In response to the comments by Murphy et al. (arxiv:0708.3677)

TL;DR

This paper defends the robustness of a previous analysis on the variation of the fine structure constant against criticisms, presenting a reanalysis that confirms their original findings with minimal scatter.

Contribution

The authors demonstrate that their fitting procedure is robust and provide a reanalysis confirming their earlier results despite differing data and methods.

Findings

Reanalysis yields Δα/α = (0.01±0.15)×10^{-5} for 21 systems.

70% of Murphy et al.'s measurements are consistent with previous results.

Fitting procedure remains robust across different data sets and methods.

Abstract

In their comment, Murphy et al. (arxiv:0708.3677) criticize the fitting procedure we used in two previous papers [Srianand et al. 2004(Paper I) and Chand et al. 2004 (Paper II)] and conclude that the above papers offers no stringent test to previous evidence for varying fine structure constant. We think this is a hasty conclusion as (a) our procedure is robust as shown in Paper II; (b) the data used by Murphy et al., in particular the error array, are different from ours and there are differences in the fitting procedure; (c) despite these differences, 70 per cent of their individual measurements are consistent with that quoted in Paper II. Our reanalysis using VPFIT with identical initial guess parameters leads to \Delta\alpha/\alpha = (0.01+/-0.15)x 10^{-5}$ for 21 systems (excluding two systems that deviate at more than 3$\sigma$ level) with very little scatter (\chi^2_\nu ~1).