Due to the fascination for night sky and celestial phenomena, the human being has been recording events like these since ancient times. Over time, recording such astronomical information has been an essential and helpful task (Accomazzi, 2010). Thus, one of the most remarkable examples of the importance of recording this information is the publication of Kepler’s laws, whose discovery was possible thanks to the observations recorded by Tycho Brahe in his famous star catalogue (Lachièze-Rey and Luminet, 2001).


Different documents reflecting the state of the night sky have appeared throughout history. The most famous ones are known as “celestial charts”, often collected in “celestial atlases” (Kanas, 2009). A celestial chart may be defined as a two dimensional representation from some region of the night sky (or from the whole sky) showing all the visible objects up to a certain brightness. Together with celestial charts, star catalogues contain specific information about the objects which appear in the charts. Included in this information, it is worth highlighting star positions in a particular coordinate system and the magnitude of brightness of the considered celestial bodies. Celestial charts were the most important astronomical document for centuries. However, the importance of both types of documents changed thanks to the revolution caused by Copernicus’ new planetary theory and the birth of new and more accurate observational instruments such as the telescope. Indeed, from then onwards, the scientific value of the data collected during the observations began to be higher than the artistic value of the pictorical depiction of charts. As a result of this, not only were celestial charts often sent to ruling kings as gifts by astronomers, but also the famous scientist Isaac Newton could not wait to see the data that the royal astronomer John Flamsteed had written down in his catalogue about Moon’s trajectory in order to verify his theories (Durán, 2012).


Celestial catalogues are books where a set of tables with numerical data is usually shown. In these tables each row stands for an object name and each column contains different data from the celestial objects. For instance, a star catalogue usually shows a number of tables where rows contain the name of different stars and columns contain interesting data from these stars (position, distance, brightness, etc.). As we can see, these columns represent the type of data by which the catalogue’s author decided to record each object. In other words, in celestial catalogues columns represent the “metadata” the catalogue’s author has associated with this type of object. In short, researchers such as astronomers and astrophysics usually catalogue celestial objects they discover.


The birth of Astrophotography, together with the construction of increasingly more sophisticated telescopes during the nineteenth and twentieth centuries led to the emergence of a new type of astronomical document: astrophotographic images. Unlike celestial charts or star maps these images usually contain only one celestial object (a star, galaxy, star cluster, etc.) or a reduced number of them. Moreover, the appearance of the radiotelescope in the 50’s caused a revolution of celestial cartography because, for the first time, images from distant celestial objects at other wavelengths out of the visible spectrum could be seen.


In turn, the beginning of the space race in the late 50’s and the advent of computers marked a milestone in the volume of astronomical information that needed to be recorded for later analysis. In fact, space missions and research projects associated with the study of the cosmos generate massive amounts of data which are collected and stored in huge databases and can be accessed from any computer connected to Internet.


Nevertheless, more and more studies are carried out in order to measure the accuracy of existing data on ancient celestial charts, astrophotographic images and celestial catalogues (Verbunt and Van Gent, 2010a, 2010b, 2012; Rivera, 2012; Bhattacharjee, 2009; McNally, 2001). The goal of a campaign like this is to have reliable data from several centuries ago. These data will allow us to study extraordinarily-slow astronomical phenomena and check them against those scientific theories which have emerged over the centuries.


From the previous section we can see that the development of Library and Information Science has been, and will continue to be intrinsically linked to the technology evolution. As new observational instruments have released new relevant astronomical data, professionals have felt the need to record these data in order to catalogue and classify the observed celestial objects, and with them the entire known universe. Consequently, each new technological and scientific advance involves increasing the specialization level, not only of the generated knowledge but also of the documentation supporting and preserving that knowledge.


In this sense, Astronomy and Astrophysics are two very specialized sciences as they are boosted by the ongoing process of globalization in which we are immersed. For this reason the documents generated by these two sciences are also very specialized, as are the searches accomplished by professionals in specialized databases. However, why is a more specialized description of the astronomical resources not carried out in our archives and libraries? The response to this question involves recalling the essence of cataloguing. We should remember that our astronomical resources are described so that users can retrieve them, because the final goal of documental description is information retrieval (IR). In the words of Ricky Erway (referring to special collections) “We need to find better ways to describe our collections so that users will find them” (Erway, 2012).


Naturally, librarians and other information professionals should play a leading role in this process of searching better documental descriptions. In this regard, A. Heck states that “it is clear that we have entered a new age where librarians have a new attitude towards IR and where scientists also have a new attitude towards their librarians” (Heck, 1993). Nevertheless, in order to fulfil such an important role, we should adopt a more active and dynamic attitude, which involves dealing with astronomical information and its typology, learning to manage it and being connoisseurs of the information sources and channels. Thus, we will set ourselves up as real and necessary intermediaries between researchers and the documentation they handle daily, as well as establish the data necessary for a better description of the resources. This will allow for successful information retrieval (Kumar, 2010; Lagerstrom and Grothkopf, 2010; Grothkopf, 2011).


