# Project settings

This chapeter provides a complete list of project settings and the description of each parameter.

Camera

Camera parameters

- Read noise - readout noise in electrons, you should enter the proper value stated in the camera’s documentation. Default: 15.0

- Gain - number of electrons per ADU, you should enter the proper value stated in the camera’s documentation. Default: 2.3

Source frames

Source frame conversion and processing parameters

- Min. pixel value - lowest value of pixel in ADU. All pixels, which are equal to or less than specified value are considered to be invalid, by default: 0

- Max. pixel value - highest value of pixel in ADU. All pixels, which are equal to or greater than specified value are considered to be overxposed, by default: 65535.

- Image data format - pixel data format in which the working files are stored. If the “Autodetection” is selected, the program keeps the format of original source files. Otherwise, the data are transformed during the Fetch/Convert operation. Default: Autodetection

- Binning - reduction of frame size. When this feature is enabled, the program will sum the pixel values from groups of neighboring pixels making one pixel for each group in the working frame. This transformation is performed in the Fetch/Convert operation. This is useful for processing images from the hi-resolution DSLR and CCD cameras. Please note, that the sum of pixel values are computed (not average), so you when you enable binning, you will probably need to increase the “Max. pixel value”. Default: No binning

- Border - skip invalid parts of the source frames. Set up frame borders to nonzero if you need to remove parts of the frames from the processing. Default: 0

Calibration

Parameters for bias, dark and flat corrections.

- Standard calibration - in the standard calibration scheme, only two correction frames are used - a dark frame, which also includes the bias, and a flat frame. The standard calibration scheme is simpler to follow, but it requires that the dark frame must be of the same exposure duration as source frames.

- Advanced calibration - in the advanced calibration scheme, all three correction frames are applied separately - a bias frame, a dark frame and a flat frame, in that order. The dark frame must not contain a bias, such dark frame is called scalable dark frame, because it need not to be of the same exposure duration as source frames.

Star detection

Parameters for detection of objects on a frame. This step is done during the Photometry operation.

- Filter width (FWHM) - full width at half maximum of the Gaussian filter. The low-pass filter is applied to the source image before searching for local maxima. If profile of objects on frames roughly corresponds to the Gaussian function, the good value for the filter width is the FWHM of objects. You can use the Quick Photometry tool in the Preview window to measure the FWHM of objects. In case the profile of objects is not a Gaussian function and the program splits stars into two or more objects, you need to raise this value. Default: 3.0

- Detection threshold - the level which a brightness enhancement must have above the background level to be considered as a real object. The value is given in standard deviations. The best starting point is the default value 4.0. Process a set of frames and check the results. If you need to detect fainter object, reduce it. If many background artefacts are considered as stars, raise it. Run the photometry again and repeat the steps until the results are satisfactory. Please note, that the filter width also affects the detection capabilities. Default: 4.0

- Minimum and maximum sharpness - minimum and maximum value of sharpness which a brightness enhancement must have to be considered a real object. The main purpose is to eliminate bad pixels, it may also help to eliminate blurred objects such as nebulaes and galaxies. Defaults: 0.2 and 1.0

- Minimum and maximum roundness - minimum and maximum value of roundness which a brightness enhancement must have to be considered a real object. This test is intended to eliminate bad rows and columns, it may also help to eliminate galaxies or cosmic particle traces. Defaults: -1.0 and 1.0

- Max. stars - maximum number of objects. This parameter is used to limit the photometry file to a reasonable number of objects. The stars are sorted by their magnitudes and specified number of stars from the top of the list is preserved, the rest is discarded. Default: 10000

Photometry

Parameters for aperture photometry.

- Aperture - the program computes brightness of stars in all defined apertures. It is possible to define at most 12 apertures. An user can select one of them when making output data, a light curve for example. The aperture is defined by its radius in pixels.

- Inner and outer radius - local background level is measured in an annulus that is centered on the object. These parameters define its inner and outer radius in pixels. Defaults: 20.0 and 30.0.

Matching

Parameters for matching stars.

- Standard algorithm - identifies similar polygons of stars and find the best match. It works well if a source frame is scaled, rotated or even mirrored with respect to the reference frame. The limitation is that it requires at least three stars on a frame.

- Algorithm for sparse fields - this algorithm can match frames which contain at least one star. Scale, tilt and position of a source frame with respect to the reference frame should be close. Otherwise, it leads to a false match.

- Algorithm for dense fields - this algorithm works well on very dense fields containing multitude of objects of similar magnitude, like globular clusters. It is slower that the standard algorithm.

Standard algorithm parameters

- Read stars - if a source or reference file contain more than given number of stars, the program reads only that number of brightest stars. This limit speeds up the computation. Default: 10

- Identification stars - a number of stars that are identified in each iteration. More information is given in the theory of operation. Default: 5

- Clipping factor - tolerance used during the iterative evaluation of the transformation coefficients. Default: 2.5

Parameters of sparse-fields algorithm

- Max. offset - maximum offset between a source frame and a reference frame in pixels. It is intended to eliminate false matches. This parameter should as high as the highest offset of an object of frames, but no higher. Default: 2.0

Parameters of dense-fields algorithm

- Clipping factor - tolerance used during the iterative evaluation of the transformation coefficients. Default: 2.5

Master bias

Parameters for making a master bias frame.

- Output data format - pixel data format in which the master bias frame is stored. If the “Autodetection” is selected, the program keeps the format of working files. Otherwise, the data are transformed into specified format. Default: Autodetection

Master dark

Parameters for making a master dark frame.

- Make scalable dark frame - make a master dark frame that can be scaled to match the exposure duration of a source frame and a dark correction frame (see the advanced calibration scheme for further information). When you check this option, you have to subtract a bias frame from your dark frames before you make a master dark frame.

- Output data format - pixel data format in which the master dark frame is stored. If the “Autodetection” is selected, the program keeps the format of working files. Otherwise, the data are transformed into specified format. Default: Autodetection

Master flat

Parameters for making a master flat frame.

- Output data format - pixel data format in which the master dark frame is stored. If the “Autodetection” is selected, the program keeps the format of working files. Otherwise, the data are transformed into specified format. Default: Autodetection

- Output mean level - the program normalizes the master flat frame so its mean level is equal to a given value. If it is set too high, the output frame has many overexposed pixels. On the other hand, too low value raises the noise when a integer pixel format is used, because pixel values in a frame are rounded to the nearest integer values. Default: 10000

Merge frames

Parameters for frame merging.

- Output data format - pixel data format in which the merged frame is stored. If the “Autodetection” is selected, the program keeps the format of working files. Otherwise, the data are transformed into specified format. Default: Autodetection

Find variables

Parameters for finding new variables.

- Clipping threshold - minimum share of valid brightness measurements that a star must have to be included in the mag-dev graph. This test is intended to eliminate stars that have few valid measurements only and their position in the mag-dev graph more or less random. Default: 60

Observer

Observer’s geographic coordinates.

- Name - any text identifying the observing location, i.e. name of the town

- Longitude - observer’s longitude in degrees. Use the hexagesimal format, separate the fields by a space character. Enter ‘E’ character at the first position in a string to indicate that the location is on the eastern hemisphere or ‘W’ character for locations on a western hemisphere.

- Latitude - observer’s latitude in degrees. Use the hexagesimal format, separate the fields by a space character. Enter ‘N’ character at the first position in s string to indicate that the location is on the north hemisphere or ‘S’ character for locations on a southern hemisphere.

See also

Projects, Profiles, Environment options (dialog), Project settings (dialog), Edit profiles (dialog)