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Posts Tagged ‘william optics’

Cocoon Nebula (IC5146) Widefield

January 24, 2016 1 comment

I used the snow day here in the northeast to get started on the backlog of raw data from the fall that I haven’t processed.  This is the Cocoon Nebula, with its dark nebula friend, Barnard 168.

Cocoon FINAL v2

I actually took a full night’s worth of H-alpha data, but decided to use only the RGB data here, as a slight misalignment of the telescope shooting the H-alpha would have required a different cropping of the image.

Image data:

  • Exposures:  15×10 min R, G; 18×10 min B (2×2 binning) – total exposure time:  8 hours
  • Telescope: William Optics Star71 (360mm f/5)
  • Cameras: SBIG ST-8300M
  • Mount: Takahashi EM200
  • Guiding: QHY 5L-II mono, guided using PHD2
  • Conditions:  good transparency, calm winds
  • Processing: DeepSkyStacker -> PixInsight -> Photoshop
  • Date: Sep 14 and 17, 2015

Evaluating the full-frame performance of the William Optics Star71

January 23, 2016 1 comment

I’m excited to start imaging with my new Canon EOS 6D.  Having a full-frame chip will allow some very widefield shots that would require mosaics with a 4/3 sensor, like the KAF-8300 cameras I use most of the time.  Since conditions were less than ideal, I used the first couple of nights out to run some tests.  First up is a test of the 6D with the Star71.

The obvious target:  M42.  Below is a very brief exposure (17 min total, in 15s subexposures).

M42 17 min

That is a very wide field.  5.8 x 3.8 degrees.  I didn’t even intend to include the Horsehead Nebula when I pointed the mount at M42, but the field is so wide, I accidentally captured most of it.

Are the stars sharp out to the corners?  Yes.  The image below is a crop of 100 pixel squares from each corner of the above image.  No star reduction was done in any of these images. The performance is really good.  A little distortion on the right side, but quite tolerable.

Corners

What about vignetting?  I estimate less than 10% light falloff between the center and the corners from the flat frame analysis below (the image is highly stretched to reveal vignetting).  Note that there is a dark band across the bottom.  This was consistent across my images, and I’m not sure of the source, but I suspect something to do with dcraw (this image was imported into PixInsight, which calls dcraw for conversion).  DeepSkyStacker seemed to have trouble with some of the 6D’s images too.

vignetting

The 6D and Star71 are a good pair, and it’s nice to have a DSLR again for simple one-shot color imaging, especially for wide fields.  Once I get some adapters, I look forward to running the same test with the Takahashi FSQ-106ED.

The Pleiades (M45)

January 10, 2016 Leave a comment

Somehow, I’ve never really captured an image of The Pleiades (M45). Such a bright target directly overhead, but I was mostly looking for narrowband objects instead, I suppose.

Pleiades final 8x10 crop

This image was processed entirely in PixInsight, except for the final rescaling and jpeg conversion.  I’m moving more in that direction. Frustrating and unforgiving it is, but powerful.  For such a bright object, the dust makes it more challenging to process than I’d expected.

Image data:

  • Exposures: 20×10 min L (1×1 binning), 8×10 min each R, G, B (2×2 binning) – total exposure time:  7h 20m
  • Telescopes: Two William Optics Star71s (360mm f/5)
  • Cameras: SBIG ST-8300M and QSI 583wsg
  • Mount: Takahashi EM200
  • Guiding: QHY 5L-II mono, guided using PHD2
  • Conditions:  fair transparency, calm winds
  • Processing: DeepSkyStacker -> PixInsight
  • Date: Jan 2, 2016

The Heart Nebula, IC1805, in Narrowband

January 27, 2015 Leave a comment

This is one of my favorite deep sky objects, especially for narrowband.  It just fits on an KAF-8300 chip at 350 mm focal length.  The small cluster in the core is Melotte 15.

I took three nights of exposures, which were spread over 41 days due to poor weather and holiday trips.  Maybe next year when Cassiopeia swings into view, I’ll make a similar project of the Soul Nebula nearby.

