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Thanks for the reply. I had wondered how much better sigma clipping might be. Looks easy enough to implement.
I have wondered if the skewness of the sample pixels could be calculated and that used as a threshold for pixel removal – though I suspect that might be more computationally intensive than sigma clip.
I shall have a play on some data I’m working on.
One minor tweak….
You say that you need the outer annulus mean value and standard deviation. But, in cluttered fields, does using the median value help protect you from outliers?
I did my first variable star measurement in 30 years.
Result: 20201009 01:27 Mag=14.1 (first crude estimate using AAVSO) while AA7 says 13.94. What does everyone else use?
Refined result using Gaia DR2 plus another from the following night…
20201009 01:27 2459131.60262 14.05
20201010 00:21 2459132.51466 14.30
Managed to catch it around midnight during a brief clear very transparent slot following the swirl of cloud that caused such heavy rain yesterday afternoon. The coldest night of the autumn here so far. Was 4C by the time I closed down – must bring the geraniums indoors.
It really is very faint isn’t it? When the other lobe of the nebula is the brighter of the two then you know its dim.
The faintest I received in our study – August 2009 – was 18.75, so we’re in unexplored territory.
Am kind of hoping it ends up repeating the cycle we observed, so we can say its got an 11 to 12 year cycle, but thats probably too much to hope for. 🙂
W10 has the option of sacrificing appearance for performance and also choosing whether the beneficiary is the applications you use or “background services”.
Would it be worth looking at those and trying different settings? Just a thought given that the system clearly can work without the interference.
Also, have you tried using the camera with your anti-virus turned off?
One question: is your camera a USB camera or a serial camera with a USB adaptor? Cannot vouch for those.
I’ve used: Lodestar, Superstar, Ultrastar, SX H18 and Trius 694s on a USB3 under W7 and W10. No issues.
However, if there is a problem, then if your laptop takes Expresscards, you could perhaps install an old USB2 card.
I discovered the Python Wikipedia entry this week. Highly entertaining reading. About the only thing it doesn’t do, apparently, is turn water into wine – well, thats what the zealots appear to think it seems.
Could you tell me what sort of circular polariser it was please? Am sort of surprised it was so successful against the linear signal from the comet.
Is it one that normally fits on a DSLR camera lens?
Really nice to see this.
The comet is approx 30 degrees from the sun, so the background should display Rayleigh scattering induced polarisation of a few percent. From memory, the orientation in the first image looks roughly right given the suns position pretty much below the north horizon. The comet should have its own dust response – as the Zodiacal light does – and certainly appears to here. I’m a bit perplexed by the orientation of the background polarisation in the second image though. Was the amplitude the same?
Your amplitude measure, was that a Stokes parameter or the degree of total linear polarisation or similar?
I imagine perfect alignment of the 4 polariser images is essential to the values measured when the target has fast changes in brightness. I have always had greatest problems getting good results in parts of the image with steep gradients – subpixel registration is important (I found to my cost).
I assume you only used linear polarisers.
Thanks for the clarification(s) on why you seemed to object to the device. Nice to understand the rationale. I must admit I rather liked the idea of using the PHD slit option. Seemed quite sneaky but can see why a mirror system might work better.
As you say, it ideally needs someone impartial trying both and seeing what works best in practice.
I wondered if any internal reflections made it visible. But and x/y cordinate should be enough really.
If the Lodestar x2 is being used for guiding, would it be possible to display that guiding frame in semi real time? Would really need to ask Terry or Michael I imagine.
Would make sense – the Lodestar x2 isnt a bad imager (SX7 without the cooling). But would you see where the slit was?
My take on it was that its self contained and very suitable for those lucky well heeled souls who have scopes at remote dark locations and so want the whole lot easily controllable and adjustable via a GUI. Similarly for university observatories to train up the students.
Thinking about it, there must be a market out there at some of the ITelescope type sites for a few of these. Look how long we had to wait for a spectrum of the new nova in Reticulum.
I too would be curious to see how it performed, preferably via a review done by someone not too bought-in to existing technology/manufacturers. People do tend to become tribal and sometimes don’t want to hear that something else is good in case it reflects poorly on their own purchase choices. I imagine we can all think of instances…
Morning,
I’m not really understanding what you don’t like about the new system. Concave grating corrected for astigmatism, on board ref, onboard flat and onboard focusing/guiding. I don’t do spectra, but that would certainly seem to tick some boxes.
Yep, I am ignorant, but I’m not seeing a lot to dislike beyond the price – but then again I struggle to understand why so many salivate over high end 4″ refractors when the same money would buy a 14″ Newt.
I don’t imagine the BAA will be subsidising purchase of these like they did for the Shelyak systems a year or two back.
What am I missing? 🙂
Thanks for the headsup. Am watching it now.
Blue CCDs. Excellent. I can have a camera that matches my eyes! I don’t care what colour it is as long as it still does the business but some people like their kit to be pretty. At least its not red.
For me the comet is still naked eye and about 5-6 degrees long. It was a bit hazy last night so tougher to see by direct vision but still there: https://britastro.org/node/23435
No obvious sign of banding in the dust tail but when using Live View the coma was clearly green.
Its been a real treat to have some tolerable weather and a comet with two bright tails.
We should start to see some images from Aus in about 10 days time… Hope its stays bright for them.
