Sunday, August 25, 2013

Another imaging automation program: Sequence Generator

By chance I read about Sequence Generator Pro. It's another imaging automation program - for WAY less then the programs that I looked into before. One of the most interesting features for me is that it integrates with PHD guiding. I was always struggling with TSX guiding. The other interesting "feature" is its price: $99!

I downloaded SGPro, installed it, read the helpfile and watched some of the tutorials. It has a very different concept then CCDAP:
  • It's based on profiles which describe the system setup (scope, camera, guiding, plate solver, filter wheel...) This is actually very good for as I will image with at least 2 configurations (hyperstar and focal reducer).
  • It doesn't integrate with TheSkyX which means that object selection isn't through a planetary software, but the "Frame and Mosaic Wizard" is actually really good.
It's definitively somewhat rough around the edges - many things have to be manually configured or installed. It took me a week to configure and setup everything:

  • The frame wizard relies on an external service (which was down for a day). But the good news is that it caches all downloaded data and images, so I can use those later again.
  • Automatic focussing: it's a very straightforward process. It took me a while to find the right step size though. I ended up running the focus routine with a step size of 2 and checked how many points were in the critical focus zone (the plateau of the curve).
    I then had to play with each filter to figure out which exposure time to use. I increased the exposure time step-by-step until the focus curve was smooth.
    I had to set "stop guiding during focus routine" - because I'm using an OAG, autoguiding is naturally severely affected if I change the focus too much. The last remaining issue is, that SGPro instructs PHD to select a guide star before the focus routine, then it stops guiding, runs the focus routine and restarts guiding with the previously selected guide star. But now, the guide star isn't in the same location anymore and PHD has to do some crazy guiding to get it back into center. I asked on the mailing list. Jared (one of the developers - they are both crazy active on the mainsequencesoftware mailing list) didn't have an idea how to accommodate for this, but will think about it.
  • I used this as an opportunity to start using PHD2 - which works very well. To avoid guiding on hot pixels, I have to use darks. A great advantage of PHD2 over the previous version is that it can re-use darks for subframes and doesn't try to take a new one. I had to set the threshold after which SGPro starts taking images to 0.5 - that's already pretty low for my backyard conditions.
  • SGPro uses plate solving for every slew - which is great. Makes it very reliable. Initially, I tried to use Elbrus, but it didn't always work. I then switched to astrometry.net which works great. But now I am relying on an external service - which is bad when I take the scope out. Fortunately, there is a local astrometry.net setup that I can use.
  • It was strange that I had to set the "auto meridian flip" bit - I had expected that it is set by default.
  • SGPro reads the configured ASCOM devices and offers these directly. That avoids the popup when connecting where you have to choose the ASCOM device. Nice!
  • Naming of the images is great!
  • I tried mosaics, meridian flips during imaging, multiple targets - all works very well.
  • The built-in Image Grader is great for a quick analysis of acquired images.
The only missing thing (for me) are dusk/dawn flats. It was very convenient with CCDAP to just setup the scope, rough align it and then start the CCDAP flat routine. It would wait until it's dark/bright enough and run through all the filters, dither and adjust exposure times. I wish SGPro would implement this as well.