Why does Cell Statistics Sum produce default name?

Discussion created by graemecurwen50 on Jul 19, 2011

I have rasters for the daily rainfall for the last 25 years in my study area, about 8886 of them actually.
I want to add rasters of each days rainfall to get monthly totals of rainfall.
I am using arcpy.ListRasters with a wildcard statement to generate a list of each rasters pertaining to each month in turn, and then using Cell Statistics "SUM" to add the 30 or so rasters for each month.

What is causing a problem is that an autogenerated name appears in Arc Catalogue for the sum of each month. eg sumco_ras is for jan1986, sumco_ras1 is for feb1986.... sumco_ras11 is for dec1986 and so on.
And what really confuses me is that the raster of monthly totals that appears in Arc Map actually has the correct label, that being jan1986, feb1986....dec1986.

Once I remove the correctly labelled rasters from ArcMap and then import them again from ArcCat, the default name of sumco_ras, .... sumco_ras11 appears.

Very inconvienient, and I loose track of the rasters that belong to different years.

Can anyone suggest a cause for this and a remedy?