Solar Coordinates of Observed Sun Spots

1. Equipment
2. Procedure
3. Analysis
4. Measurements
5. Forms and Java Script Program

• Equipment for drawing position of Sunspots

  

  • Telescope or 1/2 of Binocular on a steady mounting
    (mask off the finder or other part of the binocular so no sunlight passes through it)
  • Stiff board (with steady stand) on which to mount the drawing paper
  • Drawing paper with a circle and its center predrawn on it.
  • Shade around the telescope so the paper does not get Sun
  • Pencil for sketching Sunspots, tape to attach the paper to the drawing board
  
  
  

• Procedure for drawing sunspots

  • DO NOT LOOK THROUGH THE TELESCOPE AT THE SUN and DO NOT EVER LOOK AT THE SUN DIRECTLY
  • Set up the telescope so that it is pointing directly at the Sun (Use the shadow of the telescope tube to align the telescope)
  Mount the drawing board with paper so the eyepiece will project the Sun onto the paper
  • Focus the eyepiece so that the image of the Sun is in focus on the paper
  • Alternately move the board and focus the eyepiece so that the Sun's image fits the pre-drawn circle on the paper.
  • Sketch the position of each Sunspot quickly when the Sun's Image and circle on the paper are coincident.
  • Reposition the telescope and board to align the image and circle for each Sunspot position.
  • Use one of the brighter Sunspots and follow it as the image of the Sun drift off the circle - keep marking the Sunspots location on the paper so as to indicate the direction of the diurnal motion. (this is done to get the East-West direction - see the diagram below)
  
  

• Graphical Analysis of Sunspot Position

  
  • On the drawing put a straight line through the series of marks showing the direction of the image drift
  • Mark WEST at the end of the direction of drift
  • Draw a line throught the center of the circle parallel to the direction of dirft
  • Construct another line perpedicular to the previous line through the center of circle
  • Mark NORTH at the end of the perpendicular
    If you have an astronomical telescope with no erecting or right angle prism, the image of the Sun will be inverted and north will 90^o clockwize from west on the drawing.
    This will make the image a reflection of the real Sun
    (The north side of the Sun can be determined by moving the telescope northward during the drawing process and observing the pole that is exposed)
  • You now have the coordinate axes that will be used to measure the position of the sunspot
  
  

• Calculation of Sunspot Coordinates

  
  • Measure the radius of the circle representing the radius of the image of the Sun (see the above diagram)
  • For each sunspot of interest measure
    1. the distance from the center, r
    2. position angle, pa, of the radius line from North.
       The position angle should be measured as positive in the direction for North to East.
  • Enter the Date and Time into the form below
  • Calculate the Sun's Orientation (this can be done without any sunspot measurements)
    The values of the parameters B_o, P, L_o depend only on the date and time.
    The Carrington Number gives the number of rotations (#1 was on November 8, 1853)
  • Enter the radius of the Solar Image circle in the form
  • Enter the coordinates of each Sunspot into the form (6 available)
  • Click Calculate to determine the latitude and longitude of each sunspot

Java Script Calculation of the Solar Orientation Angles
and Solar Latitudes and Longitudes of a Sun Spots