LMC in 3nm NII now with Three Panels

[avandonk]

The new system has been adjusted to the point where any further minor correction would hardly be worth it. I would be chasing my own tail.

Collected some LMC data with the LMC fairly high.

Data 8x16 minutes in 3nm N[II]. Processed in a new way.

Large image 3MB. FoV 3.5 X 3.5 degrees.

http://d1355990.i49.quadrahosting.co.../LMC_NII_1.jpg


Bert

Astrograph is an Officina Stellare RH200 which has a focal length of 600mm and is F3, yes F3! Clear aperture is 200mm.
FLI Atlas Focuser.
FLI ten position filter wheel CFW-3-10 with 50mm square filters.
Astrodon E series LRGB and HA, NII, SII and OIII 3nm NB filters. Also a continuum filter 5nm.
Camera is a FLI PL16803 which has a sensor size 36.8 X 36.8 mm.
The FoV of this system is 3.5 X 3.5 degrees.
Mount is a Software Bisque PMX.

[multiweb (Marc)]

Awsome field. There is so much clarity and detail in those filaments. Is it just me or you can see some hint of spiral structure/motion across the left of the field going up and wrapping around back down centered about the tarantula? The LMC is a barred spiral right? So that would spin clockwise from our point of view?

[Larryp (Laurie)]

So much detail-superb!

[avandonk]

Here is a full resolution zip file of the eight fit stack. All subs were corrected for darks and flats. 14MB

http://d1355990.i49.quadrahosting.co...11/LMC_P1_.zip

I would be interested to see what others could squeeze out of this data.

I am just a beginner when it comes to CCD data.

Bert

[el_draco (Rom)]

My most favourite part of the sky... Excellent. What setup was used to take this shot?

Rom

[alexch (Alex)]

That looks great, Bert!

A very familiar object in a new light - full of shapes I have not seen before: transformer, koala, dragon, you name it...

Thanks for the view.

Cheers,
Alex

[jjjnettie (Jeanette)]

Superb!!

[cometcatcher (Kevin)]

I love these shots of familiar objects in a light like I have never seen before. It opens up a whole new view of the sky.

[David Fitz-Henr]

Amazing detail and structure there Bert - fascinating to look at! Will you be taking more data through other filters for a colour version?

[avandonk]

Thanks for the kind comments all. It is a bit more difficult to process this data as things you have never seen pop out!

I hope to be collecting OIII and LRGB for a mosaic of about nine panels. It all depends on the weather.

One really nice thing about 3nm NB imaging is that the Moon does not interfere anywhere near as much.

Meanwhile here is three panels in NII. 9MB

http://d1355990.i49.quadrahosting.co...LMC_3P_NII.jpg


Bert

[Martin Pugh]

Bert, as you posted your data, I opted to download and give it a go.

Image is below (50pct size 1.6mb)
http://www.martinpughastrophotograph...Z-LMC_Pugh.jpg

Having access to the FITS told me a lot. Indeed, I think both your focus and your guiding were not optimum during this capture. Your image scale is 1.79asp, while FWHM of on-axis stars was 4.5" - that's over double. Plus, most stars I measured were 20% out of round, indicating sub-optimum guiding.

HTH

Martin

[Mighty_oz (Marcus)]

That's looking pretty sweet there Wish i had your stuff.
At 600mm u should be able to do 10 min unguided images with the PMX, i know it can be done, as i've just spent a bit of time getting to that level myself at 530mm. Anyways keep them coming, always good to see your stuff.

Marcus.

[strongmanmike (Michael)]

Originally Posted by Martin Pugh

Your image scale is 1.79asp,
Martin

How is this possible? The RH200 is 600mm FL and the Proline has 9micron pixels = 3.1"/pixel...?

Mike

[gregbradley]

Yes Mike is correct that scope/camera combo is 3.09 arc secs/pixel.

Greg.

[Martin Pugh]

I kind of expected the FITS header to be correctly configured, so when I opened the image and it reported 1.79", I took it for granted. When I looked at it again, none of the values were set.

So I adjusted the FITS header accordingly, and as you would expect, the result is very similar - on axis stars now reporting 7.5-8 arcsecs.

Martin

[Ross G]

A great photo Bert.

Amazing detail.

Ross.

[avandonk]

Originally Posted by Martin Pugh

Bert, as you posted your data, I opted to download and give it a go.

Image is below (50pct size 1.6mb)
http://www.martinpughastrophotograph...Z-LMC_Pugh.jpg

Having access to the FITS told me a lot. Indeed, I think both your focus and your guiding were not optimum during this capture. Your image scale is 1.79asp, while FWHM of on-axis stars was 4.5" - that's over double. Plus, most stars I measured were 20% out of round, indicating sub-optimum guiding.

HTH

Martin

Martin I think MaximDL put the guidescope parameters in after calibrating. My guidescope is a 100mm ED with a FL of 900mm and fitted with a Lodestar binned x2. The image scale is 3.1' per pixel for the RH200 and PL16803.

The guiding is fine less than 1' arc rms.

The star elongation you picked up is due to a slow incremental flexure of the dovetail that holds the main image train. See image below. The distance measured varies by about 100 micron from a vertical to horizontal position of the image train by rotation of the mount. The dial indicator was there to give me a lateral position of the OTS in the small lateral dovetail. I am going to get a far thicker one made by Luke Bellani. The weight of the optical train with the rather tall filter holder puts a large torsion on this dovetail plate.

This flexure is almost linear with exposure time. Not noticeable at 8 minutes exposure and to what you see at 16 minutes. It is far worse at 32 minutes. It is always in the direction of gravity! That tells me straight away it is flexure. It is only a problem when imaging nearer the SCP ie with the LMC and SMC.
I have done an exposure for 64 minutes with the optic vertical going through the zenith and the stars were perfectly round.

Compressed zip of fit file here 13 MB

http://d1355990.i49.quadrahosting.co...2_11/1920s.zip

JPG version 6MB here

http://d1355990.i49.quadrahosting.co...2_11/1920s.jpg

The result you obtained with my data tells me I still have a great deal to learn. Thanks for your effort.

Bert