Methodes of Sunspot Registration

1. The INTER-SOL INDEX is defined as:
   
   IS = gr + grfp + grf + efp + ef

2. 
   

   IS	- INTER-SOL INDEX
   gr	- number of spot groups (consisting of two or more spots)
   grfp	- number of penumbral spots belonging to a group
   grf	- number of spots without penumbra belonging to a group
   efp	- number of single penumbral spots not belonging to any group
   ef	- number of single spots without penumbra not belonging to any group

   Check formula:   (grfp + grf) : gr >= 2
   

3. Contrary to the common determination "R" (SIDC Brussels) single spots (efp and ef ) are not (!) classified as groups (gr).

4. Each umbra within one penumbra is to be counted as grfp.

5. For classifying the different phenomena please use Waldmeier's schedule.

6. Pores are not registered as a spot.

7. If the telescope is smaller than ø100 mm (4 inch) we advise the direct view through filter glasses, because the method of projecting the Sun's picture onto a screen sometimes weakens the contrast.

8. Several observations on the same day or with different telescopes must be registered on separate protocol sheets.

9. Time of observation is UTC (Greenwich time).

10. Observing conditions ("Cond.") are defined as follows:
    
    

    1	very good	picture very contrasty and clear, granulation visible.
    2	good	Sun's limb or spots in slight motion, granulation visible only from time to time.
    3	satisfactory	Sun's limb or spots in moderate motion, granulation invisible.
    4	weak	Sun's limb fluttering, close spots hardly to be resolved.
    5	poor	Sun's limb is strong ebullition, detailed observations almost impossible.

11. In order to evaluate the data as soon as possible, monthly protocols have to arrive at the Paderborn observatory within three weeks after the end of a month. We accept data sent by postal mail, facsimile or by e-mail in a special format.
    
    Volkssternwarte Paderborn e.V., Postfach 1142, D-33041 Paderborn, Germany
    Fax: +49 (0)5254-932043   /   E-Mail: data@inter-sol.org
    
    For observers sending in their monthly reports by e-mail, a special e-mail protocol including detiled instructions my be downloaded from the service section of our web site. If you have any further questions please send an support@inter-sol.org to INTER-SOL.

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12. All incoming protocols are evaluated at the Paderborn Observatory, computing daily and monthly means.

13. Various telescope sizes are valued by f_i (multiplicating factor of instrument):
    
    f_i = aperture (mm) : 60mm (amateur standard refractor)

14. Observing conditions are considered by f_c (multiplicating factor of conditions):

    Conditions	1	2	3	4	5
    fc	2	1.5	1	0.5	0.1

15. n is the sum of all respected observations.

    n’ = n × f_i × f_c
    

16. The differences of the monthly means are smoothed by terms of three months:
    

    e.g.:	January:	IS=80
    	February:	IS=75
    	March:	IS=40

    Smoothed number of February:  IS' = (80+75+40) : 3 = 65

    So the final INTER-SOL INDEX is:

    IS' = gr' + grfp' + grf' + efp' + ef'

17. The monthly IS-Report is published on the internet at http://data.inter-sol.org ("members only" data section).
    Additionally, an annual printed summary of the data is send to all observers.

Please note: Our observers have to take care of paragraphs 1.-11. only.

Download IS-Documentation ISPINFOE.PDF (329 KB)