{'fraction_non_alphanumeric': 0.03338799606428337, 'fraction_numerical': 0.025122991144637587, 'mean_word_length': 4.578485181119649, 'pattern_counts': {'":': 0, '<': 0, '<?xml version=': 0, '>': 0, 'https://': 0, 'lorem ipsum': 0, 'www.': 0, 'xml': 0}, 'pii_count': 0, 'substrings_counts': 0, 'word_list_counts': {'cursed_substrings.json': 0, 'profanity_word_list.json': 0, 'sexual_word_list.json': 0, 'zh_pornsignals.json': 0}}
A Sunspot Catalog for the Period 1952-1986 from Observations Made at the Madrid Astronomical Observatory

Sunspot catalogs are very useful for studying the solar activity of the recent past. In this context, a catalog covering more than three solar cycles made by the astronomers of the Madrid Astronomical Observatory in Spain (nowadays, the National Astronomical Observatory) from 1952 until 1986 has been recovered. Moreover, a machine-readable version of this catalog has been made available. We have recovered abundant metadata and studied the reliability of this dataset by comparing it with other sunspot catalogs.


Introduction
Traditional indices for long-term studies on solar activity, i.e., sunspot number, group number and sunspot area, describe the general state of the Sun (Hoyt and Schatten, 1998;Balmaceda et al., 2009;Clette et al., 2014;Hathaway, 2015;Carrasco et al., 2016;Muñoz-Jaramillo and Vaquero, 2018). On the other hand, for studies that require a more detailed approach, sunspot catalogs are a more appropriate tool. They offer data about positions, areas and types of groups and spots, which makes it possible to track the evolution of these structures during their way across the solar disk Carrasco et al., 2014). However, each catalog has its own time coverage, contents and format. In order to expand the time coverage, fill gaps, correct mistakes and have a homogeneous source of data, the availability and merging of multiple sunspot catalogs is needed (Lefèvre and Clette, 2014;Carrasco et al., 2015).
In recent years, an effort has been made to retrieve solar data from different observatories around the world including Coimbra (Carrasco et al., 2018), Ebro (Curto et al., 2016), Greenwich (Willis, Wild, and Warburton, 2016), Locarno (Cortesi et al., 2016), Kodaikanal (Mandal et al. 2017) and Valencia . In the context of this collective effort, different datasets preserved in several libraries and archives related to the solar and magnetic observations made at the Madrid Observatory during more than one century are being digitalized and analyzed.
In particular, an observational program devoted to sunspots was carried out at the Madrid Astronomical Observatory from 1876 to 1986. A lot of metadata about this solar program can be found in López Arroyo (2004) and Aparicio et al. (2014). The first observations started in 1868, although the program was not implemented on a systematic basis until 1876. In 1986, the program ended and, as a result, there are sunspot counting and sunspot area records for the periods 1876-1896, 1906-1920, 1931-1933 and 1935-1986, which were digitized, analyzed and made available by Aparicio et al. (2014). In addition, there are sunspot catalogs for the periods 1914-1920 and 1952-1986. The former catalog (Aguilar's catalog) was digitized, analyzed and made available by Lefèvre et al. (2016), and the same task is performed for the latter catalog ("modern" catalog) in the present article.
Moreover, the astronomers of Madrid developed a program to calculate the solar constant using pyrheliometers (Antón, Vaquero, and Aparicio, 2014; A Sunspot Catalog from the Madrid Astronomical Observatory 3 2019), and, very recently, the geomagnetic measurements made in this observatory during the 19th century have been recovered and analyzed (Pro, Vaquero, and Merino-Pizarro, 2018). This article continues with this process of data recovery from one of the oldest scientific institutions in Spain. In the next sections, the "modern" sunspot catalog of Madrid Observatory (from 1952 to 1986) is recovered and analyzed.

