Global Options
Keywords: gcx

Subsections

- File and Device Options
  - CFA to use with raw FITS files
  - Serial line for gps receiver control
  - Command for uncompressing files
  - Command for compressing files
  - Gnuplot command
  - Plot to file
  - Monospaced Font
  - Phot report file
  - Obs files search path
  - Rcp files search path
  - GSC location
  - Tycho2 location
  - Catalog files
  - Preload catalogs
  - Edb directory
  - Aavso validation file
  - Force unsigned FITS
  - Western longitudes
  - Report converter output format
  - Auto-unload frames
  - New frame width
  - New frame height
  - New frame scale
  - Merge positional tolerance
  - Fits Field Names
    - Fits field for X coordinate of reference pixel
    - Fits field for Y coordinate of reference pixel
    - Fits field for WCS R.A. of reference pixel
    - Fits field for WCS Dec of reference pixel
    - Fits field for degrees/pixel in R.A.
    - Fits field for degrees/pixel in dec
    - Fits field for field rotation
    - Fits field for equinox of WCS
    - Fits field for equinox of WCS
    - Fits field for object name
    - Fits field for object R.A.
    - Fits field for object dec
    - Fits field for image scale
    - Fits field for field center
    - Fits field for field center
    - Fits field for filter name
    - Fits field for exposure time
    - Fits field for julian date of observation
    - Fits field for modified julian date of observation
    - Fits field for date/time of observation
    - Fits field for time of observation
    - Fits field for telescope name
    - Fits field for focus designation
    - Fits field for telescope aperture
    - Fits field for focal length
    - Fits field for instrument name
    - Fits field for observer name
    - Fits field for latitude of observing site
    - Fits field for longitude of observing site
    - Fits field for altitude of observing site
    - Fits field for airmas
    - Fits field for sensor temperature
    - Fits field for horisontal binning
    - Fits field for vertical binning
    - Fits field for horisontal window origin
    - Fits field for vertical window origin
    - Fits field for electrons per ADU
    - Fits field for average bias of frame
    - Fits field for readout noise
    - Fits field for multiplicative noise coefficient
    - Fits field for color-field-array layout
    - Fits field for white balance calibration
- General Observation Setup Data
  - Latitude of observing site
  - Longitude of observing site
  - Altitude of observing site
  - Observer name
  - Observer code
  - Telescope name
  - Telescope focal length
  - Flipped field
  - Telescope aperture
  - Focus designation
  - List of filters
- INDI connection options
  - INDI server host
  - INDI server port
  - INDI name of main camera
  - INDI port for main camera control
  - INDI name of guide camera
  - INDI port for guide camera control
  - INDI name of Telescope
  - INDI port for telescope control
  - INDI name of Telescope
  - INDI port for telescope control
- Telescope control options
  - Eastern limit for goto ops (hour angle)
  - Enable eastern limit
  - Western limit for goto ops (hour angle)
  - Enable western limit
  - Southern limit for goto ops (degrees)
  - Enable southern limit
  - Northern limit for goto ops (degrees)
  - Enable northern limit
  - Abort obscript gotos that cause a meridian flip
  - Mount speed when centering (times sidereal rate)
  - Mount speed when guiding (times sidereal rate)
  - Use timed centering moves for small slews
  - Precess coordinated sent to the scope to the epoch of the day
  - Amount of gear play we take out at the end of slews (degrees)
  - Mount stabilisation delay (ms)
  - Amount of pointing dither between frames (arcmin)
  - Enable pointing dithering
  - Max error we accept in telescope pointing (degrees)
- Guiding options
  - Guiding algorithm
  - Reticle size
  - Centroid area radius
  - Guide box size
  - Guide box zoom
- CCD Reduction options
  - Method used for demosaic
  - Method used for white-balance correction
  - Minimum backgound sigmas
  - Method used for stacking frames
  - Iteration limit for stacking operations
  - Clipping sigmas for mmedian and k-s
  - Run CCD reductions automatically on frame display
  - Bad pixel sigmas
- Star Detection and Search Options
  - Star Detection SNR
  - Maximum Detected Stars
  - Maximum Catalog Stars
  - Faintest Magnitude for Catalog Stars
  - Maximum Radius for Catalog Stars
- Wcs Fitting Options
  - Scale tolerance
  - Star position tolerance
  - Rotation tolerance
  - Minimum number of pairs
  - Max skip
  - Maximum pairs
  - Min A-B distance
  - Max error for WCS validation
  - Min pairs for WCS validation
  - Scale change per iteration
  - Default image scale
  - Plate Model
  - Calculate Refraction
- Aperture Photometry Options
  - Radius of central aperture
  - Inner radius of sky annulus
  - Outer radius of sky annulus
  - Center apertures
  - Max centering error
  - Discard unlocated standards
  - Move targets
  - Max center distance
  - Sky method
  - Region growing
  - Sigmas
  - Saturation limit
  - Instrumental band
  - Force iband
  - Default catalog error
  - Alpha
  - Beta
- Multi-Frame Photometry Options
  - Bands setup
  - Outlier threshold
  - Zeropoint outlier threshold
  - Minimum airmass variance
  - Minimum color variance
  - Airmass range
  - Airmass maximum range
  - Limiting magnitude from zeropoint
- Star Display Options
  - Label Target Stars
  - Label Catalog Objects
  - Label Standard Stars
  - Standard Star Label Band
  - Minimum star size
  - Maximum display star size
  - Default display star size
  - Display pixels per magnitude
  - Brightest symbol magnitude
  - Display limiting magnitude
  - Show fainter stars
  - Zoom star shapes
  - Star shapes zoom limit
  - Plot position errors
  - Plot error scale
  - Star Display Colors
    - Autodected Stars Color
    - Field Stars Color
    - Standard Stars Color
    - Target Stars Color
    - Catalog Objects Color
    - User-Marked Stars Color
    - Align Stars Color
    - Selected Stars Color
  - Star Display Shapes
    - Autodected Stars Shape
    - Field Stars Shape
    - Standard Stars Shape
    - Target Stars Shape
    - Catalog Objects Shape
    - User-Marked Stars Shape
    - Align Stars Shape
- Synthetic Star Generation Options
  - Type of star profile
  - FWHM
  - Moffat beta
  - Zero Point
  - Oversampling
- On-line Catalogs
  - Vizquery command
  - Maximum Catalog Stars
  - Maximum Radius for Catalog Stars

