Here is a list of the commands used to operate the Autoguider, with a brief description of each one. A detailed description of the command can be obtained by clicking on the command name.
This command starts the system displaying the sky area seen by the autoguider. At Cass and Prime focus and Ghril, the whole CCD is read out, with a loop time of ~6 seconds. At UES and AutoFib, the fibre(s) selected with the current fibre mode are read out. If the fibre mode is changed, the loop is reconfigured. The TV ( or acquire ) command without any arguments will toggle the loop on or off as necessary.
A field command will stop the acqiure loop before reading out the full field. At AutoFib, the CENTROID command can be issued if the acquire loop is on.
For calibration at UES and AF2, the acquire loop is used to view the calibrate stars.
The ACQWIND command defines an area on the CCD where the system will search for guide stars. This is normally set to the largest area available, avoiding the very edge of the CCD or active guide fibre.
The parameters are two pixel co-ordinates, relative to the centre of the CCD or active fibre. These two points are taken to be diagonally opposite corners of a rectangle which defines the limit of the area searched. The parameters can range from -200 to 199 in x and -144 to 143 in y. If either point is outside the area of the current fibre, an error will be generated. The fibre definitions are user configurable, so hard numbers cannot be given here.
Selecting a focal station configuration will reset the window area to the maximum appropriate area. Changing guide fibre mode with the FIBRE-MODE ( network GDM) command will also reset the search area to a sensible maximum.
The ACQWIND command is not used in normal operation. It exists for the special case where there is a binary star or a bright star in the field which is to be excluded from the search area.
During the FIELD command, the acquisition window is extracted from the full frame field image and the search performed on that extracted image. The acquisition window is shown in yellow on the display screen.
The AF2 command changes the system configuration to that for Autofib guiding.
The AutoFib 2 CCD controller is selected, via the appropriate serial port as configured by the config command , and the CCD controller is initialised. The fibre header code is set to the code appropriate for the CCD controller and the index into the dark current frame array updated to select the appropriate dark current frame to remove from the CCD images.
The application variable is set to the new application and a full frame is read out from the CCD, in order to confirm that the correct CCD is being read out and, more importantly, to get a sample of the CCD bias level which is removed during dark current removal.
The AutoFib application code expects the system to be fed with two coherent fibre bundles : a robitic probe which can move over the instrument field and a 'fixed' probe on a small radial carriage which can sample a small part of the edge of the prime focus field. The robotic probe has a field of view of 210 x 200 pixels on the CCD which is 33 x 31 arcsecs. The guide probe is only partly imaged onto the CCD and has an effective field of view of 160 x 190 pixels or 25 by 29 arcsecs.
The fibre mode selects which probe is used for guide star acquisition, and the field and guide commands operate normally within the view of the active fibre. The fibre mode can be set to display the other fibre while operating with the active one. The special function at this focus is the centroid command ( from ICL ) which reads out one or both fibres and reports averaged centroid positions to be stored to determine the field distortion in the instrument.
Use the AutoFib command to initialaise the system prior to using it, or when changing betweeen focal stations. The other commands areThe AUTOGUIDE command will automate the actions of the FIELD, SELECT and GUIDE ON commands. Default setting for each command are used, and the system is re-initialised. At UES, the slit fibre is default, and at AutoFib, the fixed ( guide ) fibre mode will be used.
The optional parameters AUTOGUIDE ON n will select the nth brightest star from the starlog to use as the guide star.
The CASS command changes the system configuration to that for Cassegrain guiding.
The Cassegrain CCD controller is selected, via the appropriate serial port as configured by the config command , and the CCD controller is initialised. The fibre header code is set to the code appropriate for the CCD controller and the index into the dark current frame array updated to select the appropriate dark current frame to remove from the CCD images.
The application variable is set to the new application and a full frame is read out from the CCD, in order to confirm that the correct CCD is being read out and, more importantly, to get a sample of the CCD bias level which is removed during dark current removal.
Use the Cass command to initialaise the system prior to using it, ot when changing betweeen focal stations. The other commands areThe CENTROID command ( available only for AUTOFIB ) reads out n images of the fibre(s) defined by fibmode; centroids them and reports the average centroid position relative to the fibre centre. Note that the cenmode paramater is now obsolete.
The TV or guide loop will be reconfigured to the given fibre mode whilst this command is running. If the system is idle, a loop will be started for the duration of the command. This command is normally run from the AF2 i-task via the autoguider D-task.
