Apogee camera driver - Linux User Guide V0.5
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1. Physical x Y Image x Y Frame Zoom 4 000 Ang 0 000 Frame Bin Scale Color Gena center none align wes Images may be automatically displayed in the DS9 image viewer Select automatic display in the main window to activate this option The DS9 image viewer is a powerful tool There is extensive online documentation available at file opt apogee html ds9 index html Most aspects are fairly intuitive configuration is done using the pull down menus contrast brightness is adjusted by holding down the left mouse button and moving the mouse around The middle mouse button centers the image at the current location 4 Advanced use 4 1 Drift scan operation The driver is equipped with preliminary support for drift scan operation In this mode the telescope is set at a fixed position and the sky allowed to drift through the field at the sidereal rate The driver automatically reads out the ccd at the appropriate rate to correct for the sidereal motion It is of course crucial that the rate be very accurately specified and that the readout software does not get pre empted by other processes in the system It is recommended that during a drift scan readout no other major activity is taking place on the computer In drift scan mode the length of the exposure is limited only by available memory For example if sufficient memory where available you could make a single drift scan from du2. cal 165 scale 2 1 Temperature 29 Temp SetPoint Fa pee S3 D 60 40 20 This panel provides control and feedback Select the required target temperature using the arrows or type in a new target temperature The graph illustrates the last minute or so of temperature readings from the camera It often takes about 20 seconds after a new target temperature is requested before the temperature changes significantly so be patient CCD So De ea Ge ey eee ATA O X Telescope System Geometry Temperature CCD Filter Catalogs sensor SIA 502a color False gain 4 5 noise 10 pixelxsize 24 pixelysize 24 This panel shows the ccd sensor details These are read only Filter This panel shows available filters and the current selection NOT YET IMPLEMENTED So Properties Alt p to open close window SE Telescope System Geometry Temperature CCD Filter Catalogs type position o KIG Catalogs See Properties Alt p to open close window oO X Telescope System Geometry Temperature CCD Filter Catalogs dss Off gt dss_dir gsc Off bl gsc_dir gsc_min 9 0 gsc_max 12 0 s rnge Off bd mgc_dir rhgc_min 5 0 rngc_max 15 0 usno_dir usno Off M usno_min oS usno_max 12 0 e This panel is used to define the locations disk network of the most commonly used catalog reso
3. O xX Telescope System Geometry Temperature CCD Filter Catalogs scope Lx200 M link serial remote localhost fratio 8 0 guide Off 7 perrcor Off Md To configure a telescope operated remotely via a network refer to the Advanced Usage chapter of this manual Select File gt Save from the pull down menu to save the changes to disk 3 1 2 Normal usage 1 Select the image type Object Flat field Dark etc 2 Adjust the exposure time as required 3 Adjust the number of frames 4 Optionally adjust the directory to be used to save images defaults to the startup directory 5 Adjust the image name For sequences of images the image number can be automatically inserted into the name at any position using a marker d For example test_ d 6 Click Observe a sequence of frames may be terminated by clicking Abort after the sequence has started The exposure s will now be taken and saved on disk in FITS format If the automatic display option is selected then the image s will also be automatically be displayed in the DS9 image viewer By default the raw image data is written to disk The auto calibrate option is used to select automatic calibrations When this option is enabled the best ie nearest temperature match calibration frames will automatically be loaded and applied Please refer to the Calibrations chapter to learn how to create libraries of calibration data for this pu
4. 3 Region mode To select a sub region for readout 1 Ensure a full frame image is displayed in DS9 2 Select Observe gt Region from the pull down menu 3 Reply to the pop up dialog use current region or define a new one 4 For new regions use the mouse to define the region in DS9 using a click and drag motion 5 Click the pop up OK when ready 6 Click Observe Region mode may also be accessed via the Observe gt Continuous pull down menu entry In this mode the sub region will be continuously exposed readout and displayed until Abort is used to stop the sequence This mode of operation should be useful for manual focusing The subregions are not saved to disk when in continuous exposure mode 3 1 4 Focus frame acquisition Focus frames consist of multiple exposures taken without reading out the image Between each exposure the image is shifted slightly on the detector either by reading out a few lines or by offsetting the telescope slightly and the focus is also adjusted We use the detector shift method as it also works on manual telescopes After each exposure a pop up dialog will appear At this point manually adjust the focus by a hopefully small known amount then click OK After all the exposures are completed the frame is read out and written to disk Special keywords are inserted into the header to allow the IRAF imfocus task to automatically determine best focus this feature is still under develo
