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  2. I have to correct myself. I now downloaded all 10 bias files, and things got more interesting. First bias frame has first three pixel rows with pixels set to exactly 0. All other bias frames have only first row with all pixels set to exactly 1120 - or rather 70 if we divide with 16. I don't know if this is due to camera or possibly due to storage / transfer (if you used failing usb memory stick or something and copied files one by one? just a thought).
  3. I'm offering this excellent William Optics 2" diagonal for sale. It's in lovely condition throughout and comes with compression rings, 2"-1.25" adapter, both end caps and original foam lined box. £79 Including signed for UK postage. Payment by BT or PayPal F&F preferred please. Stock image below, I will post some photos of the actual item tomorrow morning. Dave
  4. ZWO has very nice convention of using logarithmic gain values - with their cameras gain number represents actual gain expressed in 0.1dB.
  5. Just look at "bias" - it looks very nice. Indeed 70e is median (mean is a bit lower - I'll address this) and from quick inspection I would say that it is a good value. SGP reports e/ADU of 1 (fits header), while it is clearly not - this means that driver is not reporting proper value - no biggie as long as you know from gain table what you are using. Bias looks good, there are no zero values (except interesting issue) around. I can't explain why is actual bias level 70 when you set it to 35. e/ADU is ~1.8755, so if offset is applied prior to gain, expected value would be ~18.6617. If it is applied after, well expected value would be 35. Only option that I can think of is that offset is not set in units of e, but rather some arbitrary units. You can do a experiment and set 3-4 different offset values and shoot dozen of bias files to see how median value changes with given offset. Maybe try changing gain also, until you figure out what is going on. This is only if you are curious - I would not mind using camera like this. Now here is interesting thing - top 3 rows of pixels have 0 values in every single pixel. Like whole 3 rows have been "shut down" or not read or something like that. This might be due to drivers or has something to do with how camera was manufactured - electronic design. Do keep it in mind though - as it might cause you problems sometimes and it's good to know that artifact exists so you can take steps to circumvent any problems.
  6. Hi Jon. The mount and accessories are packed. Hermes tracked, insured, signed for and three delivery attempts is £16. I bought and used tape. Total is £201. Bank transfer would be great. M & L Greensmyth. Acc 19622066 Sort 600519
  7. cletrac1922

    Hello

    Thor Welcome from Land Down Under Perhaps rock up one night at local astronomy club, members there only too eager to help you Give you a hands on with your Orion scope John
  8. I'm just beggining in eeva but I have already noticed the equipment needed can very considerably depending on what size the intended targets are you interested in...Large dso or small galaxies or maybe even wide fields, how much light pollution do you have? You may need a light pollution filter and if its really bad you might want to design your rig to be portable so you and it can travel to darker skies. Louise is correct that astronomical darkness is waning as locations in the northern hemisphere spin south and here in the US we northerners are just pulling out of the rainy season so slow it is and has been, but if you add some additional facts like LP info what targets your after overall budget some one is likely to chime in further. Best of Luck and Clear Skies of course Stew... Freddie.
  9. I have found dark flats as important as flats to help with the background sky noise regardless of whether there are gradients. Binning is a function I use in StarTools it does two things, makes the image smaller (easier to then process) and condenses the signal at the trade of resolution (a large image I find is cumbersome to work with and thins signal clarity).
  10. Excellent! I look forward to hear how you get on with it. Looks very nice.
  11. I'll examine subs you posted, but there could be a simple explanation. I can't remember now, but it was discussed sometime ago - offset can be added at both pre amp and post amp stage - meaning that it can be multiplied by gain or not. This could be one explanation. Second explanation would be that since some vendors use gain in arbitrary units, offset might also be in arbitrary units? I remember older QHY cams having 0-100 gain in some drivers. That did not translate into anything meaningful, or one needed to measure e/ADU values to get proper correspondence. Is there a "table" or formula for gain - e/ADU conversion for this camera? Maybe offset is implemented in drivers in similar way - meaning 0-100% of possible offset ranges (which are real numbers but something like 0-220e or something like that).