#
Global Options

GCX has a large number of configuration options. They can be accesses through the options dialog, which can be brought up by pressing O or File/Edit Options. Clicking on ``save'' in the options dialog will update the default configuration file (`.gcxrc`), located in the home directory.

When the program stars, it looks for the configuration file. If it cannot be read, it will initialise all parameters with defaults.

There are two ways of modifying some of the options for a specific run: either use the `-S` command-line option for each option that needs to change, or make a configuration file that contains the option changes for the run and use the `-r` command-line option. The name used in the configuration file is listed with each option.

# File and Device Options

### CFA to use with raw FITS files

Config file | `.file.default_cfa`
Type | `multiple choice`
Choices | `none` `RGGB` `BGGR` `GRBG` `GBRG`
Default | `none`

### Serial line for gps receiver control

Config file | `.file.gps_serial`
Type | `string`
Default | `/dev/ttyS0`

### Command for uncompressing files

The command used to uncompress files; it should take the filename as an argument, and output the uncompressed stream on stdout. The command is called when trying to open files with the name ending in .gz, .zip or .z

Config file | `.file.uncompress`
Type | `string`
Default | `zcat`

### Command for compressing files

The command used to uncompress files; it should take the filename as an argument, and replace the file with the compressed version.

Config file | `.file.compress`
Type | `string`
Default | `gzip -f`

### Gnuplot command

Command used to invoke gnuplot for plotting graphs in a window.

Config file | `.file.gnuplot`
Type | `string`
Default | `gnuplot -persist`

### Plot to file

Create a gnuplot file instead of calling gnuplot directly.

Config file | `.file.plot_to_file`
Type | `boolean`
Default | `no`

### Monospaced Font

The monospaced font used to display FITS headers and help pages.

Config file | `.file.mono_font`
Type | `string`
Default | `-misc-fixed-medium-r-*-*-*-120-*-*-*-*-*-*`

### Phot report file

Output file for obscript phot commands.

Config file | `.file.phot_out_fn`
Type | `string`
Default | `phot.out`

### Obs files search path

Path (colon-delimited list of directories) searched when opening observation script files.

Config file | `.file.obs_path`
Type | `string`
Default | `.:../obs`

### Rcp files search path

Path (colon-delimited list of directories) searched when opening recipe files.

Config file | `.file.rcp_path`
Type | `string`
Default | `.:../rcp`

### GSC location

Location of gsc catalog files. Full pathname of the toplevel gsc directory.Make sure all subdirs and files names use lower case.

Config file | `.file.gsc_path`
Type | `string`
Default | `/usr/share/gcx/catalogs/gsc`

### Tycho2 location

Full pathname of the tycho2 catalog file.

Config file | `.file.tycho2_path`
Type | `string`
Default | `/usr/share/gcx/catalogs/tycho2`

### Catalog files

Colon-delimited list of catalog files to be searched or loaded into the in-memory catalog. The elements of the list are glob- and tilde-expanded so for instance /*.gcx will load all .gcx files from the home directory. The files are expected to be in gcx recipe format.

Config file | `.file.catalog_path`
Type | `string`
Default | `/usr/share/gcx/catalogs/*.gcx`

### Preload catalogs

Enable preloading the native format catalog files into memory for faster searching. Preloading takes significantly more time that searching the on-disk files by name; it's recommended only for merging catalogs or similar operations.

Config file | `.file.catalog_preload`
Type | `boolean`
Default | `no`

### Edb directory

Directory containing edb object files.

Config file | `.file.edb_dir`
Type | `string`
Default | `/usr/share/gcx/catalogs/edb`

### Aavso validation file

Location of aavso validation file. The validation file is used to determine the designation given a star name. Any of the validation file formats can be used, except the 'short form by name'. The designation should start in column 0 and the name in column 10.

Config file | `.file.validation`
Type | `string`
Default | `valnam.txt`

### Force unsigned FITS

Force all values read from a fits file to be interpreted as unsigned numbers (supporting broken files generated that way).

Config file | `.file.unsigned_fits`
Type | `boolean`
Default | `no`

### Western longitudes

Interpret fits header longitudes as western, rather than eastern. Report file longitudes are always western.