As we are currently witnessing changes in the cataloguing standards (Sainz, 2012), professionals are concentrating on the creation of standards which are adapted to the semantic web technology. However, they are not focusing on carrying out a more detailed description of the contents of the resources, that is, descriptions which allow us to indicate the desired minimum data from each type of resource.


In this respect, our contribution focuses on the data representation level at which the cataloguing rules are within the classification for bibliographic control proposed by Picco and Ortiz (2012). In particular, we are talking about a contribution based on improving the description of the contents of celestial images from space projects and missions. According to the authors, as we know, MARC 21 is a storage standard (“computer application collecting systematically descriptions and representations of bibliographic universe”), whereas consolidated ISBD and RDA are description standards (“instructions or specific rules allowing us to represent symbolically the bibliographic universe”). Despite this distinction and although the Library of Congress has recently announced (November 2012) that MARC 21 will be replaced with BIBFRAME (Library of Congress, 2012a; Picco and Ortiz, 2012; Estivill-Rius, 2011), in practice it can be observed that MARC 21 allows us to describe a greater number of elements of an astronomical resource (section 4), when compared with other standards such as consolidated ISBD and RDA (we will see that the difference is not very significant, but it nevertheless exists). Despite this, MARC 21 is constantly updated and a big effort has been made to make it compatible with semantic web. Indeed, the Library of Congress has undertaken some initiatives over the last few years such as MARCXML, MARC in FRBR, RDA in MARC, MARC Code Lists as Linked Data (Library of Congress, 2012b).


In turn, ISBD has also recently been updated. The last update was the publication of the consolidated ISBD in June 2011(ISBD, 2011) where the data on cartographic material in this new edition is presented in the area 3.1. IFLA, as the institution in charge of this standard, has also created the ISBD/XML Study Group which is currently working with Linked Data technology with the goal of adapting ISBD to semantic web. Thus they have recently published (September 2012) the ISBD namespaces in Resource Description Framework (RDF) (IFLA, 2012). 


With respect to the new cataloguing code as a substitute for AACR2, RDA (Resource, Description & Access) was published in July 2010 after about ten years of work. This standard is based on FRBR (published in 1998) and FRAD models (published in 2009) as well as the Statement of International Cataloguing Principles (published en 2009) as a substitute for Principles of Paris (1961). In spite of the fact that RDA adapts better to technology and can be easily computerised, at the beginning it did not receive a very warm welcome by the librarian’s community, hence why the suitability of its implementation was tested in the USA. One of the results of this test showed that “errors increase as a consequence of the complexity of the catalogued material and that these errors do not depend so much on the code used” (Estivill-Rius, 2011). This is one of reasons why there are so few authors who have studied how RDA interacts specifically with cartographic material, and with more general cataloguing standards. Among them we must highlight Paige G. Andrew and Mary Larsgaard who plan to publish sometime (2013) a book titled RDA and Cartographic Resources, edited by American Library Association (ALA). It is also worth noting an interesting lecture on changes introduced by RDA with respect to other standards such as AACR2 and MARC21. This lecture was given by Andrew in 2011 and was organized by ALCTS (The Association for Library Collections and Technical Services) (Andrew, 2011).


For Andrew, RDA’s greatest contribution is focusing on relationships, drawn from the “WEMI” model (Works, Expressions, Manifestations, and Items) and, if possible, including coordinates in records for maps and other cartographic materials. In the words of Andrew “the power of the WEMI model will not be realized or become truly apparent until we break away from the MARC content standard and come up with a new data-driven standard” (this idea is shared by Escolano, 2011). Mary Larsgaard agrees with Andrew with respect to the WEMI model, though she does think that RDA does not allow us to accomplish a more detailed description of cartographic materials. From her point of view, “what RDA does is to take most of the rules from AACR2 to rearrange them and often reword them”.


On the one hand, despite the fact that RDA focuses on description and access to resources, it does not allow us to carry out a detailed description of them (not even astronomical resources). However, on the other hand, RDA enhances access, allowing us to create rich relationships and associations with different records, by using the entity-relationship model of FRBR (Picco-Gómez, 2007). There are some interesting papers about FRBR’s application to cartographic material which deserve a mention: McEathron, 2002; Larsgaard, 2007; Kalf, 2008 and Morse, 2012.


In connection with the aforementioned U.S. test, celestial images are a type of resource that can be found in astronomical libraries. Unfortunately cataloguing them is not an easy task. These astronomical libraries have to catalogue their collections without using traditional cataloguing standards because of the difficulty in cataloguing them, together with the limited possibilities of enriching records with the astronomical information available, not to mention the lack of human and technical resources. A couple of important examples may be cited at European level. On the one hand, the library of Royal Astronomical Society (RAS) (RAS, 2012) makes the astronomical images available via the Internet, through the Science Photo Library site. These images are catalogued with a title, date, identification code, brief description of the image and a group of keywords (Science Photo Library, 2012). On the other hand, the library of the Astronomical Institute of the University of Cambridge possesses a digital images repository called DSpace where, if an object’s name is searched in the repository, the system brings up a table where each row displays an image of the object and each column represents a type of data by which the image was catalogued. The books can be catalogued using MARC21. Moreover, the library staff itself is in charge of scanning and cataloguing images for DSpace. In short, due to the lack of options to perform a useful description using the standards available, these important libraries are creating repositories where interfaces are based on the incorporation of the metadata available (Schaffner, 2009).


