Rahukaalam:

As per Vedic Astrology, Rahu Kaalam or Rahu Kaal is a period that is considered inauspicious for any new venture, and it is known to give unfavorable outcomes for things started during that time. It is better to avoid undertaking any auspicious event like a ritual, a new task, or a business venture. During this Rahukaalam Rahu is believed to be at its maximum, and the outcome of any venture may not be successful. Rahukaalam depends on the Sunrise and Sunset of a given day in a given location.

According to Vedic culture and astrology, Rahu and Ketu are considered to be Chaya Grahas (shadow planets). Rahu is the Northern lunar node, while Ketu is the Southern lunar node. These nodes were one entity known as Svarbhanu, who was one of the Asuras (supernatural beings possessing destructive powers) with serpentine powers.

In Vedic astrology, the seven planets (Sun, Moon, Mars, Mercury, Jupiter, Venus, and Saturn) are allotted a specific day of the week. However, the nodal planets (Rahu and Ketu) have no such allocation. They have, however, been granted the power to rule for one and a half hours every day of the week, which is known as Rahu Kalam and Yamagandam (Ketu in South Node).

Every day, a period of 90 minutes is ruled by Rahu and it is considered inauspicious. This period is mainly seen by South Indians and North Indians follow this for important Muhurths.

According to Hindu mythology, Rahu is a snake that swallows the Sun causing an eclipse. Rahu Kalam is considered unlucky because it is associated with evil, Rahu.

Rahu kalam is calculated by dividing the number of hours between astrological sunrise & sunset by 8. Rahu Kalam on Wednesday occurs at a time which is the fifth part of the day.

 YAMAGANDAM:

Yamagandam is a time of death in the Tamil calendar when only death ceremonies are fixed. It is believed that starting any activity during Yamagandam can lead to the failure or destruction of the result. To avoid failures or obstacles avoid starting any new venture during Yamagandam and it is recommended to avoid starting important, money-related, or travel activities.

Yamagandam is calculated by dividing the day hours into eight parts, with each day having a period of approximately one-and-a-half-hour duration.

Yama Gandam as the name suggests is the period associated with the Hindu demi-god ‘Yama’, who is considered as lord of death.

In India, there is a practice of checking auspicious times for performing any new initiative related to official and personal work. While checking for a good time based on panchang (panchangam in Tamil) and Hora concepts of Vedic astrology, people usually avoid the time of Yama Gandam.

It is an astrological calculation based on the movements of the planets which determine more or less auspicious times for any activity. Any activity commenced during this time invites the ‘death’ of the work or it can be considered as death or losing energies relating to that work. So activities during Yamagandam lead to a failure or destruction of the result. Therefore we should avoid commencing important, money-related, or travel activities, during this time.

Rahu Kaalam:

12.00 pm to 1.30 pm

Yamagandam:

7.30 am to 9.00 am

Read more : https://www.astroved.com/astropedia/en/wednesday-rahukalam-and-yamagandam-timings