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SDSS J1148+5251

Technical card

Imaging telescope or lens: Selfmade 443/2048 Newtonian f4.6

Imaging camera: SBIG ST-10 XME

Mount: Sideres85

Software: PixInsight

Filter: SBIG CFW-9

Accessories: SBIG AO-8Baader RCC-1 Coma Corrector

Resolution: 4196x2860

Dates: Feb. 9, 2016Feb. 25, 2017

Frames: 209x300" -30C

Integration: 17.4 hours

Avg. Moon age: 14.14 days

Avg. Moon phase: 1.64%

Bortle Dark-Sky Scale: 2.00

Mean SQM: 21.40

Mean FWHM: 2.60 job: 1533538

RA center: 177.064 degrees

DEC center: 52.870 degrees

Pixel scale: 0.342 arcsec/pixel

Orientation: -179.807 degrees

Field radius: 0.241 degrees


SDSS J1148+5251 (z=6.419)

This very distant quasar was discovered 2003 in the Sloan Digital Sky Survey II as J114816.64+525150.3 (z = 6.43), later publications shows a redshift of z = 6.419 . This high redshift causes a shift of the Lyman alpha emission line from 121.6 nm to 901.2 nm. Nearly all the light from this quasar origins from wavelengths greater than 900 nm.

The redshift z = 6.419 is equivalent to a light travel time of 12.84 billion years. The age of the universe was only 870 million years by the time the photons left the quasar.

The spectrum of this quasar shows Gunn-Peterson trough, left of the Lyman alpha emission. The Gunn-Peterson trough was caused by clouds of neutral hydrogen gas (which were not ionizied yet) on the light path to the quasar. It is is a clear sign that the quasar light had its origin in the reionization epoch of the universe.

Some scientific papers show:
- the quasar contains a black hole with a mass of 3 billion sun masses.
- there is a lot of carbon monoxide (300 million sun masses).
- Hubble images do not show any signs of the quasar host galaxy, probably because of too many dust around the quasar.

Because of the light of this quasar comes from wavelengths greater 900 nm, it was a little bit difficult to catch it. The quantum efficiency of the Kodak KAF3200-ME chip in the range 900 nm - 1000 nm is app. only 17% (average).

I have measured the image with the software Astrometrica and the Gaia catalog, the results are shown at the inset (bottom left). Please zoom into the image many times to see all the details. The leftmost image shows a comparison image, where I have averaged 6 images from the Hubble Legacy Archive, total integration time 1.7 hours. In my image the quasar, marked as SDSS1148, is satisfactorely showed with a signal to noise ratio of 12.4 . The location of the quasar differs from the scientific papers by 0.2". The limiting (Gaia broadband G) magnitude of my image is +23.9 mag. (for S/N=5) or +24.5 mag. (for S/N=3).

This is and will be my deepest image ever concerning redshift. More distant quasars my ccd camera cannot see, it is restricted to wavelengths below 1000 nm.




Sky plot

Sky plot


SDSS J1148+5251, DetlefHartmann