The CONFIG command changes the system configuration tables. These determine the hardware environment in which the autoguider operates. THe system has currently 3 serial ports which control the various CCD controllers at the Cassegrain, UES and Prime Focus platforms.
The Config command allows changes to which controller is mounted where; which ccd camera is mounted in each system and the fibre header code sent with the CCD pixel data to be set.
The full forth dictionary in the Autoguider system contains words which are commands. If you mistype a command, the effect may be negligible, but it may cause you severe pain later in the night. To safeguard against accidental system corruption, a sealed vocabulary containing all of the normally used words has been created.
Selecting the OBSERVER vocabulary seals off all the engineering and system administration commands and allows only those commands needed for routine use. This is the default operation.
Selecting the ENGINEER vocabulary ( and search path) opens up all the standard vocabularies. This gives access to all of the system variables and source code..."Beyond this point there be dragons" as they used to say.
The FIBRE-MODE command selects which of the fibres imaged onto the Autoguider CCD are to be displayed, and also which fibre is to be used for the field command to search in and for the guide loop to use.
The FIBRE-MODE or FM command takes one parameter, the mode number which ranges from 1 to 4. Modes 1 and image a single fibre, wihch is used a the guide star source. Modes 3 and 4 imaage 2 fibres with the CTA or TV command but also select which one is to be used for guiding. When issuing this command from ICL, the mode number has logical equivalents.
The command is available at UES and AutoFib configurations only. The names of the fibres change between UES and Autofib, but the function is identical.
At UES: Mode ICL name guide source imaged 1 slit slit slit 2 coarse xyprobe xyprobe 3 slit+view slit both 4 coarse+view xyprobe both At AutoFib Mode ICL name guide source imaged 1 fixed fixed fixed 2 mobile mobile mobile 3 fixed+view fixed both 4 mobile+view mobile bothIf the TV loop is reading out on or more fibres it is reconfigured to read out the new selection without stopping the loop. This may take a few cycles to happen. It is no quicker to simply select the fibre mode than to stop the loop, set a new mode and restart the mode.
If the Guide loop is active, using one of the fibres, then only the 2 modes which have that fibre as the guide source are valid. Atempting to change to a different guide fibre when the current one is in use will cause a "bad fibre mode" error. If you wish to use a different fibre as the guide source, stop the guide loop first.
The CCD is exposed for the current integration time and the full CCD frame read out. The stored dark current pattern is subtracted and the resulting flat field displayed. The Aquisition window, shown by a yellow box is searched for n stars, those found are entered into a table called a starlog. The stars are found in order of peak pixel value. The progress of searching the field can be followed, as each star is marked with the cursor as it is found and its statistics calculated. The table is then sorted to produce a starlog ranked by brightness with the brightest star as number 1.
The brightest star is then selected ready to use in the guide loop. The window size is reset to the default for that configuration and the guide error buffers cleared. The star is marked on the CCD display with a cross.
If you want to use a different star than the brightest one, use the SELECT STAR n command.
At Cass or Prime or Ghril configurations, you should not need to alter the acquisition window, unless there is a saturated star in the field of view and another which you wish to use. Changing the acquisition window is done with the acqwind command.
At UES and AF2 configurations, the acquisition window is set by the Fibre-mode command which selects which fibre is to be used for guiding.
The GHRIL command changes the system configuration to that for Ghril guiding. This will become useful when a CCD head is installed in the Ghril lab.
The Ghril CCD controller is selected, via the appropriate serial port as configured by the config command , and the CCD controller is initialised. The fibre header code is set to the code appropriate for the CCD controller and the index into the dark current frame array updated to select the appropriate dark current frame to remove from the CCD images.
The application variable is set to the new application and a full frame is read out from the CCD, in order to confirm that the correct CCD is being read out and, more importantly, to get a sample of the CCD bias level which is removed during dark current removal.
Use the GHRIL command to initilaise the system prior to using it, ot when changing betweeen focal stations. The other commands areThe GUISIZE command selects the size of the guide window. The new size will be shown on the display.
Valid sizes are from 15 to 100 pixels.
If the guide loop is active, the guide window is resized without brreaking the loop. With multiple readout windows, in the UES and AutoFib configurations, it will take several frames before the new window can be configured.
You cannot select more stars than were found with the field command.
You cannot select more than star 8 or less than star 1.
The GUILOOPS command sets the number of integrations to be averaged for each error packet sent to the TCS. The TCS averages between 3 and 10 of the autoguider output errors, due to its loop gain, so this facility is not often needed.
Use this facility when the seeing is bad, and the star position is jumping around on the CCD, without the telescope having to move very far.
