This year the festival of Maha Shivratri will be celebrated for two days, on 24 and 25th February. Chaturdashi tithi will begin in the night of 24 on 9.30 pm and will go on next day till 9.15. Thus both days will be called Maha Shivratri, only for the delight of devoted Shiv bhakts.
These are the perfect time (Shubh Muhurt) for Shivratri Poojan this year :
Nishith Kaal Pooja : 24.08 to 24.59
Parana : 6.54 to 15.24 (25 February)