For TM data, the reference in the ENVI help is: Crist, E.P. and R.C. Cicone, 1984 “Application of the Tasseled Cap Concept to Simulated Thematic Mapper Data,” Photogrammetric Engineering and Remote Sensing, Vol. 50, pp. 343-352. The coefficients used for TM-5 are the same as listed in this reference. Note that the coefficients should be applied to DN values and not calibrated reflectance values as is required for TM-7 data. Brightness coefficients are: .33183, .33121, .55177, .42514, .48087, .25252 Greenness coefficients are: -.24717, -.16263, -.40639, .85469, .05493, -.11749 Third coefficients are: .13929, .22490, .40359, .25178, -.70133, -.45732

The coefficients from MariM is right. BUT, these coefficients is for landsat4 TM image, not for TM5! So, the file type in Tasseled Cap transform of ENVI shoule not be landsat 5 TM. In fact, the landsat 5 is launch at 3-14,1984. By the way, please see the "Landsat_TM_Tasseled_Cap_In_RGB.alg" in erdas software, which gives the right TM type.