symmetal

Assuming you're using the ZenithStar 73 scope in your signature MM, and not binning, putting the large and small circular dust spots into the Astronomy Tools Dust Calculator puts the small dust circles 1.1mm in front of the sensor and the large dust circles at 10.1mm from the sensor. The smear pattern circle structure are a similar size to the small dust spot circles.

10.1mm seems a reasonable distance for the sensor protect window at the front of the camera, while the sensor itself could quite easily be 1.1mm from the front of the sensor cover glass so I'd put my bets on you having to clean the sensor itself (or the front of  its cover glass to be more precise) rather than the camera sensor protect window. 😉 That'll mean opening up the camera, though that's fairly easy. You could change the four desiccant tablets at the same time if you wished.

Your mono camera of course won't have the colour filter that's shown (Bayer matrix) 

I've used one of these sensor cleaners on my ASI071, as I ended up with dust on it after opening the camera to change the desiccant tablets, and the cleaner worked very well. You may need to use a couple of the cleaning wands on yours to make sure as your marks are more extensive..

Edit I was assuming that was a full size image you initially posted of the flat, but it's dimensions are 50% that of full size so it's either binned 2x2 or resampled to 50% before positing, or it's a crop of the original full size image. If it's binned then the Astronomy Tools dust distances calculated need to be doubled which doesn't make much sense so I'm hoping it's a full size crop. 🙂

If the Astronomy Tools calculator wants the radius of the dust spots entered and not their diameter, (it doesn't say), then it being resampled 50% means the original distances I calculated are correct. 😁

Alan

If it's a stabilized power supply, (as most are nowadays), which means it gives a fixed voltage output, independent of the current drawn, up to its max current rating, then it will be fine. As long as it can supply the current the mount and asiair need is the main thing. Five amps is a commonly stated rating for suitable supplies.

If you're unsure then give the model number of your current supply and we'll tell you. 🙂

Alan 

As stacking with those 'patterned' flats does seem to improve the final images, it would suggest a dirty film deposit on the sensor which the flats are 'correcting'. If it was ice it would be more randomized and using those flats would make the stacked images look worse.

Perhaps the previous owner has 'cleaned' the sensor but didn't do it carefully enough, and has left some smear stains which is what you're seeing.

Alan

If it's ice and still forming at 0C it must be fairly high humidity inside the camera. Did you still cool the camera to 0C when you took the indoor flats? A quick check to eliminate whether it's ice is to take some flats without cooling the camera. Is the camera new or second hand? If the humidity inside the camera is too high, it will still form ice when cooling indoors as the sensor should be sealed from the outside air humidity.

If it's still present when uncooled then it could be a dirty film deposit on the sensor.

Alan

It looks suspiciously like ice forming on the sensor. Flats will show it up very well, while lights may not, or only slightly, depending on how fine the ice crystal structure is.

What temperature are you cooling to? Nowadays I just cool to 0C to avoid ice problems. The ASI2600 has low dark current compared to older cameras and the small improvement in dark noise going below 0C is not worth the hassle of having to deal with possible dew or ice on the sensor. 🙂

Alan

13 hours ago, StarHugger said:

Thanks for sharing, This Gent also makes X Flare vids, his go back a ways...

Thanks. Very dramatic. 😁 Mine was just to show the Sun over several days and the flares happened to be in that period. The spot at bottom left looked to flare as well just before coming into view and threw up some large prominences too.

11 hours ago, Steve Ward said:

You just need to download "JHelioviewer" and you can access all of NASA's historical SDO data and make your own videos from it ... 😉 

Thanks. I've just downloaded it and it looks very comprehensive. Making my own videos from the raw fits data is very satisfying too. 😃

Alan

Here's a 5min 20sec video of the Sun I made using the GOES-18 SUVI HDR image data at 304 angstroms, (30.4nm). It's made from 9636 frames at 5 frames/sec from 1200 on 21st Mar to 2304 on 25 Mar (4.5 days) so it's at x1200 normal speed. Along with the bright flares there are some large prominences from other areas of the Sun, particularly around the times of the flares.

Flare at 2307 on 21st Mar, X1.8

Flare at 0632 on 22nd Mar, X1.7

Flare at 2234 on 22nd Mar, X6.3

The flares are clipped on the video as if I adjusted the gain/gamma to not clip them, the rest of the Sun would be fairly black. 🙂 The Sun is already fairly dark in the video but bright enough to see what's going on. I've used a colour similar to that used by NASA in their images of this wavelength. It's at 50% size to keep the file size down so it's worth viewing at its 640x640 resolution to avoid it looking too blurry. Right click to download it.

