Default Values


  1. The Default values tab is shown below:



  1. It consists of three sections: Observer, Other FITS keywords and Precision:


    1. The Observer section requires your Observer name, your AAVSO obscode1 (leave empty in case you don't want to produce AAVSO reports), your Latitude and Longitude (East is positive) and Elevation. 

      Some of this information may be present as Keywords in the FITS Header of your FITS images. If that's the case, Phoranso will give preference to the Keyword in the FITS Header. This applies to all Default values parameters marked in green color.


Certain software packages adopt an alternative convention for expressing the observer's Longitude, representing East of the meridian as a negative value. If your FITS file originates from such software, check the Flip Longitude sign box. This prompts Phoranso to treat the Longitude value as negative, when East of the meridian. Note that Phoranso does not alter your FITS header, particularly the SITELONG or LONG-OBS keywords. The flip of the Longitude sign occurs in memory. When this option is selected, the flip also applies to the value displayed in the green Longitude text field.

    1. The Other FITS keywords consists of Keywords which are mandatory for Phoranso but which are not always present in a FITS Header.

Image scale is a measure of angular resolution in your image. It tells you how many arc seconds are represented by each pixel in your image. In case you don't know this value for your equipment, you may calculate it using the online CCD Calculators tool. 


The image height value is typically extracted from the FITS header, and denotes the image's height in arc minutes. In scenarios where this extraction isn't feasible, Phoranso resorts to the default value set here. This parameter exclusively serves the ASTAP solver.

BSCALE represents the scale factor to be applied to pixel values to convert them to physical units. Use 1 if you don't know the value for your equipment. The pixel conversion to physical units is done using the formula P = BZERO + BSCALE * V, where:

        • V is the pixel value, 
        • P is the physical value
        • BZERO is an additive offset used to shift pixel values. It  is added to the scaled value (BSCALE * V)


EGAIN is the electronic gain factor of your CCD or CMOS camera. It represents the amplification applied to the signal generated by the CCD or CMOS sensor, before it is digitized and stored as pixel value in the image data. It is specific to each CCD or CMOS camera model and included in the specifications of your camera. This factor is usually included as a Keyword in the FITS Header of your image. If not, Phoranso uses the value supplied in this dialog box. 

FILTER refers to the optical filter used when capturing your FITS image. Phoranso typically reads the FILTER value from the FITS header. If this value is missing or no filter was used during imaging, enter C or Clear in this field. Be sure to enter the same value in the FILTER mapping table found in the Settings window under the Photometry menu.

    1. The Precision section allows to specify the number of decimal places to be used for representing time and magnitude values in Phoranso.


  1. Each time you modify one of the Phoranso settings, the new Settings value is automatically saved to the active Settings file. 

    You may also decide to manually save your Settings to a file, using Save settings. This allows you to create multiple Settings files each containing different Settings values.  

    Load settings will fill the contents of the Settings dialog box with the values from your selected Settings file.



(1) AAVSO obscode is the official AAVSO Observer Code which is assigned by the AAVSO. It uniquely identifies an observer and is mandatory to submit reports to the AAVSO.