Config file | `.file.west_long`
Type | `boolean`
Default | `yes`

### Report converter output format

The output format string used by the report converter. See the on-line help for a description.

Config file | `.file.tab_format`
Type | `string`
Default | `name ra dec mjd smag "v" flags`

### Auto-unload frames

Unload unmodified frames from the frame list whenever possible to reduce memory usage. The frames will have to be reloaded if needed again.

Config file | `.file.mem_save`
Type | `boolean`
Default | `yes`

### New frame width

The width of a newly-created blank frame in pixels.

Config file | `.file.new_width`
Type | `integer`
Default | `1024`

### New frame height

The height of a newly-created blank frame in pixels.

Config file | `.file.new_height`
Type | `integer`
Default | `768`

### New frame scale

The default wcs scale of a newly-created blank frame in arc seconds per pixel.

Config file | `.file.new_scale`
Type | `real`
Default | `4.00`

### Merge positional tolerance

The distance in arc seconds below which we consider two stars to be the same object when merging recipe files.

Config file | `.file.merge_tolerance`
Type | `real`
Default | `3.000`

## Fits Field Names

### Fits field for X coordinate of reference pixel

Config file | `.file.fits.crpix1`
Type | `string`
Default | `CRPIX1`

### Fits field for Y coordinate of reference pixel

Config file | `.file.fits.crpix2`
Type | `string`
Default | `CRPIX2`

### Fits field for WCS R.A. of reference pixel

Config file | `.file.fits.crval1`
Type | `string`
Default | `CRVAL1`

### Fits field for WCS Dec of reference pixel

Config file | `.file.fits.crval2`
Type | `string`
Default | `CRVAL2`

### Fits field for degrees/pixel in R.A.

Config file | `.file.fits.cdelt1`
Type | `string`
Default | `CDELT1`

### Fits field for degrees/pixel in dec

Config file | `.file.fits.cdelt2`
Type | `string`
Default | `CDELT2`

### Fits field for field rotation

Config file | `.file.fits.crota1`
Type | `string`
Default | `CROTA1`

### Fits field for equinox of WCS

Config file | `.file.fits.equinox`
Type | `string`
Default | `EQUINOX`

### Fits field for equinox of WCS

Config file | `.file.fits.epoch`
Type | `string`
Default | `EPOCH`

### Fits field for object name

Config file | `.file.fits.object`
Type | `string`
Default | `OBJECT`

### Fits field for object R.A.

Config file | `.file.fits.objctra`
Type | `string`
Default | `OBJCTRA`

### Fits field for object dec

Config file | `.file.fits.objctdec`
Type | `string`
Default | `OBJCTDEC`

### Fits field for image scale

Config file | `.file.fits.secpix`
Type | `string`
Default | `SECPIX`

### Fits field for field center

Config file | `.file.fits.ra`
Type | `string`
Default | `RA`

### Fits field for field center

Config file | `.file.fits.dec`
Type | `string`
Default | `DEC`

### Fits field for filter name

Config file | `.file.fits.filter`
Type | `string`
Default | `FILTER`

### Fits field for exposure time

Config file | `.file.fits.exptime`
Type | `string`
Default | `EXPTIME`

### Fits field for julian date of observation

Config file | `.file.fits.jdate`
Type | `string`
Default | `JDATE`

### Fits field for modified julian date of observation

Config file | `.file.fits.mjd`
Type | `string`
Default | `MJD`

### Fits field for date/time of observation

Config file | `.file.fits.dateobs`
Type | `string`
Default | `DATE-OBS`

### Fits field for time of observation

Config file | `.file.fits.timeobs`
Type | `string`
Default | `TIME-OBS`

### Fits field for telescope name

Config file | `.file.fits.telescop`
Type | `string`
Default | `TELESCOP`

### Fits field for focus designation

Config file | `.file.fits.focus`
Type | `string`
Default | `FOCUS`

### Fits field for telescope aperture

Config file | `.file.fits.aperture`
Type | `string`
Default | `APERT`

### Fits field for focal length

Config file | `.file.fits.flen`
Type | `string`
Default | `FLEN`

### Fits field for instrument name

Config file | `.file.fits.instrument`
Type | `string`
Default | `INSTRUME`

### Fits field for observer name

Config file | `.file.fits.observer`
Type | `string`
Default | `OBSERVER`

### Fits field for latitude of observing site

Config file | `.file.fits.latitude`
Type | `string`
Default | `LAT-OBS`

### Fits field for longitude of observing site

Config file | `.file.fits.longitude`
Type | `string`
Default | `LONG-OBS`

### Fits field for altitude of observing site

Config file | `.file.fits.altitude`
Type | `string`
Default | `ALT-OBS`

