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Sky Charts 


Planetary observation : 

Moon+Venus+Jupiter conjunction  April 23 1998 

  • To avoid unnecessary screen refreshing on a slow computer, you can first disable the automatic screen update by a right mouse click to "Immediate update"  and select "Differed update". 
  • Click "Catalog parameters"  then  "Planets" page. 
    • Check the "show planets" box. 
    • Select topocentric coordinates (very important for Moon position). 
    • Select appearance "According to the size and the magnitude". 
    • Deselect "Show stars behind the planets".
    • Click "OK". 
  • Click  "Date / Time". 
    • Deselect "Use system time". 
    • Enter time offset "Time = UTC + 2" (April 23 is during European summer time ). 
    • Enter Date "1998 - 04 - 23" (ISO format) and Time "06 00". 
    • In "Simulation", enter "No. of runs 5", "Step 1", select unit  "hours". 
    • Click "OK". 
  • Click "Find"  
    • Select "Planets". 
    • Select "Jupiter". 
    • Click "OK". 
  • Click "Field width"  
    • Drag cursor to "+06° 0' ". 
    • Click "OK". 
  • If you have disabled the automatic screen update, click now  "Immediate update"  and select "Immediate update". 
The following screen will be displayed,( depending on the star catalog selected - Tycho in this case) 

Click on image for full resolution

You can change some display variables like coordinate grids, or zoom Venus and Jupiter to show their real diameters instead of their magnitudes. 

You may also change the observatory location ( "Observatory" ) to show the effect of the Moons parallax.

To see if this conjunction was visible from your location, first set your observatory coordinates and the local time if outside Europe. Then click  "Horizon chart" 

Click on image for full resolution

From Geneva, Jupiter was only eight degrees above the horizon. The same operation on the Sun shows it to be six degrees below the horizon in civil twilight 

You can also obtain this information directly from the main chart. Click "Tools"  then "Identification".."Long" or press "Alt" key when selecting the object. We obtain the following screen instead of the status bar information. It shows the azimuth and elevation bearings as well as the rise,transit and set times (only for the position corresponding to the first time step).