Gets the RA and DEC from a star image using astrometry.net without creating other files except the output.

solve.sh

#! /usr/bin bash

# Using python to get the RA, DEC from a wcs file: https://groups.google.com/d/msg/astrometry/0ICnBUecOx8/S1to9wayBQAJ
# Physical meaning of "Field rotation angle": https://groups.google.com/d/msg/astrometry/KEPzYd7fHis/hGDGMUwMBgAJ
# Possible program flaw of rotation near poles: https://groups.google.com/d/msg/astrometry/Uicir_i1E_o/nJsjjDeEBwAJ


solve-field \
    --no-plots \
    --no-verify \
    --resort \
    --corr none \
    --solved none \
    --match none \
    --rdls none \
    --index-xyls none \
    --new-fits none \
    --temp-axy \
    --crpix-center \
    -O \
    --depth 30,40 \
    "$1" > out.txt
# 26_07_-_20_27_08_image8_900.jpg
# python -c "from astrometry.util.util import Sip; wcs=Sip('26_07_-_20_27_08_image8_900.wcs'); print wcs.radec_center()"

To time this script on your system, simply execute this script as follows:

time bash solve.sh <image-filename>