5. found as members of the global array CCAPIW The element of arrays can be examined using the syntax e g for CCAPIW array names CCAPIW 3 Code generation The scripting interfaces are created using a mixture of custom code the Ccd library and an automatically generated interface The automatically generated portion is created using SWIG Simple Wrapper and Interface Generator Note that older versions of SWIG may not be capable of generating functioning wrapper code for C Tcl Please use the included version 1 3a5 or later SWIG is very easy to use All that is required is a 1 file which defines the methods and instance variables for the object In many cases this file can be copied directly from the h header file for the object Once the i file has been prepared the wrapper code can be generated using a command such as usr local bin swig tcl8 c apogeePPL i Note that there is a slightly different file for each interface type This allows us to generate shared libraries which are named according to the interface type To add a new method to the CCameralO object the following steps are required add C code for the method to CameralIO_Linux interface cpp add definitions to CameralO_Linux h add the same definitions to apogee interface i Once the revised CameralO_Linux interface cpp and apogee interface i code has been sucessfully compiled e g for an ISA interface g 02 g fpic c CameraIlO_Linu
6. gz DS9 for Linux fiasco 1 0 tar gz Image compression package fitsTcl 2 0 i386 rpm FITS tools for tcl ftools 2 4 1386 rpm Massive astronomical data reduction suite in C tcl gimp 1 2 0 tar gz Image manipulation package with extensive capabilities gimp data extras 1 2 0 tar gz Add ons for GIMP gsl 0 4 1 1386 rpm GNU scientific subroutines imlib 1 9 7 3 1386 rpm Image management conversion library imlib cfgeditor 1 9 7 3 1386 rpm extras for imlib imlib devel 1 9 7 3 1386 rpm_ devlopers version of imlib libjpeg 6b 10 1386 rpm jpeg library libjpeg devel 6b 10 1386 rpm_ developers version of jpeg library libpng 1 0 5 3 1386 rpm_ PNG library libpng devel 1 0 5 3 1386 rpm developers version of PNG library libtiff 3 5 4 5 1386 rpm TIFF library libtiff devel 3 5 4 5 1386 rpm developers version of TIFF library netpbm tar gz large set of image conversion utilities novas c 2 0 i1386 rpm Astrometry routines from the US Naval Observatory opt Full unpacked developers version of drivers for easy browsing python 1 5 2 13 1386 rpm The python scripting language python devel 1 5 2 13 1386 rpm developers version of python python docs 1 5 2 13 1386 rpm_ extensive documentation for python python tools 1 5 2 13 1386 rpm extra tools for python pythonlib 1 23 1 noarch rpm python libraries sexarticle ps gz description of sextractor sextractor 2 1 0 1386 rpm automatic star galaxy location skycat 2 5 3 i386 rpm fea
7. overscan region and keep only the part of the image containing useful data This latter step usually trims off not only the overscan region but the first and last few rows and columns of your data If you pre flashed the chip with light before each exposure there will still be a non zero amount of counts that have been superimposed on each image This extra signal is also an additive amount and needs to be subtracted from your data In addition there may be column to column variation in the structure of the bias level and this would not have been removed by the above procedure To remove both the pre flash if any and the residual variation in the bias level if any we will make use of frames that you have obtained with a zero integration time These are referred to in IRAF as zero frames may also be called bias frames We need to average many of these taken with pre flash if you were using pre flash on your object frames process the average as described above and subtract this frame from all the other frames Dark current is also additive On some CCD s there is a non negligible amount of background added during long exposures If necessary you can remove the dark current to first order by taking dark exposures long integrations with the shutter closed process ing these frames as above and then scaling to the exposure time of your program frames However it s been my experience that the dark current seldom scales linearly s
8. test and call initialization code newpackVersion c stub code to specify version info newpack c the implementation The implementation will typically consist of a routine named newpackAppInit which defines the available commands plus code for the commands themselves The interface from Tcl to C is easy to use The code in opt apogee src ccd can serve as a template for the most common functionality 5 CCD library The Ccd library can be interactively loaded into a wish shell using the command load opt apogee lib libccd so The Ccd loadable library is a Tcl extension which provides simple commands for manipulating the raw data generated by the readout of a CCD camera The following commands are available read_image load a FITS file into an in memory buffer write_image write raw image data to a FITS file write_cimage write bias subtracted image data to a FITS file write_dimage calculate dark frame and write to FITS file write_zimage calculate zero frame and write to FITS file write_fimage calculate flat image and write to FITS file write_simage calculate sky flat image and write to FITS file shmem_image copy image data to a shared memory segment show_image transfer image data to DS9 via shared memory store_calib calibrate the current in memory frame write_calibrated calibrate and save to disk list_buffers print a list of in memory buffered images set_biascols specify the bias columns set_bia
