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I’m no expert but would start with the flat field issue – that seems a decent easy-win as the background brightness variation from vignetting is hiding the extent of the comet.
How many counts were in your RAW flat field frames?
As a very late addition, I have had 2 years of messing about with Mini PCs and trying to use two different Wifi extenders so the MiniPCs ran off a Wifi network in the dome…. The Minipcs are convenient as they sit quite happily on the plastic cover that goes over the polarscope on the NEQ6 meaning fewer cable tangles.
However, I found that, due to Microsoft’s updates, its not tenable. Every time they applied a Windows update the connection died and I had to connect a monitor/keyboard/mouse and tell it (yet) again my manual addresses, my DNS preferences, gateways, masks etc. Last weeks failure occurred 30 mins into the observing run meaning I lost my sky model. Enough is enough. I’m going over to using the ethernet output of a TP-Link adaptor and yet another cable.
I suspect you can work consistently over Wifi if you use Linux machines in the dome but my chosen camera software does not work under Linux – may have to change that…
So, TL:DR given a choice between Wifi in dome and ethernet in dome while using Windows, just say no to Wifi.
The pier is bespoke – the farmer/astronomer who made it and welded it all only made 2. Not a commercial effort, but I managed to buy one from him when he gave up the hobby for a while.
I think the only bit easily modified will be the metal plate supported 3-4″ above the top on 3 thick bolts. I looked at upgrading the bolts once and found they were a weird Imperial threading, so will reluctantly stick with them and – if need be – create a new plate from scratch.
Anyway, the rest will wait until winter now then. Will post more then…
Thanks for that.
Thats similar to the FLO adaptor for an EQ8 https://www.firstlightoptics.com/pulsar-observatories/astro-essentials-pulsar-pier-adaptor-for-eq8cq350cem120myt-mounts.html#faq but half the price – the FLO plate also works for Ioptrons and the SB MyT. Thanks for spotting it. Not sure how I missed it.
For either of those I have to take the existing EQ6 adaptor plate off. I was hoping for something that might go over the top. I was probably being unrealistic. But I had figured its an obvious upgrade path for people who are not going as up market as the MyT or 10 microns and hence someone might have done it.
I will have to check the diameter of the central hole.
I shall wait until a rainy day in winter, dismantle the scope, clean the mirror and see how difficult it will be to remove the existing EQ6 pier adaptor – it was attached by the previous owner via araldite and bolt or just rusted bolt… I really don’t want to replace the pier as its rock solid. Its times like this I wish I still had access to a machine shop. 🙂
Could you supply a link to the SGL discussion?
Also, why not use an OAG and the existing top rail for the refractor?
Just had a thought. Could you collect a bunch of Nikon RAW format images, allow the DeepSkyStacker software to align them and output a median filtered image in FITS format?
DeepSkyStacker certainly used to be free – AstroArt is not (though the demo version used to be).
Just a thought.
I believe AstroArt can handle Nikon RAW files – though I have never done so myself.
It is probably a bad idea to estimate the linearity of a sensor from jpgs as the scaling will be different for each picture.
I certainly recall seeing Jupiter at mag -2 (I think) very obviously 3minutes after sunset on Ascension Island – though it was nearly overhead from there. I’m sure I would have seen it at sunset had I not been busy watching for a green flash – yep, got that too. Ascension is ideal for them.
You had better weather than us – went out to garden twice and it started raining!
Thats a nice video. Love the pollen blowing through. Thats a really helpful figure to have – thanks. I shall adopt that instead of my crude guess.
In about 2000 or 2001 there was a planetary conjunction not far from the Sun (8degs or so I think). Phil Alner of Cody Society and I observed Jupiter, Saturn, some stars and (I think) Mars through a Zeiss 160mm f/15 refractor. While the planets were clear and easy (though the glare from the nearby Sun pretty fierce – don’t try this at home kids) I don’t recall seeing any of the moons of Jupiter which are mag 5. I think we decided the limiting mag was 3ish elsewhere on the sky.
It looks intermittently clear here this afternoon. I may give it a try.
Yeah, polarisation makes a huge difference depending on where you are looking on the sky. Similarly, filtering.
I had a bash at imaging Polaris with an 80mm f/7 refractor a few years back using an H-alpha filter to filter it into the red. Unfortunately, the images kept on saturating as sunrise approached – but I was using a CCD whose shortest exposure was about 0.08sec.
With a modern CMOS sensor I imagine I could do a lot better now.
Thats a useful looking book. Will grab a copy off ebay.
The calcs I am doing are based around the standard CCD S/N calculation mentioned by Steve Howell in his “Handbook of CCD Astronomy” – derived from Mortara&Fowler plus Newberry and others
Something like…
SNR=Nstar*t/sqrt(Nstar*t+npix(Nsky*t+Ndark*t+Nread*Nread))
where:
t – exposure length
Nstar – electrons from the star
npix – number of pixels covered by star
Nsky – electrons from sky in each pixel
Ndark – dark current electrons
Nread – read noiseLets be honest. Some people don’t do nice chats.
I had a nearby neighbour with 500W halogens on the back of their house. Eventually I had to try the light nuisance route with the local council. I got a letter suggesting I buy thicker curtains…
Four usable, or part usable nights here, in the last 2 weeks (all night last night) – I know because 2 weeks ago was when a Windows 11 update totalled the network between my house and the dome. Not that I am counting the clear nights since, you realise.
I’m expecting several more clear nights before I manage to mend the network…
I have to do it myself as while Microsoft have admitted some people had probs with a recent update, they are not planning a quick fix. Unfortunately, my full knowledge of networking fits on the back of a stamp – written using a crayon. Its not a fun learning curve.
Ah yes. Have never used one of the duo/tri/quad band pass nebula filters and don’t use OSCs. Agree: one of those filters would require properly corrected optics.
I was just looking at how much a Takahashi 106 costs these days and even a Borg 72mm is no change out of £2.5k – and lets not even mention the TB 203.
I’m probably just mean, but I always think “Ouch” if handing that much money over for something that isn’t necessary. Mortgages and such like taking precedence.
I am impressed that you now see refractors down to f/3.9 but a 72mm isn’t really giving that much light to filter. My approach would be a mono CCD/CMOS, single band filters and a SW 80 achromat and a focal reducer/coma corrector – but, yes, that wouldn’t be running at f/3.9. Can see why the 8″ V2 RASAs are so popular.
Taks and fast EDs are great for those who can afford them.
Reading the JAMA link Nick gave, it looks like they think that you might be somehow taken by surprise by the Sun reappearing and instantly damaged.
Which is kind of weird as the end of totality is always easy to see coming and I must admit I have yet to hear of the Diamond Ring damaging anyone’s eyesight.
I could only imagine a problem for people whose eyes remained fully dilated (for some medical or pharmaceutically induced reasons) or who were using a telescope/binoculars during the Ring or forced themselves to keep staring after the Ring was over. Other than that, it sounds tosh to me. But, as Nick wisely says, your experience may differ*.
*Its a bit frustrating that everyone now needs to protect themselves from the wrath (legal or otherwise) of people not thinking about the potential consequences of their own actions.
