How To calculate the Position of Gulik in Your Birth chart as per vedic astrology-jyotish
Just like rahu and ketu, gulik or the sub planets (not visible but effective) are points of longitude which carry malefic energy in the cosmos. These are called upgrahas or sub planets.

The location of these planets is calculated from longitude of sun based on Vedic astrology or jyotish.

• Longitude Gulik  known as Dhoom: Add 4 rasis or signs(=90 = (4 x 30  degrees) + 13 degrees + 20 minutes

The effects are inauspicious

• Longitude Vyatipat :   Dhoom Longitude  –[(12)x30 Degrees]

The effects are inauspicious

• Longitude of privet: Vyatipat + [(6)x30 degrees]

The effects are extremely in auspicious

• Longitude of Indradhanus or chap :  privet – [(12)X30 Degrees]

Effects are in auspicious

• Up ketu:  Chap + 16 degrees + 40 minutes

The effects are malefic in nature.

These above planets are malefic by nature, though not physically visible.
Effects of Gulik
If any one of the above like Up ketu,chap,parivesh,Vyatipat or dhoom is close to sun or surya, and Chandra or lagna  will destroy the length of life/longevity or wisdom of the person.

Gulik period Calculation For any Day as per vedic astrology- jyotish
The division of the day. Divide the duration of the day of any weekday into 8 equal parts. The eight portion is without a lord. The seven divisions are ruled by 7 planets, starting from the planet ruling the week day. Like for Monday, its moon starts and for sun day its sun starting.

The portion of the day ruled by shani(Saturn) is the gulik

Also on similar lines divide night duration into 8 equal parts , starting from lord of the 5^th from week day(That is if it is Monday, then this lord is Friday, so Gulik is Saturday the 2^nd divisions of night).

The 8^th position is without lord. The Saturn’s position is a gulik sun’s (suryya) portion is called  Kaal, Mangal’s or mars  section  is called  Mrityu or death, Guru’s or Jupiter’s  portion is Yamaghantak and Budh’s  or mercury’s portion is Ardhaprahar.

The starting of the day is taken at sunrise.

The position of the Gulik , the degree that is  of the ascendant at the time Gulik starts( that is Saturn’s period stars) would be longitude of the gUlik at a given place. Based on longitude the effects of gulik for particular person could be estimated.