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We show that disc continuum fitting can be used to constrain black hole spinin a subclass of Narrow Line Seyfert 1 (NLS1) AGN as their low mass and highmass accretion rate means that the disc peaks at energies just below the softX-ray bandpass. We apply the technique to the NLS1 PG1244+026, where theoptical/UV/X-ray spectrum is consistent with being dominated by a standard disccomponent. This gives a best estimate for black hole spin which is low, with afirm upper limit of $a_*<0.86$. This contrasts with the recent X-raydeterminations of (close to) maximal black hole spin in other NLS1 based onrelativistic smearing of the iron profile. While our data on PG1244+026 doesnot have sufficient statistics at high energy to give a good measure of blackhole spin from the iron line profile, cosmological simulations predict thatblack holes with similar masses have similar growth histories and so shouldhave similar spins. This suggests that there is a problem either in ourunderstanding of disc spectra, or/and X-ray reflection or/and the evolution ofblack hole spin.

A new way to measure supermassive black hole spin in accretion disc dominated Active Galaxies