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From the menu Edit → Preferences. Set the global preferences and options for the program.


You can change the program language from the list.

Select if you want to use Celsius or Fahrenheit temperature scale in the program.

The program record all the messages to a file. You can look at the log using the function in the Help menu. It also save the images in the case the auto-focus fail to find stars or when plate solving fail, they can be used later to help to adjust the parameters.
The log file and failed auto-focus images are conserved for a period of 30 days, then they are automatically removed.
In case of problem with a device driver you can get more detailed information by checking Verbose device log.
By default the program show hint text over the buttons, you can disable this option here.

Python command
Set the command to start a Python script. You can use a specific Python installation by changing the default value.

TCP/IP server port
Set the port the TCP/IP server will listen on. Use the default unless it is already taken by another program or if you run multiple instance of CCDciel.

Log folder
The location to save the session log.

Sequence folder
The location to save and load the sequence files. This can be modified for a more simple file access location.

Temporary folder
Normally you not need to change the temporary file folder. This is only required on Windows if the default path based on your user name contain accentuated non-ASCII characters. Be sure you specify a path with only ASCII characters.


Capture folder
The base capture folder should be specified. The other configured sub-folder are created under this one.

File and folder name
You can specify how the image files are named and if they are stored in named folders. A typical imaging session will produce a great number of files, so this help to select files in the processing software.

One way of working is to make subfolders based on object name and select for file names all details; object name, the filter, a date sequence, exposure time, binning.

For folder name you have the choice between two date. One to make a folder with the same UT time as for the file name, the other is based on local time and change at noon to allow to put all the files for a given night to the same folder.

For file name, if Date/Sequence is checked the UT date and time is appended, otherwise a sequence number is appended. You can select a fixed sequence length or let unchecked for variable length.
You can reorder the different elements with a mouse drag and drop of the sequence number column.

Select the separator character you want between the fields, and the length of numeric sequence.

The file format can be FITS or Astro-TIFF, a 16bit TIFF file with addition of all the FITS header information that is supported by a number of processing software.

The saved FITS files can be compressed with fpack to use less disk space.

You can save the image in bitmap format in addition to the standard FITS or Astro-TIFF file.
Select also the file format you want. BMP and JPG are stretched 8bit images, PNG and TIFF are saved as linear 16bit, the same as the Save picture menu.

Custom headers
It is possible to define custom headers to add to every captured FITS file.
Enter valid keyword and values in the table. It is possible to set text or numeric values.
If a keyword is already set by the standard CCDciel processing and you add the same keyword here your value take precedence and replace the standard value.
For example the following input:

Add the following to the header:

Use the available script function if you need to add headers with a dynamic value.


Preset list
Each new observatory name is added to the preset list for an easy later retrieval.
This is useful if you transport the same equipment at different location.
But please do not use this option to work with different equipment, in this case you need a specific profile for each.

General information
The information on top will be set in each FITS file for the OBSERVER, ORIGIN, TELESCOP and INSTRUME keyword.

Observatory coordinates
The latitude and longitude of the observatory is used to get the Alt/Az position of the object, or for the scope_alignment script. It is mandatory you set them before you can use the timing functions in the sequence planner.

Rise/Set condition
The “Horizon profile” and “Minimum observing elevation” are used to compute the object rise and set time in the sequence planner. If this values are set the rise/set time are relative to this limits.
You can set only one value or both. In the last case the highest elevation is used.
The horizon profile file is the same as the local horizon line in Skychart.

Azimuth origin
Select if you prefer to use the azimuth counted from the North or from the South. This only affect some display in the program, the object azimuth recorded in the FITS header is always from the North.


Sensor temperature
Configure how you prefer to cool down and warm up you CCD sensor.
Consult your camera documentation to know if you need to limit the temperature change.
In this case check “Limit temperature change” and indicate the maximum rate in degree per minute.
Check the corresponding box if you want your camera to start cooling as soon it is connect to the program and indicate the target temperature you want.

Sensor properties
Enter the camera pixel size and maximum ADU, or if applicable for your driver, check the box to get it automatically.
The maximum ADU is used to avoid saturated stars during autofocus and photometry.
The pixel size is required to speedup the astrometry solving by estimating the image scale.