This mode outputs an average of n samples. There is inly one output per n frames read from the CCD. An alternative mode would be to output a running average of the last n samples, this would lead to smaller latency in the system. If you wish this implemented, request it via Pete Fishwick or Stuart Barker.
The GUIWIND command moves the guide window to be read out at ccd coordinates (x,y) relative to the centre of the active area of the currently selected object ( full frame or fibre window ). The new position will be shown on the display by a white box.
Valid parameter ranges are -200 to 200 in x and -144 to 144 in y. If the coordinate given is outside ther range for the valid limit, the window will be placed at the nearest position in x and y to that requested.
If the guide window is not active then this position is inserted into the starlog as a pseudo star in order to allow guiding from a pre-determined position without having to do a field command.
If the guide loop is active, the guide window is moved without brreaking the loop. With multiple readout windows, in the UES and AutoFib configurations, it will take several frames before the new window can be configured.
This command is useful as GUIWIND 0 0 , to reset the window to a known place if it has tracked off.
The CCDCUR command allows the corsor to be moved around the screen ubder keyboard control. When RETURN is pressed, the cursor position is output, in several coordinate systems. The relative movement as well as the distance from the currelt window/fibre centre area also reported, in pixels and also arcseconds at the current plate scale.
The CGUIDE command uses CCDCUR to place the cursor manually under cursor control over a point in the CCD area. The guide loop is then started with the readout window centrd on this point. This is much quicker than doing another field if the star can be seen already.
The XYGUIDE command starts the guide loop with the readout window centred on the pixel coordinate given. The coordinates are referenced from the CCD origin. ( bottom left ).
The SLIT-GUIDE command starts the guide loop with tracking disabled and the window reading out the centre of the slit fibre. This should be centred on the centre of the slit. The current coordinates of the centre of the slit are 102,163. ( this may change if the camera / probe alignment are altered). The TCS command AUTOGUIDE ON 102 163 should be issued to keep both systems aiming for the same point.
The GUIDE command starts or stops the guide loop which will repeatedly read out a window from the CCD, calculate the centroid of the single star imaged and report this to the Telescope Control System computer. The window read out will be centred on the currently selected star from the starlog created with the FIELD command. The star selection can be overridden with the GUIWIND command.
If window tracking has been enabled ( off by default), the window will follow the star if it moves close to the edge of the window on the CCD. Do NOT enable window tracking for the UES slit - move the telescope instead.
If the star gets near to the edge of the CCD or fibre boundary, the centroid position will cross a boundary drawn in blue on the display. This will cause a border error and the guide loop will abort.
The HELP command displays an index of help pages one per useful command. enter the page number to see the page(s).
The IDLE command stops either the guide loop or tv loop according to which is currently running. This is normally issued when the system is in an unknown state. If this fails, and a loop is stuck on, ( which can happen if the CCD controller physical/logical connection is intermittent) then try the KILL-TRACK command.
The KILL-TRACK command stops the guide or tv loop in an unclean fashion. The ccd controller and interface area re-initialised and the display the loop processes brought to a known state.
This is intended for used when the system hangs when an operation failed due to a programming error. It is useful when an intermittent serial port conection or a ccd controller power cycle or reset has confused the autoguider system. If this fails, you may have to RELOAD or even reset the system.
As the system gets more robust / stable, the need for this command is reducing.
The >> command increases the colour look up table shift one place. The << command decreases the colour lok up table shift one place. The default shift is 2 bits.
This facility will be avialable from ICL when the D-task is upgraded. The network command is LUT101(n) -8 < n < 8
These commands allow the ccd frames taken from the camera to be recorded to hard disk and replayed through the guide process.
If you are having trouble with the telescope, this is one way of recording the error signals. If the centroiding is dodgy, then this can allow you to show someone what happened the next day.
This is a very rudimentary system, and is not guaranteed to be robust. It was written to make the best use of commissioning time to investigate guiding algorithms with real star images, especially of the slit. The recording and replaying system are robust. The disk area is orgnised by a linked list in the space above the image directory. If one of the links is broken, you are stuffed. This will only happen if this area of disk is used by some other system.
No attempt is made to check for available disk space, and the program will terminate if it gets a disk error - you should still be able to replay up to the end of the disk, though this has not been tested as the disk was 1Gbyte long. At the time of writing, the operational disk is small, and the development system disk is 1Gbyte of which only 10 Mbyte is used for each system version, 100Mb for images and 800 Mb for recordings.