Alan 

From your last post Malcolm, I think that the Star Adventurer would be the best option for you. The first two are not Goto though. Even if you don't polar align but just set it to your latitude and in the home position point it roughly northwards, you would be able to use significantly longer exposures than you can get with a tripod before your stars get elongated. Alt/Az mounts need to track in two axis and at varying speeds depending on where you're pointing, as well as giving field rotation at longer exposures, while EQ mounts just track in one axis at a fixed speed so should always give better results, other things being equal. 

Star Adventurer Mini Bundle £249

Star Adventurer 2i Wi-Fi Pro Pack £335

Star Adventurer GTi £469 with Goto

DSLRs not needing darks is more to do with them not being able to set a fix sensor temperature, and as darks vary with temperature, using them tends to produce worse results then not using them. 🙂

Alan

It's worth taking a look at capture programs like APT or NINA. APT is more geared towards DSLR cameras, with a free trial period but is very reasonably priced. It's probably easier to work with for somebody new to using capture programs. NINA is free. Both will give a lot of image information that will be useful to you. NINA will give optimum exposures info but I believe it needs the sensor data from Sharpcap to work them out.

It may be worth starting another topic asking if anyone has 60D, or similar sensor data from Sharpcap as you'll likely get more people seeing it.

Alan

Pity you can't run Sharpcap. if somebody reading this topic has a Canon 60D and can post the data they obtained from Sharpcap it would help a lot.

What capture program are you using to get your images, as the dedicated astro ones  provide an image analysis which gives the mean, median, max and min pixel values for either the whole image or a smaller area like a 21x21 pixel area. Unless you have a lot of nebulosity in your images the median ADU will be the ADU of the background dark sky. This is the figure you need for doing read noise swamping calculations. You can usually get a direct readout displayed of the xy coord and pixel ADU value by moving your mouse over the image dark sky background. The 60D is a 14 bit camera I believe though the ADU displayed will usually be 16 bit so will vary between 0 for black to 65535 for white.

As well as the read noise you need to know the camera gain in electrons/ADU at various ISO settings to determine optimum exposures. Sharpcap would have given this information so hopefully someone can provide the data.

Alan 

The easiest way to get actual camera sensor info is to use Sharpcap's Sensor Analysis, (the free version will provide this) which gives read noise and a host of other info, and also gives optimum exposures based on read noise swamping. The 60D can be set to provide raw image data so should work ok for sensor analysis.

As to why 5x, it's because at around that level the read noise contribution to your image is effectively made insignificant compared to the noise you're getting from the image's sky background. For a detailed discussion you can read this thread if you have a spare weekend. 😁 Measuring the sky background ADU values from one of your images lets you calculate the sky background noise contribution (after removing the average camera bias value) and the rest follows as detailed in the thread topic. It's easier though to let Sharpcap do the hard work. 🙂

10 sec subs I'm sure won't be long enough to swamp the read noise unless you have very light polluted skies, like central London, and certainly not at SQM 20, so to counteract this it would mean having to have a longer total integration time, in order to match the results of the total integration time of read noise swamped exposures, as far as image noise is concerned.

An EQ mount would be much more useful to use for fainter objects like DSOs, as longer exposures can be made without dealing with the image rotation problem you get with an Alt/Az mount, though depending on the EQ mount (ie. how much money you want to spend), and your lens focal length you will likely need a guide scope for exposures more than around 30s.

Supernovae and variable stars can likely be captured with short exposures on an Alt/Az mount but you're limiting the type of objects you can image. You'll likely want to expand your options over time, so an EQ mount is a better choice in my opinion.

Alan

8 hours ago, vlaiv said:

Sorry, did not mean to do that.

It's ok vlaiv I was only joking. 😊

8 hours ago, vlaiv said:

We might be focusing on bits that are less important.

What do you say about:

- paper coming out about selection of regularization weighting function

- fact that choice of weighting function that produces finite value is related to the symmetries in physics

I can't really comment on that myself as it's getting beyond my knowledge level on the subject. I only watched the video due to the clickbait title, in which case the video succeeded in what it wanted to achieve. I see someone has posted the video in the comments to the Terence Tao page you linked to. I don't think Mr. Tao would appreciate that. 🙂

8 hours ago, iantaylor2uk said:

Actually a much better video on the same topic

Thanks Ian for that link. I'll watch it fully later on, but his comments at the start saying that the Numberfile video is wrong on every level made me smile a little. 🙂

Alan

I looked at the link vlaiv but got lost fairly quickly when he started calculating Riemann zeta functions where Re(s) <= 1 and where the results are divergent. If you apply analytic continuation 🤔 to the zeta functions > 1 into the realm where they are <= 1 and throw some Bernoulli numbers into the mix, out pop these fixed numbers, of which -1/12 is just one of many. If you apply the positive zeta function to these fixed numbers you end up with series like these

1+1+1+1.... = -1/2

1+2+3+4... = -1/12

1+4+9+16.... = 0

From the article:

Quote

Clearly, these formulae do not make sense if one stays within the traditional way to evaluate infinite series, and so it seems that one is forced to use the somewhat unintuitive analytic continuation interpretation of such sums to make these formulae rigorous. But as it stands, the formulae look “wrong” for several reasons. Most obviously, the summands on the left are all positive, but the right-hand sides can be zero or negative. A little more subtly, the identities do not appear to be consistent with each other.

