NGC5907 with relic accretion loop.

[ollypenrice]

This image does not compete with R Jay GaBany's discovery rendition!

However, it does show hints of the debris left behind by a dwarf galaxy's absorption into the edge on spiral we see here.

We may get another night on it tonight but in case we don't, and because our guests are leaving tomorrow, I wanted to get a finished version done before they do. This accretion loop is seriously faint so to be sure I wasn't inventing it I kept my eye on a pure log stretch, inverted and equalized, by way of reference. The data clearly does contain the loop.

TEC140/Atik460/Mesu 200. L 6 hours, colours 8x10 minutes.

Taken with Marcel Vonk from the Netherlands.

Olly

 

 

[steppenwolf]

7 minutes ago, ollypenrice said:

The data clearly does contain the loop.

No doubt about that - well done ......... or should I say chapeau? ?

[tooth_dr]

Pretty impressive. Is this accessible to mere mortals? And what sort of exposure times for L?

[Allinthehead]

Very nice work Olly and Marcel.

[ollypenrice]

59 minutes ago, tooth_dr said:

Pretty impressive. Is this accessible to mere mortals? And what sort of exposure times for L?

For the work of the immortals see GaBany's rendition!

This was a very mortal capture in a 5.5 inch scope. In luminance we did two runs of three hours, one using 15 minute subs and one using 30 minute subs. Rather as I feared, the Atik 460 did not thrive on the long subs as the Atik 11000 does with its low QE and deep wells. If we get another crack at it tonight it will be in 15 minute subs. They were better. The 30 min subs didn't seem to bring more faint stuff but did bloat on the bright. Lose-lose. You live and learn...

Olly

[tooth_dr]

16 minutes ago, ollypenrice said:

For the work of the immortals see GaBany's rendition!

This was a very mortal capture in a 5.5 inch scope. In luminance we did two runs of three hours, one using 15 minute subs and one using 30 minute subs. Rather as I feared, the Atik 460 did not thrive on the long subs as the Atik 11000 does with its low QE and deep wells. If we get another crack at it tonight it will be in 15 minute subs. They were better. The 30 min subs didn't seem to bring more faint stuff but did bloat on the bright. Lose-lose. You live and learn...

Olly

Thanks Olly for that.  Perhaps some day I’ll point my scope at it ?

[tomato]

Another testament to your collective skills and superior sky. 

BTW, the galaxy is exceptionally good too.?

[ollypenrice]

A reprocess with the same data.

This time, when combining the two 3 hour sets (15 mins subs for one, 30 min subs for the other) I summed them in Registar rather than averaging them. This was much better for the faint stuff but made for bigger stars, so I used very little of the L on the stars, mostly leaving them from the RGB layer.

Olly

 

[Magnum]

18 hours ago, ollypenrice said:

Rather as I feared, the Atik 460 did not thrive on the long subs as the Atik 11000 does with its low QE and deep wells. If we get another crack at it tonight it will be in 15 minute subs. They were better. The 30 min subs didn't seem to bring more faint stuff but did bloat on the bright. Lose-lose. You live and learn...

Olly

Very nice Olly, interesting what you said about the 460 not thriving on long subs due to shallow wells. Im usually doing 10,15 or 20 min subs in narrowband with my Atik 314 which has similar wells 19500 for the 314 vs 18,000 for the 460, but would i be better doing shorter subs say 5 mins and just collecting more of them like the CMOS guys are doing, bearing in mind the 285 chip is still one of the cleanest CCD sensors around, at 4e RN it doesnt match the low levels of read noise of the new cmos chips but in all other regards is still cleaner. my maths isn't quite good enough to work out the ideal exposure with my camera , Starizona has an ideal exposure calculator but that says for unfiltered images, so i dont know wether to trust it for calculating with my Ha subs, but it seams when i do it tells me i should use 12min subs.  Last night with 10 min subs and 7nm ha filter my background ADU was about 420 which doesnt seem very high.

[ollypenrice]

1 hour ago, Magnum said:

Very nice Olly, interesting what you said about the 460 not thriving on long subs due to shallow wells. Im usually doing 10,15 or 20 min subs in narrowband with my Atik 314 which has similar wells 19500 for the 314 vs 18,000 for the 460, but would i be better doing shorter subs say 5 mins and just collecting more of them like the CMOS guys are doing, bearing in mind the 285 chip is still one of the cleanest CCD sensors around, at 4e RN it doesnt match the low levels of read noise of the new cmos chips but in all other regards is still cleaner. my maths isn't quite good enough to work out the ideal exposure with my camera , Starizona has an ideal exposure calculator but that says for unfiltered images, so i dont know wether to trust it for calculating with my Ha subs, but it seams when i do it tells me i should use 12min subs.  Last night with 10 min subs and 7nm ha filter my background ADU was about 420 which doesnt seem very high.

The only way is to experiment in my view. It doesn't take long and you're not going to throw anything away even if it isn't optimal.

Olly

[Petergoodhew]

Nice Olly. I was tempted to have a go at this one but clouds got in the way! 

R Jay GaBany combined his Lum with a synthetic lum from the RGB.  Were you not tempted to do likewise?  I would have thought this would indeed a case to make every photon count (apologies to Steve!)

[ollypenrice]

5 hours ago, Petergoodhew said:

Nice Olly. I was tempted to have a go at this one but clouds got in the way! 

R Jay GaBany combined his Lum with a synthetic lum from the RGB.  Were you not tempted to do likewise?  I would have thought this would indeed a case to make every photon count (apologies to Steve!)

I did look at the data with this in mind and made a synthetic lum. However I felt that the accretion loop signal from the filtered subs of only 10 minutes was so low as to risk weakening the result in the stack. I should give it a try though, since I do have it on file.

Olly

[johnfosteruk]

On 14/09/2018 at 18:50, ollypenrice said:

For the work of the immortals see GaBany's rendition

Not immortal, I don't like his stars. There's no doubt its an amazing piece of work, what he's pulled out in the detail is tremendous but as I said, his stars... no.