I don't know Steve Harper personally, however I have learnt a lot from him through Lance Keimig's Night Photography book. Steve Harper is Night Phogoraphy Guru who has contributed to the world of Night Phogoraphy and put things into scientific and structural approach, and I have to say I admire and respect him a lot.
I just got to know about Steve Harper has passed away on August 19, 2016 via Tim Baskerville(the nocturnes) website, You can see that the image I posted above is a screenshot from thenocturnes.
A very big lost to the world of night photography, really. And thank you for all the hard works and knowledge you have shared to the world.