### Fits field for airmas

Config file | `.file.fits.airmass`
Type | `string`
Default | `AIRMASS`

### Fits field for sensor temperature

Config file | `.file.fits.snstemp`
Type | `string`
Default | `SNS_TEMP`

### Fits field for horisontal binning

Config file | `.file.fits.binx`
Type | `string`
Default | `CCDBIN1`

### Fits field for vertical binning

Config file | `.file.fits.biny`
Type | `string`
Default | `CCDBIN2`

### Fits field for horisontal window origin

Config file | `.file.fits.skipx`
Type | `string`
Default | `CCDSKIP1`

### Fits field for vertical window origin

Config file | `.file.fits.skipy`
Type | `string`
Default | `CCDSKIP2`

### Fits field for electrons per ADU

Config file | `.file.fits.eladu`
Type | `string`
Default | `ELADU`

### Fits field for average bias of frame

Config file | `.file.fits.dcbias`
Type | `string`
Default | `DCBIAS`

### Fits field for readout noise

Config file | `.file.fits.rdnoise`
Type | `string`
Default | `RDNOISE`

### Fits field for multiplicative noise coefficient

Config file | `.file.fits.flnoise`
Type | `string`
Default | `FLNOISE`

### Fits field for color-field-array layout

Config file | `.file.fits.cfa_fmt`
Type | `string`
Default | `CFA_FMT`

### Fits field for white balance calibration

Config file | `.file.fits.whitebal`
Type | `string`
Default | `WHITEBAL`

# General Observation Setup Data

### Latitude of observing site

Used to annotate frames' fits header, and for calculation of objects' hour angle and airmass. Set in decimal degress.

Config file | `.obs.latitude`
Type | `real`
Default | `44.431`

### Longitude of observing site

Used to annotate frames' fits header, and for calculation of objects' hour angle and airmass. Set in decimal degress, E longitudes negative.

Config file | `.obs.longitude`
Type | `real`
Default | `-26.114`

### Altitude of observing site

Used to annotate frames' fits header, and for scintillation calculations; In meters above sea level.

Config file | `.obs.altitude`
Type | `real`
Default | `75.0`

### Observer name

Used to annotate frames' fits header.

Config file | `.obs.observer`
Type | `string`
Default | `R. Corlan`

### Observer code

Used to annotate AAVSO format reports.

Config file | `.obs.obscode`
Type | `string`
Default | `CXR`

### Telescope name

Used to annotate frames' fits header.

Config file | `.obs.telescope`
Type | `string`
Default | `SCT`

### Telescope focal length

Used to annotate frames' fits header, and for calculating the initial WCS image scale (together with the camera pixel size). In centimeters.

Config file | `.obs.flen`
Type | `real`
Default | `200.0`

### Flipped field

Set the inital wcs as flipped (CDELT1 and CDELT2 having opposite signs). The star matching algorithm does not handle flips, so this has to be set right. A normal (non-flipped) field has N up and W to the right.

Config file | `.obs.flipped`
Type | `boolean`
Default | `no`

### Telescope aperture

Used to annotate frames' fits header, and for estimating scintillation noise. In centimeters.

Config file | `.obs.aperture`
Type | `real`
Default | `30.0`

### Focus designation

Used to annotate frames' fits header.

Config file | `.obs.focus`
Type | `string`
Default | `Cassergrain`

### List of filters

Space-delimited list of filters used to set the choices in the obscript dialog. They are also used as default names for the filters in filter wheels that don't supply their own names

Config file | `.obs.filters`
Type | `string`
Default | `v r b i RI GI BI clear`

# INDI connection options

### INDI server host

Config file | `.indi.indi_host_name`
Type | `string`
Default | `localhost`

### INDI server port

Config file | `.indi.indi_host_port`
Type | `integer`
Default | `7624`

### INDI name of main camera

Config file | `.indi.camera_main_indi_name`
Type | `string`
Default | `CCD Simulator`

### INDI port for main camera control

Config file | `.indi.camera_main_indi_port`
Type | `string`
Default | `/dev/video0`

### INDI name of guide camera

Config file | `.indi.camera_guide_indi_name`
Type | `string`
Default | `CCD Simulator`

### INDI port for guide camera control

Config file | `.indi.camera_guide_indi_port`
Type | `string`
Default | `/dev/video0`

### INDI name of Telescope

Config file | `.indi.scope_indi_name`
Type | `string`
Default | `Telescope Simulator`

### INDI port for telescope control

Config file | `.indi.scope_indi_port`
Type | `string`
Default | `/dev/ttyS0`

### INDI name of Telescope

Config file | `.indi.fwheel_indi_name`
Type | `string`
Default | `Telescope Simulator`