Predefined ROI
Manage a list of subframe size and position that can be quickly selected from the frame tool

Gain / Offset
Select if you want to manage the camera gain and offset from CCDciel or use the fixed value set in the camera driver.
If this box is checked you must set the gain and offset in the Preview, Capture and Sequence box. You must also set the gain and offset you want for the auto-focus and slewing operation.
This can work only if the camera driver expose this values. For ASCOM driver this is available only with new drivers using the version 3 of the camera interface.

Short exposure stacking
Check Show stacking option for Preview/Capture/Sequence if you want to use this options. You can let it disabled to not risk an unwanted use during the imaging session.

  • Star alignment align the frames on a reference star. Use it for EAA along with the dark, BPM and debayer option. No further pre-preprocessing is possible when any of this option is used.
  • Apply Dark and BPM apply the setting from File → Dark frame and File → Bad pixel map.
  • Apply Flat apply the setting from File → Flat frame.
  • Debayer the image using the preview setting.
  • Floating point file using 32bit FITS file. This ensure the maximum of precision and prevent data overflow. Be careful how to use this kind of image with your processing software.
  • Add images or Mean of images is the operation used to stack the images.
  • Save individual images before stacking in a specific folder named with the object name and the time the stacking start.

Readout modes
If your camera support different readout modes you can activate the use of specific readout mode for different actions.
Then select which one to use for the different operations. Normally you want the select the best quality mode for Capture and a fast mode for the other.
With INDI DSLR this is a combination of the CAPTURE_FORMAT and TRANSFER_FORMAT property to select from RAW, FITS, or different JPEG quality.


This settings affect only the preview, the FITS files are always recorded in RAW format to allow further preprocessing.

Color preview
If you use a color camera you can debayer the preview image by checking the corresponding box and selecting the color pattern for your sensor. The Automatic option use the value set by the camera driver of the DSLR raw file. If this not work try the other option in the list. You can also do some color balance with the cursors on the right. For DSLR raw files you can select to use the color balance set in the file. By default the background color is neutralized, this can be disabled if the image do not contain a classic sky background.

Reference image
The reference image help you to frame a previous image, for example to continue a sequence.
Select the threshold and color for the display of the reference image.

Image clipping
The image clipping indicator level. You can set the low and high threshold in ADU for this indicator.

Bad pixel map
The bad pixel map prevent the auto-focus function to lock on a hot pixel.
Select the threshold for detection of hot pixels for the bad pixel map.

Image cursor
Select the type and size of mouse cursor you want over the image display.

Check the box to show the Video tab if available for your camera.
Select the preview rate for the video. Video require a suitable camera and is available only with INDI devices.

Custom image type

This allow to define additional custom image type in addition to the standard Light, Flat, Dark, Bias.

Add one row per type, with a name and optionally a script with parameters to run when this type is selected or unselected.

For the camera driver, all this additional type are of type Light.

A typical use is to light a neon lamp for spectroscope calibration, but this can be use for any purpose, for example to subclassify the Light exposure according to your need.

After definition here, the custom type are available in the Capture or Sequences options.


Automatic flat
Configure the method to use to capture a flat series from a sequence.

Twilight flat
For the twilight flat it is require to configure the automatic exposure as the sky lightness change a lot during dusk or dawn.
You can also configure this automatic exposure for a use with other light source.
At each exposure the program will adjust the exposure time between the two limits to maintain the image level.
Set the shortest exposure time that give an uniform sensor illumination. This depend on the kind of shutter used by the camera.
Set the longest exposure time you want for a flat. You have to take the corresponding dark separately.
Then give an image mean level range that make an acceptable flat. Start with 80% of your camera full range but check there is no saturated part in the center of the flat image, specifically if the vignetting is important.

Select this method if you use dome flat or light panel.
You can also select automatic exposure, but at the difference of the twilight flat the exposure is adjusted only once for each filter, then the same exposure time is use for the series.
If you need to point the telescope at a specific position to frame the panel you can enter the required azimuth and elevation.


Star profile
Select the camera ROI size of the zoomed window for the single star focus mode.
Normally a single pixel star is rejected as a hot pixel. If your optical configuration produce undersampled image with single pixel star you can check this box. But be careful to make a bad pixel map to reject the hot pixel.

