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Sh2-132 in Narrowband

Both of my WO Star 71s are back from China (see previous post), cleaned, and as good as new.  Maybe better.  It took a few days after their return for some clear weather to arrive, but I was so happy to have them back.  William Yang was a good guy to deal with in this whole matter.

Sh2-132 is an odd nebula in that it can be hard to find.  Not so much because it’s not a reasonably bright narrowband target, but because it has no appeal to visual observers, so it’s not well-marked in most atlases.  Not all of the Sharpless objects are worthy targets (in fact the majority are duds), so it can be hard to tell that this one stands out from the emission nebula crowd.

It’s a photogenic target in the Hubble/SHO palette if you can take enough exposures to reveal the details, and several amateur images of it have popped up this season.  The SII is particularly dim, and if I could do it again, I would double the exposure time there.

Sh2-132 in the Hubble/SHO Narrowband Palette

Sh2-132 in the Hubble/SHO Narrowband Palette

Image data:

  • Exposures: 42 x 10 min Ha, 41 x 10 min OIII, 43 x 10 min SII
  • Telescopes: Two William Optics Star 71s (360mm f/5)
  • Cameras: SBIG ST-8300M and QSI 583wsg, 2×2 binned
  • Mount: CGEM
  • Guiding: QHY 5L-II mono, guided using PHD2
  • Conditions:  wind gusts over 25 mph… far from ideal
  • Processing: DeepSkyStacker, PixInsight, Photoshop
  • Dates: Oct 25-27, 2014
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  1. Renae Gage
    November 17, 2014 at 1:48 pm

    Gatsby,

    Thanks for the running commentary on this scope. It is on the top of my watch list for reasons similar to your own. I image with a QSI683, so I am very curious about your experience with the focuser and the CCD, as this is obviously much heavier than the DSLR on which your initial comments on the focuser were based. It appears that you are still focusing by hand. How would you rate this on the scale of misery? Are you aware of any motorized options?

    Thanks,

    Renae

    • November 17, 2014 at 7:49 pm

      Hi Renae –

      The focuser works just fine with the QSI583 for me (as well as the ST-8300 with FW8300-8, which I think is heavier). Tightening the rotator cured any sag I was getting initially. To focus manually, I use a Bahtinov mask, so no misery at all. At f/4.9, it is very sensitive to focus, but the locking mechanism doesn’t shift the focus, and it seems temperature-stable. Typically, when I start a second night of imaging and check the focus, it is still locked at optimum focus from the previous night. At this point, I have no plans to motorize, though I’m sure you could use either a Robofocus or nSTEP focuser solution for it.

      Best,
      Charlie

      • Renae Gage
        November 17, 2014 at 8:11 pm

        I use the fine focus aids on Nebulosity. My issue isn’t that fine focus can’t be detected by a mask or software. Rather it’s that any manual focus necessarily shakes the scope and destroys that detection, so that the best one can do is closer and closer guesses. Motorized focus eliminates this problem. It is good to know that the focus lock doesn’t screw up your position though. Thanks again for great info.

        By the way, I think your dual 71 system for narrowband is genius, given your conditions. I have somewhat darker skies to play with, but if I ever go narrowband to any greater extent, I’ll be copying your system. Nicely played.

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