  12. Treat the battery negative terminal and everything connected to it as Ground or 0 Volts. I assume all the equipment is fixed to the rotating roof so as you say there is no actual physical. connection to the earth for a true Ground connection. Ground in your instance is just a nominated point which you can call zero volts to which all the other voltages are referenced to. As your system has no physical ground connection you can't make any voltage measurements with your multimeter if you connect your black meter lead to a true ground like you will have in your home. So you have to nominate one voltage in your system to act as a ground for making measurements. The most logical is the battery negative terminal. Talking in terms of 12V+ and 12V- could imply +12V and -12V which have 24 volts between then. Calling the 12V- terminal 0V or Ground for convenience, removes any ambiguity in labeling. As your system is only 12V powered you don't need a physical ground or earth connection for safety reasons like you would with mains voltages. Ground and Earth are the same thing but it's more common to use Ground particularly with DC. From Wikipedia Alan
  13. Point being? Density in this case is - take any interval within 0-1 range, 0.3-0.4 for example and divide length of that interval with count of numbers within that interval or 0.1 / ∞ ~ 0 (any finite number divided by infinity is infinitesimal). This statement is not correct, and again one has to be careful when working with infinities. Basic division or types of infinities are countable infinity and uncountable infinity. Interesting fact about rational numbers is that there is countable infinite number of them - same as integers - this means that there is "the same number" of rational numbers and integers. Have a look here: https://www.homeschoolmath.net/teaching/rational-numbers-countable.php Page already emphasizes important sentence, and I'll just copy it here: "a set is countable either if it s finite, or it is infinite and you can find a one-to-one correspondence between the elements of the set and the set of natural numbers" Finding one to one correspondence between two sets in fact means they contain same number of elements (as for each element in one set there is exactly one corresponding element). Real numbers on the other hand are uncountable - meaning there is vastly more real numbers than both integer numbers and rational numbers - again point given above, difference being all irrational numbers.
  14. Dave - just to say I ordered and have received the dual channel dew heater control as per your suggestion at: /www.dewcontrol.com/Dual_Channel_Digital_Dew_Controller/p3099125_13437758.aspx It looks well made, and arrived quickly. Looks just the job - thanks. Annie
  15. I'm planning to use Sharpcap for Polar alignment, which gets good reviews, using a Starlight Express Lodestar X2 mono guide camera, combined with a William Optics 200mm FL x 50mm guide scope, which I calculate provides a FOV of 1.85 x 1.38 degrees. I've been using this set-up successfully with PHD2 for sometime. Given the above parameters + before proceeding further with Sharpcap I wanted to confirm: 1. Will the pixel size of 8.6 x 8.3 nm, which is not square, work OK with Sharpcap and plate solving, which I understand is an integral part of the polar alignment routine? 2. Will the installed ASCOM driver for this camera used with PHD2 be OK with Sharpcap or do I need something else - if so which one? Thanks, Graham
  16. We have to be aware of infinities and there place in the real world...to take an example highlighted upon before and look at it differently. There are obviously more non-integer numbers than integers.... I think this makes sense. In fact there are infinitely more non integers than integers.... again look at 1 & 2 and count the non-integers between them ( might take a while ). Statistically Integers do not exist ! It can have weird effects when you move from reality to imagination. It would seem to make sense that infinities do not exist in the real world, ie nothing you can observe can be infinite. ( or be part of anything infinite ).
  17. this is mybest effort of jupiter with a little mak 90 and an asi290mc
  18. Today
  19. Isn't density a ratio.... and hence by definition....rational ?
  20. I never thought about the possibility that too few darks can add noise... I have to make sure to remember that darkframes are just as important as lightframes haha. What exactly is binning? I may be confusing it with drizzle. Also, if a gradient is barely noticable, are flats really needed? I tend to crop images more and more, except for targets that are too big for my FOV like M31.
  21. That's a great set, I particularly like m57. I have found 100+ lights with 30 flats, 30 dark flats and bias makes a difference and if do use darks then it is 30 again. Too few darks I find adds noise. There is a point of diminishing returns but me me that is controlled more by how long I will stay outside or whether the object is moving out of view. For uploading as I bin my images they are always nice and small file size so are around 3 MB each only.
  22. Thanks for that. They look very useful. James
  23. Here you go https://www.orbitalfasteners.co.uk/en/products/m6-concrete-anchor-ankerbolt-socket-bolt-m8-thread?utm_medium=google_shopping&utm_source=google&utm_campaign=google_shopping&gclid=EAIaIQobChMItoC3662C4gIVzLDtCh2noA1mEAQYASABEgIklvD_BwE
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