Focuser correction
If this is not already done by your focuser driver you can activate a backlash compensation. But be sure to let it disabled if the compensation is done elsewhere. Indicate the number of additional steps to use for the compensation, this must be greater than the actual backlash, don't hesitate to use a large value.
Indicate the direction the focuser will always finish to move, the best depend on your configuration. If you configure the auto-focus this control is disabled and will be set to the same as the focus move direction.
If it take some time for the focus position to stabilize after a move you can set a delay to wait after every focuser movement. This is more likely of use if the motor directly move the primary mirror of a SCT.

Filter offset
For each filter you can set an offset in focuser steps that will be applied to the focuser when you change the filter.
The filter exposure factor is used for the auto-focus functions and the automatic sky flat. For example if your R filter require 2x the exposure of the L filter and the Halpha 30x set : L=1 R=2 Ha=30
For narrow band filter this exposure factor can be very large. In this case you can use the option “Allow to select a brighter star for high filter exposure factor” in the auto-focus preference.

Temperature compensation
Temperature compensation and automatic triggering of autofocus after a temperature drop can be set in tab Sequence


This section is initially empty. It can be hard to fill with the right values for your specific equipment. It is strongly suggested you use the focuser calibration wizard to set the correct default parameters.

After the wizard is run it select the preferred Dynamic method. You can return at this page if you want to change the method or adjust some parameters.

Select the auto-focus method:

  • Dynamic: (hyperbole curve fitting) This method can be used with either an absolute or relative position focuser. Like the dynamic method it de-focus the star(s) and tries to fit the corresponding HFD values(s) to a hyperbole function. From the hyperbole function the bottom position so the focus can be calculated. This method has the advantage that it doesn't require a calibration in advance. It also requires less de-focusing of the stars (can work in bottom non-linear part of the curve) and therefore will work with fainter stars.
    This method will work well if you want to use the option “stay in place” for autofocus and it will use multiple stars for reliable detection.
  • V curve: (asymptote crossing) This is a method for an absolute position focuser. It will measure the size (HFD value) of a de-focused star at several focuser positions to calculate the best focus position. In advance your system has to be analyzed using the V-curve learning tool. This routine will measure the star size (HFD value) as function of the focuser position of your setup. The slope of the two linear lines (asymptote) left and right of the focus position are constant and they cross at the best focus position. Temperature changes, filters and slippage will only shift the focus but not the slope of the two lines.
    Once the V-curve (the slope of the two lines) has been measured accurately and saved using the V-curve learning tool, every auto focus operation will be done quick and efficient.
    This method work best with a single bright star and you need to configure the focus star magnitude you want to slew to before the autofocus routine is executed.
  • Iterative: A dumb method that move in one direction or another as long the star diameter is smaller. Movement step is reduced at each direction reversal. It has the advantage to work with any kind of focuser, including DC motor, and you can start with a very de-focused star. But it is slow and imprecise.
  • Planet This method is similar to Dynamic but it use a measurement of the image sharpness instead of the star HFD. This make this method suitable to focus on the Sun, the Moon or the planets.
  • None: If you want to use your focuser only manually.

Performance comparison V-curve and dynamic focusing:

MethodTarget fieldV- curve focusingDynamic focusing
Slew to database starAlways a bright star +++ +++
Slew to database star +
Allow to select a brighter star
Narrow band filter +++ +++
Stay in placeMedium bright stars ++ +++
Stay in placeFaint stars + ++
Stay in placeNarrow band filter + faint stars - -
Dynamic focusing can work in the bottom non-linear part of the V-curve. HFD as low as 4 (twice minimum)
V-curve focusing requires a peak HFD value of typical 15 to 20. Below peak value HFD is 10, the focus result will be less accurate.

Common parameters

  • Exposure time to use for the auto-focus operation. This time is multiplied by the filter exposure factor above.
  • Gain and Offset to use for the auto-focus operation. This require you activate the camera option
  • Binning to use for the auto-focus. Use binning 1×1 unless you are way oversampled.
  • The move direction of the focuser. Depending on you setting the focuser can work better when moved in or out of focus.
  • Autofocus tolerance is the maximum HFD that can be considered as a successful focus. If the HFD after and auto focus operation is higher than this value the focuser position is set back to it's previous value.
  • The minimum SNR of the star during the measurement. If a measurement SNR is lower than this value the auto focus operation is canceled and the focuser position is set back to it's previous value.
  • Number of exposure per point The number of exposure we take to get a mean HFD value for each focuser position. Increase this value if the seeing is not good. But set to 1 when using multiple stars detection.

