pete_l

Four gigaBYTES of memory, or 4 gigaBITS (i.e. 512MByte)? The Altair advertisement is not explicit and I doubt there would be any way for a user to tell. Personally I would like to see a photo of the circuit board to validate one or the other.

I built something like this a few years ago. Before you start, make sure that the blocks aren't too wide. I used standard 40 x 20 x 20 blocks. With a small GEM on top, the blocks were too wide to allow a telescope to move unrestricted. There were positions when the OTA would bang into the corners of the blocks.

I think that one major reason why such small telescopes were suggested had more to do with price than usability. In the 1960s optical gear in the UK was very, very, expensive. Most telescopes would have been hand-made and therefore of dubious optical quality. They also didn't have the modern glasses, design tools or eyepieces we take for granted. Even today, prices increase very quickly with aperture: it must have been even worse 50+ years ago. I reckon that is why the recommendation for binoculars started. More due to cost than providing decent views (and it was only eyeballing, photography was virtually non-existent in the amateur sphere). Even so, they would start at more than twice the weekly pay of most people (roughly £10 a week in 1963, before tax). So £30-£50 for a pair of 10x50s was a luxury item - think £1,000 now! Even army surplus was pricey. There's an interesting article about binoculars here

There is no single reading that defines your sky darkness for all time. I take SQM readings from my site occasionally and can say that it varies a lot. Mostly I get values in the mid-21's 21.4, 21.5, 21.6 However the value changes with the seasons, with the sunspot cycle with the time of night and with many other factors. Also SQM can be very high when the place is completely clouded over! ? While SQM reading also give some idea of transparency - with little in the way of particles / water vapour to reflect back light from sources of pollution, it tells us little about steadiness, which seems to me to be a more valuable metric. The best ever was at the beginning of January this year when it was -8°. Here's the photo

The most cost effective route into astrophotography is a s/h modified DSLR. There are companies and individuals out there who buy used DSLRs and modify them to sell on. You can either pick up an "off the shelf" one or have them modify a DSLR that you own. There is nothing really to gain from buying a new one - a low shutter count used model is just as good. I have a mix of one shot colour astro CCDs, mono CCDs with filters and modified DSLRs. The major advantages of the DSLR are about simplicity: ease of attachment to the telescope, getting results quickly, less cabling, simple to use, the software to run a colour DSLR is less complex and they have a large sensor size. The disadvantage is that you won't take Hubble quality images.

Thank you, that is useful information. Unsurprisingly, we get "muddy rain" a few times a year in southern Spain. While rain is generally welcome (some years we get a total of 200mm) this effect seems to mix the greatest amount of red dust with the least amount of water. The result is no significant rainfall but the need to wash the car!

The map is a little optimistic. The best I have measured with my SQM is 21.6, though 21.5 is not uncommon when the moon is down. Though I do have a 360° view and 200+ clear nights a year And hours of full darkness during the summer For reference, here's the data for the Calar Alto observatory. It's about 50km from my place and is home to the largest telescope in mainland Europe. I was up there last June and I was surprised that the inside of the main dome was illuminated. They do get a bit of LP from Almeria city and their numbers are theoretically a bit better than mine. However being 7000 feet up, they have much steadier skies which seems to count for a lot.

I have always considered 3D printers to be novelty items - over-priced and with few practical applications. However, the market does seem to have changed in the past year. The Creality Ender3X is getting good reviews for < £200 and I am now giving it some serious thought. However, I still feel that they are far less useful (and much more hassle) for the average person than all the publicity and promotion would suggest. Without wishing to start a war here's an interesting video:

Indeed. Once you have found that. I would suggest you look on the site's home page : https://stellarmate.com/ The description of the actual function is very well hidden in all the hype, buzz-words and eye-candy.

Yes, the Linux community is its own worst enemy. The good news is that STELLARMATE is a completely packaged hardware and software product. You just buy the box from some outfit in the USA and once it is delivered and you've paid all the excess VAT and import taxes, it is a case of following the instructions. Provided you can decode the jargon that is inherent therein. I've been "doing" software for nigh-on 40 years now, professionally. I have been doing various things with Unix (the precursor to Linux) since the early 1980s. Yet I still have difficulty wading through the publicity material for many products. And that is not down to my lack of technical skills. You would think it would be the simplest thing in the world for every new tech. product to have an introductory line on the home page of their website, right at the top, along the lines of X is a piece of software that runs on .... and is used to ..... But in their enthusiasm or inexperience hardly any amateur entrepreneurs ever think of doing this. It often takes several minutes for the casual visitor to work out whether (as in this case) the "product" is hardware, software, a combination of both or whatever. All I can say is: take whichever route is easiest.

