Pradosh is an auspicious occasion to perform Shiva Pujan. In December 2012, Pradosh vrat dates are: December 11 & December 25.
December 11, 2012 Pradosh Vrat (Tuesday): Bhauma Pradosh
Pradosh of December 11 falls in Kartika Masam as per Telugu, Kannada, Gujarati & Marathi calendars and it falls in Margashirsha Month as per North Indian Hindi calendars.
December 25, 2012 Pradosh Vrat (Tuesday): Bhouma Pradosha Vrata
Pradosh of December 25 falls in Margashirsha Month as per all Hindu calendars.
As both Pradosh vrata falls on Tuesday (Mangalwar), Mangal Graha pradosha puja (Kuja Graha Shanti) is observed. In some places, Kuja graha shanti pujas are also observed along with Pradosha kaala Shiva Puja.
Pradosha Kaala Shiva Puja time is between 4.30 to 6 in the evening. Pradosha Ashtakam is a popular prayer chanted during Pradosh Vrat.