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 overhead position of the Sun, Moon and selected star can be displayed on the Map Feature.
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.
Pressing this button displays a settings dialog, that allows you to set:
* The epoch used when entering RA and Dec. This can be either J2000 (which is used for most catalogues) or JNOW which is the current date and time.
* The units used for the display of the calculated azimuth and elevation. This can be either degrees, minutes and seconds or decimal degrees.
* Whether to correct for atmospheric refaction. 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.
* Air pressure in millibars for use in refraction correction.
* Air temperature in degrees Celsius for use in refraction correction.
* Relative humidity in % for use in refraction correction.
* Height above sea level in metres for use in refraction correction.
* Temperature lapse rate in Kelvin per kilometer 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 Learnmonth data can be linearly interpolated to the observation frequency set in the main window.
* The units to display the solar flux in, either Solar Flux Units, Jansky or Wm^-2Hz-1. 1 sfu equals 10,000 Jansky or 10^-22 Wm^-2Hz-1.
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).
* 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, 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, 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.
In order to assit 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 grahp title will indicate the object is not visible on that particular date.
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.
When using the Find feature in the Map GUI, you can search for "Sun", "Moon" or "Star".
<h2>Stellarium Interface</h2>
In Star Tracker:
* Set target to Custom
* Press Show settings dialog and ensure Stellarium server is checked
* Press Start
Then in Stellarium:
* Enable Telescope Control plugin and restart
* Press the telescope button in the main toolbar
* Press "Configure telescopes..."
* Press "Add a new telescope"
* Set "Telescope controlled by" to "External softare or a remote computer"
* Set "Name" to "SDRangel" (Optional)
* Set "Coordinate system" to "J2000 (default)"
* Press OK
* Press Connect
* 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/solarflux/sx-4-en.php
Salar radio flux mesaurements 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