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Messages - STAstro

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1
Gallery / Cocoon Nebula in HaRGB
« on: 2019 January 06 13:50:07 »
IC5146 - Cocoon Nebula in HaRGB

Located in the constellation of Cygnus lies the Cocoon Nebula (IC5146), this nebula is an emission nebula. This is my first ever attempt to image this target, again like previous targets I am limited to around 2.5 hours per night on this target due to trees and the house getting in the way.
 
Image Details:
56x150S in R
56x150S in G
66x150S in B
101x300S in Ha

Acquisition Dates: Sept. 25, 2018,  Sept. 27, 2018,  Sept. 29, 2018,  Oct. 20, 2018,  Oct. 22, 2018,  Oct. 26, 2018,  Oct. 28, 2018,  Oct. 29, 2018,  Nov. 14, 2018,  Nov. 17, 2018,  Nov. 18, 2018,  Nov. 30, 2018,  Dec. 7, 2018,  Dec. 9, 2018,  Dec. 12, 2018,  Dec. 13, 2018,  Dec. 27, 2018,  Jan. 4, 2019
 
All frames had 101 Darks and Flats applied, the Ha layer was blended using the new NBRGB Script in PixInsight 1.8.6, the more zoomed in picture is of the same data but with a 2x drizzle applied then cropped
 
Equipment Details:
Imaging Camera: Qhyccd 183M Mono ColdMOS Camera at -20C
Imaging Scope: Sky-Watcher Quattro 8" F4 Imaging Newtonian
Guide Camera: Qhyccd QHY5L-II
Guide Scope: Sky-Watcher Finder Scope
Mount: Sky-Watcher EQ8 Pro
Focuser: Primalucelab ROBO Focuser
FIlterwheel: Starlight Xpress Ltd 7x36mm EFW
Filters: Baader Planetarium RGB and Ha
Power and USB Control: Pegasus Astro USB Ultimate Hub Pro
Acquisition Software: Main-Sequence Software Inc. Sequence Generator Pro
Processing Software: PixInsight 1.8.6

Flickr Link: https://www.flickr.com/photos/30345959@N08/46584362762/in/album-72157688487449350/

AstroBin Link: https://www.astrobin.com/384658/

Thanks for looking



2
Thanks Juan

XISF files are all well and good (I save them as this the first opportunity I can), however when dealing with Flats, Darks and Especially BIAS frames then they are straight off the camera so they are in FITS format, I decided that 999 BIAS frames was good enough in the end rather than 4096 :D

With regards to the Issue on Windows, I wonder if you run PI on say Windows 2012/2016 Server you may not hit the maximum open files limit since Windows Server is designed to have more files open, unless it is down to a single process can only have that number of files open

3
I have a Core i9 10 Core / 20 Thread CPU, I have defined in my config that there should only ever be 18 threads (In order to leave some compute available for other running applications), however I have noticed this morning when performing an image registration using the star alignment tool that it reported "22 Threads" which I find a little odd considering

1. I do not have 11 Cores/ 22 Thread CPU
2. I have limited PI to only perform using 18 threads

Everything else seems to run fine such as Calibration, Integration etc they are all limited to 18 threads as expected.

What information would you need, pretty re-producible

4
Colin

How do you have your swap space configured for PixInsight?

I have 8 Swap folders configured on my Fusion I/O card, if you add say another three swap folders into PixInsight and perform the benchmark again, you might be where you expect to be

I will be tring this out on my MacBook Pro too very soon

Simon

5
General / Re: Benchmarks
« on: 2019 January 01 04:19:09 »
I didn't know that :)

Anyway, one thing I have discovered is that PixInsight doesn't seem to use MultiThreads to disks for SSD Optimization, now I understand why...because not everyone has SSDs right!

I have done some bench marking and that's pretty clear, SSDs work optimally when you saturate the queues on the SSD, for example all SSD Vendors publish their performance results based on an optimal workload, usually 4K and an outstanding I/O of 16, I am using a FusionIO IO3 3.2TB PCIe adapter which are pretty much up there with the fastest Flash drives around, however the swap performance was only around 933MiBs/sec, so I have created 4 swap folders on the FusionIO Card and specified them in the Directories and Network settings in PixInsight and I am now close to 2000MiB/sec, I think I can push this futher as I am not even touching the sides on the FusionIO Card yet.

Would be interesting to know exactly how PI works at a workload level such as Block Size, Outstanding IO etc

6
Thanks Rob

My Flat frames are the following exposures

L - 0.08s
R - 0.86s
G - 0.32s
B - 0.14s
Ha - 2.90s
OIII - 0.96s
SII - 4.15s

I'll take some dark flats anyway as I am just building my new library due to Gain/Offset change recommendation by QHYCCD, I'll inspect the 4.15s frames and see if the amp glow is evident, but since I am doing dark flats anyway...meh :)


7
General / Benchmarks
« on: 2018 December 31 12:08:57 »
Hi All

I wondered if everyone runs the benchmark at all?  Maybe we should all post our benchmark results and share any best practices?