The Heart Nebula (IC1805)

The Heart Nebula (IC1805)

Image data:

  • Exposures: 32 hours total: 96 x 10 min Ha, 43 x 10 min OIII, 53 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:  mild winds on two nights
  • Processing: DeepSkyStacker -> PixInsight -> Photoshop
  • Date: Nov 21 2014, Dec 31 2014, and Jan 1 2015

The Cone Nebula/Fox Fur Nebula/NGC2264 Area

January 24, 2015 Leave a comment

Between snow storms, I’ve been able to squeeze in the occasional night of imaging.  It was a less than ideal night–poor seeing and all sorts of polar alignment issues plagued me–but I’m please to finally have an image of the Cone Nebula… or Fox Fur Nebula if you prefer…or Christmas Tree Cluster.  Whatever you call it, putting NGC2264 (the cluster) into your goto mount will get you there.

Somehow, I’ve never captured this one before.  That region of the sky has so many highlights (M42, IC2177, The Rosette, Horsehead…) it takes several years to get to them all.

Cone Nebula Widefield in H-alpha

Cone Nebula Widefield in H-alpha

Image data:

  • Exposures: 39 x 10 min H-alpha exposures
  • Telescopes: William Optics Star 71 (360mm f/5)
  • Cameras: SBIG ST-8300M, 2×2 binned
  • Mount: CGEM
  • Guiding: QHY 5L-II mono, guided using PHD2
  • Conditions:  calm, but damp
  • Processing: DeepSkyStacker -> PixInsight -> Photoshop
  • Date: Jan 22, 2015

A Quick Look at Comet Lovejoy C/2014 Q2

January 23, 2015 Leave a comment

It’s not often that we get a bright comet so high in the sky.  Luckily, I was able to seize a couple of hours of clear skies to image Comet Lovejoy while it was in Aries.  I took separate L, R, G, and B exposures across a 1×4 mosaic, since I knew the tail could be really long.  This extended tail was also very dim, barely showing with 3-minute exposures.  Because comets are moving targets, I only took a single 3-minute exposure for each channel, then moved the field of view.  You can actually see the effect of this movement a little in the head of the comet, where the L exposure came about 20 minutes after the R.

Comet Lovejoy, Jan 20, 2015

Comet Lovejoy, Jan 20, 2015

It’s easy to lose your sense of scale here.  This is a tremendous field of view.  Below is one of the uncropped mosaic images used to generate the above. Each of the four overlapping frames you see is 2.9 x 2.2 degrees, so the total field of view is around 7 x 3 degrees!

Uncropped mosaic view

Uncropped mosaic view

Image data:

  • Exposures: 1 x 3 min L, R, G, and B exposures in a four-part mosaic
  • Telescopes: William Optics Star 71 (360mm f/5)
  • Cameras: SBIG ST-8300M, 2×2 binned
  • Mount: CGEM
  • Guiding: QHY 5L-II mono, guided using PHD2
  • Conditions:  calm
  • Processing: DeepSkyStacker -> PixInsight -> Photoshop
  • Date: Jan 20, 2015

The Bubble and the Lobster Claw

January 10, 2015 Leave a comment

There is an area on the border of Cassiopeia and Cephus that’s packed with deep-sky objects, including the assortment shown here.  The main nebula here is the Lobster Claw, Sh2-157.  Above it and to the right is the famous Bubble Nebula, NGC7635. In the upper right is the cluster M52.  The nebulae at middle right and lower right are Sh2-159 and NGC7538, respectively.  The very dim nebula the goes off the right edge of the image is Sh2-161, and the little star cluster at middle bottom is NGC7510. So that’s at least five distinct nebulae and two star clusters (there would be more if we considered how other catalogs, like the LBN and IC, define the objects).

The Bubble and Lobster Claw NebulaeWith all of that said, this is the second year I’ve imaged this area, and I haven’t been happy with either result.  The Lobster Claw is not particularly photogenic, and it’s fairly hard to process well.  Given the chance to do it again, I’d probably either use a longer scope to focus on the Bubble Nebula alone, or go even wider with a telephoto to capture the sea of nebulosity in the whole area.

Image data:

  • Exposures: 60 x 10 min Ha, 33 x 10 min OIII, 27 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:  strong wind gusts
  • Processing: DeepSkyStacker -> PixInsight -> Photoshop
  • Date: Nov 18 and 20, 2014
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