  Understanding the effects of rotation in stellar evolution is key to
modelling early-type stars, half of which have equatorial velocities over 100
km/s. The nearby star Altair is an example of such fast-rotating stars, and
furthermore, it has the privilege of being modelled by a detailed 2D
concordance model that reproduces most of its observables. The aim of this
paper is to include new asteroseismic frequencies to improve our knowledge of
Altair, especially its age. We processed images of Altair obtained during July
2022 by the Transiting Exoplanet Survey Satellite using the halo photometry
technique to obtain its light curve over this observation period. By analysing
the light curve, we derived a set of 22 new frequencies in the oscillation
spectrum of Altair and confirmed 12 previously known frequencies. Compared with
model predictions, we could associate ten frequencies with ten axisymmetric
modes. This identification is based on the modelled visibility of the modes.
Moreover, nine of the modelled frequencies can be adjusted to simultaneously
match their corresponding observed frequencies, once the core hydrogen mass
fraction of the concordance model is set to $X_{\rm core}/X_{\rm
ini}\simeq0.972$, with $X_{\rm ini}=0.739$. Using the combined results of a 1D
MESA model computing the pre-main sequence and a 2D time-dependent ESTER model
computing the main sequence, we find that this core hydrogen abundance sets the
age of Altair to 88$\pm$10 Myrs, which is slightly younger than previous
estimates.
