SKY WATCHER 10" Newtonian Astrograph
A few years ago, Sky Watcher created a new series of fast newtonian telescopes that are F/4 and they called them "Quattro", which in Latin means "4". Those kind of telescopes when we started doing astronomy were pretty rare and expensive but now made simple and affordable for anyone.
A week ago we decided it was time to upgrade our gear from the old 8" f/1200mm Orion UK we were using to a new big and fast telescope that would be great for astrophotography and science imaging all together, as we love not only to do pictures of the galaxies and nebulas, but also doing some variable star and exoplanet photometry. So we purchased the Sky Watcher 10" F/4 Quattro Newtonian telescope, we actually new the 8" telescope of the same family by a friend of ours who owns one, but we never imagined how exciting this instrument will be. The 10" is a pretty big and heavy telescope and it is on the limit of our old Orion Atlas EQG mount (the same model as the Sky watcher EQ6 but on black colour), the weight of the OTA (optical tube assembly) is about 15.1 kg and when we added the CCD, filter wheel and guide scope, the total weight went to 16.4 kg.
Oh, we love that telescope
Here we need to mention a few more things about that telescope. First of all we love the dual speed focuser, it is a really nice focuser were you can easily adjust a motor controller and use it by your astrophotography software. It is also very well build and steady enough to hold our Canon EOS6D full frame DSLR or the SBIG ST8300M CCD camera with the 2" Atik filter wheel. Also we loved the internal buffers for managing the stray light (especially us who do astronomy from the center of Athens, a small city with more than 4.5 million people living in). This is probably the best ad on for that big telescope. The only thing that we did not like about that telescope is that the main mirror is completely exposed to the elements, which is great for fast cooling of the telescope, but also great for light coming inside the telescope from the back of the mirror. We managed to address this issue by using a small piece of black cloth to cover the back of the telescope just before we start our session.
First light, and then Second light
After unboxing the telescope and fitting everything on the new rig and the old mount, we decided to do some testing to see what we actually have in our hands, we must say we were pretty much excited to see this scope in action as we have seen other telescopes like that and they were perfect. The first night was really amazing, a brand new mirror and a fast focal length was ready to shoot some stars and get an exoplanet lightcurve, the target was set to be WASP-92-b . With the old 8" newtonian for the same target we needed about 120sec exposure time, but now with this bigger and faster telescope we only had to use 90 second exposure time.
RA 16h 26m 48.2s, Dec +51° 02' 51.6" Pos Angle +359° 23.4', FL 1000.4 mm, 1.11"/Pixel
Field of View as annotated by "nova.astrometry.net"
The night had amazing clarity and no wind at all to move the telescope on the mount, but there was a jetstream that made the seeing conditions to go terrible. Nevertheless we were already outside capturing data, and a few hours later we got the results.
As you can see on the graph above, because of the bad seeing conditions we had a big scatter on our data, and also we lost the beginning of the eclipse. But we must say at this point that this already looks better than the data we were capturing with the old telescope.
After a few days of more clouds, a second night was clear for us to do the star test, we decided to go as usual, monochrome and narrowband on a nebula, and the reason for that is that we live in the center of light pollution of Greece. The target was NGC-2264. Unfortunately due to bad weather again we collected only 7 frames of 5 minutes exposure each on Hα' filter, but even that was really enough for the new telescope to show how good it is.
Here we feel it is time to talk about a big problem of this telescope ... Comma. Because this telescope is big and fast, it means that it has a lot of "comma" almost in the entire FOV which is not noticable when you image with a small sensor camera, but it is very obvious with a camera like the one we use that is equipped with the KAF8300 sensor. So for astrophotography it is absolutely useless unless you use a separate glass that is called "Comma Corrector".
In the short future we plan on getting a comma corrector for that telescope in order to start doing some serious astrophotography, for now we will do more exoplanets and we will keep you up to date with these projects.