A few interesting LMC objects in Ha

[Shiraz]

Hi

despite the almost incessant wind, managed to scrape together some Ha on some of the very interesting stuff in the LMC and increase the data on a previously posted object. The quality is variable, with seeing/tracking noise resulting in 2-3 arc sec FWHM, but it is nice to have something to post at last :).

All images are cropped to fit and there is a software binned version for three of them, as well as a full res crop. Have also included a HaRGB of the seagull region to see what colours might be like (err wierd!) - colour is a work in progress trying to figure out how to deal with wildly varying star sizes (and must also remove a couple of hot pixels that slipped through..).

Thanks for looking. Ray

[gregbradley]

A wonderful post. That last colour image is exquisite. Love it. Such wonderful colours and hues.

One way to handle varying star sizes in RGB subs is deconvolution. You decon the fatter colour to match the thinner colour stars. It may take more than one go at decon to do it. You can overdo decon but one of the advantages of the small high QE Trius is images from it will take a lot of decon without artifacts.

Greg.

[tilbrook@rbe.ne]

Superb work Ray!:thumbsup::thumbsup:

I see what you mean by the variable seeing, but the seagull and NGC 1934 are superb. I love the colour version of the seagull good variation.

Still astonishes me what you can do with your setup!

Cheers,

Justin.

[marc4darkskies]

Cool collection there Ray! :thumbsup:

2 to 3 arc sec FWHM isn't bad at all - about average. Within that range, decon should take care of the differences you're seeing IMO. Does your processing s/w do decon?

Cheers, Marcus

[Shiraz]

thanks Greg. Yes, I was surprised at the colour image, but still need to work on processing. The big problem is that the Ha stars are much smaller than the colour ones, so the nebula surrounding the stars has no colour data (it got lost in the fatter stars). I tried decon and morphological processing, but got nowhere. looks like I will need to separate out the stars and the nebula for different processing and "heal" the nebula in the star regions. Rick did something similar, putting broadband stars in a narrowband image, so it can be done. Startools heals the nebula effectively, but I now need to work out how to get the narrowband stars back in there, but with broadband colour.


Hi Justin. Thanks for your comments. the seeing was wind affected and very variable for these images, but last night was wind-free for the first time in yonks - and the blue channel seeing was around 5-6 arc sec at one stage :P. Bring back the wind!

The scope is a continuous battle to keep everything aligned and yet not so tightly held that it distorts - you know how it is. The biggest problem is that everything is interconnected - eg recently had some atsigmatism appear - did it come from the primary, the secondary, the coma corrector, the filters or the collimation??? In the end, it turned out that the secondary glass had gone slightly pear shaped. A problem like this that would be of limited consequence at 2 arc sec sampling, but was a major issue at 1 arc sec. Works really well when it is in a good mood though.



Thanks Marcus. I generally get somewhere around 2-2.5 arc sec on a good night in Ha and always use deconvolution in Pixinsight. However, the amount of data I had here was limited (eg 20 minutes one night, 25 the next etc.) and the objects are fairly faint, so I had to go very light on with deconvolution to keep the noise under some sort of control. The other effect was that wind gusts did not appear to change the central peak FWHM much, but added a low level "jitter" skirt from the occasional big excursions - the skirts blew out the bright stars when stretched (eg on N70), even though the nebulae did not suffer much. Need a stiffer mount to fix this.

regards Ray

[gregbradley]

[QUOTE=Shiraz;1052586]thanks Greg. Yes, I was surprised at the colour image, but still need to work on processing. The big problem is that the Ha stars are much smaller than the colour ones, so the nebula surrounding the stars has no colour data (it got lost in the fatter stars). I tried decon and morphological processing, but got nowhere. looks like I will need to separate out the stars and the nebula for different processing. Rick did something similar, putting broadband stars in a narrowband image, so it can be done.

