# Limit Magnitude divide 2 arcsec

How can I derive limit magnitude in 5sigma/2arcsec ?

I have the limit magnitude in 5sigma which derive from the magnitude with SNR reach 5. But I can not understand what the meaning of dividing 2arcsec.

• Do you mean arcsec^2 ? Oct 15 '20 at 16:14
• No, just 2arcsec. May it means the diameter.
– GHC
Oct 18 '20 at 5:56