CALIPSO UTC and Profile time in L2 data
I'm trying to collocate CALIPSO retrievals with those from another instrument. I've downloaded the L2 dataset that I need (CAL_LID_L2_05kmAPro-Standard-V4-20), but when I look at the two time variables available ("Profile_UTC_Time" and "Profile_Time") these are in formats that I don't recognize and don't know how to convert to more standard datetime formats.
For example, the first time values for the Profile_UTC_Time in one of the data files is 80101.36959844. From both the metadata and the name of this file (''CAL_LID_L2_05kmAPro-Standard-V4-20.2008-01-01T08-52-14ZD.hdf'), I can see that the scan starts at "2008-01-01T08:52:14Z," which makes me think that the 80101 corresponds to 2008-01-01. However, I'm not sure about the numbers following the decimal point; I checked and they don't correspond to the number of seconds past midnight (8:52:14 would be 31934 seconds). Do you know how these values should be interpreted?
As for the Profile_Time variable, I'm getting values like 473294144.8958215 for the first observation in the above file, and I'm not sure how to interpret that. I do understand the difference between the local profile time and the UTC time, just not how to interpret the values that exist in the dataset. Any insight you can provide, or documentation you can point me towards, would be very appreciated!