Option valid when running from a sequence

  • Default behavior for Focus star selection when the autofocus is run from a sequence. Select if you want to slew to a bright star or stay on the object you are imaging to do the auto-focus. This can be selected object by object in the target editor. When using the Autofocus button in the Star profile tool it always stay at the current position, allowing you to manually select the target.
  • When measuring multiple stars it is possible to select the sensor area used for focusing in percent of the sensor area, the default is to use 30%.
  • If you stay on position, you can select to Pause guiding during autofocus or not. You must pause when using a OAG, but it is recommended continue guiding when using a separate guide scope.
  • Focus star selection when using “Slew to focus star”. Select the magnitude of a star that give a good SNR for the auto-focus operation using the above exposure time. The telescope is moved to a nearby star of this magnitude to run the auto-focus. You can set here the precision require for the slew to put the star in half the image height. Use a lower precision than for target slewing to speedup the process. If Allow to select a brighter star for high filter exposure factor the program can use a brighter star to avoid too long exposure time with narrow band filter.

If the auto-focus fails to find stars and the journaling to file is active, the image is saved in the same folder as the log so you can review them later to help to adjust the parameters.

Dynamic parameters

  • Number of dynamic points: The number of points we take on the curve. Do not set too high as this is done at every focus operation. Recommended default value is 7.
  • Movement between points: The number of focuser steps we move between each measurement of the curve. It must be set high enough to make a measurable change in star diameter, but not to high so faint stars can still be detected. The HFD value should increase at least twice the minimum. So if the focused stars have a typical HFD value of 2.5, the resulting V-curve should reach a HFD value of 5 or higher. Larger steps will make it less vulnerable for focus drift but due to the larger HFD values it requires brighter stars for enough signal to noise ratio. The maximum focuser movement in and out of current position will be (Number of dynamic points)*(Movement between points)/2

V curve parameters

  • Start focus HFD: The focus starting point on the V curve used to determine the Near focus position. Use a high value near the top of the V curve but inside the measurement area. A typical value is 20.0.
  • Near focus HFD: We move the focuser to get this HFD to make the measurement on the V curve. This is not the focus HFD, it must be half way on the linear part of the curve. For example if your focus HFD is 3.0 and you make a V curve up to a HFD of 20.0, you can set 10.0 here.
  • Slippage correction If your focuser is prone to slippage you can activate a correction here. You must have configured the filter offset and the focuser focuser temperature compensation, so we can be confident that the remaining offset is slippage.

The autofocus routine finds the focus in four focus movements using the slope information from the V-curve learning.

  1. Move beyond the Start focus HFD to (1) taken into account any temperature drift. This to fix any mechanical hysteresis in your system.
  2. Move to calculated Start focus HFD (2) taken into account any temperature drift. Here a number of exposures is taken and the average new start HFD is calculated.
  3. Based on the average new start HFD of step 2) move using the slope factor to the calculated Near focus HFD position (3). This (3) will be already adapted to any focus drift and should be spot-on. Take a number of exposures and use the average new near HFD and slope factor to calculate the new focus position.
  4. Move to the new calculated focus position (4).
  • - If the SNR, signal to noise is too low, the routine is aborted.
  • - Any focus drift will result in a drift of the new start HFD but not in the new near HFD.

Iterative parameters

  • Initial movement in focuser steps. This is the movement we use between measurement on the first iteration. It is then divided by two every time we change the direction.
  • Final movement in focuser steps. When we reach this movement value we consider we are at the focus. This is typically the focus tolerance of your optical system.

