Kevin Gurney

Hi Andy

The airmass for Regulus was around 1.35, that for Castor 1.15…

They were taken on the same night.

I am using a C11, and bright stars inevitably straddle the slit (already the slightly wider one at 35mu).

I might try an experiment with moving the collimator axis a little.. you know, the screw on the bottom of the Lhires.

Keep safe