I found the YouTube video misleading and with some sloppy errors, as I mentioned above. 0 or -1/2 are just as 'important' as -1/12, along with many others, in 'saving us from infinity'  and the article and video ignores the simple fact that the results are just the value of the series' if extended backwards from 1 to zero which is plainly evident if you plot the series, (in the traditional way 🙂), and then discard the whole series, including infinity, leaving you with just the value at zero. That's what I find the most annoying. 😟 This doesn't need analytic continuation, Bernoulli numbers, or carefully manufactured weighting functions to get the same result.

"This reminds me of string theory and elements of quantum field theory" in the video was the icing on the cake to give it some more 'wow' factor.

I used to enjoy Numberfile when they dealt with real world number facts to create amazing real results, but will be wary from now on, especially with this presenter.

Thanks vlaiv for getting me annoyed. 😁

Alan

Ding ding!! Round 3: 😁

22 hours ago, vlaiv said:

Point is not in the infinite sum being equal to -1/12, but rather it is that we have some value that is -1/12 and that there are different ways to calculate it - one of which fails but we know why it fails and when we encounter this way of calculating - we know what the answer should be - regardless if we can't actually pull off that particular calculation.

But it's explicitly stated in the video that the infinite sum is equal to -1/12. All I see is the value of -1/12 is the same as a projected value that would be obtained if N = 0, and not if N = ∞. But 0 is outside the range of the series. That's my main concern. Removing ∞ from the result by using a 'suitable' smooth transition weighting function, has also removed the results of the higher partial sums completely too, not just at infinity, and you're left with the residual -1/12. This doesn't seem anything to be surprised at really, and is actually not relevant to the sum of the series in the real world.

Below he has written the Sigma sum from 0 to ∞ when shouldn't it be the sum from 1 to ∞ 🤔 If N=0 then the partial sum is 0 and not -1/12 which ruins everything.

Also the hard transition he is indicating at N has a rounded top. Surely it would be a sharp cutoff as I've shown in red.

The symbol C below is the smooth weighting function e^(-n/N) when N is large. For the result to be -1/12, C must equate to 0 which it doesn't here as the result still goes to ∞. He quickly dismisses this and uses another more complicated weighting function using a cosine, which he admits he reverse engineered to produce the result of -1/12 

This is the graph of the cosine weighting function which, surprise surprise, produces the result he wants, by converting an actual divergent function into a fabricated convergent function and as it produces a fixed result, can amazingly be used as a substitute for the divergent function. At as low a value as N=4 the partial sum results have been virtually elimated so of course ∞ has been removed from the result.

The series sum should be expressed as 

(Weighting function which gives the result we want) * (sum of 1+2+3+4.....+∞) = result we want. ***round of applause***

This doesn't look as clickbaity as 1+2+3+4.....+∞ = -1/12 so wouldn't get so many views. 😁

Alan

10 minutes ago, vlaiv said:

Perhaps one criteria is that weighing function needs to tend to 0 as one moves to the right of N at greater speed than the speed of N approaching infinity and similarly that weighing function needs to tend to 1 as one moves to the left from N (again going faster than N goes to infinity) - or some other requirement like that.

But this means that at N the answer is always less than the value that would be obtained with a weighting function of 1, depending on the weighting function, and it's all these values of N which are being summed, so you're not summing the series but summing the weighting function result.  The higher the value of N, the closer the weighting function result gets to zero and therefore the weighting function results graph approaches a minimum fixed value equal to where the 'real' plotted summation result crosses the y axis. Why bother doing the summation with fancy weighting functions when plotting the first few partial summation results on a graph gives the same answer right away.

It's an answer alright, but to say 1+2+3+4... = -1/12 is just a theoretical mathimatical convenience to avoid dealing with infinity, rather than a realistic meaningful answer.

Alan

The value of -1/12 is just the value where a graph of the results of the partial summations of 1+2+3+4... if extended backwards would cross the y axis. From Wikipedia

Similarly the series 1+1+1+1... when plotted intercepts the y axis at -1/2

To say that if the graph is extended to infinity the result is the same as if was extended to zero in the other direction is obviously wrong, but if you manipulate the results of the partial summations by using a smooth cutoff function, and therefore get the result of every partial summation incorrect, and a lot less than it would be (as shown on Numberfile's brown paper writings) than if you had used an actual real hard cutoff, you can create any result you wish.

