Recently with the installation of the Orion Optics VX12 telescope in my obsy, nearly everything was in place for me to try astroimaging with my Celestron CGEM in my obsy. On Monday night, I finally had the clear skies to try this out.
Now the thing to note is that the entire imaging setup is at the maximum weight limit of the CGEM ~ 18kg, so I was not expecting it to perform perfectly – that would require an upgrade to a much better mount. But I wanted to see if my obsy protecting the telescope from the wind would at least give me a better chance of getting 2 minute subs of deep sky objects without the need to upgrade the mount, as this should allow me to attain enough data to process and get good images of many different small DSOs.
I decided to turn to the Whirlpool Galaxy M51 for my first subject. Imagine seeing this DSO fairly clearly on my laptop screen with just a 2 to 4 seconds of exposure at the maximum gain of the ZWO ASI178MM-cooled (Gain 510). This clearly allows me to adjust the object to be well centered on the screen.
I ran into 2 unfortunate problems that night which I could not resolve and hence I was unable to capture any useful images for processing. This I had to fix during the daytime on Tuesday, so I could have another try at it when the skies are clear again.
The Prolific PL2303 USB-Serial converter I bought from eBay to allow the laptop to connect with my Celestron CGEM could not work, as the wrong driver was installed by the system. I was hoping to use PHD 2 for guiding my imaging setup. It was only in the morning that I managed to solve this by selecting the driver manually for this adapter (using the 184.108.40.206 – 07/10/2011 driver, instead of the newer driver from 2015). So now I can actually control the CGEM with my laptop. Great!
Because I could not control my CGEM using the serial cable, I had to resort to connecting via the ST4 guiding port of the guide camera (QHY5L-II mono) to the autoguider port of the CGEM. This did not work as it just could not connect and hence I could not calibrate the guiding – this step wasted most of the time that night. In the morning, I also found out after searching on the internet that this is a known problem with this camera and PHD 2. But now that problem 1 is solved, I don’t need to worry about solving problem 2.
Test image from the night:
As a result of all the problems I encountered, I only managed to grab one unguided image during the whole session using Gain 200 2 min sub with the ASI178MM-cooled. It does have oblong stars owing to the lack of guiding. But I just wanted to show what I was seeing that night and my setup could do (and hopefully even better with pinpoint stars). Just bear in mind that M51 normally appears very small in images I’ve seen on the internet, even with significant cropping. The image below is actually uncropped (only resized down for the web), and shows that M51 fills up quite a fair bit of the sensor – a benefit of using such a small sized sensor when imaging small deep sky objects.
This highlights the fact that the ZWO ASI178MM-cooled is not only a great camera for astroimaging, but it can also be useful for video astronomy. Clear skies.