the entry form in the next image below.




           Pointing the Telescope
           The "TELESCOPE (next)" panel controls four main functions of the telescope:

                  where the telescope is pointing, either at a stationary position on the sky defined by an azimuth "AZ" (angle along the
                  horizon) and an altitude "ALT" (angle above the horizon) or by a position on the moving sky defined by a Right
                  Ascension "RA" and Declination ("Dec") corresponding to celestial longitude and latitude (for more information, see
                  Using a Remote Imaging Telescope );
                  the position of the telescope's focal point, which needs to be at the location of the camera's detector (the MONET
                  telescopes let you shift the position of the second mirror to match things up)(the current value is somewhere around 51
                  mm);


http://www.astro.physik.uni-goettingen.de/~hessman/ImageJ/Book/…20ImageJ/Observing%20with%20the%20MONET%20Telescopes/index.html              Page 5 of 10
Introduction to Astronomical Image Processing with ImageJ : Observing with the MONET Telescopes                                         05/02/2007 04:37 PM


                  the choice of filter (currently available are ultraviolet "U", blue "B", visual/green "V", red "R", and near-infrared "I"); and
                  the "Rotation" field controls the angle of the image on the sky and should only be used by those who know what they
                  are doing.

           In addition, there are buttons which halt the telescope ("STOP") and, once the telescope has been stopped, a "PARK" button
           to shut down the telescope when you are finished.




           Enter any reasonable combination of RA+DEC, ALT+AZ and/or
           focus/filter and press "GOTO" (a message should appear at the bottom
           saying that something is being changed and/or the telescope is slewing).
           Wait until final state reached as shown in the "TELESCOPE (current)"
           panel (you can speed up the process by refreshing your UI window).




           The telescope positions altitude (0 < ALT < 90), azimuth (0 < AZ < 360), and Declination (-50 < DEC < 90) are angles which
           can be input either as decimal degrees (e.g. "+65.7225") or in degrees, arcminutes, and arcseconds (separated by spaces or
           colons, e.g. "65 43 21" and "+65:43:21" both mean 65 degrees + 43 arcminutes + 21 arcseconds). Right Ascension is given
           in celestial time (0 < RA < 24), either in decimal hours or hours, minutes, and seconds (same format).




                                                                    The current status of the telescope - for example if your choice of
                                                                    position, focus, and/or filter has been reached - in shown in
                                                                    "TELESCOPE (current)" panel (left panel in the basic observing
                                                                    window). In addition, the Greenwich-based "Universal Time" ("UT") and
                                                                    the "Local Siderial Time" ("LST") or "star-time" (the Right Ascension
                                                                    currently on the North-South meridian) is shown (soon to be animated -
                                                                    the values are currently only updated when the UI window is refreshed).




           Making an Observation
           The observations are made with a CCD camera attached to the telescope and the filters selectable in the "TELESCOPE
           (next)" panel. There are three types of observations which can be selected using the pull-down menu in the "CAMERA" panel
           (lower middle of the UI window) :

                  "Normal" observations taken with the shutter of the camera open (i.e. with light) for some chosen exposure time;
                  "Dark" observations taken with the shutter of the camera closed (i.e. no light but just the thermal background noise in
                  the camera) for some chosen integration time; and
                  "Bias" observations taken with zero integration time and hence containing neither light nor any thermal background
                  noise but just any electronic signal present.

           For more details of how one calibrates CCD images, see Calibrating Raw Images ).




http://www.astro.physik.uni-goettingen.de/~hessman/ImageJ/Book/…20ImageJ/Observing%20with%20the%20MONET%20Telescopes/index.html                     Page 6 of 10
Introduction to Astronomical Image Processing with ImageJ : Observing with the MONET Telescopes                                     05/02/2007 04:37 PM




           After you have pointed the telescope, select the camera mode
           ("Normal", "Dark" or "Bias"), the binning ("1x1" or "2x2"), enter
           the desired exposure time, and press "EXPOSE". When the
           camera message at the bottom disappears, the exposure is
           finished and the image is available to be downloaded.



