This question/answer comes from the LPDAAC archives but the link is no longer online so I'm posting the formatted text here. Note that the naming conventions changed in 2003 (see below)

Question 6/27/2003 12:18:46 PM
How do I interpret the ASTER granule IDs and file names?

Answer 10/24/2003 8:34:13 AM
There is no quick way to relate the ASTER granule IDs to the ASTER file name.
However, there is a way. Please see the example below for interpreting the IDs and name:
Example granule ID: SC:AST_L1A.002:2004799662

FOR DATA FROM 2000-2001

Corresponding file name: pg-PR1A0000-2001111802_042_013
and pg-PR1A0000-2001111802_042_013.met

The acquisition date and time in the EOS Data Gateway for scene
SC:AST_L1A.002:2004799662 is
05 Nov 2001, 10:37:24.

However, the values in the file name (pg-PR1A0000-2001111802_042_013) are for the date and time that the scene was produced.

Here is how to interpret the file name:
PR1A0000: Processing level
2001:Production date (year)
11: Production date (month)
18: Production date (day)
02: Sequence number of production plan for that particular day
042: Processing strip number
013: Sequence number in the processing strip

To match a file name with an image that is in our archive, you can use the Ground Data System (GDS) ID – IDOFASTERGDSDATAGRANULE

For example: ASTL1A 0111051037240111180891 (from scene SC:AST_L1A.002:2004799662/ file pg-PR1A0000-2001111802_042_013)

Format: ‘ASTL1A YYMMDDHHMMSSyymmddNNNN’ where,
YYMMDD:observation date
HHMMSS:observation time
yymmdd:the data granule generation date
NNNN:the data granule sequential No. per day

So ASTL1A 0111051037240111180891:
011105: observation date
103724: observation time
011118: the data granule generation date
0891: the data granule sequential No. per day

FOR DATA FROM 2003- onwards

Since June of 2003, the ASTER level 1 file naming convention has been changed.
The new file name carries data acquisition date and time, that makes file name and granule ID matching easier. It breaks down as follows:

AST_L1B_003_03202000015450_11132002093512.hdf

The first string of numbers after
"AST_L1B_003_" is the acquisition date and time.
The second string of numbers is the production date and time.
AST_L1B: product name
003: processing version
03: acquisition date (month)
20: acquisition date (day)
2000: acquisition date (year)
015450: acquisition time (01:54:50)
11: processing date (month)
13: processing date (day)
2002: processing date (year)
093512: processing time (09:35:12)

However, some of the ASTER data in DataPool still use the old file naming convention.

It looks like the following:
pg-PR1B0000-2001021503_007_001
PR1B0000: Processing level
2001: Production date (year)
02: Production date (month)
15: Production date (day)
03: Sequence number of production plan for that particular day
007: Processing strip number
001: Sequence number in the processing strip