Dennis, I didn't get the 4.4 event you mentioned but you and I use different methods. You could be right. We can check once things settle down.

Looks like we've had the 5.0 aftershock you were wondering about. In fact it looks like there have been two of them. These are the events I've seen in your windows.

1999/10/19 12:20:44.0 34.7100N 116.3400W 5.0 4.6
1999/10/21 01:54:35.0 34.8000N 116.4100W 1.7 5.0
1999/10/21 01:57:38.0 34.8600N 116.3900W 4.4 5.0

The last two are both 5.0 but are 3 minutes apart so they must be separate events. Again, we can check this later.

The Jones/Reasonberg method is in no way similar to what I do to compute the background seismicity. To compute background seismicity I depend on catalogs back through 1970. The Jones/Reasonberg formula is a mathematical expresssion for which I plug in: the size of the main shock, the size of the event I'm wondering about, the time since the main shock, and the length of the time window. Hope this helps.

Alan