John Hothersall
21-07-2012, 06:52 PM
SPX350 F4.5+F9, Mintron, Baader RGB filters. IR742nm filter.
Been looking through a list of distant quasars and red shift of 5 at 21st mag seems the limit but this one was very bright and in Eastern Sag away from Milkyway. With z=3.7732 at 12bn yrs old (calculated with Hubble parameter at 70.8 km/s/Mpc) was at mag 17.6. Tried it at 2 focal lengths but night was breezy.
Imaged it with no filter then with RGB. IR742nm seemed little different from the red filter.
First image No filter+RGB F4.5.
no filter 25min RGB 10min each 2.56sec subs.
Second image IRGB at F4.5.
IR742nm 30mins GB 10mins each.
Third image No filter F9.
no filter 25mins 2.56sec subs.
Thanks, John.
Been looking through a list of distant quasars and red shift of 5 at 21st mag seems the limit but this one was very bright and in Eastern Sag away from Milkyway. With z=3.7732 at 12bn yrs old (calculated with Hubble parameter at 70.8 km/s/Mpc) was at mag 17.6. Tried it at 2 focal lengths but night was breezy.
Imaged it with no filter then with RGB. IR742nm seemed little different from the red filter.
First image No filter+RGB F4.5.
no filter 25min RGB 10min each 2.56sec subs.
Second image IRGB at F4.5.
IR742nm 30mins GB 10mins each.
Third image No filter F9.
no filter 25mins 2.56sec subs.
Thanks, John.