NAME: disphase PURPOSE: Apply distance and phase angle correction to observed magnitudes. DESCRIPTION: Apply standard asteroidal-law corrections to observed magnitudes given the distance, phase angle, and the G coefficient. Magnitudes are corrected to 1 AU from Sun and Earth and to 0 degrees phase angle. The default of this routine is to use equation A4 from Bowell etal. in Asteroids II (see page 550) and called the Lumme and Bowell model. An option is provided to compute the IAU standard correction from equation A5 found on page 551. According to the Bowell chapter, these expressions are valid only for 0<=G<=1 and phase angle less than 120 degrees. However, the chapter also claims the expressions are useful outside this range. Note that the computation blows up in single precision if G < -0.85. If the input value for G is out of range then the returned magnitude is set to -99.99. This prevents getting back a value of NaN for hmag. CATEGORY: Photometry CALLING SEQUENCE: disphase,mag,r,d,phang,g,hmag INPUTS: mag - Observed magnitude. r - Sun-object distance in AU. d - Earth-object distance in AU. phang - Phase angle of observation in degrees. g - IAU standard G value (phase angle coefficient). OPTIONAL INPUT PARAMETERS: KEYWORD INPUT PARAMETERS: H2MAG - Flag, if set reverses the sense of the calculations and takes H as the input magnitude and then computes the apparent magnitude for the output. IAU - Flag, if set will force the use of the lower accuracy IAU standard calculation. The default is to use the Lumme and Bowell model. OUTPUTS: hmag - Magnitude corrected for distance and phase angle. KEYWORD OUTPUT PARAMETERS: COMMON BLOCKS: SIDE EFFECTS: RESTRICTIONS: PROCEDURE: MODIFICATION HISTORY: 2008/04/12, MWB, slight change to deal with bogus values for G 2016/01/06, MWB, added H2MAG keyword option 2016/01/13, MWB, added IAU keyword option