Yes, it does give the impression of being designed by a committee: too many compromises. Price-wise it is comparable to an 8 inch SCT And in F-ratio, too. It doesn't seem to be different enough to attract much market share, given that there are so many SCTs occupying that market segment.

As regards obstructed views, one thing to take into account is light pollution. If you have the option, losing sight of the most "orange" segment of sky will lose you the least. I wouldn't be too concerned with losing sky beneath Polaris: everything that is under it will rotate around to be above (i.e. higher in the sky) at other times of the year. One other thing you may care to consider is bats! They are a protected species and you are not allowed to disturb their breeding sites and habitats. It would be unfortunate if you were unable to use your observatory because some made their home there. It would also be worth looking at ways to discourage other wildlife (incl. wasps, ants and other insects) from taking up residence in your observatory - or even inside your kit. In the winter it would offer a nice, sheltered, cosy, environment, And some plastic insulation can be quite tasty (so I'm told) - especially for mice. Birds, too, might find it an attractive place to nest!

Yup, I've got one on the bench as I write this. I bought the "bare" ESP32 - €3 from China . The green matrix board is designed for it and you can see the names of the "pins" (if you flip it over, there are connections for an ESP12 instead). The black component to the left is an Arduino compatible USB -> power + serial You can program it through the Arduino IDE and lots of Arduino and ESp8266 libraries have been ported to this device. Many of them actually work! ?

Yes. I'm watching the "fun" on CN with interest. If this mount can deliver on its claims then the version with the encoders looks veeeeeery desirable. But it is a big "if". Though there seems to be a huge amount of hostility from owners of established high-end mounts (even though none of them have ever even seen one of these mounts yet) who just "know" that it can't be any good. Who will turn out to be vindicated? I'll wait for the real-world experiences and honest test results from users who know what they're doing before making any judgements or decisions.

I think "upwards" is the important word there . In 2003 I paid £900 for my GPDX + SS2k (the goto system) and it is still in use today.

The thing is, that while Vixen have been making essentially the same product in different guises for the past 30 years, all the "cheap" chinese manufacturers have been upping their game. It has now reached the point where a mass-produced mount has the same abilities, functions and features for a fraction of the price that the old "quality" products are offering. It is the same situations with cars. Maybe 40 years ago, if you wanted reliability and performance there were just a few top-end manufacturers with something suitable. Now even a family runabout is more reliable and has more features than a Roller from the 1970s. Since you are talking about visual use, you don't need the low PE of a high end mount. Plus, a 6kg payload is just about an ED80 with a guider and DSLR - so that also makes the Vixen an unsuitable imagers' mount. It is really just for imaging that the old advice about spending more on the mount than the scope comes into play.

It looks like one of these: Virgo 50800mAh Car Jump Starter Though to describe it as a "jump starter" sounds just a leeeetle optimistic. When looking at the quoted capacity of these devices in general, it does appear that the mAh value advertised is that of the internal 3.7 Volt cell(s). So divide that value by the ratio of the output voltage to the cell voltage (in this case: 12 / 3.7 = 3.2) - then knock off a bit for the internal 3.7->12V inverter's efficiency: call it 10% and you end up with about 14 Amp-Hours as 12V. Still pretty impressive for the size and weight.