*******************************************************************************
The Official PixInsight Benchmark version 1.0
Copyright (C) 2014-2015 Pleiades Astrophoto. All Rights Reserved.
*******************************************************************************

Benchmark version ...... 1.00.08
Input checksum ......... 2cd72b67e12fff2812ef5b5da054ab2a70a25e23
Serial number .......... M70B7J5Z775H5ACCBCOMZRGZTL1IWF2T

CPU Identification
CPU vendor ............. GenuineIntel
CPU model .............. Intel(R) Core(TM) i9-7900X CPU @ 3.30GHz

System Information
Platform ............... Windows
Operating system ....... Microsoft Windows 10 Pro
Core version ........... PixInsight Core 01.08.06.1448 (x64)
Logical processors ..... 20
Total memory size ...... 31.706 GiB

Execution Times
Total time ............. 00:55.99
CPU time ............... 00:38.20
Swap time .............. 00:17.75
Swap transfer rate ..... 933.753 MiB/s

Performance Indices
Total performance ...... 8401
CPU performance ........ 9909
Swap performance ....... 5172

*******************************************************************************

8
General / Re: Confusion about Darks / Flats / BIas / Dark Flats
« on: 2018 December 31 12:02:18 »
Thanks Niall

Helps a lot :)

9
Hi Rob

Fancy seeing you here :)

Surely I must subtract the BIAS from the Flats though right?

Regards
Simon

10
General / Re: Confusion about Darks / Flats / BIas / Dark Flats
« on: 2018 December 31 10:49:35 »
Thanks again Niall

So one final question, in your opinion, when is it neccesary to create flat darks?  Since my LRGB Flats are all sub-second, and my narrowband ones are <4 seconds, are flat darks really neccesary? 

Since my Lights and Darks will be taken at the same exposure time, and my Lights, Darks and Flats all taken at -20C I don't have any need to perform scaling on the darks :)

Simon

11
Guys

I am a bit lost here now, I have followed the LightVortex steps on creating a SuperBIAS from 999 BIAS frames, however I am a little concerned about the results, the first two images show the MasterBIAS on the left and the SuperBIAS on the right, the 2nd image shows the resulting MasterDark after calibrating all the dark frames against the MasterBIAS (Left) and SuperBIAS (Right), all images have had an STF applied.

The third image is a MasterDark with no BIAS deducted which to me looks a lot more "Normal"

Why do my MasterDarks look so bad when the Master/SuperBIAS has been deducted?  Does anyone have an example of their MasterDark when BIAS has been subtracted during the calibration of the darks?

12
I just got this when trying to combine 3996 BIAS Frames, I am using x64 Windows 10 with 32GB RAM, Core i9 10 Core, my Page file size is 12089Mb, I might increase this since I am using an NVMe M.2 device for Windows, speed should not be an issue

13
General / Re: Confusion about Darks / Flats / BIas / Dark Flats
« on: 2018 December 31 02:09:38 »
Hi Nial

Thanks for your reply, I also use a cooled imager and also set it to -20 so that I can image all year round too, however the QHY183M does not have a mechanical shutter, so in essence the dark frames are dark flats for the exposure time of 90s, 150s, 300s and 600s.  Because my flat frames for LRGB are all sub second exposures the need to subtract dark flats from them is not required, also you could argue that my narrowband flats are all sub 4 second, so again the need to subtract dark flats from them could be argued also.

My main question is around BIAS frames and where these should be subtracted from, as I said I only subtract them from the Flat frames at the moment and leave the BIAS signal in the Darks so they are being subtracted fromt he lights, however I came across this page on DSS website giving three ways to correctly calibrate light frames and it states at the bottom "Any other combination leads to improper calibration so you should stick with one of these 3 possibilities." which lead me to believe that my processingmethod is not correct.

http://deepskystacker.free.fr/english/theory.htm#CalibrationProcess

The nearest I come to it is Alternative Method 1, however in that method the BIAS is subtracted from the darks and then the darks subtracted from the flats, but surely this is then scaling the darks to compensate for the shorter exposure on the flats, because it is also stating that the BIAS needs to be subtracted from the lights (Obviously because it has been removed from the darks and flats)

I understand that you can't have BIAS in the Darks or Flats if you intend to subtract it from the lights, I also understand that you should not have BIAS in both the Darks and Flats at the same time as you would be subtracting the BIAS twice in pre-processing, so which method is correct?

1. My current method - Subtract BIAS from Flats, then deduct darks and flats only from Lights
2. Subtract BIAS from Darks and Flats and then Subtract Darks, Flats and BIAS from Light frames

Regards
Simon

14
General / Confusion about Darks / Flats / BIas / Dark Flats
« on: 2018 December 30 14:16:28 »
It's that time of year again when I build my new Calibration Library (Since moving to Unity Gain as well), so my Calibration Frames are as follows

1. 101xDarks for Each Exposure Length (90, 150, 300 and 600 Seconds) - Used to create Master Dark for each exposure length
2. 101xFlat frames taken as same Gain/Offset as Darks and Lights for each colour filter
3. 3500+ BIAS Frames with same Gain/Offset as Flats, Darks and Lights

Now I have always done the following
Calibrated Flats against Master/SuperBIAS since my flat frames are sub 4 seconds (LRGB are all sub second) to create Master Flat for each filter
Combined all Darks to create Master Dark for each exposure length (Not subtracting BIAS)
When Calibrating Lights, only the Master Flat and Master Dark are subtracted (Since Darks contain BIAS Signal)

However, I am reading that I should be deducting the BIAS from the darks and then in the Light frame calibration I should be deducting the Master/SuperBIAS from the lights, so the question is, should I only be doing this is I am scaling my Darks?

TIA
Simon


15
New Scripts and Modules / Re: Subframe Selector PCL Module
« on: 2018 December 30 14:07:04 »
Am I missing something here, in your screenshots it shows the Subframe Selector and the Measurements window combined, in my 1.8.6 on Windows 10 it shows them as two separate windows


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