Feb 242010


sometimes it’s helpful to write down your goals to keep track of them in a busy life. Ok, here my imaging and astronomy related goals for 2010:

  • Image Mercury
    The quick messenger of the gods is a hard nut to crack due to it’s small apparent diameter and close elongation to the sun but there are a number of days around the maximum elongation periods that offer best conditions to image mercury in daylight. I never imaged mercury before and am curious if I’ll be able to capture some surface details. Mercury is very fast on it’s orbit around the sun but rotates very slow around it’s own axis. It’s possible to capture thousands of frames within several hours and select the best of them for stacking. Using an IR-pass filter or red filter helps to increase contrast during daylight and tame the seeing.
  • Image Saturn
    Saturn opposition 2010 is coming soon. I hope that weather is getting much much better than it has been over the last months.
  • Solar imaging
    The currently beginning solar activity cycle should provide interesting targets to image the sun in white-light, CaK and H-alpha. I should finish the upgrade of my PST to a larger aperture.
  • Lunar imaging
    Nothing much to write. If the opportunity is there, I’ll be imaging :)
  • Captifier
    A first working test version has to be in place soon. Constant development will follow.

Let’s see what turned out to be realistic at the end of the year…

Solong & cheers,

Feb 232010

quick update: I added a mercury 2010 chart to the ephemerides. Quite a lot opportunities to image mercury at max. elongation during daylight – I’m looking forward to the messenger of the gods.

Click for details

Cheers, Oliver

Feb 212010

skies have been clear around 21:00 last night but until I had setup and collimated the already cooled C11 clouds rolled in again. Seeing was not bad at all but I managed to shoot only 1 AVI with 1400 frames with the red filter before skies were completely covered and first snow flakes started to fall :( This Mars opposition isn’t mine…
I used 700 frames of the only AVI and processed the stack differently than I usually do, not too bad considering the circumstance.

Click for larger version

Cheers, Oliver

Feb 042010

I had to fiddle with a number of issues delaying the advancement in the project.

  1. GDK/GTK+ is not thread aware under Win32
  2. Polling a file descriptor under Win32 does not work using VC++2008 since GLib is compiled against msvcrt.dll and it’s almost impossible to convince VC++2008 to do so
  3. GTK+ 2.18.5/Cairo has a bug on Win32 giving an incorrect Windows GDI device context for a drawing area

To continue with the project I gave up inter-thread messaging  and sacrificed the separate grabber-thread. Polling frames from the camera is now done in the idle callback of the main loop and only saving data is done in a separate thread. This should still be a sufficient task splitting on a two core processor to achieve seamless captures at high framerates.
Reverting back to GTK+ 2.16.6 fixed the window DC bug. OK, time to move on with the actual tool development, I still don’t regret not using MFC :)
Overall CPU utilisation looks good running the tool at 60fps, performance should be ok. I changed the provisional GUI to a one window look:

Cheers, Oliver

Feb 012010


some drawbacks regarding Captifier: After a lot of debugging, testing and trying workarounds I finally read that GDK (and thus GTK+)  is not thread-aware under Win32 as it is under Linux. Great, I found that out, too Рthe hard way ;)
I’m currently evaluating two alternative strategies to overcome the issue: Interthread-messaging to announce frames to display or integrating the grabber thread in the main thread… The decision will depend on the camera interfaces that are planned to be integrated sooner or later…

Best, Oliver