Configuration and settings

AstroTortilla stores its configuration files in the user's application local settings directory structure, under the\AstroTortilla directory. You can also store additional (partial) configuration files for quickly switching between various setups. It is recommended you save the configuration files into the default directory. You can remove any unwanted sections from the saved configuration files, e.g. leave only the solver specific section in the files. This enable creating a quickly switchable profile library for different telescopes and for annotated plots from stacked images.

The configuration file structure uses the familiar INI-file structure and it is currently in 7bit ASCII only. The percent -sign (%) must be escaped with another escaped-sign in the configuration file.

# Comment
option = value
another_option = different value

There is no need to have any particular section present in a configuration file, and it is recommended you edit the additional saved configuration files to cover only the parts of AstroTortilla settings you want to change quickly and easily on the field.


A sample of configuration file sections:

settings_path = C:\Users\MyUserId\AppData\Local\\AstroTortilla
log_file = 
log_level = ERROR
last_gotoimage = 
work_directory = s:\tmp
settings_pathreserved for future use
log_fileLog file name (name only or absolute path)
last_gotoimagereserved for future use
work_directoryIf set, all work will be done under the given directory. The temporary data is not deleted at exit.

iterlimitarcmin = 1.0
iterlimitcount = 5
solver = AstrometryNetSolver
syncmode = 0
exposure = 5.0
camera = CaptureCamera
iterlimitarcminAccuracy limit for iterative GoTo correction
iterlimitcountMaximum number of successive correction iterations
solverLast used solver module
syncmodeLast used synchronization mode
exposureDefault exposure time in seconds
cameraLast used camera module

shell = S:\cygwin\bin\bash --login -c "%%s"
downscale = 0
scale_max = 4
scale_xrefine = 0
configfile = /etc/astrometry/backend.cfg
scale_low = .5
xtra = --sigma 50 -N none --no-plot
searchradius = 180
scale_units = degwidth
year_epoch = JNOW
shellExecution string for using undec Cygwin. Note that %%s is in escaped form in the config file.
downscaleImage downscaling factor (0=disabled)
scale_maxUpper limit for image scale
scale_lowLower limit for image scale
scale_xrefineFactor for setting the scale_max and scale_low parameters based on solved image (0=disabled)
scale_unitsdegwidth, arcminwidth or arcsecperpix
configfilePath to configuration file (in Cygwin)
xtraAdditional command line options to solve-field
searchradiusAssumed telescope pointing accuracy radius (180=whole sky)
year_epochEpoch used in solution coordinates, JNow or J2000

If you see a systematic error of a few arc-minutes, you can try changing the epoch setting.

The fastest way to solve an image is to use a scale_low a bit smaller than your actual image size and searchradius of around 45 degrees (eg EQASCOM cannot sync with >45degree mismatch), to use binning instead of down-scaling, to disable plotting and to optimize the exposure-time and --sigma values for approximately 100-200 stars. One additional performance test is to make sure your Cygwin doesn't have Bash autocomplete enabled, it can add several seconds to the solve time if enabled.

The search radius and RA/dec information is not used when solving an image from "GoTo image" or "Add bookmark from image".

propertyagelimit = 1.0
syncaccuracy = 1.0
syncmaxwait = 2.0
lastselection = ASCOM.Simulator.Telescope
propertyagelimitMinimum telescope property refresh interval
syncaccuracyPost-sync reported coordinate accuracy limit
syncmaxwaitTimeout limit for sync-operation
lastselectionLast used ASCOM Telescope device name

bm-0 = 21h29m58.57s,12:10:15.59,1.0,M15
bm-1 = 05h34m48.42s,-05:38:06.04,-3.5,M45
count = 2

This format is subject to change.

bm-*Bookmark entry RA,dec,rotation,name
countNumber of bookmarks (last+1)

Camera specific sections:

filter = -1
binning = 2

lastcamera = 
binning = 1

directory = S:\tmp
binning = 1

binning = 1
hostname = localhost
port = 21701

windowtitle = ^PHD Guiding.*
topmargin = 49
rightmargin = 48
classname = .*
bottommargin = 70
leftmargin = 3
binning = 1

path = C:\Program Files\Nebulosity2\
setfilterwheel = -1
setcamera = False
setextfilterwheel = -1
resetpath = 
binning = 1
nebulosity = 2

Various camera specific settings.

Camera settings

The MaxImDL and Nebulosity camera modules support using a specific filter for solved images. Setting a filter value to -1 means current filter, any other value is passed as filter index to supporting imaging software.

Binning is always set as symmetric, and it's supported by MaxImDL, Nebulosity and ASCOM camera modules.

