Adaptive optics with a Laser For Astronomy

Results with the laser: UGC 1347

August 1998
Below are 6 image sections showing the image improvement achieved with the Laser Guide Star when it was pointed at UGC 1347, a galaxy in the Abell 262 cluster 63 Mpc away. The LGS-corrected PSF isn't perfect, but these results represent a big step forward.

Each image is 5.4'' across with a pixel scale of 0.08'', and arbitrary colouring.

Galaxy: UGC 1347
tip-tilt
star
compact
HII region
nucleus
OPEN
LOOP
LGS off 1
LGS off 2 LGS off 3
CLOSED
LOOP
on LGS
 LGS on 1 LGS on 2 LGS on 3

The star used to correct tip-tilt is shown on the left. From the upper open loop image the seeing is estimated to be 1.1'', and the lower image shows that when the loop is closed on the laser (pointing halfway between the star and galaxy) the resolution improves to 0.4''. The peak intensity also increases by a factor of 2.5 in the closed loop image.

The right-hand set of images show the effect on a compact HII region in the galaxy and the galaxy's nucleus, which are both 41'' from the star. The HII region still has a stellar appearance and is unresolved (with a diameter probably less than 50 pc). The closed loop image of the nucleus shows that it is completely resolved with a diameter of 1.8'' (560 pc).

The image below of the profiles (intensity cuts along the x-axis) through the star, nucleus and compact region clearly shows the increase in peak intensity and improvement in resolution (FWHM given in pixels).