M51 – The Whirlpool Galaxy

After about two months of bad weather on the week-ends I was finally able to make it to Anza on April 20th 2012. I already knew I was going to shoot at M51 but I was pretty excited to test my new guiding setup.

Being caught in traffic made me arrive pretty late and was forced to setup in the dark. That went OK but I quickly realized that I was going to have some problems with the OAG.

I have no dark sky at my house to even roughly test things out but I did do some tests during day light. The electrical pole I aim at was probably too close as I was never able to reach focus on stars. That was a bummer but fortunately enough I just had to remove one of the large threaded extension on the 8″ RC to fix that. Then I realized that I really didn’t need any 1.25″ extension for the SSAG once the large extension was removed. But finally and sadly, I realized that the SSAG wasn’t sensitive enough to make out of the faint stars around DSO’s. I slew to some Magnitude 4 and 5 stars and the SSAG was able to see them, but really what can I do when there is just nothing that bright around my DSO’s? I quickly decided to move on and reinstall the SSAG on my AT65EDQ and start guiding the same old way.

I also realized that the AT2FF field flattenner isn’t working that great when installed this far from the CMOS sensor. I think that if I am able to get my OAG setup working, I will have to lose the Field Flattenner. Anyway, I’ve now got some more research and thinking on the table.

Back to M51. Because I lost so much time with OAG problems, I decided to spend the rest night working on M51. I tried some new PHD settings (i.e. longer calibration steps) and it did seem to make it both more reliable and more accurate. I started off with 5 minutes subs and moved to 10 minutes subs. As usual I like to combine long and short exposure to widen the dynamic range of my astro-photographs. I ended up with 3.25 hours of data. I stacked the images with DSS in EWA mode. Calibration included both temperature matched dark frames and flat frames. Final post processing was done with Pix Insight.  Technical details listed under the picture!

  • Date: April 20th 2012
  • Camera: Canon 500D Baader Modified and CP30T-EOS Cooled (Sensor maintained at 10 C – Exif temperature: 10 C)
  • ISO: 1600
  • Exposures: ~ 3.25 hours of integration time (300 s and 600 s subs)
  • Mount: Losmandy G11 Gemini 2
  • Imaging Telescope: AT8RC w/ AT2FF
  • Guiding Telescope: AT65EDQ w/ SSAG
  • Calibration: Darks, Flats
  • Stacking: DSS (Entropy Weighted Average)
  • Final blending/processing: PixInsight 1.7 and Adobe Photoshop CS5
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