Practices on Observational Astronomy is a new program designed for the academic teaching of Astronomy in universities. It is born with the idea of filling a hole in this area and with the aim of being used in all possible universities. For this object, the program is completely free, and it has been developed with certain care so that its requirements about memory and processor are as low as possible. To install it download the archives below and execute the installer. The program includes detailed documentation and it is supplemented with a suggested guide of practices to obtain the whole yield possible of the program. Next a shortly description of the exercises designed is exposed.

1. Eclipse, saros cycle.

The practice of eclipses has two main parts: the study of the saros cycle with the help of a program written in language BASIC, and the study of sequences and maps of visibility of eclipses.

In the first one you can obtain the results and characteristic of all the eclipses that are given in 18 year-old intervals, according to the cycle saros. Then the program graph the results to facilitate their interpretation. One can see the beginning and the end of the successive series saros, so much of Sun as of Moon.

In the second part the objective is to see sequences of eclipses of Sun and of Moon, and the maps of visibility of them. Specially the eclipse of October, 3, 2005, whose anularidad crosses Spain. Also there are interesting additional exercises as calculating the theoretical duration of a cycle saros, or the difference TT - UT for the year 484 A.C., observing the total eclipse of Sun on 14 of January of this year. When simulating it in TT with the program from the town of Athens, the eclipse passes to certain number of degrees away from totality. According to the historical chronicles the eclipse was really total from Athens.

2. Firmament.

The firmament practice allows to represent the firmament from any town and date. One can study the movement characteristic of stars and the precession along thousands of years. Also, it is possible to visualize the firmament in any system of coordinates: equatorial, ecliptic, galactic, and horizontal. It can also be used indistinctly the following projections: stereographic, polar, spherical, and Cartesian. Objects can be identified (planets, comets, and 3000 asteroids) and you can obtain this way the coordinates of each one in each system. You equally can look for objects and to modify the field of vision. It have only been included the catalogs of indispensable objects to work. The script of practices outlines mathematical exercises that supplement the practice.

3. Disks and coordinates.

This practice is probably the most elaborated one of all. It is possible to simulate the apparent aspect of the Sun, the Moon, planets and satellites like they would be observed from a certain town. This is equivalent to observe them with a hypothetical telescope that didn't invest neither it rotated the image, just as it happens to the altacimutal refractors provided with an erecting prism. With this practice one can study the daily movement of the Sun, the phases of the Moon, and the dynamics of the geocentric Solar System. Also, the program is able to configurate any pair of photographs of the Sun, Moon, or planets to obtain the heliographic, selenographic or planetographic coordinates of any feature in the photograph. The script of practices outlines additional exercises related with the calculation of heliographic, selenographic, and planetographic coordinates.

4. Solar system I.

The objective of this practice, very similar in their aspect to that of the firmament, it is to represent the trajectories in the sky of the planets, comets, and asteroids, in order to identifying the dates of the opposition, conjunction, stationary points, and quadratures. Using the projection in horizontal coordinates it is possible to study the maximum elongations of Mercury and Venus, as well as the solar analemma.

5. Ephemerides.

The object of this practice is double: on one hand, to study the code of a program of ephemerides calculation and prediction of eclipses carried out by the author in language FORTRAN 90, and, on the other hand, to carry out a practical calculation of ephemerides to obtain the apparent equatorial coordinates of a planet, using the subroutines of the code of the previous program in the appropriate order. This practice, the same as the third, implement a group of concepts explained in the Astronomy difficult to apply up in practices form. This practice, in fact, is the only one with content and exclusively mathematical objectives.

6. Solar system II.

This practice allows to study the heliocentric Solar System. The program presents the planets, and some comets and asteroids. Also, the constellations and the lines of reference of ecliptic coordinates can be visualized. The objective of the practice is to observe the movement of the planets from the Sun and from the Earth, to identify the instants of opposition, conjunction, and quadrature, and to estimate the ecliptic coordinates of the planets projecting its position on the ecliptic. Also, the program allows to observe the orbits of almost all the space probes rushed up to now, being able to study the history of the space exploration.



- Precise recreation of the positions of the planets, the Sun, and the Moon among the years 1000 B.C. at the 3000 D.C., using the theories VSOP87 and ELP2000 of the Bureau des Longitudes of Paris. Elliptic elements have been used to improve the speed, although with errors always lower than 5¨.

- Precise recreation of eclipses. Representation of sequences of the same ones and of maps of visibility for any country. Possibility to add other detailed maps for each country by the user.

