Towards the restoration of the jantar mantar observatory instruments at Delhi: Calibration and observations with the jaiprakas and ram yantra

Abstract

A database of positional astronomy observations using the Jaiprakas and the Ram Yantra of the Jantar Mantar Observatory in Delhi, is presented here. The purpose of this database is to give an overall idea of the state of the instrument at present, prior to the planned restoration of the instrument surface markings by the Archaeological Survey of India. The observations and the related documentation of procedures involved, are also aimed at providing templates for the planned restoration of the instrument surface markings. The restoration process can utilise the methods outlined here, for the drawing/etching of the markings for the measurements of altitude and azimuth on the one hand, and right ascension and declination (for the Jaiprakas) on the other, using these methods. The time markings along the equator can also be undertaken with the procedures discussed. Markings relating to the rising and/or culmination of the Zodiac signs, which may have been present originally on the Jaiprakas, have not been investigated. The required markings for the same would have shifted with precession of the axis of rotation of Earth, and drawing them according to current positions would be different from the original markings. Conservation practice requires a restoration to the original design, but in this particular case such a restoration would not make any astronomical sense.