Planet parameters

  • Number of points: The number of points we take on the curve. Set high enough to leverage the seeing fluctuation on the planet surface. The default is the value measured for the dynamic focus during the focuser calibration, but it is recommended to increase at least to 15.
  • Movement between points: The number of focuser steps we move between each measurement of the curve. It must be set high enough to make a measurable change in image sharpness, but not too high because at a certain point more defocusing do not make less sharpness. If the curve show flattening on the top you need to reduce this value. The default is the value measured for the dynamic focus during focuser calibration. The maximum focuser movement in and out of current position will be (Number of points)*(Movement between points)/2

Expert trick

At the bottom of the preference list, you can set a defocus amount to apply after the focus point is reached. This can help to image with a constant defocus value when doing photometry measurement with a color sensor.

Temperature compensation
Temperature compensation and automatic triggering of autofocus after a temperature drop can be set in Sequence


Global options
It is important the program know your telescope focal length to estimate the image scale to speedup the solving process. Enter telescope focal length, or if applicable for your driver, check the box to get it automatically.

You can also adjust the timeout (in seconds) for a solve operation.

Software selection
Select the software you want to use for the astrometry resolution of the images, you can use , Star Locator Elbrus , PlateSolve 2 or ASTAP.

For each software you can adjust a few option to make them work quickly and reliably with your images. options

  • Maximum search radius: Is a tolerance in degrees to the telescope position. Set this value high enough if you use the plate solving to make a pointing model.
  • Scale tolerance: The tolerance on the pixel scale derived from the focal length and pixel size.
  • Downsample: the image by this factor. Use at least 4 or 8 for DSLR images. For CCD it is better to use binning.
  • Maximum number of source to consider.
  • Other options: any other option you want to give to the solve-field command. See man solve-field, for example --use-sextractor.
  • Use online, in this case specify your API key from this site.
  • Use custom script: Use a script instead of the solve-field command. There is two example with the program, one for remote execution using ssh, the other for remote solving with the python script.
  • On Linux or macOS you can specify the path to the solve-field program if it is not installed at a standard location. Let this field blank to use the default system search path.
  • On Windows only, you need to specify the Cygwin path to where is installed, for example C:\cygwin. See the installation instruction for more details.
  • You can setup as the fallback option if the primary configured solver fail. This let you use a faster software like ASTAP as the primary solution and retry with only if it fail because of difficult condition like half cloudy sky.

Elbrus options

  • Elbrus images folder: the folder where Elbrus wait for new images to solve.
  • Images folder Unix path: Unix only, the unix path corresponding to the previous one where CCDciel save the image for measurement.

PlateSolve 2 options

  • Program folder: the folder you install the PlateSolve2 program.
  • Wait after solve: the number of second the PlateSolve2 window remain visible after solving is complete.

ASTAP options

  • Program folder: the folder you install the ASTAP program.
  • Maximum search radius: Is a tolerance in degrees to the telescope position. As ASTAP is very fast there is no reason to change the 90° default value.
  • Downsample: For large images (>3000 pixels wide) select binning. It is recommended to keep the default value of 0 that let ASTAP select the best depending on the image size.


You can adjust how to correct the mount position after plate solving a control picture.

Correction method

  • Mount sync will send a Sync command to the mount after plate solving before to Slew at the requested coordinates.
  • Pointing offset will compute the RA/Dec offset and send to the mount a Slew to coordinates modified by this offset.

If your mount allow to sync anywhere select “Mount sync”, if not select “Pointing offset” to make the correction in software.
“Pointing offset” can be useful if your telescope use a pointing model, this avoid any problem by using Sync with the model, but this can result in a wrong position to be reported in other software.
With Eqmod it is best to disable the pointing model and select “Mount sync” here. With EQAscom, in Alignment/Sync select “Dialog based” and “Nearest point”. With INDI EQmod select “sync mode=standard sync” and “alignment mode=nearest point”.

Pointing options
Then set the precision you want/can reach and the maximum number of pointing/correction retry before to give up. Beware that any backlash in the mount drive can limit the possible precision.

Control exposure

If you define a Finder camera you can select which camera to use.

Set the parameters (exposure time, gain, offset, binning and filter) for the control exposure. This must give enough stars with your telescope/camera combination for the astrometry resolver to work.

If your mount need some time to stabilize after the movement you can increase the delay to wait before to take the plate solving picture.

When using a separate finder, specify the Focal length and if you want to use an alternative solver, other than the main one for the main or guide camera.


Configure here what you want to do when the mount reach the meridian.

