Fig 1.
Flowchart for star selection modes.
The rhombuses represent decisions made by the user.
Fig 2.
Defaults matrices for azimuth and zenith.
a) Shift from north 0°. b) Extreme zenith 100°. c) Shift from north -50°. d) Extreme zenith 80°.
Fig 3.
ORION screenshot of the star identification process in automatic mode under default matrices option.
The chosen star is Capella.
Fig 4.
Relationship between zenith angle and radial distance with polynomial adjustment of degree 2.
Fig 5.
Selected (green dots) and discarded (red dots) points in the image sequence for the Alphecca star.
Fig 6.
Calibration result: a) azimuth matrix, b) zenith matrix, c) ratio of zenith angle to radial distance with polynomial adjustment of degree 2.
Fig 7.
ORION screenshot for checking the calibration feature using the star Alioth.
Fig 8.
Performance of the obtained calibrations matrices for Alioth star positions: a) azimuth obtained with the calibration for the located star position (brightest point) as a function of the real star azimuth; b) zenith obtained with the calibration for the located star position (brightest point) as a function of the real star zenith; c) absolute pixel distance between the star position given by the calibration matrices and the position of the assumed real center of the star in the image (brightest point in a square box defined by the height or width of the sky image) as a function of star azimuth angle (red dotted line represents the mean absolute distance); d) absolute pixel distance between the star position given by the calibration matrices and the position of the assumed real center of the star in the image (brightest point in a square box defined by the height or width of the sky image) as a function of star zenith angle (red dotted line represents the mean absolute distance); e) absolute pixel distance between the star position given by the calibration matrices and the position of the assumed real center of the star in the image (brightest point in a square box defined by the height or width of the sky image) for each available image (red dotted line represents the mean absolute distance).
Table 1.
Calibration check for others stars.