9. Apogee camera driver Linux User Guide V0 5 Dave Mills rfactory theriver com December 2001 Contents 1 Introduction 2 Installation 3 Graphical User Interface The Main window First time setup Normal usage Region mode Focus frame acquisition Properties window 4 Advanced use Drift scan operation Remote control 5 External packages Appendix Processing CCD images 1 Introduction The Linux Apogee camera drivers have been developed by The Random Factory Tucson AZ in collaboration with Apogee Inc The drivers provide both low and high level interfaces for controlling AP KX LISAA and SPH Series cameras Parallel port PCI and ISA interfaces are supported 2 Installation The driver and accompanying packages are packaged using the gzipped tar archives To install either the runtime or developer version e mkdir opt apogee e cd e tar xvzf mnt cdrom apogee driver 0 5 tgz runtime OR e tar xvzf mnt cdrom apogee driver devel 0 5 tgz developer If your cdrom is mounted at a different location use the df command to view the list of mounted devices then substitute that path in the command This installation will place the files in the directory opt apogee Although it is possible to install the software to a different location this is not recommended as it will be necessary to manually change the location in some of the scripts included with the drivers Run the module installation script opt apog
10. ady for use The camera is initialized and temperature control has been switched on 3 1 The main window ol BANCO Merah mera EX File Edit Observe Calibrate Tools Help target test Exposure in seconds 1 0 ra 00 00 00 00 Number of frames fa dec 00 00 00 00 Exposure type Object E 7 J observer Dave Mills Configure data directory site Tucson File name test latitude 31 57 11 768 itude 26 Observe longitu 07 26 27 97 W Automatic display W Overwrite files W Automatic bias subtraction Automatic calibration uses library frames 3 1 1 First time setup The GUI is initially configured for Tucson AZ To set the location click the button next to the location A window will open showing a list of locations use the mouse to scroll the list until you reach your city then double click it The latitude longitude and name will be inserted into the main window If your city is not listed simply delete Tucson and type the name in There are a number of WWW sites can be used to lookup your longitude latitude based on City or zip code If a computer controlled telescope is being used open the properties window Options gt Properties or Alt p select the Telescope tab and select the appropriate telescope type from the pull down menu This facility is not yet completed LX200 support is expected for the next release of this package Sl Properties At p to open close window
11. copy so you have lots and lots of signal compared to read noise or if you have high sky background on direct images so that read noise is again immaterial then the signal to noise will be little affected by whether you have only a few bias frames However in this regime the quality of your flat fielding is all important if you want to get the most out of your data The following list contains the type of calibration images you may need and provides some guide to the consideration of how many you may want to have bias frames These are zero second integration exposures obtained with the same pre flash if any you are using on your objects If read noise will sometimes dominate your source of error on the objects take 25 bias frames per night Take them over dinner and you ll never notice it You will want to have anew sequence of these each day dark frames These are long exposures taken with the shutter closed If your longest exposure time is over 15 minutes you may want to take an equal length dark frame subtract a bias frame from it and decide if you are worried about how much dark current is left Applications where dark current will matter are long slit spectroscopy and surface brightness studies cases where the background is not removed locally If you do find that you need to take care of dark current then you should take at least 3 and preferably 5 to 10 dark frames during your run each with an integration time equal to yo
12. crosecs 14 Take a short and then long drift scan to verify Drift scan mode is still experimental Measured per line drift rate at current DECis 300000 Calculate per line rate for DEC 00 00 00 Per line drift rate for DEC 00 00 00 is 300000 Number of rows for drift image 512 Calculate duration and per line rate in microsecs Total image duration hh mm ss 00 05 06 Microsecsond delay per row 300000 Start drift scan exposure ee If you get good long drift scan exposures at the two different DEC positions you are all set up If not start again at step 1 as the most likely cause is that your telescope is NOT perfectly polar aligned 4 2 Remote control There are two methods for using the GUI via a remote computer 1 Standard X windows Use the standard X windows display redirection facility to point the display to another computer named other for example eg setenv DISPLAY other 0 The xhost ccd name command must also be issued on the other computer to allow remote displays to take place where ccd name is the name of the camera control computer Finally start the GUI as usual the windows should appear on the other machine This method only works if both computer are running a nix type operating system X windows is available for MS Windows but it is usually expensive 2 VNC Use the VNC Virtual network computing software which is free and open sourc
