NGC891 Take 2

[geoflewis]

I first shot this target excatly 1 year ago (5Nov2017) with an almost full Moon in the sky. Last night I had another go with no Moon, but very hazy poor transparancy conditions, so still far from ideal.

C14+Optec FF/FR; QSI583wsg-5

L=18x10mins; RGB 9x10mins each for a total integration of approx 7.5 hours. All frames binned 2x2.

Each channel calibrated and stacked in ImagesPlus. Stacked channels star aligned and cropped in Registar. Post processing with ImagesPlus and PS(CS2).

I'm finding Registar does a great job aligning the stacked channel images, so many thanks to all those that persuaded me to buy it, in particular Carole Pope (@carastro) who also provided me with some excellent tuition at Kelling Heath back in September.

Thanks for looking,

Geof

[tooth_dr]

Looks like you could just pick it up off the screen. Delightful ?

[geoflewis]

Just now, tooth_dr said:

Looks like you could just pick it up off the screen. Delightful ?

Thanks very much.

[don4l]

Very nice Geof!

[geoflewis]

Thanks Donal. I was down your way recently, popped in to see PCB.

Geof

[jjosefsen]

If my calculations are correct that is some serious long focal length imaging you are doing, judging by the gear used.

Well done, and very interresting target!

[geoflewis]

1 minute ago, jjosefsen said:

If my calculations are correct that is some serious long focal length imaging you are doing, judging by the gear used.

Well done, and very interresting target!

Thanks and yes, in truth it's a crazy FL for DSO, but I like the up close and personal results . The C14 native is 3900mm (F11), which the Optec telecompressor reduces to around F7, so still ~2500mm. Fortunately the AP1200 barely knows that it has the C14 atop and guides very well using PHD2. Last night's session averaged around 0.5 arcseconds RMS each axis, with extended periods down below 0.4 arcsecs. I just wish the sky had been more pristine, transparancy was poor.

[Ruud]

It's a beautiful image. Awesome and magnificent!

[Sunshine]

Wonderful image! so well defined and contrasted.

[Craney]

With a focal length like that, you are a significant amount closer to the object than the rest of us, that's why it has come out so well......  

 

(seriously though, excellent work with the tracking....  it aint easy with dealing with metres instead of milli-metres)

[geoflewis]

8 hours ago, Ruud said:

It's a beautiful image. Awesome and magnificent!

 

7 hours ago, Sunshine said:

Wonderful image! so well defined and contrasted.

 

7 hours ago, Craney said:

With a focal length like that, you are a significant amount closer to the object than the rest of us, that's why it has come out so well......  

 

(seriously though, excellent work with the tracking....  it aint easy with dealing with metres instead of milli-metres)

Thank you Ruud, Sunshine and Craney, I'm glad that you like it.

It's fun imaging at this focal length, but I'm never too sure how the end result will turn out. It can also be problematic guiding through the camera's OAG as there have been several times that SGP/PHD2 couldn't automatically find a suitable guide star in the pick off prism due to the small FOV. For this target there was a choice of 3, almost like Christmas ?. I also resist performing a meridian flip as that too can result in no guide star after the flip with targets in a more baren region of sky. Fortunately with this mount I can usually image a couple of hours or more past the meridian (CW up) with no issues, so if I start out early with higher altitude targets, i.e. those that transit within, say, 30 degrees of the zenith, then I can stay on target for up to 7 hours without flipping, which makes data capture easier.

Geof

[Craney]

Have a go at Stephan's Quintet , that certainly needs a good focal length to bring out detail.... and I think it is still quite visible in the evening sky.

My 10"F4 with Atik 414ex   ( usually a winning combo on smallish objects ) could not get 'near' enough.   I almost added a powermate in the optical train !!   OMG, that would cause the retired Brigadier DSO imager-general to spit out his coffee in disbelief.....  although, probably would have needed excessive exposure due to the low luminosity and that plays upon the guiding accuracy....

Still, long FL does mean there are just so many weird and wonderful objects to have a go at.

Rgds,

Sean.

[geoflewis]

1 minute ago, Craney said:

Have a go at Stephan's Quintet , that certainly needs a good focal length to bring out detail.... and I think it is still quite visible in the evening sky.

My 10"F4 with Atik 414ex   ( usually a winning combo on smallish objects ) could not get 'near' enough.   I almost added a powermate in the optical train !!   OMG, that would cause the retired Brigadier DSO imager-general to spit out his coffee in disbelief.....  although, probably would have needed excessive exposure due to the low luminosity and that plays upon the guiding accuracy....

Still, long FL does mean there are just so many weird and wonderful objects to have a go at.

Rgds,

Sean.

Hi Sean,

Yes that target has been on my bucket list for quite a while, but I never seem to get around to it, so thanks for the gentle prompt. Unfortunately it's already transiting by the time I'll get on it now, so I'll need 2 or 3 clear nights to get enough data and once again I've probably missed a trick not attempting it about a month earlier. I hung in trying to image Mars longer than I oroiginally planned this year (with no real benefit), plus we had family visiting from USA for most of Oct, so AP took a low priority last month.

Cheers, Geof