In recent years society has witnessed a major revolution in the field of geoinformation. In a short period of time people have gone from using simple street maps to being guided. They have seen the birth of global positioning systems (GPS - Global Positioning System), as well as the use of free software which allows us to navigate virtually almost anywhere in the world through any computer connected to Internet. Indeed, programs like Google Earth are a true innovation for the field of navigation, which is growing at an ever increasing rate. In fact, among other applications, this program offers the opportunity not only to navigate by land (Earth) (2012a) but also by the night sky (Sky) (2012b).


Bearing in mind the free software available (Mc Cool, 2009), we have decided to support our research by Google Sky, firstly because, as the astronomical application of the company Google (third most valuable brand in the world according to the study BrandZTM Top 100 Most Valuable global Brands 2012) it is one of the most popular programs, and secondly, because it links two important astronomical databases all over the world: SIMBAD (Set of Identifications Measurements and Bibliography for astronomical data) (SIMBAD, 2012a) and NED (NASA / IPAC Extragalactic Database) (NED, 2012a).


As we will see in section 3, SIMBAD is a database managed by the Centre de Données astronomiques de Strasbourg (CDS) which receives FITS images (Flexible Image Transport System) (a storage system containing selected metadata) and data from research projects and space missions (ProEspacio, 2011). Once the data have been analyzed, selected metadata are added to the image. Some of this metadata come from FITS records, once any incorrect data have been removed. Moreover, it should be taken into account that there may be information from different projects which are observing the same regions in the sky; hence why the process of obtaining relevant metadata needs to be conducted with care. In the same way, NED collaborates with several astronomical research projects from which it receives information in exchange. Like SIMBAD, when images are recorded in the database, metadata coming from FITS, together with data released in articles and specialized websites are extracted before being stored.


In short, the enormous volume of information generated by observatories and research projects (measured in Terabytes per month (Hernández et al, 2009)), not only justifies the existence of these large databases, but it implies the need to manage this information by using all of the techniques available. This will enhance the value of the information. It is at this point that professionals of documentation play an important role. To cite an example, the staff working in these databases are already applying data-mining and web-mining techniques (Wenger and Oberto, 2010), due to the increasing interoperability between NED and different astronomical archives and other services. These techniques (Mazzarella, 2001) are part of the new applications performed by NED in the Virtual Observatories. This is what is happening now, but the role that information managers will play in the future of mega-databases should not be overlooked.


SIMBAD is a database created by the Astronomical Data Centre in Strasbourg (Centre de Données astronomiques de Strasbourg -CDS-). The CDS “defines, develops, and maintains services to help astronomers find the information that they need from the very rapidly increasing wealth of astronomical information, and in particular of on-line information” (Wenger et al., 2000). 


The fact that SIMBAD is one of the best databases in the world of Astronomy and Astrophysics is no trivial matter. In the 80’s it started to be used as a reference for bibliographic research into Astronomy and Astrophysics (Debois, 1989), as R. Shobbrook and F. Genova claimed in the 90s: “SIMBAD and its host, the Strasbourg Observatory, needs no introduction. It is probably the best known database in the field of astronomy and has been around as an online service since 1981” (Shobbrook and Genova, 1995). This is evidenced by the significant increase in requests per day that the database has experienced in recent years (Wenger and Oberto, 2010). SIMBAD is currently an important resource within online astronomical services and the so-called Virtual Observatories (VO) (Wenger, 2007).


This database contains information about stars, galaxies, non stellar objects (planetariums nebulas, cluster, etc.) and additional objects observed in several wavelengths (radio, infrared, X ray). “The only astronomical objects specifically excluded from SIMBAD are the Sun and Solar System bodies” (Wenger et al., 2000).


The second largest database that Google Sky links to is known as NASA / IPAC Extragalactic Database (NED), and it is managed by the National Aeronautics and Space Administration (NASA) together with the Infrared Processing and Analysis Center (IPAC). It has been in operation since June 1990 and provides an enormous amount of astronomical and astrophysical data covering multi-wavelength. Moreover being immersed in a continuous process of expansion and revision makes it one of the best worldwide databases in this discipline (Corwin, 1995).


This is an online research resource designed to support scientists, educators, space missions and observatories, etc., by providing information about objects outside the Milky Way. Their main goal is to maintain all basic data about extragalactic objects updated (galaxies, nebulas, etc.), including references to the literature in Astrophysics (Mazzarella et al., 2001).