13. d low level command to scope 1x200_set_date set the date 1x200_set_filter set filter 1x200_set_site set site details 1x200_set generic parameter set 1x200_pos set position ra dec read_scope low level read from scope 1x200_obj_sync sync on current position The syntax required for each call can be determined interactively by simply calling the function without any arguments The required syntax will then be printed out Future versions of this library will include support for automated observation scripting with multiple objects filters etc 7 Remote use Not Yet Implemented The software bundle includes a comprehensive solution for remote control of camera and telescope functions Every function in each loadable libary can also be enabled for remote access by appending the server portnum specifier to the GUI startup command In this case the local interface will not display any of the elements of the graphical interface but will open a socket and accept future commands via that channel The remote machine should then start a copy of the GUI using the syntax opt apogee bin apogeegui remote server portnum
14. e This package supports the remote viewing on the ccd GUI desktop on nix windows and Mac platforms Even better multiple remote users can simultaneously view the same dekstop and even share interaction rights with the applications Given fast network connections fast ethernet this is a near optimal solution The VNC package is just one of the items in the bundle of extras included in the cdrom version of the Linux Apogee Drivers cd available from The Random Factory Future releases of the driver will also include support for true client server use of cameras In this situation the GUI will actually run on the remote machine and only the low level camera access code will run on the camera controller computer 5 External packages The Linux Apogee camera driver is free open source software However we do offer an enhanced distribution on cdrom which adds a wealth of extra tools for both user and developer The following list describes the current contents of the cd distribution SW1IGManual pdf User manual for the Simple Wrapper and Interface Generator package apogee_devel tar gz Developers version of the drivers apogee_runtime tar gz Standard runtime user distribution astrotcl 1 4 4 sre tar gz A set of astronomical tools for tcl ccdlinux modaudine tar gz_ The drivers for for the Audine Gemini open hardware cameras cfitsio 2 0 3 4 1386 rpm_ C language FITS utilities ds9 2 0 tar gz The DS9 sources ds9linux 2 0 tar
15. ee modinstall A couple of pop up dialogs enquire for the camera type and interface address ISA parallel interfaces The installer will check if there is already a pre compiled driver module appropriate for your system If no compatible module is available the installer will rebuild one from source If rebuilding is necessary you will need to install the GCC compiler if it is not already installed The appropriate module is loaded and the installer will offer to make the module load automatically on reboot the commands to do this are added to the etc rc d rc local file Once the software is installed it needs to be configured for each camera user Log in as the user and type opt apogee install Once this setup step has been completed the interface can be started with the command startapogee 3 Graphical user interface The graphical user interface is still under development It provides easy acces to the major functions such as image acquisition temperature control and calibration image management The program may be started from an xterm by typing startapogee The program will open a small main window and then create a message window which shows the progress of the system startup operations On a slow machine this make take a minute on a modern machine eg 600Mhz cpu the startup only takes a couple of seconds and the messages will probably update too quickly to be read Once the message window closes the system is re
16. feet to obtain a good level of sky exposure in each of your filters while the sky is getting darker and darker Only the truly desperate would take twilight flats in the morning For direct imaging I would recommend 3 to 5 exposures in each filter stepping the telescope slightly in between the exposures so that any faint stars can be effectively cleaned out You will find that you need to keep increasing the exposure time to maintain an illumination level of 10 000 electrons blank dark sky exposures Some observers doing sky limited direct imaging may wish to try exposures of blank sky fields rather than twilight sky as the color of twilight and the color the dark sky do differ considerably Obtain at least three and preferably four long exposures through each filter of some region relatively free from stars stepping the telescope 10 15 arcseconds between each exposure The trick here of course is to get enough counts in the sky exposures to make this worth your while Unless you are willing to devote a great deal of telescope time to this you will have to smooth these blank dark sky exposures to reduce noise but the assumption in such a smoothing process is that the color response of the chip does not vary over the area you are smoothing You might try dividing a U dome flat by a V dome flat and seeing how reasonable an assumption this might be Also if the cosmetics are very bad the smoothing process will wreak havoc with your data if yo
17. fset shutter_speed normal bed test2 0 trigger 0 M f line_timeout data_bits 16 maxbiny 63 EIL System Geometry Temperature CCD Filter Catalogs S This panel reports camera configuration parameters which will not normally need to be changed indeed many are readonly Geometry EE Properties Alt p to open close window oO x Telescope System Geometry Temperature CCD Filter Catalogs columns 532 skipe E startcol ao H numcols 511 binx E hf lush be o driftscan off M rows 532 br aS skipr E startrow 7A numrows 511 biny E vf lush RF This panel provides easy editing of all the relevant parameters to competely define the readout region Subregions can be defined by editing StartX StartY NumX and NumY Binning can be set in each axis and so on Every change is immediately tested and any illegal combinations will cause the background color of the panel to change It will not be possible to obtain an image if an illegal combination is selected In general the only parameters which will be manually adjusted are the binning factors Sub region definition is more easily performed using the pull down Observe gt Region menu selection in the main window Temperature Seas Properties Alt p to open close window o E S Telescope System Geometry Temperature CCD Filter Catalogs target 30 0 backoff 2 0
18. ll the commands Tcl is currently aware of The camera_init script also creates a CAMERA variable which acts as a software pointer to the C structure used to control the camera Tcl commands typically protect the user against incorrect usage For example the CAMERA object may be commanded using the syntax CAMERA command arg1 arg2 Typing CAMERA xyzzy will result in an error report because xyzzy is not a valid camera command This error report helpfully includes a list of all the commands that the CAMERA referenced object does understand The most useful commands are listed below CAMERA InitDriver cameraNumber This command needs no additional arguments it performs camera initialization It will not normally be necessary to use this call as it will have been done as part of the camera_init tcl script CAMERA read_ Status This command returns an integer representing the readout status of the camera Typically this will be stored in a tcl variable and then printed out in user friendly format E g set s S CAMERA read_ Status switch s 0 set t Idle 1 set t waiting for trigger 2 set t exposing 3 set t downloading 4 set t line ready 5 set t image ready 6 set t flushing BIR default set t ERROR code s puts stdout Camera status is s CAMERA Expose duration shutter Take an exposure of the requested duration expressed in seconds The value of the shu
19. o you need to be careful Furthermore you will need at least 3 dark frames in order to remove radiation events cosmic rays and unless you have a vast number of dark exposures to average you may decrease your signal to noise The bottom line of all this is that unless you really need to remove the dark current don t bother The next step in removing the instrumental signature is to flat field your data This will remove the pixel to pixel gain variations and in the case direct imaging the larger scale spatial variations If you are doing direct imaging then you are probably happy by normalizing the flat field exposures to some average value The final step in the flat fielding process is to see if your twilight sky exposures have been well flattened by this procedure if not we may have to correct for this Apogee camera driver Programmers Guide V0 5 Dave Mills rfactory theriver com December 2001 Contents 1 CameralO object 2 Scripting interface Tcl 3 Code generation 4 Tcl Tk and loadable libraries 5 Ccd library 6 LX library 7 Remote control 1 CameralO object In the unlikely event that you should find it necessary to use the C interface directly there is a small sample of code in the file opt apogee src apogee CCameralO_example cpp This code should be easily comprehensible to anyone familiar with C For example to create a new camera object cam new CCameralO To call a method for example InitD
20. pment Support for electronic focus position adjustment will be made available in future releases of the package For systems where no electronic readback of focus position is available it can be simulated by attatching a calibrated disk to the focusser 3 2 Properties window The properties window can be accessed either by selecting Options gt Properties from the pull down menu or by typing Alt p whilst the pointer is in the main window In each case repeating the operation will close the window again The window consists of a set of tabbed panels click the tab name to view the panel Telescope panel Sl Properties At p to open close window EO Telescope System Geometry Temperature CCD filter Catalogs scope Lx200 M link serial M remote localhost x fratio 6 0 guide Off 7 perrcor Off gt This panel is used to select the type of telescope in use If your telescope is not yet supported or does not have computer control then select Manual Enter the correct focal ratio remembering to take into account any focal reducers that are installed Use guide to select auto guiding NOT YET IMPLEMENTED Use perrcor to select automatic periodic error correction NOT YET IMPLEMENTED System Seen Properties Alt p to open close window Telescope Oo x base 0x378 mode 0x2 test 6 guider_relays 0 M frame_timeout 60 cable SHORT maxbinx 6 register_of
21. river result cam gt InitDriver cameraNumber To set the value of an instance variable cam gt BaseAddress 0x378 2 Scripting interface The simplest way to program using the driver is via the provided scripting interface libraries An interface is provided for the Tcl Tk language This language is easy to learn due to its interpretive nature That is you type commands directly to a command line and they are executed immediately Interfaces to other languages python perl and more can also be automatically generated using the SWIG package included in the devel release of the package 2 1 Tcl To begin a Tcl Tk session open an X terminal start a csh shell and prepare the environment by typing source opt apogee scripts setup env prepares the environment This will initalize your shell to use the included version of wish the Tcl Tk windowing shell Another version of wish may already be installed on the system but it is recommended that the included version be used to avoid and potential library version conflicts opt apogee bin wish8 3 starts the tcl tk shell A small gray window will open Re select your xterm window and type source opt apogee scripts camera_init tcl command line only or source opt apogee scripts gui tcl gui interface plus command line The appropriate driver library will be dynamically loaded and new commands will be added to the Tcl shell Type a at the prompt to get a list of a
22. rpose An option to perform automatic bias subtraction is also provided Use the geometry properties to adjust the frame dimension BIC SkipC and NumY to provide a reasonable number of bias columns 6 Se Properties At p to open close window O xX Telescope System Geometry Temperature CCD Filter Catalogs columns 532 rows 532 bic qe bir f3 skipe 6 skipr 2 startcol bo startrow o numcols 511 numrows 511 binx no S biny f1 hf lush je Slush fa E driftscan jor x then enter the column numbers in the entry fields provided Selecting Automatic bias subtraction will then automatically average the data in the bias columns and them from the image before writing it out In this case the bias columns will not be included in the written image For the most flexible post processing the images are written including IRAF compatible header information This allows the images to be easily processed using the IRAF ccdred package available as part of the Linux for Astronomy cdrom distribution available from http www randomfactory com Ifa html In addition to the main window there are a number of auxillary windows to control less frequently used facilities These windows can be accessed via the pull down menu s or via hot keys Alt p will open close the Properties window Alt c will open close the Calibrations window Alt d will open close the Drift scan window 3 1
23. sk until dawn Of course all the image data will be sitting in the memory of your computer until the exposure completes when the data is written to disk Given the possibility of a power failure or other computer problem you should limit your drift scan exposures to an hour or so thus minimising data loss should the unthinkable occur Using drift scan mode will require some setup effort on the part of the user Here is a checklist of steps we used to test this mode 1 Ensure that the telescope is VERY well polar aligned 2 Switch off the telescope drive 3 Point the telescope at the celestial equator DEC 00 00 00 4 Use short normal mode exposures 1 minute to observe the direction of drift 5 Align the ccd camera so that the stars drift down the ccd in perfect alignment with the ccd columns 6 If possible calculate the appropriate per row drift delay using the fratio sidereal rate and ccd pixel scale good luck 7 Otherwise take short drift scan exposures 500 rows and step through a set of different drift delays As a guide we found the optimal equatorial drift delay to be 344000 microseconds using a 8 F 6 scope with an Ap7p camera 8 Plot the drift delays vs length of star trails 9 Determine the zero point drift delay 10 Enter the optimal delay into the drift scan GUI 11 Take a short and then long drift scan to verify 12 Move to a different DEC position 13 Click Calculate duration and per line rate in mi
24. srows specify the bias rows The Ccd library commands interact swith Apogee drivers in the following manner a driver library Bufferlmage call will store an image in a named memory buffer Ccd library calls then reference the image by that name For example CAMERA Expose 10 1 CAMERA BufferImage testimage write_image testimage myfile fits would take a 10 second exposure with the shutter open read out the image and store it in a buffer named testimage and finally write the raw image data to a disk FITS file named myfile fits The syntax required for each call can be determined interactively by simply calling the function without any arguments The required syntax will then be printed out Future versions of this library will include image arithmetic and conversion functions 6 LX library The LX library can be interactively loaded into a wish shell using the command load opt apogee lib liblx200 so The LX200 loadable library is a Tcl extension which provides simple commands for interacting with a telescope which support the protocol used by LX200 series telescopes The following commands are available open_scope open a link serial to the telescope close_scope close the link to the telescope 1x200_mode query the telescope mode 1x200_clockfmt query the clock format in effect 1x200_goto slew to target 1x200_object define target from catalog 1x200_ext define target from extended catalog write_scope sen
