Sunday, March 13, 2011

Unique Quasars

One of the comments from Hennawi about my paper was he wanted to know how many unique quasars were simulated in the QSO catalog.

I wasn't exactly sure how to define "unique" quasar.

The simulated i-band fluxes range from 15 to 22.5. They are simulated to 4 decimal places.
The simulated redshifts (z) range from 0.5 to 5.0. They are simulated out to 6 decimal places.

If I define unique to be the same out to the maximum decimal places provided, then there are only 2 simulated quasars that are repeats of each other (0.00002%)

If I define unique to be within 0.1% magnitude/redshift of each other, then there are 6285 (out of 10 million) are repeats (0.06%).

If I define unique to be within 1% magnitude/redshift of each other, then there are 62,824 repeat objects (0.6%).

Anyway, so I guess I should ask Joe how he wants me to define repeats.

Here is the code to do this:
file = '/clusterfs/riemann/raid001/jessica/boss/Likeli_QSO.fits.gz'
qsos = mrdfits(file, 1)

imean = mean(qsos.i_sim)
zmean = mean(qsos.z_sim)

percent = 1.0/100. #simulated quasars within this percentage of each other
ierr = imean*percent
zerr = zmean*percent

imult = round(1./ierr)*1.
zmult = round(1./zerr)*1.

roundqsosz = round(qsos.z_sim*zmult)/zmult
roundqsosi = round(qsos.i_sim*zmult)/imult

uniqz = uniq(roundqsosz)
uniqi = uniq(roundqsosi)

all = where(qsos.z_sim GT -99999)

repeatZ = setdifference(all, uniqz)
repeatI = setdifference(all, uniqI)

help, setintersection(repeatZ, repeatI)

Also can be found in the following log file:

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