  Attosecond transient absorption spectroscopy (ATAS) is used to observe
photoexcited dynamics with outstanding time resolution. The main experimental
challenge of this technique is that high-harmonic generation sources show
significant instabilities, resulting in sub-par sensitivity when compared to
other techniques. This paper proposes edge-pixel referencing as a means to
suppress this noise. Two approaches are introduced: the first is deterministic
and uses a correlation analysis, while the second relies on singular value
decomposition. Each methods is demonstrated and quantified on a noisy
measurement taken on $\text{WS}_2$ and results in a fivefold increase in
sensitivity. The combination of the two methods ensures the fidelity of the
procedure and can be implemented on live data collection but also on existing
datasets. The results show that edge-referencing methods bring the sensitivity
of ATAS near the detector noise floor. An implementation of the post-processing
code is provided to the reader.
