The Admiral

I guess covering them with electricians tape would also serve (in red of course ;<) ), though not really an engineered solution. I hope you recover well with your 're-engineered' knee. Ian

Huh ha! I just said an incentive, not that I'd actually do it! Ian

My take from this is that as we "approach the terminus of life" (as Clive James so succinctly put it!), we owe it to our family to draw up a list of what we have, preferably with 'advert ready' photos. It would be a nightmare for those without any knowledge of what we do to sort out our gear. I'm trying to heed that thought and have just started to get the list together. I've no doubt that when all our, err, junk, is contained in a list we'd be astonished at what we've amassed. Perhaps it'd be an incentive to de-clutter . Ian

I think covering the lawn with a (permanent) plastic sheet would be worse for your lawn, if I understand you correctly. The rain at least keeps the grass watered, which it wouldn't be under plastic. Also if it does rain before you observe the plastic will be slippery. Can't you make the location into a garden feature with hard landscaping for use during the summer, but easily converted to your needs in winter? Ian

Gradients and colour balance are common in astrophotography, and astro-orientated software is designed to correct that. That's not to say that it can't be done with other software, but it's not in their genes. I understand your problem with the techno-babble associated with the 'art', particularly if you haven't any previous experience with processing conventional photography images, but with use it becomes more familiar. There's an abundance of information on the internet, but it does all take time to trawl through. No-one said it would be a quick process , but have patience, you'll get there in the end. Actually I think what you have is a good start, especially for such a short exposure. When I was doing it I used total exposures up to a couple of hours, all done in 30s chunks! That's a lot of files and it needed a reasonably brisk computer to wade through them all. With 10s subs you will certainly end up with a huge number of subs to process, but it is worth trying to get as much exposure as possible. Worth pointing out that StarTools doesn't stack subs, so DSS can come to the rescue here. I've heard good reports of AstroPixelProcessor (not tried it myself), and which does stack subs as well. More expensive than StarTools, but a totally different workflow, but not in the same league price-wise as PI . SWAG72 of this forum has done some tutorials on it (https://www.swagastro.com/astro-pixel-processor-tutorials.html), but there are others around. Good luck, Ian

I think if you're not careful you can end up spending a lot of money just testing out various software options. Even Photoshop Elements is far from cheap, and PS itself is 'rented' on a subscription basis. PS also does far more than you would need, unless you have an interest in conventional photography as well. StarTools is probably the cheapest dedicated astro processing package, but it may not be to your liking, though the good thing is that it has an unrestricted trial, except it doesn't allow you to save. Pixinsight is quite expensive and from what I understand needs a fair bit of computing power, though it is extremely powerful, and therefore takes a fair bit to become competent with it, especially as the trial is time limited. It's not cheap either. Anyone know if the PS plug-in will work with Affinity Photo? Sorry, not much help, but as happy-kat says, make use of trials. Ian

I have no idea what might have caused it, but surely this wouldn't necessarily be true if the star(s) are bright enough to saturate the sensor? I rather prefer the explanation being a transient movement of the mount. Is it a manually operated barn door tracker? Then again, it's suprising that there is no star streaking, which would mean it would have to move between exposures? Hmm! Ian

Presumably you stacked the RAWs and ended up with a FITS/TIFF from DSS. You need an image in which data has not been thrown away or locked in during the editing process. For that reason you shouldn't re-process JPEGs, particularly as they are only 8-bit and are not lossless, and you need 16 bits as a minimum. I'm not sure about PS, because IIRC the data is frozen in after each processing step. Perhaps a PS user could comment here. RAW processors, like Lightroom for example, always apply the processing steps from the beginning on the RAW file, so if you change the processing, then the result is always a new process on the original RAW. PS may remember the steps, I don't know. Don't get me wrong, I'm not recommending LR for astro processing, but it is useful in tarting up (sorry, polishing) your final image. You could have a look at StarTools (https://www.startools.org/), and although the processing is approached differently to other applications, it is relatively cheap and the trial version is unlimited except that you can' save. If you are used to PS though you might find it too 'cloak and dagger'! Worth a look though. I can't point you to an individual thread, but a search would find plenty. In the the process of subtracting the darks , the noise is combined, so you will end up with a result which contains both the noise of the image and the noise in the dark. So you want to reduce the noise contributed by the darks to a reasonable level (you can easily control that) and the way to do that is to do a lot of them. I typically did around 50 of them, but 20 might be considered OK. Each to his own. The other important issue though is that the background noise is very sensitive to sensor temperature, so unless the darks are taken at the same temperature they may not be representative. This can a big problem with DSLRs where the sensor temperature is not controlled. Not only that but camera manufacturers go to some lengths to subtract noise before committing the RAW to file, so the noise behaviour can't be easily ascertained. Having said all this, with Alt-Az imaging and short exposures, you may not see any difference. I've both used darks, and just replaced the master dark with the master bias. If you have significant sensor unevenness, such as from amp glow, or a large number of hot pixels, you may have to do them however. Yup, discarding subs because of trailing is a problem! Fact of life I think, so you always need to do more than you think . Hope that helps. Ian

Hi, and welcome to the thread. I think they are very good for someone just getting into the 'art', and I agree it just shows what can be achieved with Alt-Az imaging. I was going to say 'with basic equipment', but your Meade is hardly that ;<). Your stars are sharp and round, and there's nice colour in M13, blue to gold, with detail to the core. My only comment is that the sky looks 'very' black, which suggests perhaps you could do with raising the black point a little. That of course might reveal more noise, but more subs will always help there. How many darks did you use? There is some debate about using darks with DSLRs, but if you do, certainly a good number is required otherwise they can introduce more noise. Something to bear in mind. Ian

