Blog Archives: Astro Sessions

Flame and Horsehead Nebula

I’ve got approx 6 hours of Ha and RGB data on the Horsehead and Flame Nebula.  I need more, I aim for around 20 hours.  In the meantime, I am enjoying practising processing using books and internet forums.  Processing is hard, no doubt about it, and it is starting to click for me albeit slowly.  I think the key is similar to normal photography.  The best images are made in the camera no amount of processing will make a poor photo amazing.  Anyway, here is the latest HaRGB combination of this target.

Processing Technique in a Nutshell

Linear Processing

Ha Linear:

  1. Dynamic Crop
  2. DBE
  3. Mask and AT Noise Reduction
  4. Invert Mask and Deconvolution using Star Mask and Local Deringing Support.  Generate PSF using Dynamic PSF.

RGB Linear:

  1. Register against Ha Linear
  2. DBE
  3. Mask and AT Noise Reduction
  4. Invert Mask and Deconvolution using Star Mask and Local Deringing Support.  Generate PSF using Dynamic PSF.

Create HaRGB Linear Image

Create a HaR image:

  1. Extract channels of Linear RGB.
  2. Use Pixel Math to create continuum map x 2. (http://pixinsight.com/tutorials/narrowband/theory/en.html)
    1. C1 = B/N
    2. Denoise using AT the C Map
    3. Use Pixel Math so Bnew = N * C1
    4. Repeat but this time C2 = Bnew/N
    5. Denoise C2
    6. Use pixel math so Bfinal = C2*N
    7. End result is HaR.

Create HaRGB:

  1. Use linear fit setting original R as reference and appy to the new HaR.
  2. Use channel combination to combine HaR with G and B from original image.
  3. Result is HaRGB.

 

Non Linear Processing

Stretch the Image:

  1. Use script Masked Stretch to initiall stretch the image.
  2. Use Histogram to final stretch the image.  Adjust channels if needed so peaks are aligned on R, G and B.

Create LSS+SSS Using Masks:

  1. Create Star Masks to generate LSS and SSS
  2. Use Histogram Transformation to stretch LSS and SSS being careful not to clip any pixels.
  3. Combine LSS and SSS using PixelMath LSS+SSS

Further Processing:

  1. Use HDRMultiscaleTransform
  2. Use LocalHistogramEqualization using clone mask and also invert
  3. User CurvesTransformation for Saturation Boost and Contrast Boost with Star Mask
  4. Use ACDNR

Finishing Touches in PS:

  1. High Pass
  2. Merge Ha with RGB again with Luminosity set to 50%
  3. Add frame and text then save for web

The Moon 19th April 2013

I had a go at some Lunar using my IMG 132E camera.  I spent around 4 hours in the cold getting to grips with the software and settings and practising focusing but I think it paid off.  Before now, I hadn’t really spent the time to learn the camera or the software, too focused on DSO imaging.

So here is a 4 panel mosaic from the 19th April 2013.

For each panel, the best 40% frames out of 1,000 frame AVI were used running at approx 18 fps.  The resolution of the AVI was 1280 x 1024, which is large!  I did experiment with 640×480 which ran at approx 60 fps but I need to revisit that.  I understand there are merits for high frame rate, but I think that may be more important for Plantary imaging rather than Lunar.  I’ll give it another go next time the moon is out over the Summer.

Processing was done in Autostakkert! and Registax 6, with a little post processing in Adobe Photoshop for final touches and saving to JPG.

Milky Way from near Saint-Jean-d’Angle

Just spent a nice two weeks in France, first to Normandy for 3 days to attempt to visit some museums (hard with a 2yr old) then to a child friendly Gite near Saint-Jean-d’ Angle which is reasonably close to La Rochelle.

You could make out the Milky Way with the eye, although it did look like a cloud.  This shot is taken with a modified Canon 40D on a standard tripod.  Around 60 x 30 second exposures were used and stacked and processed in PixInsight.  I used continuous shooting with a remote shutter locked with the button engaged since my camera is missing its USB port.  Lens was set to 10mm which equates to 16mm on a 1.6x CCD.

 

Jupiter vs. Moon

01:30 – On a night with heavy Aurora activity the Moon occults Jupiter.  In typical English fashion we were graced with the usual weather so saw neither. Surprised?  Not really.  I think I need to go to the Doctors I must have Cataracts it surely cannot be this cloudy permanently!

03:44 – The clouds have actually parted, clear skies and brilliant views of Jupiter grazing the moon.  Venus is rising nice from my visible horizon.  Got a few pics and a video to look at tomorrow.

NGC 6888 (Crescent Nebula) – HaRGB

Invested in some spacers and I think I have managed to get rid of most of my elongated stars issue with the QHY8L.  I was also graced with some clear skies for a few hours so I put the Atik 314L+ to work on the 80 ED and the QHY8L on the 100 ED to try my first ever HaRGB, which is a combination of Ha data with RGB.  So the Atik 314L+ was shooting mono through my 7NM Ha filter and the QHY8L to handle the RGB in one go (it’s a one shot colour a.k.a. OSC).

Got to say I am quite pleased with the result considering how much data I used in the final process.

Image Details

Subs: 5 x 600s from QHY8L on 100ED & 5 x 600s from Atik 314L+ on 80ED
Processing:
Calibrated and stacked in PixInsight, post processing in PixInsight and CS5.
Kit:
SW 100 ED DS Pro and 80 ED DS Pro on HEQ5 Guided with QHY5 Finder Guider.  Imaged with QHY8L OSC cooled to -15 and Atik 314L+ mono with Ha 7NM filter cooled to -10

RGB

NGC6888 RGB

Ha

NGC6888 in Ha

 

Ha RGB Combination

NGC6888 HaRGB Combination

 

 

M13 – A closer look

After some more analysis at the individual subs for M13 taken on the 12th May 2012 it is apparent that their is trailing in the stars due to poor guiding.  This combined with poor focus (which could be a result of tracking errors) and poor seeing I think has resulted in a lower quality image, lacking colour and sharp detail.  The image itself is still good in my opinion, but I was expecting better.

Take a look at the image here, this is a crop from the top left of a sub, stretched so you can see it.  I know this isn’t my usual spacing issue as the stars are not elongated toward the middle of the image (they would be stretched toward the bottom right in this image) but instead they are rotational.

I knew I had a balancing issue due to adding more kit to the mount and not correctly balancing it, this was shown also in the PHD graph which was far from flat at times.  Unfortunately, due to rushing and trying to make use of the only clear sky in months I wasted it with these mistakes.  I know for next time.  Until then, clear skies!