Spotlight on Jewels

[Peter Ward]

I've been in the process of nailing down the collimation and orthogonality of my CCD camera (totally nailed it :cool:...I now have pristine stars to the very edge of the 16803)

Anyway, I digress.... I figured, while I was there, rather than take just test shots, might as well take a proper picture of the Jewel Box. Fuzz ball seeing...but Meh...least it was clear.

The edge diffraction from Mimosa was a surprise! ...but I figured..looks cool...so might as well own it.

The end result is here (http://www.atscope.com.au/BRO/gallery423.html)

[LewisM]

That's a BIG multi-coloured God Ray to the top left...

[multiweb]

Quite a feat to get a corrected field at that FL over such a big sensor. Another one for the cool wall, Luftwaffe run and all. :thumbsup:

[Peter Ward]

:lol: You think?

I did gamma stretch it...well...just a little...:D

[Stevec35]

Well that's something new and different - looks great!

Steve

[gaseous]

Fabulous photo! Am I right in saying that the Jewel Box is NGC 4755, not NGC 290 as stated on the link? Sorry for being a prat if I'm wrong.

[atalas]

Very cool Peter!

[PKay]

From a newbie perspective this image is a benchmark (aside from the unexpected diffraction...which is nice).

Very well done.

[Peter Ward]

Thanks guys. :thumbsup:



Thanks.... Also a lame error...you are indeed correct! The page data has been amended.



Ta Steve... Mimosa was just catching the edge of the baffle...just a few arc minutes repositioning caused the ray to disappear.



A shame it's not Eta Carina. Bombs away! :D

[gregbradley]

Nicely done. The Jewel Box is an elusive creature.

The rainbow flag is an interesting artefact. Getting the 16803 squared up is not a trivial exercise - care to share your procedure?

Greg.

[bigjoe]

Indeed it does look kind of cool...My wifes favorite cluster to view.
bigjoe.

[Peter Ward]

Thanks Greg,
As you know squaring on a 16803 can be a challenge.
1) If you have mechanical sag in the secondary or focuser this needs to be eradicated as you'll be chasing your tail until that is fixed. (fortunately the Alluna has none that I've been able to measure).

Collimate your telescope to the limits of your ability to get everything centred. I use a Takahashi Collimating scope with a M100 adapter made by Precise Parts.

Lock everything down, and re-check the collimation to make sure there has been no movement by torquing up the locking bolts

2) Calculate your focuser's step travel per step. (travel distance/ number of steps)

3) Use CCDinspector to get the orientation of the focal plane tilt.

4) The tilt in my system was along the X-axis. I focused at the bottom of the CCD, then again using the stars at the top edge. Looked at the step difference and got a number. From that got a distance.
Then I used some precision plastic shim stock (coloured so you can easily pick the right thickness) trimmed a small strip and placed it under the edge of the nosepiece that needed raising.

Took another test shot (or ten). Round stars to the edge.

Poured myself a single malt. :)




Thanks Joe.

[Andy01]

Lovely image Peter, great colours!
I particularly like the spotlight effect :cool3:
Very Hollywood, lol :lol:

[Jeff]

Oh man, can't help remembering those recreational drugs back in my uni days. Experimenting in the name of science. Peace brother. :innocent:

[gregbradley]

[QUOTE=Peter Ward;1358746]Thanks Greg,
As you know squaring on a 16803 can be a challenge.
1) If you have mechanical sag in the secondary or focuser this needs to be eradicated as you'll be chasing your tail until that is fixed. (fortunately the Alluna has none that I've been able to measure).

Collimate your telescope to the limits of your ability to get everything centred. I use a Takahashi Collimating scope with a M100 adapter made by Precise Parts.

Lock everything down, and re-check the collimation to make sure there has been no movement by torquing up the locking bolts

2) Calculate your focuser's step travel per step. (travel distance/ number of steps)

3) Use CCDinspector to get the orientation of the focal plane tilt.

4) The tilt in my system was along the X-axis. I focused at the bottom of the CCD, then again using the stars at the top edge. Looked at the step difference and got a number. From that got a distance.
Then I used some precision plastic shim stock (coloured so you can easily pick the right thickness) trimmed a small strip and placed it under the edge of the nosepiece that needed raising.

Took another test shot (or ten). Round stars to the edge.

Poured myself a single malt. :)



Thanks for the procedure. I have mine trimmed up but last time it was more painful than I remembered and I lost a night over it.

Greg.

[Peter Ward]

Yes, a PITA for sure...but when done well, thankfully only needs doing once. :thumbsup:

[SimmoW]

Yes thanks for posting that procedure Peter!

[Ross G]

What a beautiful and unique photo Peter...a real "composititon".

I love the colours and detail.

The huge beam coming through looks so cool!

I photographed the Witch Head Nebula in Coonabarabran about 3 years ago and I got a similar sized beam coming into the frame from Rigel, hitting the witch right on her nose!
Seeing your photo gives me the confidence to maybe post it.

Ross.

[batema]

Beautiful photo and yes very unique but it looks great.

Mark

[Peter Ward]

Very kind Ross. The surprise for me was the spectral dispersion from Mimosa.

I've also seen this effect before when imaging the Horse-Head but the diffraction then was almost monochromatic.

I suspect I picked up diffracted colour as the guiding was pretty much perfect over the RGB capture....after all, this is what diffraction gratings do!

[el_draco]

Unique image of such a gorgeous cluster. Never seen it like this before. Magic!

[Atmos]

Very nice Jewel Box and the Technicolour Raincoat is quite intriguing!

I have considering using my Atlas as a way of calculating how far my lower left corner is out but just haven't done it! Glad to know that it is an effective way of doing it.

[Peter Ward]

:thanx:



Glad you like it...as for the squaring on calculation, yes it's fairly straight forward. The only tricky bit is getting the direction right!

P.S.
It was yours truly who...some 25 years ago.... discovered how to measure mount tracking errors with the then "new" SBIG ST4 autoguider.
(does anyone still remember using illuminated reticles? )

It occured to me if I record a track-log with no guiding corrections, the results would map the Periodic error.

I mentioned it to Alan Holmes at SBIG.

It never occurred to SBIG someone would turn the autoguiding of their venerable autoguider OFF!

The STV then followed with PEC measurement as a "feature" :doh:

[Atmos]

The things that happened when I was 3 years old :lol:

[marc4darkskies]

Love it Peter! :thumbsup: If you can't beat the extraneous light / lens flare / diffraction, embrace the serendipity!! :lol:

[Peter Ward]

Ta Marcus....sometimes you need to go with the flow :)

hope it will not be too long before you are imaging again!

[FlashDrive]

Very nice indeed .... :)