Celestial cartography

When I started pursuing astronomy as a 14 year old boy somewhere in seventies last century, there were no computers, no printers, no copy machines and no calculators. I regularily atended courses for schoolchildren at the Astronomical observatory of Zagreb and soon participated in amateur work that was carried there, covering a lot of observational astronomy. There was a small, but quite good library and there I met Sky and Telescope for the firs time. Some books were also there, mostly in english, but also in Russian, which I do not spek, but was able to read with the help of a dictionary. The star charts vere very rare, and the observatory itself had a single copy of Becvar Star atlas and catalogue (later distributed in the USA by SKy Publishing Corp. under name Atlas of the Heavens) and just a few simpler guides through the night sky.

My first sky chart was a simple planisphere from a primary school geographic atlas, and after that a larger planisphere published by the Zagreb Observatory. Everything else we have had to copy by hand, and I draw my share of variable star charts, simple finder charts, etc. Later on, first personal computers appeared, and I remember drawing my first maps with the help of a Commodore 64 and its ingenious 4-color plotter. Soon after PCs took over and I transfered my files and rewrote programs to the new system.

Thus, when I needed some charts for my tutorals i was preparing for children groups I led at summer schools of astronomy, I was ready to plot my charts with the help of a PC. However, the plotting program itself was a problem, and after a while I made a very unusual choice: Latex. Latex is an excellent program for typesetting all kind of teksts, so it can be puzzling why use it for drawing sky charts. My reasons were simple: first, I already knew how to use Latex because I used it to wrote scientific articles. Its huge advantage was that it could produce beatifull equations of any complexity. Also, it was freeware then, as it is now. Buying a software was at that time no option due to high prices. One resorted to the DOS that came with the PC and maybe some cracked program obtained from who knows where. I was never a friend of illegal software for one reason or the other, and as comercial software was expensive, I had to rely to my programming or freeware (I did not change my mind so far). Now, Latex had something I needed a lot: among its many capabilities was a rudimentary, but powerfull set of comands for drawing pictures. Add to this complete mathematical fonts, including all grek letters and many simbols used in sky maps, and you could understand why I chose Latex. Also, Latex set of comands is written in a simple ASCII file that can be easily edited, and it allows very fine tuning of every element (be it a lletter, or a point in a picture). I wanted the capabilitiy of fine tuning the star and object labels and so on, so that I can produce charts without overlapping symbols or cluttering of labels that is hard to decpher unde the red light. Naturaly, there is a price for this: The Latex files are large, and tuning them manually takes a lot of time. Modern Latex systems have graphical interfaces and editors that ease the work, but it is stil a many step project. One would first write the input Latex file, run it through the system, usually two times, so that the system can set many internal parameters correcty, run the resulting file through a viewer to see the results, return back to the input file, correct the errors and so on. Still, the charts I made were very nice and very flexible.

 


Seasonal sky maps I produced back in 1994. and refined several times. They show the appearance of the evening sky through the seasons (at the begginig of astronomical night), plus the circumpolar (northen) sky for latitude of about 45 degrees N. Stars to the magnitude of 4.5. are shown, with a few fainter ones, if they are needed in the constelation figures. Very simmilar maps are used in three popular books I wrote untill now (all three in croatian language) in slightly modified versions and sizes. The version here is rechecked and internationalized, i.e. star and constelation names are internationally accepted ones, contrary to croatian constelation names and croatizied star names used in the books. There are 7 maps in the set: northern sky, summer, autumn, december, winter, march, spring and june.

Finder charts for messier objects that I started to assemble back in 1990'ties. I was not satisfied with the charts I had at hand so I produced a set of charts with a large scale (20 mm per degree) for a few most difficult areas (Virgo, Coma Berenices, Saggitarius, etc.). I made two sets of them: one set are normal charts, the other are mirror reflected, so I could use them on any scope. The charts are minimalistic, i.e. only stars and the brigtest nebulae are plotted, and only a few key stars are labelled on each map. The data for the nebulae are summarized on the page 2 of the chart. All stars down to mag. 9 are plotted, as are nebulae down to 12th magnitude, even if this is not very accurate for the nebulae. Data for the stars are taken from the SAO catalogue, and for the nebula from the Saguaro Astronomy Club Database V6.0. A file with the magnitude scale and map scale is also included in each set. The normal maps are here, and the mirrored maps are here.

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Last Revised: 07.02.2011.