You can now report fainter than observations as the limiting magnitude of the image.
To do this you do a regular analysis, applying the sequence and go to the photometry report page. At the bottom of the target table you will see what the limiting magnitude is. There is a new column with check boxes that allows you to say that a given target is to be reported as fainter than the limiting magnitude.
The limiting magnitude is estimated as described here:
http://www.aavso.org/ccd-views-315
This method is applied to the three faintest stars in the sequence, and the average of the results is reported.
Geir