No attempt is made to see if the frames can be written to disc in the time available, though this is not though to be a problem with a 80 Kbyte max image data rate.
The RECORD command starts the system recording movies. it starts a background task which copies the raw ccd data to disk once each frame. The results are undefined if you issue this twice. The details of the recording entry in the list area printed on the screen as it starts. The recording will stop when the guide loop stops.
STOP-REC stops the current recording and updates the recording list entry with the number of frames. If the system is not recording, this does nothing.
GMOVIE reads back a movie, copying the frames into the same buffer as DICI uses,
then calling the guide centroid, display and plot routines to simulate guiding.
You are prompted for the movie index and a time delay between frames.
.MOVIES displays the linked list of movies on the system. If it gives a disk error then the linked list is broken or one of the recording descriptor blocks has been overwritten.
n DELETE-REC removes the recording number n from the list. All the others above it in the list will be shuffled down one, so that if you delete recording 5, then recording 6 will become 5; 7 will become 6 etc. The actual disc space is not affected until the last recording is deleted when all the disk space above the new last recording becomes available for recording. You cannot delete recording 0.
This recording facility is basic but effective. Useful additions would be a description field in the recording descriptor. Mail me or Gareth Jones if you wish this enhanced. Each recording descriptor hold a link to the next descriptor; the last one points to number 0. Each descriptor says what window setup is used, what block size per frame and how many frames in the movie.
If you wish to delete all the movies, it can be done simply, phone me and I may tell you how.
abg@ast.cam.ac.ukThe PRIME command changes the system configuration to that for Prime focus guiding.
The Prime focus CCD controller is selected, via the appropriate serial port as configured by the config command , and the CCD controller is initialised. The fibre header code is set to the code appropriate for the CCD controller and the index into the dark current frame array updated to select the appropriate dark current frame to remove from the CCD images.
The application variable is set to the new application and a full frame is read out from the CCD, in order to confirm that the correct CCD is being read out and, more importantly, to get a sample of the CCD bias level which is removed during dark current removal.
Use the PRIME command to initialise the system prior to using it, ot when changing betweeen focal stations. The other commands areThese commands display the Utility Network interface packet tables for receive and transmit. These can be used for diagnosing utilnet faults. The commands are the same as for the DMS or other forth UtilNet systems.
These commands select which system is loaded on RELOAD or reset. The development system is normally at blocks 0 - 4000 on disk and the released or old system is on 20000 - 24000 on disk. Beware that these commands rely on the system source code baing in the correct place and that the starting block ( 1000) is the same in each case.
The STATS command displays in the graphics screen a table showing the statistics of the guiding performance. Max, Min, mean and RMS figures are given for the following parameters:
The statistics will apply to those samples since the last time the guide loop was started, or the CL-STATS command issued.
The STATS-DUMP engineering command will show the same info on the terminal.
The guide process is initialised ready to read out a window centred on the CCD coordinates given in the starlog.
If the guide loop is active, the guide window is moved to the coordinates given in the starlog, and the guide loop will start reading out from this area of the CCD. The reference point for the error plots is moved to the coordinates from the starlog. The star is marked on the CCD display with a cursor. The curent guide window size will be indicated with a box around the star.
You cannot select more stars than were found.
You cannot select more than star 8 or less than star 1.
The SETINT command changes the integration time used for field acquisition, tv and guide loops. The integration time is given in milliseconds. The range of 50-50,000 mS is valid. Unambiguous shortenings can be entered. If the engineering vocabulary is active the command can be shortened to n INT.
If the guide or TV loops are active, the effect will be seen in the next frame read out which may be the next frame but one displayed. The system maintains a model of the ccd readout process and will insert a delay in the loop to make sure that the total loop time allows enough time to both display and process the image. Thus an integration time of 50 ms will not result in a 50 Hz frame rate.
Note that the EXPOSURE command will do 5 exposures of 0 ms and 5 of 10 seconds, and leave the int time set to 10 seconds.
To prepare the system for operational use involves selecting the correct system configuration and cooling down the appropriate CCD to its operational temperature.
First ensure that the system is switched on - if the display is showing the normal screeen then it should be OK. If the screen is blank, switch on the appropriate VME rack in the 3rd bay from the right in the control room. The system should boot up normally, draw the display and eventually give you a prompt:
Choose your focal station , the CCD head will be selected and a full frame read out, this will establish the CCD bias level and let you see a frame which will allow you to confirm that you have selected the correct focus.
