DATA POLICY:
If the Debrecen tilt angle data are used in any publications, please refer to these papers:
Baranyi, T.: 2015, Comparison of Debrecen and Mount Wilson/Kodaikanal sunspot group tilt angles and the Joy's law, MNRAS, 447, (4): 1857-1865, doi:10.1093/mnras/stu2572
Győri, L., Baranyi, T., Ludmány, A., Photospheric data programs at the Debrecen Observatory,Proc. of the Intern. Astron. Union, 6, Symp. S273, 403-407, 2011, DOI: 10.1017/S174392131101564X



FORMAT OF THE DATA

The format is the same as the format of "g" rows in SDD except for the 20 last columns of tilt data. 
The part of tilt data contain 4 sets of 5 columns. The sign convention follows that of the 
Mt Wilson and Kodaikanal tilt datasets: the sign is positive if the leading part is closer to the solar equator.

The first set of the columns of tilt data was computed by using all the spots and their corrected whole spot (U+P) area as weight.
The method of determination of following and leading parts is the same as that of Mt Wilson and Kodaikanal tilt datasets.
It is based exclusively on the geometrical properties of the measured spots. The area-weighted heliographic longitude 
of the sunspots (the longitude of the centroid of the whole group) separates the leading and following parts. 
If there are several umbrae in a common penumbra, at first the area-weighted positions of these 
umbrae are calculated by weighting with the umbral area. In the next iteration, the weight is the common 
penumbral area, and the position used in the second iteration is the position determined in the first iteration. 
The leading (following) portion of a sunspot group defined as the portion located to the west (east) of the area-weighted centroid.
The area-weighted longitudes and latitudes of the leading and following parts are calculated in a similar way.

  The tilt angle is calculated by the following formula (including the deg-rad conversion)

    tilt=ATAN(|Bf-Bl|/|Lf-Ll|/COS(B/360*2*PI))/2/PI*360*SIGN(ABS(Bf)-ABS(Bl))

    Bf, Bl = Area-weighted latitude of the following/leading part
    Lf, Ll = Area-weighted longitude of the following/leading part
    B      = Area-weighted latitude of the whole group


The columns are:
Area-weighted latitude of the sunspots in the following portion
Area-weighted latitude of the sunspots in the leading portion
Area-weighted longitude of the sunspots in the following portion
Area-weighted longitude of the sunspots in the leading portion
Tilt angle (999999 in this column means that there is no data, there was only one spot in the group. 

The second set of tilt data was computed by using only the umbral position and area data as in the case of the Mt Wilson and Kodaikanal tilt datasets.
The method of determination of the (umbral) area-weighted position data as well as the tilt angle data is similar to the method of the first set
but it contains only one iteration.
The columns are:
Area-weighted latitude of the sunspots in the following portion
Area-weighted latitude of the sunspots in the leading portion
Area-weighted longitude of the sunspots in the following portion
Area-weighted longitude of the sunspots in the leading portion
Tilt angle (999999 in this column means that there is no data, there was only one spot in the group. 

The last 10 columns of third and fourth sets are similar to first 10 columns of tilt data but in that case 
we use only the polarity of sunspots to separate to the following or leading portion of the group
independently from the geometrical position of spots.
Since the DPD does not contain polarity data the last 10 columns do not contain information. 
They are only included to keep the SDD tilt data format.