[Chaos-l] Wil Tirion's _The Cambridge Star Atlas_

[MSN]

Jon, great review!! SLR

Sent from my iPhone

On Aug 5, 2010, at 1:18 PM, Jon Stewart-Taylor <joncst at earthlink.net> wrote:

> Hi all.  During my observing session last night at Farrington Point, i was using a copy of Wil Tirion's _The Cambridge Star Atlas_ (which i'd checked out of the library) to hunt things down.  I currently use Tirion's _Bright Star Atlas 2000_ as my main atlas, and was curious how the two compare, especially since _BSA_ was out of print for some years.  The first obvious difference is that _TCSA_ has a  moon map, listing about 250 craters as well as the various mares.  The map is inverted as per Newtonian 'scopes, but at a scale perhaps more suited to binoculars.  The monthly whole-sky maps are divided per-hemisphere in _TCSA_, as opposed to the one-chart-fits all approach in the _BSA_, and are are a pretty blue with the Milky Way in a lighter blue.  More importantly, there are 12 in _TCSA_, intended for use from 9 to midnight, compared to 7 in _BSA_ labeled with  the 16 month//time combinations each of the 7 charts cover.
> 
> The most important differences between _BSA_ and _TCSA_ are limiting magnitude and scale.  _BSA_ is a  mag 6 atlas, and covers the sky in 10 full-page charts. _TCSA_ is a mag 6.5 atlas, and covers the sky in 20 full-page charts.  _TCSA_ also lists fainter objects, some as faint as 12th mag, in contrast to the usual mid 10th magnitude limit for BSA. These differences mean that BSA is a better unaided-eye, binocular, and Telrad reference, while _TCSA_ is a better finder-scope and telescope reference.  Using _TCSA_, i sometimes had to flip back and forth between pages to get the layout of the bright stars used for Telrad hopping.  Conversely, the extra half magnitude, and especially the finer detail, helped in using the finder to close in on the targets.
> 
> The _BSA_ has a set of tables at the front, one listing all the Messier objects and one each for the double stars, clusters, galaxies, and nebula shown in the whole atlas.  Both atlases (atlasi?) have tables for each chart listing the objects on that particular chart.  _TCSA_ has 4 charts at the end showing the distribution of each kind of object over the whole sky: kinda fun, but not something you'd refer back to all that often.
> 
> Bottom line is that you probably don't need both of these.  If you want to do primarily unaided eye or binocular observing, _BSA_ is probably better, especially given you can usually get it for under $12 including shipping.  For telescopic purposes, _TCSA_ has better charts.  It also costs about twice as much, on the order of $24 in hardback.  Either is a good choice to pair up with _Turn Left at Orion_.
> 
> Hope this was useful.
> 
> J.
> -- 
> Jon Stewart-Taylor:  joncst at earthlink.net
> Chapel Hill Astronomy: http://www.rtpnet.org/chaos
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