  • Do nothing: select this option if your mount is not affected by the meridian (fork mount).
  • Automatic flip: automatically do a reversal of the mount to continue to track past meridian.
  • Run a script: run a script that do the meridian flip.
  • Abort: abort the current capture and stop the mount.

Automatic flip options

The first two parameters allow to loss the minimal time during a capture sequence. Set the difference between them as long as the capture exposure time. Otherwise the sequence can be paused until it reach the time for the flip.
Also be sure the flip do not start too early because this can be the cause of mount sync error in case of polar alignment error or telescope cone error because many mount do not accept to sync across the physical meridian.
To avoid error during the flip procedure it is important the mount and program observatory coordinates and time are set precisely.

  • Can track past meridian for: the number of minute your mount can safely track past the meridian without flip. This depend on the declination, set the smaller value here.
  • No flip until past meridian for: the minimum number of minute after the meridian we wait before to initiate the flip. Set this value to at least 10 minutes to avoid mount sync error near the meridian. You can set a negative value here to flip before the meridian, be sure the mount can accept that and support to set SideOfPier.

Actions to take as part of the meridian flip:

  • Set mount SideOfPier if available: Set SideOfPier directly to the mount, otherwise use Goto command.
  • Suspend dome slaving: This can prevent a full rotation with some dome.
  • Autofocus after meridian flip: In some case the focus point can move after a flip.
  • Calibrate autoguider after meridian flip: If your mount do not report the side of pier to the autoguider you can check this option to force a new calibration.
  • Pause before meridian flip:
  • Pause after meridian flip: this two checkbox give you a prompt before or after the flip to let you the time to do some manual operation on the mount (moving the counterweight for example).
  • Timeout: The maximum time we wait for the pause after the meridian flip, if you not close the prompt after this time the sequence continue automatically.
    Before the flip the pause is limited by the maximum time the mount can track without a flip.

Precise centering of the target using plate solving after the flip is done automatically and only require you configure the plate solving correctly.


Software selection Select your autoguiding software, this can be PHD2, Internal guider, Lin_Guider or only dithering using mount command.

PHD2 options
For PHD2 you need to set the network name of the computer running PHD2 and the port number.
Check if you want to start PHD2 if it is not running when connecting. Indicate the command to start PHD2, the default value correspond to the default PHD2 installation on the different platform.

Set the options for dithering between the exposure, the number of pixels (in the guide camera) and if you want to dither only in RA (if you have a lot of DEC backlash).
If the option Dither while downloading from the camera is checked the dithering will start as soon the previous exposure is complete, making profit of the image download time to advance on the dither.

Settle tolerance
The settle tolerance define how we consider the autoguiding as good after a dither operation or after it start.
It must stay within the number of pixel for Min.time. But we wait for the maximum of Timeout if this is not possible.
Set also the maximum time to wait if a new calibration is required.

This set the guide lock position for use with a reflective slit spectrograph.

Star lost recovery
In the case the guide star is lost we can cancel and restart the current exposure after a number of guide step without star. This is for the case we know the current exposure will be lost anyway so there is no need to loss more time by completing this exposure.

Then if the star is not recovered after a given time we can try to restart the guiding. This is useful if the star as moved just out of the search area. But this can also make the sequence to continue with an unacceptable offset, this can be avoided by checking for target drift. A value of zero disable this function.

Finally we can abort the current sequence after some time. Useful if the target is behind tree or cloud, maybe the next target is at a better position.

Guiding drift control
If the current guide position drift by more than the configured value a message is show in the log and eventually the current exposure is canceled and restarted. We can wait for the delay to let the guiding to recover before to restart the exposure.
The current sequence target can be aborted if it still drift after a number of consecutive restart.

Internal guiders

Define the Dithering and Settle tolerance options that have the same meaning as above.
Setup the guide camera to use in the devices setup.
All the internal guider specific settings are at the Internal Guider tab.

Lin_Guider options
For Lin_Guider you can choose to communicate by a local Unix socket or by the TCP network, on Windows only the TCP option is available. The selection must correspond to the one in the Lin_Guider general setting.

Set the number of pixels for dithering between the exposure.

Dither only options

With this option no auto-guiding is done but the program can initiate dithering between the exposure.

