A galaxy at the edge of the Universe

These two photos show the extremely distant galaxy with redshift z = 4.4, detected near QSO 1202-07.

(a) The left image was obtained with the SUSI CCD camera at the ESO 3.5-metre NTT telescope. It is the sum of 6 single exposures in red colour of the QSO 1202-07 field with a total integration time of 60 minutes. Most of the objects seen are galaxies; the faintest ones have approx. red magnitude R = 26.5. The brightest star-like image at the center of the field is of the 18th magnitude QSO. The galaxy in the line of sight at redshift z=4.4 is barely visible, 2 arcsec NW of the QSO. This corresponds to ~ 12 kpc at the cosmological distance. The red magnitude is R = 24.3. Full Width Half Intensity of the stellar images in the combined frame is 0.52 arcsec. North is at the top and East to the left. The field size is 45x45 arcsec.

(b) The right photo is of the same field as (a), but now including 12 single exposures with total integration time of 120 min and therefore showing even fainter objects. The QSO, as well as a nearby star (upper right quadrant) which was used to determine the point spread function (the shape of the image of a supposedly point-like object), have been subtracted by image processing. This allows a clearer view of the high-redshift galaxy which now shows some evidence of structure, suggestive of spiral or irregular morphology.