Structure of the Catalogs
The "modern" catalog was published in an internal journal of the observatory called Boletín Astronómico del Observatorio de Madrid (BAOM). Issues were published quasi-annually containing mainly information about astronomical observations made in this observatory. One of the sections is devoted to solar activity. In there, depending on the year, there are different sub-sections with data about daily sunspot numbers and group counting (recovered by Aparicio et al., 2014), the sunspot catalog described in this work, protuberances, filaments and chromospheric faculae, among others.
Each sub-section devoted to the modern sunspot catalog contains metadata (explanation about instruments, observers, methodology and data) and one year of the catalog organized in two tables. The first one contains daily data about positions and areas of sunspot groups (main catalog), and the second one contains the Waldmeier classification for each group (catalog with Zurich types). The main catalog is sorted by date and spans the period 1952-1986, whereas the catalog with Zurich types is sorted by numbering of the groups and only spans the period 1952-1956.
The solar observations were performed with a Grubb telescope (20 cm aperture and 3 m focal length) and a Herschel helioscope eyepiece. As a result, 25 cm diameter images were projected onto a screen. Then, the sunspots were drawn on templates.
The data to elaborate the original catalog were obtained from those drawings. iii) Solar rotation number and day. iv) Number of the group. The first group observed is assigned number 1. The numbers are kept from one day to the next one, but the count starts from 1 every year.

v)
Heliographic longitude in degrees.
vi) Heliographic latitude in degrees.
vii) Projected area in millionths of the solar disk (msd) divided by 2.
viii) Area corrected for foreshortening in millionths of the solar hemisphere (msh).
ix) Total sunspot area for the day (corrected for foreshortening).
x) Notes: the way the groups disappear.
The columns in the Zurich types catalog are: i) Number of the group. iii) Date when the group was recorded for the first time.
iv) Date when the group was recorded for the last time.
v) Number of days with records of the group.
vi) Evolution of the group (Waldmeier classification).
vii) Sunspot area and date when the group reaches its maximum size.
In relation to the author of the catalog, some aspects have to be taken into account. On the one hand, there were a lot of observers who made the drawings to elaborate both sub-sections, the one with data about daily sunspot numbers and group counting (recovered by Aparicio et al., 2014), and the other one with the modern sunspot catalog. On the other hand, the main observer of each year used to draw up the sunspot catalog. Table 1 lists the names of observers and authors of the catalog.
where SA(msh) is the sunspot area in msh, SA(mm 2 ) is the sunspot area in mm 2 , SA(msd) is the sunspot area in msd, r is the distance from the center of the group to the center of the disk, and R is the radius of the image (12.5 cm). We found that Equation 1 does not work properly (even supposing that the units of measurement in column 7 could be larger or smaller than mm 2 ). However, Equation 2 does by taking column 7 as SA(msd)/2 (not as SA(msd)) and column 8 as SA(msh).
This can easily be confirmed by comparing the data with another available source for group areas. The Greenwich catalog (often called RGO catalog) contains areas in msd and in msh, and we can actually match day by day the different groups of both catalogs (see Figure 2). This comparison will be explained in depth in Section 4. Here we show only the relevant information.

Errors in the Catalog
There are different ways to check for inconsistencies in the catalog. They depend on what kind of information is available. In this case, we have heliographic latitude and longitude as well as two types of areas for the individual groups (columns 7 and 8, see Section 2), and the total area of the groups observed on one day. This gives us mainly three possible checks:

i) Compute SA(msh) from SA(msd) and vice versa (by means of Equation 2)
and compare to the actual values in the catalog.
ii) Compute the longitude from central meridian (LCM = L -L 0 ) from the heliographic longitude (L) and L 0 (input is the date). If LCM is not in the right range, then, most probably the longitude had an error.
iii) Compute the total daily area from the group areas.
Once we have computed these values, and detected a possible mismatch/problem, we have to check the origin. Some errors are the consequence of an error in another parameter/column. For example, if the longitude value is corrupted, the computation of the corrected area is affected. So i) or iii) might be the consequence of ii).
If the errors were due to a mistake during the digitization process, i.e. did not appear in the paper catalog, they were corrected straight away. If however, they appear in the same way in the original paper catalog, we can only use our best guess to correct the mistake. So we propose two versions of the catalog with flags: i) the original catalog with flags, and ii) the version where we propose corrections for the detected errors that are not due to faulty digitization. A description of the flags can be found in Table   3. Of course, we can use comparison catalogs to detect errors or especially infer corrections for these errors. This is done is Section 4. The resulting correction propositions are a result of intra and inter comparison between available and overlapping sunspot catalogs.

Comparison with Other Sources
We can compare the Madrid catalog with information from other overlapping sunspot catalogs. The Debrecen catalog could be used, but considering the very limited overlap (DPD starts in 1974), and the fact that RGO should be limited to 1976, it has not been done here. We use the USET catalog (1940-now) and the RGO catalog (1876-1976/1986). Because of the differences in areas in RGO before and after 1976, we cut the RGO analysis in two parts around 1976.

