Pier 5 - M16 and M17

How are you finding the new filters Richard ?

Mixed.

I had some trouble with severe gradients on IC1396, but that was partly due to not having enough subs. I managed to subdue it and the results are here: PIER-05 IC1396 using HaO3 filter (roboscopes.com). I have also been struggling with OSC on dust clouds and IFN. My attempt at LBN629 (job 2152) suffered from horrible gradients and the flats seemed to be under/overcorrecting.

It may be that the data was taken at low elevations and with moon interference, so I will keep plugging away, but I am not getting as good results as before the filter wheel and new filters.

Ok

Re flats, we are installing a new flat panel mid June on the next visit as we could do dome flats before but the dual bands made dome flats quite difficults, Tit should make flats much easier for you and us :)

Using the dual bands is a new learning curve that will more than likely take you a few attempts to get in the swing of things

See how it goes :)

Indeed I also noticed more gradients in the pics after the filter upgrade even with no filter selected.

In this dataset the gradient wasn´t as big though, I could easily handle it with a single DBE step in PI.

Here´s my result with a little more "reddsich" saturation :-)

Could you let us know if the gradients are still present in standard colour images please as the system hasn't changed in that respect as the existing extension tube was swapped out for the wheel is all.

A clear hole is a clear hole whatever the light travels through :)

Steve

Just take a look at the M81 M82 competition dataset from April for instance - great data but also great gradient in pure OSC data without filter. Never had such gradients in Pier 5 datasets before?! Even though you´re right with "a hole is just a hole" - something seems to be different now - maybe some reflections or different tube lengtths so reflections now hit the sensor where they didn´t before?

Indeed I also noticed more gradients in the pics after the filter upgrade even with no filter selected.

In this dataset the gradient wasn´t as big though, I could easily handle it with a single DBE step in PI.

Here´s my result with a little more "reddsich" saturation :-)

Very nice Martin. I like the richer colours you have used.

Yes, this dataset was not badly affected by gradients. I don't know whether it was the Ha-O3 filter or the imaging conditions.

Could you let us know if the gradients are still present in standard colour images please as the system hasn't changed in that respect as the existing extension tube was swapped out for the wheel is all.

A clear hole is a clear hole whatever the light travels through :)

Steve

Could you let us know if the gradients are still present in standard colour images please as the system hasn't changed in that respect as the existing extension tube was swapped out for the wheel is all.

A clear hole is a clear hole whatever the light travels through :)

Steve

Steve,

I see that for the first few jobs using OSC the gradients are very severe.

See for example LBN 629 before and after DBE. (STF applied using HistogramTransformation). This is just to illustrate the gradients, you can wrangle them down, but it is not easy. Similarly, SH2-73 after DBE. This was not my experience previously with Pier 5. It was very easy to remove any gradients.

Not sure what is going on, but there is something.

Just take a look at the M81 M82 competition dataset from April for instance - great data but also great gradient in pure OSC data without filter. Never had such gradients in Pier 5 datasets before?! Even though you´re right with "a hole is just a hole" - something seems to be different now - maybe some reflections or different tube lengtths so reflections now hit the sensor where they didn´t before?

I had the same experience with the M81/M82 dataset.

OSC seems to be more affected than Ha-O3.

I had an older SH2-73 (job 1971). So I took the integrated image and processed it in the same way as in my previous message - Straightforward DBE then STF fixed with HistogramTransformation.

It does not show the heavy gradients we have been getting since the upgrade. How much this is due to equipment and how much to weather conditions/seeing/target altitude I cannot say.

Same thing with the latest P5 dataset (2151 p5 Angel IFN  961). Heavy red gradient on top left corner and green from the bottom.

Just STF applied on stacked image

Same thing with the latest P5 dataset (2151 p5 Angel IFN  961). Heavy red gradient on top left corner and green from the bottom.

Just STF applied on stacked image

Yes Martin, something has definitely changed.

I attach three P5 stacked images from before the update. All just stacked and STFed.

Yes there are gradients, but these were easily removed with normal processing.

Both VDB-152 and the Iris Nebula are areas of faint nebulosity. M3 less so, but still shows a clean background.

I am looking into this atm and trying to figure out what the cause is. I did use the the latest flats on P5 M81 data I did notice some gradients with it but it was nothing I was concerned about as it processed out reasonably well.

It might be that the flats are very slightly over exposed, the other thing is I can just make out some patches on some of the frames possibly due to frosting or dew on the chip while taking the flats but is very difficult to see it. So I have done some new for the OSC and Lum for you to try. I will ask Phil to get them uploaded. 

Regards

Peter

I am looking into this atm and trying to figure out what the cause is. I did use the the latest flats on P5 M81 data I did notice some gradients with it but it was nothing I was concerned about as it processed out reasonably well.

It might be that the flats are very slightly over exposed, the other thing is I can just make out some patches on some of the frames possibly due to frosting or dew on the chip while taking the flats but is very difficult to see it. So I have done some new for the OSC and Lum for you to try. I will ask Phil to get them uploaded. 

Regards

Peter

 

Thanks Peter.

Hopefully a new set of flats will solve the problem.

Perhaps also the new flats panel will help.

My interpretations of the data using this new filter. I used two different ways to extract the Ha and Oiii data from the original lights and recombined them as HOO. 

I really live these dualband filters!

Cheers

Manuel

PS: I tested the new OSC May 23 flats on the LBN629 data.  Much better, but still heavy gradients ... I am wondering whether there was some "light pollution" when taking the lights.

Very nice indeed Manuel. Haven't tried the separation technique yet. One to put on the "to-do" list.

However, inspired by your image and also the one from @Martin94b I have increased the saturation, tweaked the local contrast and reduced the stars.

I think this one works better, but clearly not as good as going through the separation process you used.

Very nice indeed Manuel. Haven't tried the separation technique yet. One to put on the "to-do" list.

However, inspired by your image and also the one from @Martin94b I have increased the saturation, tweaked the local contrast and reduced the stars.

I think this one works better, but clearly not as good as going through the separation process you used.

Very nice image indeed!  FYI, I have used Astro Pixel Processor to do the channel separation. It can obviously also be done with PI.