The X-ray spectrum and variability of the Seyfert 2 galaxy NGC 7172

We present evidence of flux variability, on bath short (hours) and long (months) time-scales, of the Seyfert 2 galaxy NGC 7172. These results are based on the ASCA observation of NGC 7172 performed in 1996 May. The source was detected at a rather low Aux level, about 3 times fainter than its usual state (including 1 yr before, when it was also observed by ASCA). The source also varied by about 30 per cent during the observation, confirming the presence of a type 1 nucleus in its centre. However, its spectrum appears to be flatter than the typical Seyfert 1 spectrum (in agreement with findings on other Seyfert 2s), posing problems for the unification model unless complex absorption is invoked.