BKSo, on 30 Dec 2016 - 08:18 AM, said:
I tried to observe the quasar last night with my 4"sct under a red zone sky without suceed I could not even identify the star field. The question is what kind of sky does it take to observe this target with a small telescope
"When bright" It should be an easy target in a 4" SCT, but unfortunately we have light pollution/haze etc...
I had a similar "impossible" challenge, when I first attempted it and the Mag 7.2 HD212989 signpost was impossible to find in my 8" SCT!! - All you can do is try another night and get away from city lights!
With regards to locating:- I started by copying the S&T finder chart and performing a mirror image and then rotated 180 degrees to make North the top, such that it exactly matched my SCT view through a diagonal. I also chose an eyepiece to give me a ~1 degree FOV (similar to the 1.2 x0.8 degree chart) so I had a good sense of scale.
As the wide S&T chart is not ideal to easily locate HD212989, I used 7x50 binoculars to familiarise myself with the area. I ran an old computer program (I like Skyglobe, but any will suffice) to help identify it's exact location.
The C5 (125mm SCT) Telescope was now 'knowingly' pointed at HD212989 and then used to 'hop' to the correct area using the S&T detailed chart. I must confess, I did familiarise myself with the chart first. (Note only the brighter stars will be visible)
It soon became obvious, that a point of light did not belong there. I then looked for nearby patterns of stars to ensure I was observing the correct spot and hence confirmed I had identified the Quasar.
In my C90 (90mm Mak): Due to light pollution/haze, the Quasar was only occasionally visible using adverted vision. So I had concentrate my gaze to one side of where I suspected it to be. This places the star on a more sensitive part of the retina. It takes practice, but will often allow you to see a magnitude fainter.