Observational Asteroid Studies

 Analysis

• plot differential magnitude versus time for each night (remember, lower magnitude is brighter); examine plots to estimate period
• check comparison stars for variation
• perform Fourier analysis and examine power spectrum to determine potential rotation periods
• phase back data to see if period 'works'

The following set of instructions maybe used to perform analysis step.

• From the mag files created by qphot; text dump all the mag files for a night into one results file.
 
• The asteriod must be the first object the asteriod is ID number 1. The compstrars are ID number 2 and geater. 

 
• The results file is used to use by program anliz.

 
• Program anliz does the following
                - Data file to plot the differential magnitude versus time for all nights.
                    Use this plot to estimate period.
                - A check can be done for variation in comparison stars
                - Light time and magnitude corrections can be made
                - The option is given to the user to leave out selected stars
                - The output file can be in harris format or standard
 

 
• The following iraf txdump settings should be used to use program anliz.
                -text files ="*.mag.1"
                -fields ="image,id,otime,mag,merr,itime,xairmass"
                -expr ="yes"
                -(headers =no)
                -(parameters =yes)
                -(mode ="ql")

 
• The Harris program can be used if the output is in Harris format.

 
• The Harris program can determine potential rotational period .

 
• This program performs Fourier analysis.

 
• It also phases back data

 
• The files that are created by the Harris program create a fitted curve and curves for each night of data.

 
• Using gnuplot the curves can be plotted to see how the fit curve and each nightly curve compare and check to see if the period 'works'.

• At this point you should have determined the spin rate and the amplitude for the asteroid.

| Return to Asteroid Page |