The Star Tracker feature plugin is for use in radio astronomy and EME (Earth-Moon-Earth) communication.
It calculates the azimuth and elevation of celestial objects and can send them to the Rotator Controller or other plugins to point an antenna at that object.
The plugin can communicate with Stellarium, allowing Stellarium to control SDRangel as though it was a telescope and for the direction the antenna is pointing to be displayed in Stellarium.
* Whether to correct for atmospheric refraction. You can choose either no correction, the Saemundsson algorithm, typically used for optical astronomy or the more accurate Positional Astronomy Library calculation, which can be used for >250MHz radio frequencies or light. Note that there is only a very minor difference between the two.
* Temperature lapse rate in Kelvin per kilometre for use in refraction correction.
* What data to display for the Solar flux measurement. Data can be selected from 2800 from DRAO or a number of different frequencies from Learmonth. Also, the Learmonth data can be linearly interpolated to the observation frequency set in the main window.
Select the date and time at which the position of the target should be calculated. Select either Now, for the current time, or Custom to manually enter a date and time.
Displays the Solar flux density. The observatory where the data is sourced from, frequency and units can be set in the Settings dialog (5). The field is updated every 24 hours, or can be manually by pressing the download Solar flux density data button (3).
To manually enter RA (right ascension) and Dec (declination) of an unlisted target, select Custom RA/Dec.
To allow Stellarium to set the RA and Dec, select Custom RA/Dec, and ensure the Stellarium Server option is checked in the Star Tracker Settings dialog.
* Cassiopeia A, Cygnus A, Taurus A, and Virgo A at ultra-low radio frequencies - https://research.chalmers.se/publication/516438/file/516438_Fulltext.pdf
When target is set to Custom RA/Dec, you can specify the right ascension in hours of the target object. This can be specified as a decimal (E.g. 12.23, from 0 to 24) or in hours, minutes and seconds (E.g. 12h05m10.2s or 12 05 10.2). Whether the epoch is J2000 or JNOW can be set in the Star Tracker Settings dialog.
When target is set to Custom Az/El, this will display the corresponding right ascension.
When target is set to Custom RA/Dec, you can specify the declination in degrees of the target object. This can be specified as a decimal (E.g. 34.6, from -90.0 to 90.0) or in degrees, minutes and seconds (E.g. 34d12m5.6s, 34d12'5.6" 34 12 5.6). Whether the epoch is J2000 or JNOW can be set in the Star Tracker Settings dialog.
When target is set to Custom Az/El, this will display the corresponding declination.
When target is set to Custom Az/El, you specify the azimuth in degrees of the target object. The corresponding RA/Dec will be calculated and displayed.
For all other target settings, this displays the calculated azimuth (angle in degrees, clockwise from North) to the object.
When target is set to Custom Az/El, you specify the elevation in degrees of the target object. The corresponding RA/Dec will be calculated and displayed.
For all other target settings, this displays the calculated elevation (angle in degrees - 0 to horizon and 90 to zenith) to the object.
 
In order to assist in determining whether and when observations of the target object may be possible, an elevation vs time plot is drawn for the 24 hours encompassing the selected date and time.
Some objects may not be visible from a particular latitude for the specified time, in which case, the graph title will indicate the object is not visible on that particular date.
The Solar flux vs frequency plot, shows the solar flux density data from the Learmonth observatory as a function of frequency. The measurements are made at 245, 410, 610, 1415, 2695, 4995, 8800 and 15400MHz.
When the target (11) is set to Custom Az/El and the Sky temperature plot is displayed, a curve showing the drift scan path over a 24 hour period will be displayed.
To setup a drift scan through a particular target object, first set the target (11) to that object. This will set the azimuth and elevation to point at the object.
You may want to set the Time (8) to Custom and a few hours in the future, so that the elevation is at a maximum when pointing at the target.
Then switch the target to Custom Az/El and Time back to Now, and the drift scan path that sweeps through the object will displayed.
The Star Tracker feature can send the overhead position of the Sun, Moon and target Star to the Map. These can be enabled individually in the settings dialog. The Moon should be displayed with an approximate phase. Stars (or galaxies) are displayed as an image of a pulsar.
* Enter Right Ascension/Declination or press "Current object" to get RA/Dec of currently selected object
* Press "Slew" to send the RA/Dec to Star Tracker
Star Tracker will continually send the RA/Dec of its target to Stellarium and this should be displayed in Stellarium with a crosshair/reticle and the label SDRangel (or whatever name you entered for the telescope).
To see the rough field of view of your antenna, open the Ocular configuration window and under Eyepieces, add a new eyepiece with name SDRangel.
Set aFOV to the half-power beam width of your antenna, focal length to 100 and field stop to 0.
Then select the SDRangel telescope reticle and press Ocular view.
Solar radio flux measurement at 10.7cm/2800MHz is from National Research Council Canada and Natural Resources Canada: https://www.spaceweather.gc.ca/forecast-prevision/solar-solaire/solarflux/sx-4-en.php
Solar radio flux measurements at 245, 410, 610, 1415, 2695, 4995, 8800 and 15400MHz from the Learmonth Observatory: http://www.sws.bom.gov.au/World_Data_Centre/1/10
150MHz (Landecker and Wielebinski) and 1420MHz (Stockert and Villa-Elisa) All Sky images from MPIfR's (Max-Planck-Institut Fur Radioastronomie) Survey Sampler: https://www3.mpifr-bonn.mpg.de/survey.html
408MHz (Haslam) destriped (Platania) All Sky image and spectral index (Platania) from Strasbourg astronomical Data Center: http://cdsarc.u-strasbg.fr/viz-bin/cat/J/A+A/410/847
This uses a gnomonic projection. To change to cylindrical/plate carree, with the centre of the galaxy at the centre of the image, edit header.hdr to have:
CTYPE1 = 'GLON-CAR'
CTYPE2 = 'GLAT-CAR'
CRVAL1 = 0
CRVAL2 = 0
Then convert with:
mProjectQL source.fits dest.fits header.hdr
FITS files can be scaled (Scale > ZScale) and exported to .png with SAOImageDS9: https://sites.google.com/cfa.harvard.edu/saoimageds9