### INDI port for telescope control

Config file | `.indi.fwheel_indi_port`
Type | `string`
Default | `/dev/ttyS0`

# Telescope control options

### Eastern limit for goto ops (hour angle)

Config file | `.tel.elimit`
Type | `real`
Default | `-1.0`

### Enable eastern limit

Config file | `.tel.elimit_en`
Type | `boolean`
Default | `no`

### Western limit for goto ops (hour angle)

Config file | `.tel.wlimit`
Type | `real`
Default | `1.0`

### Enable western limit

Config file | `.tel.wlimit_en`
Type | `boolean`
Default | `no`

### Southern limit for goto ops (degrees)

Config file | `.tel.slimit`
Type | `real`
Default | `-45.0`

### Enable southern limit

Config file | `.tel.slimit_en`
Type | `boolean`
Default | `yes`

### Northern limit for goto ops (degrees)

Config file | `.tel.nlimit`
Type | `real`
Default | `80.0`

### Enable northern limit

Config file | `.tel.nlimit_en`
Type | `boolean`
Default | `yes`

### Abort obscript gotos that cause a meridian flip

Config file | `.tel.abort_flip`
Type | `boolean`
Default | `yes`

### Mount speed when centering (times sidereal rate)

Config file | `.tel.centering_speed`
Type | `real`
Default | `32.0`

### Mount speed when guiding (times sidereal rate)

Config file | `.tel.centering_speed`
Type | `real`
Default | `0.5`

### Use timed centering moves for small slews

Config file | `.tel.use_centering`
Type | `boolean`
Default | `yes`

### Precess coordinated sent to the scope to the epoch of the day

Config file | `.tel.precess_eod`
Type | `boolean`
Default | `yes`

### Amount of gear play we take out at the end of slews (degrees)

Config file | `.tel.gear_play`
Type | `real`
Default | `0.10`

### Mount stabilisation delay (ms)

Config file | `.tel.stabilisation_delay`
Type | `integer`
Default | `1000`

### Amount of pointing dither between frames (arcmin)

Config file | `.tel.dither`
Type | `real`
Default | `0.5`

### Enable pointing dithering

Config file | `.tel.dither_en`
Type | `boolean`
Default | `no`

### Max error we accept in telescope pointing (degrees)

Config file | `.tel.max_point_err`
Type | `real`
Default | `0.05`

# Guiding options

### Guiding algorithm

Algorithm used to determine the guide star position error. The reticle algorithm determines the error as the ratio between the total flux in box-shaped areas located horisontally and vertically around the target position; The ratioed reticle tries to maintain the initial flux ratio, rather than a unit ratio.

Config file | `.guide.algorithm`
Type | `multiple choice`
Choices | `centroid` `reticle` `ratioed_reticle`
Default | `centroid`

### Reticle size

Size of the reticle in pixels. Must be an even value.

Config file | `.guide.reticle_size`
Type | `integer`
Default | `2`

### Centroid area radius

Radius of area inside which the target centroid is calculated.

Config file | `.guide.centroid_box`
Type | `integer`
Default | `2`

### Guide box size

Size of box around the target guide star position used by the guiding algorithm.

Config file | `.guide.box_size`
Type | `integer`
Default | `16`

### Guide box zoom

Zoom level of the small image of the guide box.

Config file | `.guide.zoom`
Type | `integer`
Default | `4`

# CCD Reduction options

### Method used for demosaic

Config file | `.ccdred.demosaic_method`
Type | `multiple choice`
Choices | `bilinear` `vng`
Default | `bilinear`

### Method used for white-balance correction

Config file | `.ccdred.whitebal_method`
Type | `multiple choice`
Choices | `none` `camera` `user`
Default | `none`

### Minimum backgound sigmas

Minimum number of sigmas the background must have for multiplicative background alignment to be performed when stacking frames.

Config file | `.ccdred.min_bg_sigmas`
Type | `real`
Default | `3.0`

### Method used for stacking frames

Config file | `.ccdred.stack_method`
Type | `multiple choice`
Choices | `average` `median` `kappa_sigma` `mean_median`
Default | `kappa_sigma`

### Iteration limit for stacking operations

Config file | `.ccdred.iterations`
Type | `integer`
Default | `4`

### Clipping sigmas for mmedian and k-s

Config file | `.ccdred.sigmas`
Type | `real`
Default | `2.0`

### Run CCD reductions automatically on frame display

Config file | `.ccdred.auto`
Type | `boolean`
Default | `yes`

### Bad pixel sigmas

Number of frame sigmas a pixel must deviate from the median of its neighbours to be considered defect.

Config file | `.ccdred.badpix_sigmas`
Type | `real`
Default | `12.000`

# Star Detection and Search Options

### Star Detection SNR

A star must be above this threshold above the backround to be considered for detection. Expressed in sigmas of the image. Useful range between 3 and 24.

Config file | `.stars.det_snr`
Type | `real`
Default | `9.0`

### Maximum Detected Stars

The maximum number of starts the program will extract from an image. If more are found, only the brightest are kept.

Config file | `.stars.det_maxstars`
Type | `integer`
Default | `200`

### Maximum Catalog Stars

The maximum number of starts the program will extract from a field star catalog. If more are found, only the brightest are kept.

Config file | `.stars.cat_maxstars`
Type | `integer`
Default | `300`

### Faintest Magnitude for Catalog Stars

Config file | `.stars.cat_maxmag`
Type | `real`
Default | `16.0`

### Maximum Radius for Catalog Stars

The maximum radius from the frame center in which we look for catalog stars. The actual radius depends on the frame size; this is a global limit. In minutes of arc.

Config file | `.stars.cat_maxradius`
Type | `real`
Default | `120.0`

# Wcs Fitting Options

### Scale tolerance

The maximum amount by which the image scale is changed during the fit. A value of 0.1 implies that scales between 0.9 and 1.1 are accepted. Using a lower value for this parameter will decrease the running time and reduce the chances for an incorrect fit.

Config file | `.wcs.fit_scale`
Type | `real`
Default | `0.10`

### Star position tolerance

The maxiumum position error, in pixels, between a star and a catalog position at which we still consider that the two match. It is unadvisable to increase this parameter much without a coresponding increase in the minimum number of pairs, or the chances for incorrect fits are greatly augumented.

Config file | `.wcs.fit_tol`
Type | `real`
Default | `1.5`

### Rotation tolerance

Maximum accepted field rotation, in degress A value of 180 will match fields with any rotation. Using a lower value for this parameter will decrease the running time and reduce the chances for an incorrect fit.

