Redshift 6 Quasar (CFHQS J1641 +3755)

(Cooperation with Ken Crawford)

clic for 36% size 1250 x 934 (450 kB)

Clic here for 60% size 2249x1580 (760 kB)

Clic here for a 100% size enhanced crop 1900x151548 (809 kB)


About this Image

Just 1.5 degree north from the bright globular M13 an elusive dim object is embedded in a sparkling field of faint galaxies.
It is an extremely distant quasar, named CFHQS J1641 +3755 with a measured redshift of 6.04. This means the light we collect on earth left the quasar 12.7 billion years ago when our universe was at 7% of it's present age. The discovery of this and 3 other high redshift quasars up to z = 6.43 was published in June 2007.


I recently stumbled upon a link to this publication and found it so exciting that I selected the one quasar with the best location for my site and started exposures to see what could be possible for an amateur.

After having taken 4 hours of luminance there were objects up to mag 23 visible, but the quasar did not show up. Further investigation (lit. 3) showed that the emission spectrum of high redshift quasar starts above 800 nm, beyond the L band. Ken Crawford helped me out with his 20" scope and the IR sensitive KAF-6303 based camera with a clear filter. His 4.4 hours (narrower field) were combined with my own files. In the combined image the quasar shows up at exactly the predicted position, Maxim reports a visual magnitude of 24.8.


Position: RA 16:41:21.64 DEC +37:55:20.5 North is up.

Below you see a negative mouse-over image of the quasar area (3 arc min wide) showing some visual magnitudes (as reported from Maxim) in 150% size.


Overview discovery: 1.

Discovery publication: 2.

The redshift seven barrier: 3.

Overview active galaxies and quasars: 4.

Sky & Telescope publication: 5.

Technical Details

K. Crawford

16" cassegrain at f/10
20" RCOS at f/8.2

K. Crawford
MK-100 GEM
Paramount ME
K. Crawford
SBIG STL-11000M at -15C, internal filter wheel, AO-L
Trifid Gold 6303 at -15C
Filters Astronomik LRGB
Date June 19-25, 2007.
K. Crawford
Sky Conditions mag 5 sky, raw FWHM 1.3 - 2" for L, temperature 20;
Exposure JS:
K. Crawford:
L:R:G:B = 240:90:60:90 (30 min subexposures),
C = 255 min (15 min subecposures)
Processing Image aquisition in Maxim DL 4.56; preprocessing and deconvolution in CCDstack; other in Photoshop;