  A fiber-fed Echelle spectrograph at 2.3 m Vainu Bappu Telescope (VBT),
Kavalur, has been in operation since 2005. Owing to various technological
advancements in precision spectroscopy in recent years, several research
avenues have been opened in observational astronomy. These developments have
created a demand to improve the Doppler precision of our spectrograph.
Currently, the stability of the instrument is compromised by the temperature
and pressure fluctuations inside the Echelle room. Further, a better wavelength
calibration approach is needed to carefully track and disentangle the
instrumental effects from stellar spectra. While planning a possible upgrade
with an Iodine absorption gas cell, we measured the raw stability of the
spectrograph using a series of calibration frames taken with the ThAr gas
discharge lamp. The time series data were analysed with cross-correlation
method and the shift in ThAr emission lines was accurately measured across
different Echelle orders. In this paper, we present our stability analysis
methodology and results for the Kavalur spectrograph. We also identify possible
sources of error and discuss our strategy to mitigate them.
