It is believed that worshipping Lord Shiva on a day with Arudra Nakshatram is auspicious. If the Arudra Nakshatram comes on a Monday then it is highly auspicious. This year this is coming on October 7th 2012.
Performing of Abhishekam to Lord Shiva on the day of Arudra Nakshatram brings high returns.
The legend behind the same
As per Indian Mythology Daksha Prajapati had 27 Nakshatras as his daughters. He married them to Moon and asked him to look after each of them equally. Moon as an usually tendency is more inclined to some, but he neglected Arudra the most. Arudra complained to her father that Moon was neglecting her. Daksha Prajapati cursed Moon to wane (the waning phase of moon). Moon prayed to Lord Shiva to help him over come the curse.
Lord Shiva advised Moon to perform Sahasra Ghatabhisekham to the Shiva Lingam, at Sarnath on a day when there is Arundathi Nakshatram for one year. Moon used to perform Sahasra Ghatabhisekham to the Shiva Lingam with full devotion. Once he performed 999 Ghata Abhishekam and the last one slipped off and hit the Lingam.
Shiva appeared and told Moon that because of his negligence Moon would have a waxing phase of 15 days and a waning phase of 15 days.
So to overcome any type of sin one should perform Abhishekam to Shiva Linga on a day with Arudra Nakshatram.