           Each image is given a long name which helps to identify where and when it was taken and what kind of image it is. This long
           name can be seen by placing your mouse cursor over the short "Last image:" description (e.g. "Dark #2" in the figure above)
           which then shows a "tool-tip" message of the form
                                              McD_{YYYY}-{MM}-{DD}T{hh}-{mm}-{ss}_{x}{f}.fits

           where {x}="N" for "normal", "D" for "dark", and "B" for bias exposures, and {f} is the filter, if relevant (dark and bias images
           don't contain any light, so the filter doesn't matter). For instance, a normal image taken in the "V"-filter at MONET/North at
           12:34:56 UT on Dec. 25, 2007 would be given the name McD_2007-12-25T12-34-56_NV.fits and the bias image taken
           soon thereafter might be named McD_2007-12-25T12-35-41_B.fits




           Downloading the Images
           Either download the image by pressing the "Get" button or click on the "List all" link which will give you a new window
           showing the JPG "thumbnails" (full-sized!), the FITS headers as text files, and the compressed FITS files, all of which can be
           downloaded using standard browser techniques.




           Focusing the Telescope
           Focussing is done via a series of images with different focus settings, still a painful process due to the long refresh times - a
           focus table based on the temperatures is forthcoming or you can simply adopt the last focus value used at the current
           temperature and recorded in the on-line log.




           Making Flatfield Imagess
           Flatfield images can be made either by observing the blank sky at sunset or sunrise (a set of suggested star fields with
           relatively few stars is available at http://www.astro.physik.uni-goettingen.de/~hessman/MONET/blankfields/) or by closing the
           roof, turning on the white lamp, and pointing the telescope at the position ALT=17, AZ=213.




http://www.astro.physik.uni-goettingen.de/~hessman/ImageJ/Book/…20ImageJ/Observing%20with%20the%20MONET%20Telescopes/index.html                Page 7 of 10
Introduction to Astronomical Image Processing with ImageJ : Observing with the MONET Telescopes                                    05/02/2007 04:37 PM




           Parking the Telescope

           Shut down the telescope by pressing the "STOP" button and then (when it appears) the
           "PARK" button in the "TELESCOPE (next)" panel. You should see a "Parking telescope
           ..." status message at the bottom of the UI window and - if lights are on - the mirror
           covers closing.


           Please park the telescope BEFORE closing the enclosure to insure that any moisture on the roof panels doesn't drip down
           onto the telescope mirror.




           Closing the Enclosure


           When the telescope is parked, press the "CLOSE" button in the "ROOF
           and LIGHTS" panel. When the roof is closed (wait until the "Left / NW"
           and "Right / SE" buttons are blue, indicating that the roofs are really
           closed). Make sure the lights are off.




           Maintaining the On-Line Logbook
           The Twiki-based on-line logbook is necessary for two reasons: (1) until the user and project administration is integrated into
           the portal software, it provides the only reasonable means or organizing groups spread all over the world; and (2) the early
           users need to be able to share their experience (problems, solutions to problems, focus values,....) in a well-documented
           fashion not possible via, e.g., a simple email list (imagine trying to pull focus values out of dozens of individual and randomly
           organized emails).


           Go to the MONET Twiki calendar page.
           Let's assume you want to make a May
           01/02 entry. Here's the calendar with a
           single previous 30/01 entry from the
           night before.


                                                                                                  Invoke the Editor and you'll see the
                                                                                                  Twiki formatting code: the square
                                                                                                  brackets define internet link consisting
                                                                                                  of document names and labels. We
                                                                                                  want to add an entry for 2007-MAY-
                                                                                                  01/02 called Log07May02 with the name
                                                                                                  01/02 to the list of log entry links.




