4.5.2 Comparison of Surface Brightness Profiles

We compared surface brightness profiles with JFK92, JFK95a, and Jedrzejewski (1987). The plots of $\Delta \mu = \mu_{\rm our} - \mu_{\rm literature}$ vs. $\log(r/{\rm arcsec})$ are shown in Figure -.

There is a good agreement with JFK92 and JFK95a. The only discrepancy is for R269. This discrepancy could not be fully explained by the hypothesis that we estimated the sky background level too low, since we can not move our sky level above the level found in the galaxy profile. We found, that the discrepancy could be fully explained by the hypothesis that JFK92 and JFK95a estimated the sky background level too high by 5%-9%, see Fig. . This is likely since they had a smaller field of view than we did, and since R269 is a very extended galaxy.

The comparisons with Jedrzejewski (1987) shows problems with the sky determination. This has been seen in other studies that has compared with Jedrzejewski, e.g. JFK95a.

Jedrzejewski (1987) obtained photometry in Johnson R ($R_{\rm J}$). We calculate the expected offset with Gunn r (r) as follows. Jørgensen (1994) found

$$r - R_{\rm C} = 0.354 \enspace ,$$ (4.8)

where $R_{\rm C}$ is Kron-Cousins R. Davis et al. (1985) found

$$R_J = R_{\rm C} -0.12(B-R_{\rm C}) - 0.07 \enspace .$$ (4.9)

Combining these two yields

$$r - R_{\rm J} = 0.12(B-r) + 0.47 \enspace .$$ (4.10)

Inserting a typical galaxy color of $(B-r) = 1\hbox{$.\!\!^{\rm m}$ }15$ gives a typical offset between Gunn r and Johnson R of $(r - R_{\rm J}) = 0\hbox{$.\!\!^{\rm m}$ }60$. This has been used in Fig. .