As a follow-up of the previous May 12/13 detection limit observations,
we observe SAO 248381 and IRC+60228 with C_90 and Theta UMi with C_160.
The predicted fluxes are:

   SAO 248381:   68 mJy at 100 um
   IRC+60228 :   68 mJy at 100 um
   Theta UMi :   55 mJy at 160 um

We compare two different observing strategies, implemented via AOTs:

 - triangular chopping with C_90, and rectangular chopping with C_160;
 - a sequence of staring observations (implemented via sparse maps),
   with two background positions, thw sequence imitates triangular chopping.

Comparison of the results derived from the two observing modes will help
to find out the advantages/disadvantages of these observing strategies,
and may help observers to prepare faint source observations for the second
Call for Proposals.