Illustrated Guide to Astronomical Wonders question

[Nibor]

I hope someone can help with a query regarding the charts as shown in the Constellation guide sections of "Astronomical Wonders".

I am finding the guide a great help and a very good introduction for a newcomer but I am a bit stumped with understanding the captions next to the finder charts.

I understand the field width / finder width / eyepiece field circles but what does the LM 9.0 figure refer to? (eg page 258, M13)?

Page 36 "Chart Number" mentions "field width and height" so I assume it is the height but what does LM stand for and what is the number?

I am sure this will be obvious once it has been explained!!!!

Many thanks in advance.

Robin

[brantuk]

LM would be the limiting magnitude - give this a read:

http://en.wikipedia.org/wiki/Limiting_magnitude

(I can't find an explanation in the glossary or index at the back)

[Nibor]

Brantuk,

Thanks for your help.

I have looked at Wikipedia and others and am I right in thinking that this particular chart shows stars down to LM 9.0? Whereas , say, Chart 36.2, page 365 shows stars down to mag 6 ?

Robin

[brantuk]

On page 258, LM 9.0 refers to the object itself (ie M13) with a field width of 15 degs.

On page 365 it's comparing M76 at different zoom levels with a 30 deg field width against a 10 deg field width. Depending on how much you magnify it stars appear at different magnitudes in the finder/eyepiece and this book is refering to star charts of different scales.

On page 17, I found the explanation of this under "Stellar Magnitudes" - it's a lot better than my description wich may be confusing (but I know what I mean lol)

[Nibor]

Brantuk,

Many thanks for your time on this topic - I think I've got it at last!!

Cheers

Robin

[brantuk]

Glad to help Robin