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CCDciel is free software released under the terms of the
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en:documentation:preferences

Preferences

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

Files

With this menu 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 it is important to preserve the details for later processing.

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. This is all depending on personal preferences and image processing software used later.

If Date/Sequence is checked the date and time is appended to the file name. If it is not checked a sequence number is appended to the file name.

You can reorder the different elements with a mouse drag and drop of the sequence number column.

The base capture folder should be specified.

Normally you not need to change the temporary file folder. But this may be necessary in the case astrometry.net cannot work with the default one.

At the bottom you can select to save all log messages to a file for further inspection or debugging. it is recommended to always let it checked.

And you can activate a TCP/IP server to get remotely the status of CCDciel


Observatory

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

The latitude and longitude of the observatory is used to get the Alt/Az position of the object, or for the scope_alignment script.

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.


Preview

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

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. If you don't know what to select, make a test on a colorful subject on daytime. You can also do some color balance with the cursors on the right.

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.

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

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.

Preview stacking allow you to stack the preview frames in real time. This feature is normally use for demonstration in public event.
You can select to disable this option to not risk an unwanted use during your imaging session.
Using a dark frame subtraction before the image addition improve the result quality.
This dark image must always be in 16bit format, even for a 8bit camera.

Select the preview rate for the video. Video require a suitable camera and is available only with INDI devices.


CCD 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 (Celsius) 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.


Flat

Configure the method to use to capture a flat series form a sequence.

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.

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.


Focus

Select the size in unbinned pixel of the star detection area and the size of the zoomed window for the focus mode. If you use a binning different than 1×1 for the focus operation the window size is reduced accordingly.

If this is not already done by your focuser driver you can activate a backlash compensation.
Indicate the number of additional steps to use for the compensation. this can be greater than the actual backlash.
Indicate the direction the focuser will always finish to move. The best depend on your configuration but be sure to use the same value as the auto-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.

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 typically have to turn the focuser OUT to correct for tube shrinkage. For a refractor you typically have to turn the focuser IN since the change in refraction coefficient is dominant and much larger then 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 empirical. Start with an almost zero factor=1 and monitor the autofocus focus position in the log as function of the reported temperature. If you sufficient 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.

For each filter you can also set a focuser 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 two time the exposure of the L filter set : L=1 R=2


Auto-Focus

This section 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.

Select the auto-focus method:

  • V curve: This is the preferred method for an absolute position focuser. By measuring the size of a defocused star it can accurately calculate the ideal 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 lines left and right of the focus position is constant. Temperature changes, filters and slippage will only shift the focus but not the slope of the two lines. Once the V-curve (slope) has been measured accurately and saved using the V-curve learning tool, every auto focus operation will be done quick and efficient.
  • Dynamic: This method can be used with relative position focuser. It require you start very near of the focus position and it make a small V curve every time.
  • Iterative: A dumb method that move in one direction or another as long the star diameter is smaller. I as the advantage to work with any kind of focuser and you can start with a very defocused star. But it is slow and imprecise.
  • None: If you want to use your focuser only manually.

Common parameters

  • Exposure time to use for the auto-focus operation. This time is multiplied by the filter exposure factor above.
  • 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 HFDthat 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 higher than this value the auto focus operation is canceled and the focuser position is set back to it's previous value.
  • Autofocus star list, 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.

V curve parameters

  • 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.
  • n.exp : The number of exposure we take to get a mean HFD value. Increase this value if the seeing is not good.
  • 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.
  • 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 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.

Dynamic parameters

  • Near focus HFD: the HFD we start to use n.exp exposure to get a mean HFD.
  • 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.
  • Movement between points: The number of focuser steps we move between each measurement of the curve. The maximum focuser movement in and out of current position will be (Number of dynamic points)*(Movement between points)/2

Iterative parameters

  • Near focus HFD: the HFD we start to use n.exp exposure to get a mean HFD. When the HFD is higher that this we take a single exposure to speed the process.
  • 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.

Astrometry

Enter the camera pixel size and 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.

Select the software you want to use for the astrometry resolution of the images, you can use astrometry.net , Elbrus star locator or PlateSolve 2.

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

Astrometry.net options

  • Minimum 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.
  • Create plot of the result: create png image with indication useful for debugging.
  • Other options: any other option you want to give to the solve-field command.
  • 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 astrometry.net python script.
  • On Windows only, you need to specify the Cygwin path to where astrometry.net is installed, for example C:\cygwin. See the installation instruction for more details.

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.

Slew

You can adjust how to correct the mount position after plate solving a control picture.
If your mount allow to sync anywhere select “Mount sync”, if not select “Pointing offset” to make the correction in software.
Use “Pointing offset” with EQMOD to not fool the pointing model.

Then set the precision you want/can reach and the maximum number of pointing/correction retry before to give up.

Set the parameters (exposure time, 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.


Meridian

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.
  • Abort: abort the current capture and stop the mount.

Automatic flip options

  • 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. This two parameters allow to loss the minimal time during a capture sequence, otherwise you can wait for a long as a single exposure time.
  • 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 must check this option.
  • 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 after meridian pause, if you not close the prompt after this time the sequence continue automatically.

Autoguider

Select your autoguiding software, this can be PHD2 or Lin_Guider.

For PHD2 you need to set the network name of the computer running PHD2 and the port number.

Set the options for dithering between the exposure, the number of pixel (in the guide camera) and if you want to dither only in RA (if you have a lot of DEC backlash).

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.

In the case of guide star lost (passing clouds…) we can try to restart the guider after some time. This is useful if the star as moved out of the search area, but if the clouds are still there we can start guiding on a hot pixel. A value of zero disable this function.
Then we can abort the current sequence after some time, maybe the next object on the plan is in a clear area.

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.
The Star lost and Settle tolerance options are not used by Lin_Guider.


Planetarium

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.


en/documentation/preferences.txt · Last modified: 2018/02/21 16:11 by pch