The Swan Nebula

[JohnH]

With the Orion Starshoot through the WO SD66 - approx 30x30s images stacked and levelled in Maxim EE, halo and noise reduction in IP. UV/IR cut was in place and TEC was off.

[spearo]

John,
very nice. How do you rate the starshoot compared to the 20D ?
and did you notice the three small bluish dots at 9'o'clock? what do you reckon these are?
frank

[JohnH]

Not really fair to comapare these two - one is $1500+ the other less than half that. One a general purpose DSLR the other a dedicated astro cam. Still FWIW here are the main points of difference:

Canon gives much better resolution (8 Mp vs .4 Mp) but is far less (we are talking an order of magnitude here) sensitive - especially to Ha.

The OSS is lighter.

OSS has TEC to minimise noise.

OSS has a small sensor and is not suitable for DSOs at long FL - I get similar fov with the OSS at 400mm and the Canon at 1800mm!

Stacking/Masking/Dark Subtraction/Colour balance and other processing with the OSS is possible with the supplied s'ware - Maxim EE. Canon needs additional s'ware and cables to do long exposures.

So I like them both - they match the scopes they are on well. I can image with the Canon on the WO66 but have to crop a little as I get SA at the edges of the image, but the OSS on the VC200L with no FR is not very useful (probably ok for planets/moon - I have not tried - yet).

I find processing the OSS very different from than processing the Canon frames, the files are smaller which is good but the calibration is tedious (by hand) and getting colours right seems much harder - but that is probably because I like IP over Maxim EE fortunately IP2.8 supports the OSS. The stars seem to bloat readily in the OSS images. However it is fast and easy to use - just 30s gets you a lot of photons and you don't need to guide as a result.

Bit of a ramble there, not sure if that is what you wanted - pm me if you want any more on the OSS - I bought this mostly for guiding (and have not really got that working properly yet but that is anpther story) so I took this image to ensure my clear moonless night was not a complete write off...

The blue wobbly line looks too big to be a hot pixel - which is odd as I did do Darks. Could have been Neptune I suppose - must have been aroud there somewhere that night....

[JohnH]

I checked in CdC and cannot get any planet in the FOV at the time these frames were taken (2200 in Sydney on 28/8/6)....I think I must have CdC setup wrong - it also shows up in one of my Canon frames:

[EzyStyles]

beautiful swan shot john esp from the OSS. what is TEC btw?

[Octane]

Eric,

Thermoelectric (Peltier) cooling, I would suspect.

Regards,
Humayun

[Lester]

Hi John,

very nice image.

[JohnH]

Spot on Octane! Keeps the CCD noise low by dropping the chip temp approx 20C below ambient....

[spearo]

Thanks John,
yep the long explanation was what I was after.
thanks and well done
hang in there with the autoguiding...i'm climbing the steep learning curve myself but it has it's rewards
cheers
frank

[JohnH]

Can anyone confirm this is Neptune for me - going nuts!

[JohnG]

Hi John

According to my software, Neptune is at RA 21h 21m 55s and DEC -15 39 00 in Capricorn.

JohnG :)

[JohnH]

Hmm, no-where near the Swan then :
M 17 NGC 6618
Constellation: Sagittarius
Dimension: 11.0'x 11.0'
Magnitude: 6.00
Surface Brightness: 13.00
Description: !!!,B,eL,eiF,2 hooked
Omega nebula;Swan Nebula;many F outer loops;use filter

J2000 RA: 18h20m48.00s DE:-16°11'00.0"
Date RA: 18h21m11.02s DE:-16°10'47.8"


A mystery blue blob, not in my cdc catalog, and it shows motion over 30 mins? Is it a processing artefact after all....I'll check the raw FITS files....thoughts anyone - internal reflections?

OK 105,271 is a hot green pixel - odd thing is that the dark frames did not get rid of this one...but the others are gone...

[JohnG]

I got the impression that it was an internal reflection of some kind, did you have a filter or something between the camera and telescope.

It is an odd colour for an internal reflection though, definitely not an outer planet, too much movement over a short period of time, odd though.

Cheers

JohnG

[spearo]

Well....if it turns out to be an amazing discovery of some sort...just remember who noticed it first !
HAHAhAhHAAH
frank

[JohnH]

Here is the same region with the 20D, the image is 16*3 min shots through the 8 inch at f6.3 and reduced in size 50% and heavily compressed to get under the 150kb limit, full size jpg is 4mb, tiff is 48mb. Needed to be guided of course and you can see my alignment was not great - I got rotation.

Compare to the simplicity of acquiring 30x30s unguided with the OSS using the 66mm, then again I have much better detail in the 20D shot.

They are both good is my conclusion!