Oh I see. I have used the RGB star layer under the Ha or narrowband image and then set the rgb star layer to lighten mode. Now anything lighter will show through. You can then boost the rgb star layer if needed or do a mask on the brigher stars of the narrowband image to help if needed.

I did this here and it worked well:

http://www.pbase.com/gregbradley/image/137164599


Greg.

[RickS]

A great menagerie of LMC objects, Ray! I really like the colours of the HaRGB image.

I have played around with several techniques for matching star sizes but haven't found a silver bullet yet. As Greg mentioned, deconvolution is worth a try. It's a lot easier when you're only interested in the RGB stars because it doesn't matter if the decon messes up everything else :D

Cheers,
Rick.

[dutch2]

Lovely images, Ray.
Well done.:thumbsup:

[Shiraz]

[QUOTE=gregbradley;1052589]

thanks for that info Greg. looks like it works well.


thanks Rick. The big issue is that there is a region between the RGB star edges and the much smaller narrow band star edges that does not have any nebula colour (the RGB stars swamped it) - I need to reconstitute that lost data somehow. Otherwise, using Ha as the luminance channel looks to be quite useful.


Thanks Ingrid - appreciate the comment.

regards ray

[dvj]

These are excellent!

[Ross G]

A great collection of photos Ray.

Love the detail.

Ross.

[coldlegs]

Ray
Love the colour shot. Also did a surburban shot of "father Christmas blowing bubbles" a short while ago but seeing was 3.5-4.5 so it's blurrier than yours but curiously it's about the same sensitivity as yours. Says a lot about using Ha filters to cut through light pollution. There has been nothing but wind gusts every half decent night here for about the last month also. Keep up the good work mate.
Cheers
Stephen

[allan gould]

Ray
Those are superb images that Ive gone through several times. A great set that brings out so many details in the LMC.
Really well done. Do you have the RA and Dec of your third image?
Allan

[Shiraz]

Thanks very much John - it was exciting to be able to image just a few of the interesting Ha objects in the LMC. One could spend a long time on this area and not run out of fascinating stuff.


thanks very much Ross.


Thanks for the encouragement Stephen. The wind sure has been ordinary as it heads from the cool gulf waters towards Woomera.

Thanks very much Allan. It was fun to have a look around the area. There are a few sets of Ha LMC images on the web - SteveC for example has a beauty of Henize70, the object you asked about (it's a much better image than mine, but I was glad just to get anything at all..) http://members.pcug.org.au/~stevec/n70_STL6303_RC.htm (includes RA/dec)

regards ray

[allan gould]

Thanks for that Ray as I've always been fascinated by N70 but not got around to imaging it. It's on my list as soon as this damned cloud goes away.
Allan

[strongmanmike]

Awesome collection Ray, really enjoyed having a look at them all, mega data is good to do sometimes for sure... but just zooming around and shooting cool stuff with modest exposures is great fun too and is just as valid and enjoyable IMO :thumbsup:

Mike

[Shiraz]

thanks Mike - agree with the sentiment. I don't have the time, equipment or inclination to attempt to win image quality contests (and I don't want a hobby where success or failure depends entirely on the opinions of others) - so taking "good enough" images of interesting stuff seems to make sense. High resolution detail of distant objects is of most interest, so even colour is sometimes unnecessary. Regards Ray

[Bassnut]

Excellent Ray, 2035 in Ha RGB is particularly attractive. Ive had a go myself in NB only, your rendition is an interesting difference.

[strongmanmike]

Amen to all that :thumbsup:

[Shiraz]

Thanks Fred. Really like NB, but I wanted to get some idea of what colours these things really are. Still got some way to go with HaRGB, but it does seem to be worth persevering with. regards ray

[multiweb]

Quite a collection. That colour shot is inspiring. :thumbsup:

[Shiraz]

Thanks Marc. The colour turned out better than expected, but only at an image scale where the processing artefacts are not too obvious. regards ray

[multiweb]

You're getting some amazing results with that newt. Gives me hope. :thumbsup: