Take Image Action

 

The Take Image Action window contains all the parameters for taking unattended guided or unguided images.  The window is broken into five sections: Imager Information, Autoguider Information, Dither Information, Image Save Location, and Plate Solve Exposure Information.  You can click on the image above to go directly to that section in this page.

 

Imager Information

Here you define all the parameters for the imaging detector.  The parameters here are similar to those defined in the camera control program.  Some specific notes:

 

Custom Size frame size will allow you to specify the exact size of the image you want.  CCD Commander will center as best is possible the custom frame size on the middle of the detector.

 

Calibrate Images will run a full calibration on your images as they are downloaded.  You must setup the image calibration function in the camera control program to use the proper calibration frames.  CCD Commander will save both the RAW and REDUCED files.

 

 

Autoguider Information

Here you define the parameters for autoguiding while the imaging detector is being exposed.  Autoguider Enabled enables and disables the autoguiding function.  If you are talking a Dark, Bias, or Flat-field image, you would typically disable autoguiding.

 

The Exposure Time, Guide Star X pos, and Guide Star Y pos entries are only active when the Automatic Guide Exposure function is disabled.  If you want to manually choose your guide star, enter the information in these fields.

 

Max Error to Start defines what the maximum allowable error (in pixels) of the guide star can be before the imager begins its exposure.  The autoguider will run until the guide error is less then this amount, or after Max Guide Cycles to Wait  tries.  If the autoguider is unable to achieve a value less then this, the action will be stopped and CCD Commander will proceed to the next action in the list.

 

Guider Init Delay specifies the number of seconds to wait before checking the guide error.  If you know the guider takes a specific time before it pulls in the error you can set that time here.  CCD Commander will then check the guide error after this time has elapsed.

 

Enabling the Autoguider also enables the Dither Information parameters.

 

Unguided Dither is enabled when Autoguider Enabled is unchecked.  Checking Unguided Dither will enable the Dither Information parameters.  Unguided Dither will slew the mount by the specified Dither Step to dither your exposures.

 

Dither Information

Dither Frequency defines how often the guide star is dithered during the imager exposure.  A Dither Frequency of 1 will move the guide star after every exposure of the imaging detector.  A value of 2 will dither after every 2 exposures of the imaging detector.  This can be useful when taking many short imager exposures as the dither process can take some time to complete.

 

Dither Step defines the size of the dither movement between images.  CCD Commander will always move this amount from one image to the next.  Ensure that the Dither Step size is large enough to move at least one pixel on your imaging detector.

 

Maximum Dither defines the total size of the "dither box" around the guide star or initial coordinates.  The guide star will never be more than the Maximum Dither number of pixels or arcseconds from the where it started.

 

X Axis Dither and Y Axis Dither can be used to selectively enable or disable the X and Y axis from the dithering process.

 

Maintain Dither Position With Filter Change tells CCD Commander to continue the dither position and direction even after a filter change.  Normally CCD Commander will attempt to re-use the same guide star and same dither position/direction when you image at the same coordinates with the same filter.  On a filter change, CCD Commander can also keep the dithering coherent.  This function is useful primarily when taking one image per filter and repeating the filter set like this: RGBRGBRGBRGB.  With this kind of image sequence, the dither position will adjust for every image in the set such that the like-kind sub-exposures are all dithered.  When imaging a single filter at a time, like RRRGGGBBB, it makes sense to reset the dither position with each filter change because it only matters that sub-exposures are dithered among each other.  Dithering between filters would not be necessary for this imaging plan.

 

CCD Commander will always dither in a deterministic manner.  This will ensure that every image is always offset the same amount from the previous image and that any imager defects are always at a different location in your image set.  In addition, the pattern CCD Commander follows ensures that the guide star will move a minimal amount between exposures, maximizing your imaging time.

 

Below is a plot showing how the guide star will move for a setup where the Dither Step is set to 1 and the Maximum Dither is set to 2.  CCD Commander starts with the guide star at the (0,0) position and moves a maximum of 1 pixel between each exposure.  As soon as the dither location reaches the (2,2) coordinate, CCD Commander will retrace the dither path back to (0,0).  

Image Save Location

The Use Global Image Save Location checkbox tells CCD Commander to use the path specified in the File Options setup window.  When the checkbox is checked, the Global path is shown in the Image Save Location box.

 

When Use Global Image Save Location is not checked, the "..." button is enabled.  You can then specify a different save location for this action only.  Click the "..." button to select the folder you want to use.

 

Filename Prefix defines the start of the file name given to the downloaded images.  CCD Commander will append a counter value to uniquely identify each file name.  CCDSoft may also append further information about the target to the file name.  

 

The "..." button to the right of the Filename Prefix text box opens up the File Name Builder window which helps with creating automatic file name tokens.  Visit the File Name Builder help page for more information.

 

Plate Solve and Sync after Meridian Flip

This check box will tell CCD Commander that after a meridian flip it should take an image, preform a Plate Solve, and then sync the mount to the Image Link coordinates.  This function is useful for mounts that cannot exactly center an object after the meridian flip.  Since it is not necessarily known when the meridian flip will occur, it is useful to enable this function for every imager action (assuming this function is necessary).  If the Plate Solve fails, CCD Commander will abort this action and move on to the next action in the list.

 

See the Plate Solve action for full details on each of these parameters.  Note there is no Slew to Original Location after Solve parameter here.  This function is always enabled for a Plate Solve after Meridian Flip.

 

The Perform two Plate Solves after Meridian Flip option causes CCD Commander to repeat the plate solve.  This is very useful if your mount has a significant amount of backlash after a meridian flip.  If the first plate solve cannot get the target centered properly, the second one should be able to.

 

Checking Center AO When Complete will set the AO deflection to the exact center position.  This helps with mistaken image offsets during Plate Solve actions.

 

Checking Rotate 180 degrees after Meridian Flip will cause the rotator to compensate for the meridian flip.