Some code that can be used to have your timestamp in your Bash prompt be a stardate.

stardate_bash_prompt.sh

function stardate()
{
        # There's apparently no cannon way to calculate the startdate
        # but here goes.

        # Add up all the minutes so far in the day, divide by minutes in 24 hours and format it nicely.
        DECIMAL=$(echo $(( $(date -u '+%H') * 60 + $(date -u '+%M') )) | awk '{printf("%.2f", $1/1440)}' | sed 's/^0*//')
        # Get the number of days since epoch.
        DATE=$(( $(date -u '+%s') / 60 / 60 / 24 ))
        echo "$DATE$DECIMAL"
}    

# This prompt includes the stardate, user@hostname and the current working directory.
export PS1="[\$(stardate)][\u@\h \w]\$ "