Config file | `.wcs.fit_rot`
Type | `real`
Default | `180.0`

### Minimum number of pairs

When the algorithm finds a solution with at least this many pairs, it considers it has found a good match and stops. Using less than 5 pairs will likely give many incorrect fits in crowded fields

Config file | `.wcs.fit_min_pairs`
Type | `integer`
Default | `5`

### Max skip

The maximum number of stars that don't seem to have a match in the catalog and are skipped during the search

Config file | `.wcs.max_skip`
Type | `integer`
Default | `20`

### Maximum pairs

Maximum number of pairs fitted. After finding this many, the algorithm stops.

Config file | `.wcs.max_pairs`
Type | `integer`
Default | `50`

### Min A-B distance

The minimum distance between two stars to be used as an initial wcs hypothesis.

Config file | `.wcs.min_ab_dist`
Type | `real`
Default | `100.000`

### Max error for WCS validation

Maximum RMS position error of all pairs at which the WCS is validated. Expressed in pixels.

Config file | `.wcs.validate_err`
Type | `real`
Default | `1.50`

### Min pairs for WCS validation

The minimum number of pairs needed to validate a WCS solution.

Config file | `.wcs.validate_pairs`
Type | `integer`
Default | `3`

### Scale change per iteration

Maximum scale change accepted when iterating the WCS solution. This is an internal parameter few people (if any) will want to change.

Config file | `.wcs.max_s_chg`
Type | `real`
Default | `0.0200`

### Default image scale

Default image scale used for setting the initial WCS when this information is not available from the frame header. In arc seconds per pixel

Config file | `.wcs.default_scale`
Type | `real`
Default | `1.50`

### Plate Model

Model used for plate to projection plane transformations. Simple consists of translation, scale and rotation; Linear is a general affine transformation, which includes shear; Auto selects a plate model based on the number of star pairs.

Config file | `.wcs.plate_model`
Type | `multiple choice`
Choices | `auto` `simple` `linear`
Default | `auto`

### Calculate Refraction

Enable the calculation of refracted positions of stars. If the time and/or geographical coordinates aren't precise, this option is better turned off.

Config file | `.wcs.refraction`
Type | `boolean`
Default | `no`

# Aperture Photometry Options

### Radius of central aperture

Radius, in pixels, of the central aperture from which the star flux is measured.

Config file | `.aphot.r1`
Type | `real`
Default | `4.0`

### Inner radius of sky annulus

Inner radius, in pixels, of the annulus surrounding the star from which the sky flux is estimated.

Config file | `.aphot.r2`
Type | `real`
Default | `9.0`

### Outer radius of sky annulus

Outer radius, in pixels, of the annulus surrounding the star from which the sky flux is estimated.

Config file | `.aphot.r3`
Type | `real`
Default | `18.0`

### Center apertures

Try to center the measuring aperture on the star before performing the measurement.

Config file | `.aphot.auto_center`
Type | `boolean`
Default | `yes`

### Max centering error

The maximum amount a measuring aperture is moved when auto-centering (in pixels).

Config file | `.aphot.center_err`
Type | `real`
Default | `1.00`

### Discard unlocated standards

When this option is set, standard stars than cannot be located within the specified error radius when centering apertures are not used in the solution.

Config file | `.aphot.discard_unlocated`
Type | `boolean`
Default | `yes`

### Move targets

Update the world coordinates of stars that don't have the Astrometric flag set when their apertures are centered. Useful for moving targets like asteroids or comets or instances where the coordinates of the target are only approximately known.

Config file | `.aphot.move_targets`
Type | `boolean`
Default | `no`

### Max center distance

The maximum distance from the frame center at which a standard star must lie in order to be used in the photometry solution. The distance is expressed relative to half the frame's diagonal. A value of 1 will include all stars. This option is useful when we expect large flat-fielding errors or distorted star images at the frame's corners.

Config file | `.aphot.std_max_distance`
Type | `real`
Default | `1.00`

### Sky method

Method used for sky estimation: Average uses the average of the sky annulus pixels; it's not recommended, as it will not reject nearby stars. Median uses the median of the sky pixels; it's fast and robust, but will not average out quantisation noise. Kappa-Sigma computes the sky value by clipping off pixels too far away from the median, and averaging the rest; the standard deviation of the remaining pixels is calculated, and the clipping/averaging is iterated until values converge; Synthetic mode is calaulated as 3*median - 2*mean, where median and mean are the statistics of the clipped sky annulus.

Config file | `.aphot.sky_method`
Type | `multiple choice`
Choices | `average` `median` `kappa_sigma` `synthetic_mode`
Default | `kappa_sigma`

### Region growing

Amount, in pixels, by which regions containing peaks are grown in order to exclude the tails of spurious stars in the sky aperture. A value larger than 3 is silently clamped at 3. Region growing only applies to the kappa-sigma and synthetic mode sky methods.

Config file | `.aphot.grow`
Type | `integer`
Default | `2`

### Sigmas

Rejection limit of the mean-median, kappa-sigma and synthetic mode sky estimation methods, in sigmas.

Config file | `.aphot.sigmas`
Type | `real`
Default | `3.0`

### Saturation limit

The value over which we mark the stars as being "bright", i.e. possibly saturated.