- Simulation of the apparent aspect of the Sun (including the groups of spots classified by the NOAA from 1874), the Moon, planets and satellites, keeping in mind the paralactic angle of the object as seen from each town. Values very precise (topocentric) of the position angle of pole, position angle of axis, longitude of the central meridian, and angle of the illuminated limbo, based on the last established values for the direction of the rotation axes from the International Astronomical Union, in the year 2000. Planetary renderings of great quality, without necessity of accelerating cards neither 3d libraries.

- Precise position of the satellites of Jupiter, according to J. Lieske's theory, with errors lower than 0.2¨. Precise position of the satellites of Saturn using the theory TASS1.7 (including Hyperion), with errors lower than 0.8¨. Precise position of the satellites of Uranus according to the theory GUST86. Precise position of Caronte (error lower than 0.01¨) and of the satellites of Mars

- Available catalogs: SAO (265 000 stars until the ninth magnitude), 10 000 objects of deep sky (Messier, NGC, IC, Barnard, UGC, etc., until the magnitude limit 15), limits of constellations, geometric forms of extensive nebuloses, craters of the Moon. More than a hundred of comets and more than 3000 asteroids, until beyond the magnitude 15. The program has also a catalog of orbital elements of almost all the space probes rushed so far, being able to study the whole history of the space exploration.

- Well designed and elaborated practices, with exercises outlined to deepen to the maximum in all the possible concepts. Also, guide's of practices suggestion is included, designed to take out the whole efficiency to the program. There are some necessary mathematical exercises in the teaching of the Astronomy, some of certain complexity, at the same time that others whose objective is the pure entertainment and the interesting learning. The documentation of the program is extensive and easy of continuing through a document of Word. Lastly, the program has the enough flexibility in its design as so that it is possible to modify the guide of practices, if you want, and to include other types of exercises.

- Complete support for the English language, in the whole program except in the comments of the file of objects of deep sky. Possibility of translating the program to other languagues, and adaptability of the program to any university center following the instructions of the configuration file.



Under some images are shown taken directly out from the old 1.0 version of the program. Make clic on them to enlarge. Shown images belong to the practices of eclipses, firmament, and disks and coordinates. Some different ones exist available in the Spanish version of this page.

This image shows the firmament in galactic coordinates and projection of celestial globe. The system of coordinates can be selected among equatorial, ecliptic, galactic, and horizontal. The projection system, for each one of the systems of coordinated, it can be selected among projection stereographic, polar north, polar south, spherical (celestial globe), and Cartesian. Catalogs of 10 000 objects of deep sky can be visualized, the SAO, and even photographic real textures of the Milky Way, as you can see in the image. All type of operations are allowed, as town and date changes, searches, identifications, quickly centering of coordinates, modification of the angular field, etc.. Everything it by means of simple and intuitive icons, common to all the practices and that they make this program the easiest to use of all that exist about Astronomy.


This image shows a map of visibility of the eclipse of Sun of October 3 2005. The program allows to represent maps of visibility of any eclipse in different images: World, Europe, North America, South America, …. Also, the user can add all the maps that he wants.

Map solar eclipse

This image shows the sequence of the previous eclipse of Sun. The lines represent the trajectory of the Moon (red) and the ecliptic (green). The line of pink color represents the direction of the celestial north.

Solar eclipse

In the section of disks and coordinates precise renderings of all the planets and satellites can be observed. The following images show Jupiter with Europe, and with the shade of Ganimedes transiting, the transit of Caronte on Pluto's disk, an image of Saturn and their rings, and an image of the Sun. In all the cases the program shows detailed information from all the relative angles to the orientation of the planetary axes. You can choose between observing textures or planetary coordinates. So alone placing the mouse on a planet the program will show the coordinates on their surface.







Pentium Processor 100 Mhz. Pentium II 300 Mhz or faster recommended.

16 MBytes of RAM at least. 32 MBytes recommended.

70 MBytes of free space in the hard disk.

Compatible mouse.

Operating system Windows 95. Windows 2000 recommended.



   Click down to download the installer.

Practices on Observational Astronomy, v2.0

   When you have done that you will have to configurate the program to use it in English. To do so just open a file called "configuracion", and change the word "Español" to "English". Save the change in the archive and execute the program. These and other instructions are also available in the English document of the program.

   To download more programs or updates please visit my main page.

Page of the author



For any question, suggestion, or error report, you can contact the author of the program directly in the following address of electronic mail: It is requested to the centers interested in using this program that they contact me, because I would like to know who is using my program and where.



(c) Tomás Alonso Albi. 2004. All rights reserved. The author assumes no responsibility about the precision or validity of the algorithms used in the development of this program. Also, the author assumes no responsibility about any problem that could arise as consequence of the use of the same one.