Mag 7 Star Atlas Project

Mar 28, 2017 22:25 · 860 words · 5 minutes read

The Mag 7 Star Atlas Project is still available, but no longer hosted directly on You can still find the individual maps at Cloudy Nights, or the Czech Astronomical Society mirror site.

The full color atlas with the Milky Way represented remains available at the Internet Archive. Original project desciption follows:

What is it?

This project is my attempt to produce a free, downloadable set of high-quality star charts – the Mag-7 Star Atlas – capable of being printed at reasonable resolutions on the average home printer.

The Mag-7 Star Atlas plots stars down to Magnitude 7.25, with double / multiple stars indicated by a thin horizontal bar. Plotted DSO’s (Deep Sky Objects) include all objects on the Messier list, the RASC’s finest NGC list, and the Herschell 400 list — more than 550 DSO’s in total.

I hope the Mag-7 Star Atlas will be useful for beginners who can put the printed charts in a binder to serve as their first star atlas. I think more experienced observers will find it useful as well: as a naked-eye or binocular atlas, for marking out a nights observing plan and/or to make notes on in the field and file with your observing reports and drawings.

But Free? Really?

Yes. And not just free of charge – you have other freedoms as well. This work is licenced under a Creative Commons License. Basically you are free to download, use, and or distribute this work for non-commercial purposes with appropriate attribution. You can create and distribute derived works if they follow the same licence.

If you are the administrator of an online astronomy group/forum, please consider hosting copies of the charts on your site for members. Even better, consider publically hosting or mirroring these charts.

Alternate Public Hosts and Mirrors:

  • The Czech Astronomical Society is graciously providing a mirror site for this project. Many thanks to Karel Mokry and the Czech Astronomical Society for providing this service!
  • The Cloudy Nights online astronomical community and equipment review site have now made the charts available on their website. Cloudy Nights is perhaps the largest online astronomical community, filled with nice people and plenty of information. Many thanks to Allister St. Claire and Cloudy Nights!

The Mag-7 Star Atlas

There are 20 primary charts and one supplemental chart (11a for the Virgo Coma Berenices region) comprising the complete Mag-7 Star Atlas. Based on early feedback, I’ve made two versions available: a black on white version for use in the field (where red light may interfere with different color schemes), and a version with DSO’s, constellation lines and boundaries, and gridlines highlighted in different colors. Different colors help to visually break up the charts making for a more relaxed viewing experience (whether viewing on-screen or printing in color for a “desktop” version). Apart from color, the two versions are identical. Enjoy.

UPDATED: Version 2.0, April 2007: includes corrections, new color scheme, and different symbols for different DSOs (no legend). There is also a full color version with a representation of the milky way – this is a single PDF file of about 18MB and can be found at: this location. Enjoy.

NEW: An object index is now available which lists all DSOs plotted in the atlas and provides their basic data along with which chart each can be found on. Object Index. (a place to jot your own notes per object is also provided).


Double Stars

I selectively marked double stars using the Washington Double Star catalog with the following criteria: only stars with a separation of at least 0.5 arc-seconds, a secondary component of Magnitude 11 or brighter, and were based on at least five observations, were marked as doubles on the charts.

Because separate, non-synchronized data sources were used, occassionally the star positions are not identical, resulting in the double-star marker (the thin horizontal bar) and the star being slightly offset. Also, since the magnitudes may be slightly different in each source, stars close to the Mag-7.25 cutoff may be mismarked. This means either a star could be plotted but not marked as a double (if the WDS listed it as fainter than the cutoff), or a marker might be plotted without its star — the latter being the only case you can readily notice. These are pretty rare occurrences and I’m not sure any reconciliation is worth the effort at the moment.


These PDF’s display and print as expected on Acroreader-5.05 on my Linux box. Your results may vary depending on platform and PDF viewer.

Future Plans?

I am considering developing a Mag-9 or 9.5 Star Atlas, and perhaps customized charts for particular observing lists.


The following software and data are being used in this project:

Additional thanks to members of the Cloudy Nights community for providing some feedback and suggestions.

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