The classification of intrinsic variables.5 The large-amplitude red variables.

(UB VRI) observations covering several cycles of 10 large-amplitude red field variables and three probable group members are discussed. The individual observations are published separately in a supplement. Although large variations occur between cycles on the rising branches and at maxima in the light curves, the curves for different cycles coalesce on the descending branch from phase 0.25 to near minimum light. Median values of the magnitude in all colors, obtained from light curves in intensity units, are closely approximated by observed values at phase 0.25. When the giant sequence in the (Mbol, R - 1)-plane, obtained from constant stars, is extended to higher luminosities through the use of median magnitudes of small- and intermediate- variables, the large-amplitude variables lie near this sequence at phase 0.25. The median luminosities are closely approximated by the color-luminosity relation > = - 0.65 mag - 2.5 (R - I)o , where (R - I) is used at phase 0.25. Because the periods and median colors are well correlated for the large-amplitude variables, - I)o = -0.45 mag + 0.90 log P, the color-luminosity relation is also a period-luminosity relation, = +0.5 mag - 2.25 log P. However, the well determined bolometric corrections for stars with periods between 100 and 500 days are closely correlated with color, B.C. = + 0.60 mag - 2.5(R - I), so no periodluminosity relation is expected in the visual luminosities over this range of period, Mv> = -1.25 mag. Subject headings: late-type stars - long-period variables - photometry - variable stars