25. ta A calibration run will often require careful preparation to ensure the best results Each calibration run is specified using the following items location of directory used to store the data number of frames to average to create each calibration frame minimum temperature maximum temperature exposure duration The directory to store calibration data may be independently specified for each category of calibration frame Each category also has an associated automatic option which when selected will activate automatic calibration using that category assuming that automatic calibration is enabled in the main GUI window Clicking one of the Start type calibration buttons will pop up a dialog which provides an estimate of the length of time required to run the full sequence which can be substantial The software steps through the range of temperatures selected in 1 degree increments At each temperature a set of n frames is acquired These frames are buffered in memory Once all n exposures have been acquired the appropriate calculations are made to generate the calibration frame which is then written to disk Once a library of calibration frames has been obtained they can automatically be applied by selecting the auto calibrate option in the main window DS9 Image display tool 4 SAOImage ds9 APX File Edit Frame Ein Zoom Scale Color Region Analysis Help File m42 5 5 fits Value 65535
26. tepPos GuiderRelays Guider relay on off HFlush Binning factor for column flush ImgColumns Imaging columns on detector ImgRows Imaging rows on detector Interface Type of interface LongCable Long cable indicator Mode Mode NumX Number of columns to read out NumY Number of rows to read out RegisterOffset Register offset for multiple cameras Rows Number of rows Shutter Status of shutter SkipC Number of skip columns SkipR Number of skip rows StartX First column to read out StartY First row to read out Status Camera readout status TDI Drift mode TempScale Scale multiplier for raw temperature Temperature Current ccd temperature Test2Bits Second set of test bits TestBits Primary set of test bits Timeout Image readout timeout UseTrigger Trigger status VFlush Binning factor for vertical flush For example the following commands would prepare the readout region CAMERA configure m_StartX 100 CAMERA configure m_StartY 100 CAMERA configure m_NumX 64 CAMERA configure m_NumY 64 would specify a 64x64 pixel region starting at column 100 and row 100 The camera_init tcl script includes code to interrogate the C level API and construct a generic interface to all the available methods and instance variables which can read write camera parameters The names of parameters which may be read can be found as members of the global array CCAPIR and those which can be written can be
27. tter argument is either 0 leave shutter closed or 1 open shutter during exposure CAMERA GetImage This command reads out the entire frame and saves it in memory CAMERA BufferImage testname This command retrieves the image from the camera and saves it in the PC s memory swap space Any number of images can be buffered in this way subject to available memory Once the image is in memory it can be manipulated using the commands from the Ced library For example list_buffers shows current buffers their dimensions bit depths etc write_buffer testname mytest fits stores the contents of the buffer testname on disk as a FITS format file In addition to the methods associated with a CAMERA object there is also a mechanism for access to the instance variables of the CAMERA object Each instance variable corresponds to a camera configuration parameter The syntax for examining the current value of a parameter is CAMERA configure m_ parameter name and to set the parameter to a new value CAMERA configure m_ parameter name new value The following instance variables are supported BIC Before image columns BIR Before image rows BaseAddress Base address of interface BinX Binning factor for columns BinY Binning factor for rows Columns Number of columns on detector CoolerMode Cooling mode CoolerSetPoint Target temperature CoolerStatus Status of cooler FilterPosition Filter position index FilterS
28. ture rich image viewer catalog access swig 1 3a5 tar gz Simple wrapper and interface generator vne 3 3 2r3_unixsrc tgz virtual network computing unix source vnc 3 3 3beta2_ppc_mac sit virtual network computing for mac vne 3 3 3r2_x86_linux_2 0 tgz virtual network computing for linux vne 3 3 3r7_x86_win32 zip virtual network computing for windows xite 3 4 1386 rpm Image processing tools The Random Factory also produces a very extensive collection of Astronomical software all pre compiled for Linux The current release Volumes 5 amp 6 includes over 2GB of software on a 2 cdrom set Appendix Processing CCD images This advice is paraphrased from the advice provided to professional Astronomers observing at the US National Observatory It is based on a document included with the IRAF system and was written by Dr Phil Massey currently at Lowell Observatory What Calibration Frames Do You Need The answer to this depends to some extent on what it is that you are doing The goal is to not let the quality of the calibration data degrade your signal to noise in any way If you are in the regime where the read noise of the chip is the dominant source of noise on your program objects then subtracting a single bias frame from your data would increase the noise prohibitively However if you instead use the average of 25 bias frames the noise will be increased by only 10 Of course if you are into high signal to noise spectros