Super! It looks very much like the ISS to me, one often gets signals when it's over Biscay. On it's approach towards Graves the frequency falls from a high positive shift to high negative shift as it recedes from Graves. You will be observing it during this transition phase. If the ISS is above your horizon then I'd have every reason to believe it is the ISS reflecting from the forward lobes. With Dijon as the focus, Heavens Above gives a better idea of relationships to the track. Note of course that Dijon is BST+1. Ian

Without checking out the detail, I wonder if the ISS comes sufficiently far north even to be able to get rear lobe reflection, unless it is high angle. If you do pick up the ISS the beam switching would be clearly evident. Ian

Congratulations! Looking good so far, be good to see what you get during shower activity. If it is due to reflection of a backfire beam from the Graves antenna, it will be interesting to see if you still see the beam switching. I see no reason why not, but interesting to see nonetheless. Of course, you'd need a nice long duration trail to see that readily, best during shower activity. Ian

It does indeed, but what we really need of course are the early adopters to give us some info on how it performs . Ian

TS say on their website that delivery, according to the manufacturers, is end of August. It's a pity that the Astrotrac website is very slow to update its newsletter. I would ignore Rother Valley saying that it is available and generally in stock! Ian

Well the Moon is 0.5° in diameter. Also, if you use star map programmes, such as Stellarium or Skysafari, you can judge from the coordinate lines, or you can input the FoV/scope and camera details and it will show you a frame on the sky map. Ian

The crop factor came into use in photographic circles when sensors smaller than the standard 35mm film frame became available. Then it became customary to multiply the focal length of lenses by the crop factor to give an 'equivalent' focal length as if it were on a full frame camera, because until then photographers were used to full frame film cameras. Of course, it doesn't actually change the focal length of the lens, which is fixed by the physics, but really relates to the field of view when used on a crop sensor camera. This has no place when it comes to astrophotography. The focal length of the scope is its focal length. Full stop. If you look at this page from this site, http://astronomy.tools/calculators/field_of_view/ , and select 'imaging' and put in you scope and camera details, it will calculate the field of view and resolution in arcsec per pixel. Ian

The crop factor is irrelevant to my mind. Assuming that your images are processed in exactly the same way, then one should be twice the size of the other. If you bin one and not the other, or if you crop the frame differently in processing, then that could account for it. Another thing springs to mind, depending on your settings, DSS will only give you a resultant image for which data in all frames is available. So, if there is significant drift over the imaging period, such that the frames don't completely overlap, then the image that DSS will produce will only cover the region where there is overlap, and so will cover a smaller field. Such 'hidden' cropping could account for it. Ian

Welcome to the forum Geminids. A couple of years ago Steve Nickolls and myself wanted to get more information on the head echos. We were using a script which I had written for logging meteors, not the same as the referenced Brit Astro ones, and although I forget the details now, I had sort of concluded that a faster FFT was likely needed. IIRC the FFT cycles every 33ms, which is a bit slow for head echoes I think. Mind you, I know little about FFTs, and there may well be a cunning plan to extract more information! Ian

Well, that just goes to show what can be done with the ultimate Alt-Az mount - one that is stationary! Great perseverance there AA, a fine achievement. Ian

That's nice! Now I didn't see that one at all! Ian

Will Spectrum Lab run satisfactorily on a RPi? I've always thought, possibly wrongly, that the FFT process demanded quite a bit of processing power, not to mention a 192kHz soundcard. I've set mine running at the moment to see what is coming through. Ian

. But I'm truly amazed given your location! It would be interesting to establish whether this is from any antenna backfire or the normal forward lobes (even more amazing!). I know little of long distance radio propagation, but I also wonder if it also down to some particular conditions that currently favour it, and therefore might not be reliable. DXers can obviously provide some insight here. Are you going to run for a period now? Ian

Indeed, I feel your excitement! What makes me think it is, is because there is a sharp descending frequency transient, with a more intense region at the end. With bigger meteors, the intense region will extend along the time axis at the Graves (zero Doppler) frequency, to give the appearance of a hook. But I'm sure you know this. You are most likely to see those during the meteor showers. It'll be interesting to see how frequent you see them, and how they compare with measurements made from the South of England. It would still be interesting to try VOR stations that you are able to get aligned to. I suppose the problem then might be to see meteors along with the background carrier. That leads me to wonder if you could point your antenna much higher in the sky so that the sensitivity to the direct path is reduced, and maximise reception of backscatter. After all, some professional monitoring sites have the transmitter and receiver co-located. Just a thought. Ian PS. I use Heavens Above https://www.heavens-above.com/PassSummary.aspx?satid=25544&lat=47.322&lng=5.0415&loc=Dijon&alt=249&tz=CET centred on Dijon, and on the 'ground track' tab, with a result like this I find it easy to interpret, but need to be aware of the time difference between Dijon and here. But, each to his own.

Well it does look like a meteor! It would help though if there were some axes of the chart included. I assume for example that the RHS is the higher frequency side. What is the scale? Given that the ISS is about 4x higher than typical meteor trails I would have thought it might have been more visible (though perversely I've not found this to be true in practice, the meteors can can give a lot more signal). What time was the expected transit? I don't think the 13.24 pass would have been good, and the 16.34, 18.11, and 19.48 too far north of Dijon unless there are significant rear lobes. So that just leaves the 14.58 as a potentially viable one. And the next one at 21.25. I suppose you didn't have the Spyserver running from the south of England to correlate it did you? Ian

That was one advantage of the Funcube, it would work straight into SpectrumLab, though as Biggardigger points out, it offers less control. Spectrum lab does have it's manual on line, but I confess I found it pretty hard going. A couple of years ago I would have been much more familiar with it, but time has erased much! Ian