<TABLE> <S> <C>
<PAGE>
<ARTICLE> 5
<LEGEND>
THIS SCHEDULE CONTAINS SUMMARY FINANCIAL INFORMATION EXTRACTED FROM THE
UNAUDITED FINANCIAL STATEMENT OF ATLAS-ENERGY FOR THE NINETIES-PUBLIC #6 LT
FINANCIAL DATA SCHEDULE FOR 2ND QUARTER 10-Q.
</LEGEND>
<MULTIPLIER> 1,000
<S> <C> <C>
<PERIOD-TYPE> 3-MOS 6-MOS
<FISCAL-YEAR-END> DEC-31-1999 DEC-31-1999
<PERIOD-START> APR-01-2000 JAN-01-2000
<PERIOD-END> JUN-30-2000 JUN-30-2000
<CASH> 18,640 18,640
<SECURITIES> 0 0
<RECEIVABLES> 291,868 291,868
<ALLOWANCES> 0 0
<INVENTORY> 0 0
<CURRENT-ASSETS> 310,508 310,508
<PP&E> 10,355,659 10,355,659
<DEPRECIATION> (2,759,297) (2,759,297)
<TOTAL-ASSETS> 7,906,870 7,906,870
<CURRENT-LIABILITIES> 30,730 30,730
<BONDS> 0 0
0 0
0 0
<COMMON> 0 0
<OTHER-SE> 7,876,140 7,876,140
<TOTAL-LIABILITY-AND-EQUITY> 7,906,870 7,906,870
<SALES> 389,535 770,256
<TOTAL-REVENUES> 394,331 777,356
<CGS> 52,678 101,987
<TOTAL-COSTS> 52,678 101,987
<OTHER-EXPENSES> 260,483 520,255
<LOSS-PROVISION> 0 0
<INTEREST-EXPENSE> 0 0
<INCOME-PRETAX> 81,170 155,114
<INCOME-TAX> 0 0
<INCOME-CONTINUING> 81,170 155,114
<DISCONTINUED> 0 0
<EXTRAORDINARY> 0 0
<CHANGES> 0 0
<NET-INCOME> 81,170 155,114
<EPS-BASIC> 0 0
<EPS-DILUTED> 0 0
</TABLE>