It's Working!
Well, what a difference some patience and a change of tactic makes to astro work.
The weather and cloud forecast last week was looking good (although very cold!) so I decided that I would have a try at fully automating the entire astro setup - no more trying to do a 3-star alignment / polar alignment routine via the mount’s hand controller.
I don’t have any sort of cross-hair markings on my camera screen so had no way of accurately determining when the target star was centred properly and contouring myself into a pretzel to see through the eye-piece (or at the screen) just wasn’t fun any more.
So I set everything up - the laptop, the PoleMaster camera, the guide camera, and (taking a large leap of faith) using Ekos to control my DSLR via it’s USB connection.
The polar alignment routine with the PoleMaster camera and software went smoothly. The hardest two parts were getting the mount roughly aligned to the South Celestial Pole and then identifying the Octans asterism on the laptop screen. Eventually I got Octans visible on the screen and was able to complete the alignment.
I have to say that this was a lot, lot easier and much faster than trying to follow my previous attempts. I had a near-perfect PA inside 5 minutes.
The next step was to jump across to KStars / Ekos and see how accurately the mount would slew to a target.
The choosing a target and slewing to it is a trivial exercise, then a jump to the Ekos ‘Align’ tab. Check the camera settings are OK and then simply select ‘Slew to target’ followed by the ‘Capture and solve’ button. The initial slew was out by a couple of degrees (something like 10,000 arc-seconds) but within a couple of iterations, the scope was pointed at the target to an accuracy of under 30 arc-seconds.
To the guiding tab, and all I had to do was hit the ‘Guide’ button. The settings I had were OK, and I could see the images the guide camera was capturing, a few minutes of Ekos doing it’s stuff and the mount was tracking to about 2 arc-seconds of accuracy. Depending on the sky quality in my suburban backyard, this could fluctuate between under 1 arc-second and as high as 10 arc-seconds.
For my telescope with it’s very short focal length of 357mm, this is totally perfect accuracy. If I was using something longer (like a 1000mm or higher focal length) then 10 arc-seconds might not be good enough.
Now I just need to get the focus sorted out. Then the stars will be crystal clear and as sharp as they can be.
So my workflow is now as follows:
- Set up all the gear and have it ready to go - mount, camera, dew heater, guide scope + camera, laptop, mains power supply
- Use the mount’s hand controller to do the initial setup (location, time) and then set it to “PC Direct”
- Fire up the laptop, start KStars and use Ekos to connect to the mount (as we need the slew it manually during the polar alignment operation)
- Start the PoleMaster software, connect to the camera and configure it (Southern Hemisphere, and camera settings so I can see the stars clearly)
- Polar align
- Stop the PoleMaster software
- Jump back to Ekos
- Disconnect from the mount, and then connect to all the devices that I’ll be using (mount, DSLR, guide camera)
- Go back to KStars planetarium screen and tell the mount to move to my chosen target
- Go to Ekos and perform an alignment sequence to fine-tune the pointing of the telescope
- Begin guiding
- Once guiding is working, over to the camera tab, set up the number of images I want, with the correct duration and ISO and hit the ‘GO’ button
- Copy the captured images from the laptop to the image processing machine
It’s not quite a perfect workflow, as I also need to focus the telescope. But I can’t do that easily, as I don’t have a visible target when the mount is in it’s ‘home’ position. So I usually end up doing it after the ‘slew to target’ step. Except I need to disconnect the DSLR from Ekos to use the LiveView function, and then I can’t reconnect to Ekos without shutting down and restarting KStars… It’s a pain in the arse, but I’ll solve it.
Once I have the required number of images (usually around 100 - 150 short exposures when working under a light-polluted sky) I’ll move to another target and repeat steps 8-12.
My next goal is to get to a dark sky site and get some longer duration images captured. Battling with light pollution is not much fun at all.