29. u are not successful in cleaning out bad columns and pixels This section will briefly outline what we will do with the calibration images Most of the calibration data is intended to remove additive effects the electronic pedestal level measured from the overscan region on each of your frames the pre flash level measured from your bias frames and if necessary the dark current The flat field data dome and twilight sky exposures will remove the multiplicative gain and illumination variations across the chip When you obtained your frames at the telescope the output signal was biased by adding a pedestal level of several hundred ADU s We need to determine this bias level for each frame individually as it is not stabilized and will vary slightly ss 5 30 ADU s with telescope position temperature and who knows what else Furthermore the bias level is usually a slight function of position on the chip varying primarily along columns We can remove this bias level to first order by using the data in the overscan region the typically 32 columns at the right edge of your frames data We will average the data over all the columns in the overscan region and fit these values as a function of line number i e average in the x direction within the overscan region and fit these as a function of y This fit will be subtracted from each column in your frame this fit may be a simple constant At this point we will chop off the
30. ur longest exposure You should ensure that your system is sufficiently light tight to permit these to be done during the day flat field exposures At a minimum flat field exposures are used to remove pixel to pixel variations across the chip Usually dome flats exposures of an illuminated white board will suffice to remove the pixel to pixel stuff You will want to expose the dome or projector flats so that you get sufficient counts to not degrade the signal to noise of the final images If you are after 1 photometry per pixel then you will need to have several times more than 10 000 electrons accumulated in your flats but you need to be careful not to exceed the good linearity limit in any single flat exposure Generally if you have 5 or more flats each with 10 000 electrons per pixel you are probably fine You will need a set like this for every filter and you probably will want to do a new sequence every day twilight flats If you are interested in good photometry of objects across your field you need to know if the sky looks different to your CCD than the dome flat It is not unusual to find 5 10 gradients in the illumination response between a flat and a sky exposure and this difference will translate directly into a 5 10 error in your photometry For most applications exposures of bright twilight sky either for direct imaging or spectroscopy will cure this problem With direct imaging this requires you to be very quick on your
31. urces The GSC USNO RNGC catalogs and the Digital Sky Survey can be configured Available catalogs can be used to overlay object information name mag etc on either your images or reference images from the Digital Sky Survey Catalog data can also be used to automatically calculate the World Coordinate System ie RA DEC parameters for images 3 3 Calibrations Calibrations Alt c to open close window ER zero _j automatic Select library min temp 30 max temp 10 num frames 10 exposure 0 02 dark _ automatic Select library min temp 30 max temp 10 o onum frames 10 a exposure 1 xi max temp 10 num frames 10 0 flat _j automatic Select library min temp 30 skyflat _ automatic Select library min temp 30 Create zero calibrations library Lele exposure 0 ajaj 4b ilal lap La Lh La Le max temp 10 num frames 10 KIL exposure Lale Create dark calibrations library Create flat calibrations library Create skyflat calibrations library The calibrations window can be accessed either by selecting Calibrations gt type from the pull down menu or by typing Alt c whilst the pointer is in the main window In each case repeating the operation will close the window again Obtaining the best performance from ccd cameras requires considerable calibration This window provides a simple way to automate the collection of the most common types of calibration da
32. xISA cpp DLINUX I include usr local bin swig tcl8 c apogeeISA i then you are ready to build the shared library using a command such as g shared O2 g apogeeISA_wrap c CameraIO_LinuxISA o 0 apogee_ISA so I The Camera interface is now ready to load into a wish shell using load apogee_ISA so invoked from a tcl wish shell SWIG is also capable of generating code for other scripting languages for example python Refer to the SWIG manual for details 4 Tcl tk and dynamic libraries The most recent versions of Tcl Tk have extensive support for dynamically loading libraries of code The Apogee Linux GUI makes extensive use of this capability to tune the behaviour of the interface depending upon the facilities available Dynamically loadable libraries are provided for the following Apogee parallel port interface cameras Apogee ISA interface cameras Ccd frame in memory buffering processing FitsTCL FITS file access LX200 serial interface Compressed GSC catalog access Digital sky survey access Astrometry library NOT YET IMPLEMENTED BLT graphics library In all cases libraries are loaded into a running wish by typing a command or including the command in a source d script such as load path to library lib name so To create a new loadable library the following files will normally be required assuming a package name of newpack newpackPackage c stub code to define the namespace
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