Next type START-UP and the system should cool the CCD down to a target temperature of -35 C. You will see the dark current pattern change if you read frames out during the cool down process.
The system should be ready to use.
It is normal practise to leave the system with the CCD's at room temperature. This avoid the danger of icing up the CCDs. When the system is finished with, issue the SHUT-DOWN command. This will go through each connected CCD controller and turn off the peltier cooler.
The TEMP command displays the current operating temperature of the currently selected CCD head.
The STEMP command sets the CCD operating target temperature to t degrees celsius. STEMP -35 will have the same effect as the start-up command. The currently selected CCD controller will be affected. To cool down more than one CCD, issue the command several times, with each ccd head selected.
The temperature range is -50 to +20. The actual cooling is limited to 50 degrees below ambient with the thermoelectric coolers used. The leter generation of CCD heads use a 7V Peltier which does not work as well when used with the 5V supply available. Whe all of the units have been upgraded, the oeprating voltage will change to 7V.
The CCD's have less noise and dark current when operating cooler, but there is more danger of the CCD icing up. There is an unexplained mechanism whereby the Cass CCD suffers from occasional icing up during cloudy & humid weather. Operation at -35 degrees seems to avoid this.
Operation with an iced up CCD will lead to damage as Cass. At other focii, the CCD has a quartz glass window to help aviod this.
This command displays the time taken by various parts of the guide loop during execution. The loop times should be automatically calculated such that the vme has enough time to execute the guide calculations once each loop.
The system is capable of tracking the guide readout window across the CCD to follow long term movement of the star image, for example if the telescope is given a permanent offset. As the window rarely needs to track, now that large readout windows are possible, this facility is little needed. It is OFF by default.
There is a threshold window, always centred on the star which is normally 1.5 arcsecs inside the edge of the current guide readout window. If 2 successive centroids lie outside this window, the window will be moved, to a target position centred on the current centroid. The readout window is constrained to be in the active readout area of the CCD and also inside the currnet guide fibre area. If the star is near the edge of the valid area, the readout window may not be centred on the star. The moving threshold will always be centred on the target position.
Beware of allowing the UES slit guide window to track. The system can get into a state where the window is mostly above the slit and the star is just all below slit. If enough noise etc is seen above the slit, then the system may be fooled into thinking that there is a star above the slit, the centroid will be reported in the slit and never cross the movement threshold. This will lead to the system not following the star, which will wander off the readout window and be lost.
The UES command changes the system configuration to that for UES guiding.
The UES CCD controller is selected, via the appropriate serial port as configured by the config command , and the CCD controller is initialised. The fibre header code is set to the code appropriate for the CCD controller and the index into the dark current frame array updated to select the appropriate dark current frame to remove from the CCD images.
The application variable is set to the new application and a full frame is read out from the CCD, in order to confirm that the correct CCD is being read out and, more importantly, to get a sample of the CCD bias level which is removed during dark current removal.
Use the UES command to initialise the system prior to using it, or when changing betweeen focal stations. The other commands areThe UES Autoguider is fed with 2 coherent fibre bundles of about 15 arcsecs square, one viewing the slit jaws and the other on an XY carriage in the focal plane. The XY probe is used for when there is an offset guide star avaiable, and the slit fibre is used when there is no guide star available and we have to use the wings of the object reflected from the slit jaws.
The slit image presents its own problems as a guide star, this is centroided in a different fashion to the XY probe. This is described in the centroiding section.
The ZERO-PLOT command resets the fiducial point form which the error plots are referenced to the current guide centroid. Samples after this will be plotted with the new origin. Wamples already in the guide buffer are unchamged.
The need for this command arises when the command AUTOGUIDE ON is issued to the TCS. This takes the next valid centroid from the autoguide as the target point in the field which the telescope guide loop will pull the star towards. If this is done some time after the field command or the telescope has been offset, then any difference between the field star position and the current star position due to tracking drift will be seen as a DC offset in the guide plots. For small plot scales ( 1-2 as) then one of the plots may be permanently out of range.
This command displays on the terminal screen a summary of information relating to the Nitrogen flushing of the curent CCD head. The heads are flushed to stop the chip ising up. See STEMP for a desription of the temperature control mechanism. A threshold of 5000 ml/hour is normally used, below which the CCD cooling is interlocked. The interlock temperature is +5 degrees - if the CCD is displaying this, it probably has no nitrogen flowing. Note that the threshold and flow are reported in differing scales.
This displays the mechanism and command errors for each of the utility network commands. There is a command ( and notional mechanism) for every normal sealed vocabulry command.