Here you set the mean duration of the dithering guide pulse send to the mount. This duration depend on the imaging scale and the mount guide rate. An additional wait time can be configured to let the mount stabilize after the dithering.


The Dome preference let you configure if you want to automatically manage the dome with the mount park/unpark function.

If you check the box Allow to open the dome when safety status is bad or unknown there will be NO check for the safety before to open the dome. Use this setting only if your safety monitor is not functional until the dome is open.

If you check the box Automatically slave “Dome Park” to “Mount Park”, every time you unpark the mount from CCDciel the sequence to open and initialize the dome will be taken. And every time you request to park the mount the corresponding action to close and park the dome will be taken.

Beware to carefully test this procedure before use and be prepared if something go wrong. What to expect if for example the telescope do not respond to the park request but the roof is then closed and hit the telescope? This case can be secured by using hardware switch on the mount that prevent the roof motor to start.
If you are not sure please do not use this function and open/close your dome with manual action and visual inspection.

For each of the unpark and park function you need to select the action you want in the order require by your setup. For some configuration you need to open the dome first or unpark the telescope first.
If some action is not require by your setup just ignore it, you not need to fill all the rows. For example if unparking the dome also open the shutter select only “Unpark the Dome”.
But be sure to put “Unpark the telescope” and “Park the telescope” somewhere, otherwise the telescope will never be unparked and any slew will fail.

You can also wait for an additional delay between each operation to let time for the mechanical part to stabilize.


Select the planetarium application you want to use.

You can use the planetarium to select a target, or to display a solved image or image frame.

You have the choice between Skychart. HNSKY, or a SAMP application like Aladin or Topcat.

Check if you want to start Skychart/SAMP/HNSKY if it is not running when connecting. Indicate the command to start the program, the default value correspond to the default installation on the different platform, but you may have to adapt for 32bit version on Win64 for example.

There is two additional options for Skychart.

  • Adjust the chart for the image frame to automatically zoom and center when a frame is send. When unchecked the chart is not modified.
  • Mark every astrometry result when checked a mark is set on the chart every time an image is plate solved.

Weather station

Beware this settings will never close your observatory, even in case of rain! See the Safety monitor below if you need this actions.

You define here the parameters to pause a running sequence when the weather condition are not optimal.
When bad condition are detected the program do the following:

  1. wait the end of current exposure
  2. stop telescope tracking and autoguiding
  3. wait for the sky to be clear again

When it is clear again it run the target initialization procedure, the same as when the target is first selected, checking for time range, slew with plate solving, start autoguiding, eventually going to the next target if this one is no more observable.

When you select to use a ASCOM ObservingCondition driver, you need to set the limits for every sensors here.
For INDI the limits are the Warning level of the weather driver.

You can also set a delay to wait after the weather is good again to avoid to start/stop continuously if a sensor is just at the limit. See also if your driver can average the measurement over a period to avoid this behavior.

Safety monitor

Select the actions you want to run when the Safety monitor detect dangerous conditions.
Beware that by default it do nothing!

The order to run the different actions depend on your specific equipment and need to be carefully tested.
For example if it rain you want to close the dome as soon as possible, but maybe the mount need to be parked first. In this case you must also test what it do if the telescope cannot park because of cable disconnection or other reason.

Use the function “Call external command” if you need additional actions not available in the dropdown list.

For two actions you need to set a parameter:

  • Show prompt : the time to wait before to continue automatically, in seconds.
  • Call external command: the full path of the command or script to be executed.

If you configure the Dome operation to be slaved to the mount park/unpark you only need to use the “Park the telescope” action here to also park and close the dome as configured.


This let you set some global actions taken during the execution of a sequence.

You can select to Start new exposure as early as possible, without waiting for the previous image to be saved and displayed. With this option checked you can save a few seconds between each exposure, the gain is more important when using a big camera sensor with short exposure time.
This apply to capture sequence and preview loop.

When the previous option is active you can do some measurement on every image.

The Automatic HFD measurement let you monitor the image quality and record the mean HFD in the log. The exposure time must be at least of 30 seconds to let the time for this measurement without perturbation of the sequence.

A trend of the measured HFD values is plotted in the trend tab of the focus tool.

