  Estimations of prompt photon production at FAIR (Facility for Antiproton and
Ion Research) energies using the extrapolation of existing data are presented.
About $10^{-4}$ prompt $\gamma$ with $p_{t}>$2 GeV/c per Au+Au central event at
25 AGeV are expected. With the planed beam intensity $10^{9}/s$, 1% interaction
rate and 10% centrality, at CBM (Compressed Baryonic Matter) experiment one can
expect prompt $\gamma$ rate ~100/s.
  Predictions for direct photons by some generators (PYTHIA, UrQMD, RQMD, HSD,
HIJING) are analyzed. One of the main sources of direct photons (due to meson
scatterings $\pi\rho\to\pi\gamma, \pi\pi\to\rho\gamma$) is not implemented in
the heavy-ion generators. Corresponding cross-sections for this source have
been prepared for implementation into the HSD code.
  Main experimental methods to study direct photons (subtraction method,
momentum correlations method and internal conversion method) are shortly
reviewed. High intensity beam, good tracking and good $e^{\pm}$ particle
identification of the CBM detector favor to measure direct photons by all the
methods.