Choosing suitable weighting functions you can achieve the result which is the same as when x = 0 on the graph. Interesting maybe, but not meaningful as a result of the series.

Why is a hard cutoff for each partial sum bad, when the each sum start is a hard 1 and every increment is a hard jump in value, (unless it's like in the video where the last increment result can be any value you want. 😁

Why do all these series' mentioned start from 1 and not 0. Using 0 should be perfectly valid but it would spoil the results so it's omitted but an implied 0 result is used as the answer. 🤔

Just my two penneth. 😃

Alan

Hmmmm. Hard to say. Some background...

The controller plugs in the temp probe socket on the EAF. The temp probe uses a 3 pin 3.5mm jack while the hand controller uses a 4 pin 3.5mm jack so there must be a 4 pin socket as the EAF temp probe input and therefore ring-2 and sleeve (R2 and S in the diagram) are shorted together in the EAF when the temp probe is plugged in.

The temp probe is very likely the DS18B20 which usually works with +5V, Gnd and data pins. Looking at the diagram for the diy hand controller having +5V on one of the wires would mean it gets shorted to ground at some stage which isn't good so there can't be raw 5V on any of the jack pins.

It's therefore likely that the temp probe is being used in parasite mode, where only a Gnd and data pin is used. The temp probe gets power from the data pin via a 4.7k pull up resistor to 5V inside the EAF.

The EAF likely has a microcontroller similar to the arduino inside. As the EAF has a 4 pin socket the unused pins when used with the temp probe may go to spare input pins on the microcontroller. I don't think the 4.7k in the diy is that critical , but it's likely that changing it's value wouldn't alter the focuser speed, unless possibly one of the analog input pins was being used in the microcontroller and the 4.7k in the diy controller is part of a potential divider to determine the focuser speed.

Changing the value in the diy controller won't cause any harm, and it may or may not alter the focuser speed depending on how it's connected in the EAF.

Long story short, I don't know, but the above may give you some insight. 😁

The person who published the diy controller likely just took one apart, and copied what was inside.

Alan

Here's a couple of lengthy posts on other forums relating to the same effect.

Weird grid like pattern after alignment is talking about uring Siril but is relevent to any stacking procedures. Half way down is this link to a CN topic describing a similar effect and reason.

Did you do a meridian flip betewwn the two sessions you stacked which seems to create the issue in some cases. Using another interpolation method in your stacking software should help. What stacking software are you using?

Alan

I don't think that Astronomy Tools calculator is any use for filter halos, only dust spots. With  my image I posted above with the OIII halos it says the problem distance is 1.56mm which is nonsense. To get a distance of around 12mm which is around the distance to the front protect glass the dust spot diameter needs to be about 500 pixels which is a more reasonable value, but still seems a bit large.

The filters are probably around 30mm away on the flt-98 and the calcuator says the dust circle would be 1300 pixels across which again seems larger than the typical filter dust spot diameter with this scope and camera.

The halos are possibly due to reflections between the two filter surfaces and the astronomy tools calculated distances seem to be more related to the filter thickness which maybe a clue. 🤔

Hi Alexander,

Most odd. Can you post a picture of a side on view of your setup showing the scope, flattener, camera adapter and camera.

What model Nikon camera do you have? As you said it's a DSLR I assume you have the correct Nikon-M48 adapter fitted to your camera to allow it to screw onto the rear of the flattener. Unlikely to be wrong as there are only F-mount or Z mount I believe, with the Z-mount being much longer due to it being for mirrorless cameras and also a different lens flange diameter.

Also is the flattener screwed directly onto the M54 thread on the rear of the scope. You have to unscrew the the scope's 2" eyepiece fitting first.

Alan

I posted a GOES-18 SUVI animation on this thread covering the same event if you're interested. 🙂

Alan

You may like this animation I made from the GOES-18 SUVI (Solar UltraViolet Imager) data available to download from NOAA covering 1100 to 1600 on Feb 12. Frames are at 4 min intervals. The 304 angstrom (30.4 nm) filter shows proms the best. 🙂

Alan

Good to hear. 🙂

Alan

If you opt for a 15mm m54 extension I'd be wary of the Baader ones as they have a short thread depth and I've found many male threads will reach the end of the available Baader female thread before they're fully mated. I've tend to use AliExpress for extensions and stainless steel spacer ring sets etc. as they are normally better made, with deep thread depths and knurled outers on the extensions, and are a lot cheaper. 🙂 They take Paypal too.

M54 15mm extension and spacer rings from a company I've used and that's also been recommended on here.

Alan

That's right, though I doubt you can measure it to 0.01 mm though.  

Alan