Radio Eyes Help
There are many things to learn about the main window of the program. Of primary importance is the menu bar across the top of the window. This is your primary access point to the many features of the program. The menu items File, View, Observer, etc are treated separately in the help pages. Here we will concentrate on other aspects of the main window.
Most obvious is the Sky Map. When the program loads this is an equatorial rectangular map is of the full sky. At the top of the map is the north celestial pole. Because of the projection used this single point is stretched all of the way across the top of the image. The same is true for the southern celestial pole at the bottom of the map. This projection is not one that optical observers would not find "user friendly" as it does not appear to the eye, however, the map projection is quite useful for our purposes. A secondary "Dome View" is available to help you see better how the sky would appear to the eye. The full view map has declination 90 degrees at the top and declination -90 degrees at the bottom. 24 Hours of Right Ascension (RA) are displayed horizontally.
The background displayed by default is a color representation of 408 MHz sky. The bright regions on the background are primarily the emissions of the our own galaxy. Other backgrounds may be loaded. This topic is covered separately in the help pages. By default the image is centered on your local meridian, a line running across the sky from North to South at your location. The meridian line is optionally displayed. Because many radio astronomy observations are made along the meridian, it is a useful point of reference. With time the background and objects of the display will move from left to right.
In the picture above, you will see a yellow line (composed of dots) that dips to the center of the image. This is the Horizon Line and represents the local horizon of the observer. For an observer in the southern hemisphere this line would be highest at the top of the map. With a little practice you will quickly be able to determine which part of the map is above your local horizon and which part is below. If in doubt, move the mouse cursor to a point on the map. What does the Altitude box at the bottom of the screen say? If the altitude is negative then the mouse cursor is in a region of the map that is below your local horizon. By default the horizon is simply 0 degrees of elevation, however, you can define a horizon that takes into account hills, buildings, etc. that truly determine visibility from your location.
At the upper left you see a clock/calendar and buttons labeled Real Time and UT. These are your primary time controls and display. To switch between Universal Time and Local Time displays click the UT button. You can display the sky for times other than the present or freeze the automatic updating of the screen by pressing the Real Time button. When pressed the Real Time button changes to Fixed Time.. meaning time that does not move. When you are in Fixed Time mode you can type in new times / dates into time /date display or select new dates from the drop down calendar that this display provides when you click its down arrow on the right side of the date / time display. When making a change in fixed time mode you will see a Update button with a clock face just to the right of the date / time display bar. You must click this Update button to apply your new time and date that you have selected!
In addition to the Local or UT time you can read the Local Mean Sidereal Time (LMST) in the box at the bottom of the main window. The LMST changes at a rate about 4 minutes per day faster than UT and is keyed to the value of right ascension (RA) that occurs along your meridian.
Additional displays at the bottom of the window include, the RA (right ascension), Declination, Altitude, Azimuth, and Transits In / At boxes. In normal mode the values displayed in these boxes will be keyed to the last detected position of the pointer on the screen, but they can also refer to specific points in other display modes. A label above these boxes indicates what the boxes reference.
The Transits In / At box has two display modes. In Transits In mode the box tells you how much time will elapse before the referenced point will cross your meridian. In Transits At mode the box displays at what time the referenced point will next cross the meridian. You may switch between these modes by selecting the appropriate option under the Options menu item at the top of the window. These times are important because the meridian is the line along which many radio astronomy observations are made using a mode called "meridian drift scan" where the object is allowed to drift through the beam of the antenna as the Earth rotates.
The box labeled T Kelvins at the window bottom displays values referenced in the background file's FITs table, if these values are available. For the 408 MHz background the values are in equivalent temperature in degrees Kelvin, a measurement often used in radio astronomy to indicate intensity. The values could be different for other backgrounds that measure different things. Background files are covered in more detail elsewhere in the help pages.
A general purpose status display appears at the bottom right of the main window. Above it are quick labels which indicate files being used.
Specific Menu Items
Learn about the specific drop down menu item options by clicking the corresponding link below:
Objects on the Sky Map
Sky map objects include catalog radio sources, pulsars, labels, grid lines, the Sun, etc. Click here for an additional help page that leads to descriptions of the many objects that can appear on the sky map.
Navigating Around the Sky Map.
The sky map can zoom in on area, scroll, and resize in many ways. You can center on specific objects or reference points. Click here for more information about moving around the sky map.
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