Comparison with the USET Catalog
The USET catalog contains information on the groups of spots from March of 1940 to the present. The main features of this catalog are listed in Table 4. The association process used in the present work to match groups from one catalog to another is described in Lefèvre et al. (2016). The groups in the Madrid catalog are compared to all the groups in the USET catalog. For a certain group in the Madrid catalog, the closest group (in the USET catalog) that is less than one day apart is taken, as long as the group meets a consistent distance criterion based on a preliminary distance analysis. Figure 3 shows a typical comparison of groups on the Sun's surface between the USET and Madrid catalogs. The distribution of the distance between matched groups is presented in Figure 4 with the same computation scheme that was applied in Lefèvre et al. (2016). From these two figures, it can be seen that the association process works properly. In addition, Figure 3 suggests that the USET catalog detects more groups than the Madrid one. In fact, if we compute for each day the difference between the number of groups reported in each catalog, it is interesting to note that there is this bias towards USET. 467 days show the Madrid catalog contains more groups than the USET one, 2300 days show the opposite, while 2048 days show an identical number of groups in both catalogs. With respect to the groups areas, the computation is in progress at USET, within the context of a Belgian project, but is not advanced enough to be used at this time (it should be completed and quality analyzed by the end of 2021). However, we can use the Zurich types from the USET catalog and compare them to the types from the Madrid catalog.  Figure 5 shows that we are mostly close to a one-to-one correspondence. However, the A, J or C, G and H types are less easy to classify here. For example, an H type group in the Madrid catalog corresponds to an H type group in the USET catalog, but also to a C-type group. As was mentioned in Lefèvre, Clette, and Baranyi (2011), the C-type classification suffers from a lack of determination making it sort of a "throwin-everything" class, which could explain this behavior. Other examples of classification problems are A and J classes in both catalogs. As it is easy to confuse one with the other without evolution information, this is a classical misclassification and easily explains the mismatch between two catalogs. It is also interesting to note that the Madrid catalog contains very few B-types and that what would be called a Btype group in USET is often classified as A in Madrid. This shows the bias this classification can suffer from between different sources/observers.

Comparison with the Royal Greenwich Observatory Catalog (RGO)
A description of the RGO catalog can be found in Willis et al. (2013a,b). Data about sunspot groups from 1874 to 1982 are listed in this catalog. Nevertheless, after 1976 parameters are not consistent with the previous ones since they were obtained from the Boulder Solar Region Summary on a daily basis (Hathaway, 2015). As noted by this author, areas in RGO are 40 % smaller starting in 1977. The association process used here have been the same as in the previous subsection. Figure 6 shows a typical comparison of groups on the Sun's surface between the RGO A.J.P. Aparicio et al. 14 and Madrid catalogs, while Figure 7 shows the distribution of the distance between matched groups with the same computation scheme as in Figure 4.   register minimum areas of 1 msh, neither the RGO nor the Madrid catalog is complete below 5 msh (however, the RGO catalog is more complete that its Spanish counterpart).
Lastly, a comparison of the total sunspot area from the two observatories can be found in Aparicio et al. (2014). That work provides sunspot number, group sunspot number and sunspot areas of the Madrid Astronomical Observatory for the period 1876-1986.
The series of sunspot areas for the period 1952-1986 was extracted from the catalog we present in this article. That series was compared to the Balmaceda composite (Balmaceda et al., 2009), which, for the study period , mostly comes from RGO, and the rest is calibrated from it.

Group Number Comparisons
As it was mentioned in the previous subsection, Aparicio et al. (2014)    Note in Figure 9 that in 1960, there seems to be a slight difference noticeable in the monthly and yearly values, but it is not significant.

Conclusions
In recent years, several sunspot catalogs have been recovered from archives and libraries of astronomical observatories with a long tradition observing the Sun. Lefevre and Clette (2014) highlighted the need to recover these catalogs and make inter-comparisons between them. The redundancy of data allows us to correct errors and to provide an accurate image of the behavior of sunspots during the last 150 years. In this work, an interesting catalog covering more than three solar cycles made by the personnel of the Madrid Observatory in Spain from 1952 until 1986 has been recovered. A machine-readable version of this catalog is available at HASO website. The comparisons made here between catalogs show the reliability of the data of the "modern" catalog of Madrid. No significant changes of non-solar origin have been detected in these data. In addition, we have abundant metadata, including the name of the observer for each record (a data often difficult to obtain in other catalogs made by several observers).