Very Amateur Astronomy

I’m pretty happy with these, I sat down last night intending to play Skyrim and instead and instead spent and hour or two playing around with the new MultiscaleMedianTransform and HDRMultiscaleTransform tools in Pixinsight. I based my approach off of the short tutorial on the Pixinsight forums.

First off the Cocoon.

I’m finally happy with this image, the dust clouds which have so long evaded me and now there and the dark nebula is really standing out.

I applied the same technique changes ot the Cave as well:

And again the improvement in clear to me, much more depth and contrast in the fainter areas. Now all I need is a clear night on a weekend without a bright moon so that maybe I can take something new!

Right, time to get back on with this and catch up on the last three months of work, though the past six weeks have not seen anything new due to a leg injury which the GP diagnosed as a bad sprain, and the specialist (with the aid of an x-ray) diagnosed as a fractured fibula, but only after I had been walking around of it for nearly five weeks.

Anyway, lets see what I have been up to.

NGC7380 – The Wizard or Flying Horse Nebula

43×5 minutes (215 minutes total)
250mm F4.8 Reflector
Canon 1000D (Modified)

A challenging object from my light polluted garden and really it begs for a better camera to really get the most out of it. I’ve been playng with this image in Pixinsight using some new tools in an attempt to get more out of it so there may be another reprocessing post at some point.

Caldwell 9 – The Cave Nebula

50×6 minutes (300 minutes total)
250mm f4.8 Reflector
Canon 1000D (Modified)

This came out much better than expected, and is a great region for imaging. This is also the image which saw my long running guiding issues with the CGEM finally sorted, which basically meant ignoring every bit of advice on the Yahoo CGEM users group and doing exactly as the PHD instructions recommend. No backlash correction, only guide in one direction on DEC and use a well trained PEC curve.

NGC7129 & NGC7142

58×6 minutes (348 minutes total)
250mm f4.8 Reflector
Canon 1000D (Modified)

NGC7129 is the reflection nebula,NGC7142 is the open cluster on the right.

Ngc7129 doesn’t appear to have a special name of it’s own, though I’ve heard it described as looking like a rosebud, personally I see a light bulb, with the orange glow of the edge of the bubble inside the blue reflection region being the filament. Reflection nebula, especially ones this faint are a real pig for me to process, I really didn’t expect to much form this to be honest. Although it’s not spectacular I’m happy enough with the end result.

Jupiter

Click on the images to see the animation

I spent a night testing out the OpticStar PL-131C camera as a planetary and lunar camera. I have been using it for guiding since August and for that purpose it is at least reasonable, though the sensitivity is a bit low so it does force you to hunt around for good guide stars. However I had hopes that it would make for a decent planetary camera, or at least an improvement over the modified webcam.

This animation is made up of around one and a half hours of data, a mixed bag of frames depending on the seeing but a nice result.

The same data, keeping those image in which Io was visible.

This is one of the videos which make up a single frame of the animations, the seeing was pretty good that night, very stable. I do need to invest in a 5x Barlow at some point though.

The Moon

My last image is a six frame mosaic of the moon taken with the Pl-131c through my 250mm F4.8 reflector at prime focus. To see this in it’s full glory I’d suggest clicking here to view the full sized image.

So that’s it for the last few months, hopefully now my leg is improving I’ll be able to get back to it, though the first thing I need to be doing is rearranging the shed to move the desk area to the door end so I have space to work. I’ll be doing that this weekend

The wife’s television schedule is causing more time hiding in the office than normal of late, and Fallout New Vegas can’t hold all of my attention, so instead I’ve been spending a bit of time browsing the Pixinsight forums looking into some alternative methods of imaging processing. Mainly of interest to me was the very excellent Masked Stretch script. I’m not the person to give a detailed description of how it works, but in a nut shell is performs a non-linear stretch of an image to reach a set median background level whilst controlling object growth, namely stars bloating.

I’ve also been refreshing my memory on the correct use of HDR Wavelet Transform, ACDNR, DBE for images without much background and Colour Calibration. Putting that all together I have taken a second look at three recent images to see what comes out of the other end.

The Elephant’s Trunk  Nebula I think came out the best, showing cleaner detail, better colour and contrast and a more uniform background.

My Cygnus Core image also shows great improvement I think, though I may have let a small green tinge in whilst dialling back the red. However overall I think it’s a solid step forward.

The Cocoon nebula once again, this image has become the bain of my life and even though this is a major improvement it’s still not where I want it to be. Faint dust clouds seem to be a problem for either my location, equipment or processing skills, I’m just not sure which.

A bit of sneaky in between the clouds work netted me a few hours over the weekend of reasonably clear viewing, and a good chance to test that everything was working after the trip down to France and back. As it turns out the only thing to have given up is the PC in the shed, which has had intermittent problems with video output for a while despite being tried on three separate video cards. A new motherboard may be in order there, or perhaps just an ST4 to USB converter so I can use my new laptop down there instead as it is much faster. For this weekend I dug out my old and somewhat unstable laptop as at least if has both serial and parallel ports and can talk to everything!

There is something to be said for makers of astronomy equipment taking up a method of connectivity which is actually to be found on modern computers. The inclusions of a standard ethernet port on the Vixen Sphinx is perfect. The iOptron IEQ45 mounts have USB connectivity as standard as well, so perhaps there is some movement towards this, a pity Celestron didn’t push further with the CGEM to make it stand out more from the EQ6 it is cloned from.

Anyway, hunting around for something to image I went back to my copy of The 100 Best Astrophotography Targets for inspiration and decided upon the Elephants Trunk nebula in the IC1396 region of Cepheus. I managed to grab a couple of hours on both nights, though some strong winds, annoying clouds and unwanted movement whilst imaging near the zenith caused a few lost frames.

• Canon 1000D (Modified)
• Astronomik CLS-CCD Filter
• Orion Optics 250mm f4.8 Reflector
• 29 x 5 minutes (21 x bias, dark and flat)

I have been on Holiday for two weeks to the Aveyron region of France with the extended family, a region noted for caves, castles and canyons, and for not having much in the way of flat surfaces. We made the most of it with canoeing down the Lot valley with my wife early on a misty morning and decending into the spectacular Gauffre de Padirac cave systems being the highlights. We also spend a few days camping further south near Carcassonne at Lastours for more castle exploring and a day at the beach.

Needless to say though the roof box contained my Vixen Sphinx mount, my camera and a few telescopes most of which I did not make use of as I ended up finally taking out the Canon EF 50mm lens I bought over a year ago for astrophotography and making use of it for something other that pictures of the wife and kids.

The second week of our holiday saw the moon waning and provided the ideal nights, however the weather was changeable and though I spent two nights out only one gave a full evening of clear skies.

Cygnus Central Region

Cygnus was the target for the first night being well placed above me and offering a rich area for widefield imaging. I wanted to capture the North American and Sadr Butterfly nebula regions though I notice that the Cocoon makes an appearance as well in the bottom left. Many other objects are visibly and I think this one came out the best.

• 33 x 5 minutes (bias, flat and dark applied)

Cassiopeia

The second night saw intermittent cloud until midnight which then cleared till 3am. A very frustrating night and this region was not my actual target. However after the troubles trying to get something worth having from the Sagittarius / Scutum area it was a relief to use my last hour or so to quickly gather some data from this region. The framing is a bit out, it needs to rotate anti-clockwise about 20 degrees.

• 14 x 4 minutes (bias, flat and dark applied)

Sagittarius / Scutum

This was the region I really wanted to photograph and I was saving it for the best possible night, unfortunately the weather didn’t want to play. After being clear all day the clouds rolled in from the south west almost the minute I had everything setup and ready to go. A waiting game then commenced with me comfortable in the boot of the car on my inflatable mattress watching a movie and waiting to see what would happen. I knew that in order to get this region I needed to get started on it as early in the night as possible, so a cloud delay was not good news. As it happen the clouds did eventually clear just after midnight. Unfortunately this was just a little to late for me and allowed for only a few images to be captured before it sunk behind the trees. I’ll leave this as a target for another day.

• 9 x 5 minutes (bias, dark and flat applied)

Well that was a long wait for a clear night, what an unproductive three months for astrophotography but at least the front garden looks nice in it’s new sandstone paving! Sunday night finally delivered the required combination of clear skies, less than half a moon and a following morning I didn’t need to get up to early so I set up and finally got to have a go at a widefield image of the Cocoon nebula and the dark nebula which seems to stream away from it.

The Cocoon itself is a combination or emission and reflection nebulosity, the dark nebula that stretchs out from it is a cloud of dense dust blocking out the light from the stars behind it.

Imaging Equipment

• William Optics ZS66SD
• William Optics MkII Field Flattener
• Canon EOS 1000D (modified)
• Astronomic CLS CCD Filter

Guiding and Mount

• Orion Optics 250mm F4.7 Reflector
• Opticstar PL-131C Camera
• IR/UV Cut Filter
• Celestron CGEM Mount
• PHD Guiding

Exposures

• 44 x 5 minutes
• 15 x bias
• 15 x dark
• 15 x flat

The images were calibrated, aligned, stacked and processed in Pixinsight.

With the processing of this image I took the opportunity to try some new processing techniques within Pixinsight with the aim of improving noise reduction and getting better colour from the image. You can see some of my other attempts from the NGC and Other Catalogs gallery page. The first image is from my standard technique which ended up with a poor colour balance, the second was better in that respect but suffered from noise issues especially in the regions of the dark nebula.

In the version shown on this page I used the following techniques to try and get a better result, the links will take you to the Pixinsight forum post which discusses them :

Wavelet-based noise reduction with the ATrousWaveletTransform tool

I have always used the ACDNR tool in Pixinsight before to manage noise reduction post histogram stretch / sharpening when the image is in a non-linear state. Noise reduction from this alternative newer method however can be applied to a linear image and works as many tools do in Pixinsight by working different structure size layers. This means your noise reduction can be tailored to match the level of noise you have, hopefully that way avoiding blotchy backgrounds where larger areas of noise have been let through as structure.

I was very happy with the result once I had spent some time on trial and error to achieve the best result for my image.

RGB Re-Combination using Linear Fit

Technically I am pretty sure this is not for us single shot colour DSLR imagers but I cannot complain at the result. The technique here is to do a rough stretch of your Luminance data (I used an extracted lightness image) that looks about right, then match that stretch on your RGB images before applying Linear Fit tool to the RGB to match them against a reference image. I still had to use the SCNR tool to remove excess green from the final image but I have to call myself happy with the end result. Colour seems easier to manage, and the red of the Cocoon is closer to red than my normal orange. It is not scientific and probably not right for my data but as an experiment into alternative processing I like the result.

Hopefully the wait between new images can be a bit shorted this time!