Config file | `.aphot.sat_limit`
Type | `real`
Default | `48000.000`

### Instrumental band

Name of band the stars are measured into. Used when the frame being reduced does not specify a filter or the Force iband option is set.

Config file | `.aphot.iband`
Type | `string`
Default | `v`

### Force iband

Override the filter specification from the frame header with the one set in the Instrumental band parameter.

Config file | `.aphot.force_iband`
Type | `boolean`
Default | `no`

### Default catalog error

Default standard magnitude error used when a value is not available.

Config file | `.aphot.def_std_err`
Type | `real`
Default | `0.050`

### Alpha

Parameter of the robust fitting alogorithm. It sets the fwhm of the rejection function (in standard deviations).

Config file | `.aphot.alpha`
Type | `real`
Default | `2.000`

### Beta

Parameter of the robust fitting alogorithm. It sets the sharpness of the rejection function, with higher values resulting in a sharper falloff.

Config file | `.aphot.beta`
Type | `real`
Default | `2.000`

# Multi-Frame Photometry Options

### Bands setup

A string which specifies the color indices against which we reduce various bands. It consists of a space-separated list of specifiers of the form: band(b1-b2)[=k/kerr]. In this case, "band" will be reduced against the b1-b2 color index. The optional k and kerr set the default transformation coefficient and it's error for the specified band, like for example v(b-v)=0.06/0.002.

Config file | `.mframe.bands`
Type | `string`
Default | `b(b-v) v(b-v) r(v-r) i(v-i)`

### Outlier threshold

Threshold in standard error over which we flag stars as "outliers" for easy identification. Outliers are not excluded from the fit; they are down-weighted by a factor depending on the values of the alpha and beta robust fit parameters.

Config file | `.mframe.outlier`
Type | `real`
Default | `3.000`

### Zeropoint outlier threshold

Threshold in standard error over which an image frame is marked as an outlier of the extinction fit. The existance of an outlier frame usually shows that transparency has had a significant change around that time. As a result, calculation of all-sky zeropoints is inhibited in the vicinity of an outlier frame, until a well-fitting frame is encountered.

Config file | `.mframe.zp_outlier`
Type | `real`
Default | `2.000`

### Minimum airmass variance

The minimum variance of a data set's airmass for which we try to fit an extinction coefficient. For datasets with lower variance, the extinction coefficient is not considered - which doesn't affect the result, as all frames are taken at nearly the same airmass.

Config file | `.mframe.min_am_variance`
Type | `real`
Default | `0.0010`

### Minimum color variance

The minimum variance of a data set's color index for which we try to fit a transformation coefficient. For datasets with lower variance, the transformation coefficient is not fitted, as the possibility of obtaining a meaningless value is quite real.

Config file | `.mframe.min_color_variance`
Type | `real`
Default | `0.1000`

### Airmass range

Relative size of the range of airmasses over which we calculate frame zeropoints when doing all-sky reduction. It is expressed relative to the airmass range of the valid standard frames. For example, if the standard frames are taken at airmasses between 1.5 and 2.0, an airmass range of 2.0 will enable all-sky zeropoint calculations for frames with airmasses between 1.25 and 2.25.

Config file | `.mframe.airmass_range`
Type | `real`
Default | `2.000`

### Airmass maximum range

The absolute maximum amount we add to or subtract from the standard frames' airmass range when calculating the range in which frames which are reduced all-sky must lie.

Config file | `.mframe.airmass_max_range`
Type | `real`
Default | `0.500`

### Limiting magnitude from zeropoint

The amount we subtract from the zeropoint of a frame in order to obtain the limiting magnitude used for reporting purposes.

Config file | `.mframe.lmag_from_zp`
Type | `real`
Default | `7.000`

# Star Display Options

### Label Target Stars

Show name labels for target stars

Config file | `.display.target_labels`
Type | `boolean`
Default | `yes`

### Label Catalog Objects

Show name labels for catalog objects

Config file | `.display.cat_labels`
Type | `boolean`
Default | `no`

### Label Standard Stars

Show magitude labels (with the decimal point omitted) for standard stars

Config file | `.display.std_labels`
Type | `boolean`
Default | `yes`

### Standard Star Label Band

The band from which the magnitude used for standard star labeling is taken

Config file | `.display.std_label_band`
Type | `string`
Default | `v`

### Minimum star size

The minimum radius of a star symbol on screen, in pixels

Config file | `.display.min_sz`
Type | `integer`
Default | `1`

### Maximum display star size

The maximum radius of a star symbol on screen, in pixels.

Config file | `.display.max_sz`
Type | `integer`
Default | `18`

### Default display star size

The default radius of a star symbol on screen, used when no magnitude information is known; in pixels.

Config file | `.display.default_sz`
Type | `integer`
Default | `6`

### Display pixels per magnitude

The amount the star symbols increase in radius for an increase in brightness of 1 magnitude; in pixels

Config file | `.display.pix_per_mag`
Type | `real`
Default | `1.00`

### Brightest symbol magnitude

The magnitude at which we stop increasing star symbol sizes

Config file | `.display.maxmag`
Type | `real`
Default | `5.0`

### Display limiting magnitude

Magnitude of the faintest displayed objects

Config file | `.display.dlimmag`
Type | `real`
Default | `17.0`

### Show fainter stars

Show stars fainter than the display limiting magnitude (at minimum size)

Config file | `.display.dlimfainter`
Type | `boolean`
Default | `no`

### Zoom star shapes

Scale star shapes when the image is zoomed. Regardless of the value of this parameter, aphot shapes are always zoomed, while blob symbols never are.