From my point of view having a base for a pier that is more substantial than the foundations of a house (bulding regs. say 1m deep by 60cm - but depends on the soil) seems to be going to extremes. The internet is full of people making "one-upmanship" recommendations: one person says X, the next says "not that's not enough, it should be 2*X" and the next says something even bigger / better / faster / more (hmmm, good name for an album, that! ) Here in Spain there are many houses, some still standing, that have little or no foundations at all. Now I appreciate that a pier's foundation is mainly about damping out vibrations, not carrying a load. However most home-owners also need to consider the consequences of trying to sell-on a house when there's a cubic metre (yard: in old money) of concrete sunk into what the next buyer may want to call a lawn. But on the topic of vibration damping, mass is not always your friend. To do the job properly, you don't just pour more goop down a hole: you need to know what resonances the base+pier will have - heavier == lower frequency, and whether damping out high frequency vibrations (which are usually of low amplitude) leaves you exposed to lower frequencies - such as from a passing vehicle that could have a much higher amplitude and therefore cause a larger magnitude movement to be induced into the mount, even if they aren't resonant. Oh, and if anyone even attempts to analyse the Eigenvalues for their pier design, I promise to be seriously impressed.

Have a look at this: http://www.caha.es/WDXI/CLOUDS/clouds_info.php which is used at Calar Alto as part of their environmental monitoring. I just wish I could get their level of seeing but I suppose that's what altitude is for

Since this thread is about fire and theft, it might be worth noting that people (me, especially) tend to worry about the wrong things. We recently suffered a "small" grass fire. The 20 or so fire dept. people who attended were not at all impressed. which in a place that got less than a foot of rain last year and has been in drought for the past 18 months is not that uncommon. Fortunately no-one was hurt and apart from some minor property damage (satellite dishes, firewood) nothing was lost. Since I was already in the process of reconsidering and rebuilding my observatories, anyway, this too has given me cause for a great deal of thought. I am now firmly of the opinion that people who live in areas of fire-risk should invest in one of these: and keep it handy all the time. Although I am still using wooden sheds (of the roll-off kind) as observatories, mainly because they are inconspicuous and cool down from daily temperatures of 45°C quickly, there are some precuations that I am building in to the second generation. These amount to clearing the surrounding area of anything flammable: plants, trees, bushes (though the fire did quite a good job of this). Consider fire-retardant paint on all wooden surfaces. Have a large bucket of water handy at all times. I'm thinking of about 10 tonnes of water in a tank nearby (not for swimming in or watering the plants from). Fire and smoke detectors. Lots of smoke detectors. Everywhere.

That's the problem. A real SQM measurement would only look at the gaps between stars, not a starry sample of the night sky. I have a feeling that to do so would require a very long F/L refractor and to compare sky darkness with the light intensity from a defocused known brightness star. All sounds a bit too difficult. Personally I'm satisfied with my SQM and the ability to just look upwards and think to myself: Yup, that's pretty dark!

Let's review. The Celestron 5 is a 127mm aperture F/10 scope. The Neximage 5 is a 5MPix camera with 2.2µ pixels. This gives an imaging scale of 0.36 arc-sec per pixel. Now, it's difficult to quantify your "wonderful" seeing, but as a benchmark, the professional obsy near me (Calar Alto) which houses the biggest 'scope in mainland europe at an altitude of 2,000 metres has a "seeing" figure of 0.8 arc-sec [ ref: http://www.caha.es/CAHA/MISC/seeing.html ] So even if your seeing was a truly exceptional 1 arc-sec, you'd still get 3 pixels of blur in your images, simply due to atmospheric disturbance. Increasing the aperture or focal length won't change that basic limitation. You could try two things: both are low cost, but will take extra time. The first is to employ "lucky" imaging with short exposure times. The seeing can have moments of great clarity in amongst the usual blurry stuff: the trick is finding them. You could try stacking only the best of the best frames and comparing the results with what you normally get. . The other technique is drizzle processing of your images. If done carefully, this can improve the apparent resolution. It's available as an option in Registax but it can be hit'n'miss. Some people claim good results, and some reckon it doesn't help much. I would suggest that is down to the original quality of the drizzled / stacked images. Either way, there are certain basic, physical limitations that mean you can't pull data out of an image when it isn't there in the first place. However, some experimentation could give you subjectively better looking images. Or you could move to the top of a mountain.

Rather than a 3D printer (using a commercial "shop" seems to work out at about 10p per cm³ ) what I've started using are HDPE kitchen chopping boards as a raw material. These come in nice convenient flat sheets of various thicknesses and are easily workable with hand tools and can also be heated, if you're careful, and molded into rough-ish shapes. The only drawback so far is that I haven't found an adhesive that sticks them reliably, so thickness needs to be added by mechanical attachment: screws, etc.