           Type in a new entry in the corresponding month using
           the format
           [[Log{YY}{Mon}{Day}][{StartDay}/{EndDay}]] ,
           e.g. [[Log07May02][01/02]]




http://www.astro.physik.uni-goettingen.de/~hessman/ImageJ/Book/…20ImageJ/Observing%20with%20the%20MONET%20Telescopes/index.html                Page 8 of 10
Introduction to Astronomical Image Processing with ImageJ : Observing with the MONET Telescopes                                  05/02/2007 04:37 PM




                                                                                                  Save the result. You will then see an
                                                                                                  incomplete entry link marked by a "?".




           Using your mouse, cut the example log
           content text from the bottom of the
           calendar page and then click on the "?"
           of your incomplete log entry link (see
           above). This puts you in the edit mode
           of a new (almost) blank page.




                                                                                                  Paste the example log content into the
                                                                                                  edit area, change the obvious entries (at
                                                                                                  least those to be changed at first). Note
                                                                                                  how easy it is to maintain or create new
                                                                                                  tables, since they are simply defined by
                                                                                                  entries separated by "|", the more lines
                                                                                                  of entries, the longer the table. Note
                                                                                                  also how one can combine HTML with
                                                                                                  the Twiki formatting.




           Save your results. This page can be re-
           edited as often as you like (it is wise to
           save it now and then so that a loss of
           internet connection doesn't result in the
           loss of your log info).




           The Engineering Web Interface
           The "Engineering Web Interface" ("EWI") is a collection of handy internet links which can be used as partial substitutes or as
           helpful extensions of the UI for MONET technicians and administrators.




http://www.astro.physik.uni-goettingen.de/~hessman/ImageJ/Book/…20ImageJ/Observing%20with%20the%20MONET%20Telescopes/index.html             Page 9 of 10
Introduction to Astronomical Image Processing with ImageJ : Observing with the MONET Telescopes                                        05/02/2007 04:37 PM




           THE EWI SHOULD NOT BE DISTRIBUTED PUBLICALLY OR BE STORED IN AN AREA ACCESSIBLE BY THE PUBLIC
           OR BY SEARCH MACHINES LIKE GOOGLE.




           Links
           Here are some helpful links:

            MONET / Astronomie & Internet Portal                        currently 212.123.198.194/cgi-bin/WebObjects/MONET
            McDonald Satellite Weather Forecast                         sirocco.accuweather.com/sat_mosaic_400x300_public/rs/isarTXW.gif
           Movie
            Twiki On-line Observing Log                                 http://monet.uni-goettingen.de/twiki/bin/view/MONET/OnlineLog
            CTI Cloud Sensor                                            cti001.as.utexas.edu:1080/.snap?cloudsensor.vi
            List of Blank Sky Fields (for skyflats)                     www.astro.physik.uni-goettingen.de/~hessman/MONET/blankfields/
            UBVRI Calibration Fields (WIYN)                             www.noao.edu/wiyn/queue/images/tableB.html
                                                                        monet-cam2.as.utexas.edu/axis-cgi/jpg/image.cgi?
             MONET Interior WebCam (still)                              resolution=640x480
                                                                        mcdcam-dimm.as.utexas.edu/axis-cgi/jpg/image.cgi?
             WebCam showing Mt. Locke                                   resolution=640x480
             McDonald Weather                                           198.214.229.50/cgi-bin/obs_sup/latest_5min.cgi




           An Introduction to Astronomical Image Processing with ImageJ (C) Copyright Hessman & Modrow 2006.
                                                                                                               Version: 2007 -05 -02
           None of this material may be used, copied, or distributed for commercial purposes.




http://www.astro.physik.uni-goettingen.de/~hessman/ImageJ/Book/…0ImageJ/Observing%20with%20the%20MONET%20Telescopes/index.html                Page 10 of 10

				
DOCUMENT INFO
wanghonghx wanghonghx http://
About