Config file | `.display.zoom`
Type | `boolean`
Default | `yes`

### Star shapes zoom limit

The maximum scale factor applied to star shapes. This limit does not apply to aphot shapes.

Config file | `.display.zoom_limit`
Type | `integer`
Default | `4`

### Plot position errors

Draw the amount the apertures were moved from their catalog position when stars are centered.

Config file | `.display.plot_err`
Type | `boolean`
Default | `yes`

### Plot error scale

The amount by which the position errors are multiplied when the position error plot is generated.

Config file | `.display.plot_err_scale`
Type | `real`
Default | `100.0`

## Star Display Colors

### Autodected Stars Color

Config file | `.display.color.simple`
Type | `multiple choice`
Choices | `red` `orange` `yellow` `green` `cyan` `blue` `light_blue` `gray` `white`
Default | `green`

### Field Stars Color

Config file | `.display.color.field`
Type | `multiple choice`
Choices | `red` `orange` `yellow` `green` `cyan` `blue` `light_blue` `gray` `white`
Default | `red`

### Standard Stars Color

Config file | `.display.color.apstd`
Type | `multiple choice`
Choices | `red` `orange` `yellow` `green` `cyan` `blue` `light_blue` `gray` `white`
Default | `red`

### Target Stars Color

Config file | `.display.color.target`
Type | `multiple choice`
Choices | `red` `orange` `yellow` `green` `cyan` `blue` `light_blue` `gray` `white`
Default | `red`

### Catalog Objects Color

Config file | `.display.color.catalog`
Type | `multiple choice`
Choices | `red` `orange` `yellow` `green` `cyan` `blue` `light_blue` `gray` `white`
Default | `yellow`

### User-Marked Stars Color

Config file | `.display.color.usel`
Type | `multiple choice`
Choices | `red` `orange` `yellow` `green` `cyan` `blue` `light_blue` `gray` `white`
Default | `green`

### Align Stars Color

Config file | `.display.color.align`
Type | `multiple choice`
Choices | `red` `orange` `yellow` `green` `cyan` `blue` `light_blue` `gray` `white`
Default | `orange`

### Selected Stars Color

Config file | `.display.color.selected`
Type | `multiple choice`
Choices | `red` `orange` `yellow` `green` `cyan` `blue` `light_blue` `gray` `white`
Default | `white`

## Star Display Shapes

### Autodected Stars Shape

Config file | `.display.shape.simple`
Type | `multiple choice`
Choices | `circle` `square` `blob` `aphot` `diamond` `cross`
Default | `square`

### Field Stars Shape

Config file | `.display.shape.field`
Type | `multiple choice`
Choices | `circle` `square` `blob` `aphot` `diamond` `cross`
Default | `diamond`

### Standard Stars Shape

Config file | `.display.shape.apstd`
Type | `multiple choice`
Choices | `circle` `square` `blob` `aphot` `diamond` `cross`
Default | `aphot`

### Target Stars Shape

Config file | `.display.shape.target`
Type | `multiple choice`
Choices | `circle` `square` `blob` `aphot` `diamond` `cross`
Default | `cross`

### Catalog Objects Shape

Config file | `.display.shape.catalog`
Type | `multiple choice`
Choices | `circle` `square` `blob` `aphot` `diamond` `cross`
Default | `diamond`

### User-Marked Stars Shape

Config file | `.display.shape.usel`
Type | `multiple choice`
Choices | `circle` `square` `blob` `aphot` `diamond` `cross`
Default | `circle`

### Align Stars Shape

Config file | `.display.shape.align`
Type | `multiple choice`
Choices | `circle` `square` `blob` `aphot` `diamond` `cross`
Default | `circle`

# Synthetic Star Generation Options

### Type of star profile

Profile function used to generate synthetic stars.

Config file | `.synth.profile`
Type | `multiple choice`
Choices | `gaussian` `moffat`
Default | `gaussian`

### FWHM

The FWHM of synthetically-generated stars in pixels.

Config file | `.synth.fwhm`
Type | `real`
Default | `2.50`

### Moffat beta

The beta parameter of the Moffat function.

Config file | `.synth.beta`
Type | `real`
Default | `4.00`

### Zero Point

Zero point (magnitude of a star with a total flux of 1) used to scale synthetic stars.

Config file | `.synth.zp`
Type | `real`
Default | `23.00`

### Oversampling

Oversampling factor when generating the reference psf.

Config file | `.synth.oversample`
Type | `integer`
Default | `11`

# On-line Catalogs

### Vizquery command

Config file | `.query.vizquery`
Type | `string`
Default | `vizquery`

### Maximum Catalog Stars

The maximum number of starts the program will download from a field star catalog.

Config file | `.query.maxstars`
Type | `integer`
Default | `5000`

### Maximum Radius for Catalog Stars

The maximum radius from the frame center in which we look for catalog stars. The actual radius depends on the frame size; this is a global limit. In minutes of arc.

Config file | `.query.maxradius`
Type | `real`
Default | `20.0`