Nebulosity module cannot detect current imaging directory from Nebulosity and thus it has to set the imaging directory to a temporary one. If the resetpath is set, the given value is set as imaging directory after the image for plate-solving is taken. The resetpath option supports following parameters (use escaped form in configuration file):

%(date)sCurrent date
%(night)sDate 12 hours ago

The date format is YYYY-mm-dd. The current image name in Nebulosity is not changed.

Nebulosity module has been tested with Nebulosity 2.4 and 2.5 only. Nebulosity 3 may work, but it has not been tested. Set the nebulosity option to "3" instead of "2" and point the path to your Nebulosity 3 installation directory. solver

The plate-solver engine is used to determine the location, orientation and coverage of the imaged star field. The majority of the command-line options for solve-field can be set thru the xtra configuration entry or thru the GUI entry Custom options.

Reserved options not available as custom options (showing only short variants):

-DWorking directory (thru AstroTortilla config file)
-bConfiguration file location (thru AstroTortilla)
-LScale low limit (thru AstroTortilla)
-HScale high limit (thru AstroTortilla)
-uScale unit settings (thru AstroTortilla)
-3Target RA (from telescope if applicable)
-4Target declination (from telescope if applicable)
-5Search radius (thru AstroTortilla)
-zDownscaling factor (thru AstroTortilla)
Any/all options changing output file locations and names

Recommended options to experiment with:

--sigma NSet the noise level to N
--no-plotsDo not plot the annotated image
--N noneDo not create a new FITS file with integrated WCS headers
-q N.NMinimum quad size fraction
-Q N.NMaximum quad size fraction
--odds-*See documentation
--parity neg|posTry only negative/positive parity
--objs NLimit source list to N objects
--resortSort stars by background calibrated flux
--no-fits2fitsDon't sanitize FITS files
--no-background-subtractionDon't estimate background fluctuations
--guess-scaleTry to estimate field size from FITS headers

The --sigma option can be used in conjuction with the exposure time to improve the detected stars SNR and limit the number of items interpreted as stars. Depending on your camera and telescope aperture the known good values are known to vary between 2-5 seconds of exposure and 5-200 units for --sigma.

If you have a fairly slow harddisk (e.g. netbooks), disabling the plotting functions can improve you solve time by over ten seconds. These are set to disabled by default in new installations.

If you want to solve images on disk and store the annotated images from solver, remove the --no-plots -N none options and set the work_directory in the configuration file to a temporary directory. Using the FileOpenCamera module you can annotate existing stacked images and the results are stored in solving order under the work directory.


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  • Bryan Cashion

    Bryan Cashion - 2015-03-06

    I'm fairly sure that it is the downsample parameter that is the problem. I tried most of your other settings and still solved the image, as long as downsample 2 was in place.

    Somewhere in the past threads there is a discussion of downsample. I have never used anything other than 2.


  • andy nuttall

    andy nuttall - 2017-01-22

    please can you help when i load an image in to AT this what i get in the log, i did have it working once then it just stopped so i reloaded it now this is the result.

    2017-01-22 14:07:31,539 - astrotortilla - INFO - Connecting to camera...
    2017-01-22 14:07:31,539 - astrotortilla - INFO - Exposing: 20.00 seconds
    2017-01-22 14:07:36,150 - astrotortilla - INFO - Reading image from camera
    2017-01-22 14:07:36,150 - astrotortilla - INFO - Solving...
    2017-01-22 14:07:36,275 - astrotortilla - INFO - 0 [main] bash 5280 find_fast_cwd: WARNING: Couldn't compute FAST_CWD pointer. Please report this problem to

    2017-01-22 14:07:36,384 - astrotortilla - INFO - the public mailing list

    2017-01-22 14:07:36,930 - astrotortilla - INFO - Reading input file 1 of 12: "r"...

    2017-01-22 14:07:37,477 - astrotortilla - INFO - ERROR: Image type not recognized: Could not determine file type (does the file exist?): r

    2017-01-22 14:07:37,993 - astrotortilla - INFO - ioutils.c:605:run_command_get_outputs Command failed: return value 255

    2017-01-22 14:07:37,993 - astrotortilla - INFO - augment-xylist.c:585:backtick Failed to run command: /usr/lib/astrometry/bin/ --sanitized-fits-outfile /tmp/tmp.sanitized.tnhvrL --fix-sdss --infile r --uncompressed-outfile /tmp/tmp.uncompressed.FMdtrX --outfile /tmp/tmp.ppm.V8Lb27 --ppm

    2017-01-22 14:07:37,993 - astrotortilla - INFO - No solution in 1.8s


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