Recenter sequence target that drift
For various reason you may observe the target to slowly drift in the image field during the night. The obvious symptom is large black border around the final image after registration and stacking.
You can observe this because you are not auto-guiding. But also when guiding with a separate guide scope because of slow flexion of different mechanical and optical parts.

With this option the program plate-solve every image taken during a sequence to compute the drift from the initial target position. If the drift is larger than the value set, it plan a recenter before the next exposure.
To make this possible it is required the image exposure time in the sequence is larger than the astrometry timeout.
The last point to check is the drift value you set here must be larger than 1.5x the slew precision and also larger than 2x or 3x the dithering if any.

Periodic autofocus

This options are in addition to the autofocus frequency available in the Plan definition.

Focuser temperature compensation

If your focuser can measure the temperature you can set here the temperature coefficient (in steps per Celsius) used to adjust the focuser position between the exposures, or to shift the auto-focus V curve accordingly. The coefficient is positive if the focuser needs to move UP in position when the temperature drop. The routine will adapt the focuser if the temperature difference is larger then 0.5 degrees.
Note that for a reflector telescope you have to turn the focuser OUT to correct for tube shrinkage. For a refractor you have to turn the focuser IN since the change in refraction coefficient is dominant and much larger than the tube shrinkage.
The temperature coefficient will help to reduce the number of autofocus actions required. It will work best when the temperature drops slowly and all parts of the telescope have time to adapt to the changing ambient temperature.
The compensation factor has to be measured empirically. Start with an almost zero factor=1 and monitor the autofocus focus position in the log as function of the reported temperature. When you have enough data points which show a repeatable temperature coefficient enter the estimated factor in this menu. Some telescopes like a SCT could have less predictable coefficient and you most likely have to disable the coefficient and rely on the autofocus routine only.
If the factor is set well, the result of each autofocus routine run should be close to the previous focus position.
The temperature of the last focus operation in a session is saved to make a first correction the next time you start the program, so if no change was done in the mean time you recover a not too bad focuser position.

You can also request to run an auto-focus procedure if the temperature change is more than the configured value.

The autofocus can also be run periodically after a given time interval.


When using a computer with limited resource it is good to use this resources for the main job of capturing images as quickly as possible. This can be improved by reducing the quality of the images show on screen or by totally disabling image display when a sequence is running.
None of this option affect the quality of the saved images.

Low quality image scaling use simple pixel resampling to scale the image on screen. This iimprove the speed a lot but can produce moire pattern with OSC sensors.

Do not display image during capture totally disable the display of the image during a sequence. This is a good way to optimize the inter-frame delay, but also look at the option Start new exposure as early as possible

When the option to not display the images is set, you can temporarily change this behavior using a new button that appear on the right of the visualisation tool


Email notification

You can configure email notifications that are send by the program on different conditions.

First you need to configure and test the email configuration so the program know how to send you an email.
Look at your email provider documentation for the values you need here, there is normally information how to configure an email software.

Important security information. This email configuration is saved on a separate file in the program configuration directory. The user name and password are obfuscated so they cannot be read directly in the file, but they can be read from CCDciel that otherwise cannot send you an email. So be careful to not send this file to anyone, and be sure you not use an important email account in this configuration.
It is strongly advised you create a low privilege email account to send this notifications.

Set the SMTP server address that accept outgoing request on the SMTP server port. Check the corresponding box if the server use SSL/TLS for the connection.
Indicate the User name and Password to connect to this server, and the sender From email address that is generally the same as the user name.
Finally indicate the Destination address that will receive the message. If you prefer to receive the messages on your phone, this destination address can be an email to sms gateway.

You can test this configuration with the button Send test email. This show a message if the email can be send or if there is connection error to the server. If the email is send successfully look at the destination mailbox for the message. Do not forget to also look at the Spam box.

Then select the notifications you want to receive. It is probably best to start with all the notifications, then remove the “Sequence normal end” if you want to receive only error notifications.

Voice notification

When you stay near the telescope during the capture it can be good to be alerted by some sound if something require your attention. For this case CCDciel can spell the message that are normally only show on screen.

You can configure the kind of message you want to ear from the Voice configuration tab.

A Test button allow to be sure the voice spelling is working and let you adjust the sound volume with the computer settings.

en/documentation/preferences.txt · Last modified: 2024/03/17 18:51 by pch