pipnina

I would hazard that the best method would be to use a sigma clipping method, as this will remove things that are transient between images and datasets like diffraction spikes, satellites, walking noise etc. Normalisation of the various datasets could be very important though. I'm not sure.

I was just thinking it looked like a circumstellar disk! Most objects like that are way too small for us amateurs! Even the near by orion nebula which is littered with them won't show them with the average ground based scope!

I stripped down and surveyed a bunch of middle sized electric motors recently, which were all cast steel for the stator housing and end caps... But they made the terminal boxes out of aluminium! Almost every single philips head screw holding those boxes to the steel was just corroded enough to be impossible to remove with a screwdriver (even when doing things health and safety wouldn't like to see). I had to drill the heads off of them all... One thing that can work if you can get to the heads of the bolt however, is smacking it quite hard with a hammer. The percussive force causes the corrosion products that were acting as a glue to unstick even though the bolt itself doesn't really move... It works well on motors and 200 cube/hour pumps but maybe not on telescopes! You do have to swing rather hard... If you want to never deal with corrosion in your parts however, make it out of NAB! It might cost a bit though haha. Failing anything else in your case though, try drilling through the bolt head, with the tapping size drill for that hole or thread (if the thread is known, it's almost certainly M4, M5 or M6 looking at the image though.). Once you break through to the other side of the bolt, run the tap down itand it will clear the bolt out for you. if you do it right you successfully extract the bolt without damaging the threaded hole... If you don't do it right you have a new problem haha.

I bought the skywatcher 2" OIII and UHC filters for my eyepieces *last year* in november and I still havent observed with them! I must must must get a peek of the various nebulae in cygnus and the milky way core before it all vanishes but time is running out this year again! Last year I couldn't see the NAN with my filterless 10" setup and I have been hoping that a UHC or OIII would give me that little contrast boost I need. Plus give me better views of M42 and flame, possibly help me spy the horsy.

They did and I remember watching it! Their result was quite good but had obvious troubles as I recall, and given how long it's been since stargazing live was on the TV the cameras in those phones were probably awful, meaning the nebula they pulled out of the image likely came from good data submitted from people's DSLRs or astrocams on camera lenses 😕 I did some googling and apparently this is the image created on stargazing live 10+ years ago: Hard to say what hardware contributed to the image, but It looks quite clear to me that the horsehead and M42 regions have telescope data pasted over them! Most likely viewers with scopes sent their images in. Either that or the beebs was trying to pull a fast one on us claiming a million images from the phones people had in 2012 were capable of capturing the horsy haha. I found the image in this thread on some other forum: https://www.flickr.com/groups/1574153@N21/discuss/72157651480273305/

You can find various scientific data sets here in the MAST portal. The only problem I have found is that I often don't know the file types provided for more specialist data or how to use it, but you may have more success if you know what you're looking for! Hope this helps! https://mast.stsci.edu/portal/Mashup/Clients/Mast/Portal.html

The only times I have cleaned my mirrors is when: My visual 250mm dob was sat in my room for so long that it had actual big tufts of dust and the surface appeared quite matted. I remoevd the cell and ran it under the cold tap to remove the worst in the most gentle way imagineable. Then I used demineralised waterand cotton swaps to gently swipe off what remained, using single strokes per side of cotton ball, all going in one direction until I'd gone from one side of the mirror to the other. Then, as the cotton was not as clean as the water I used, I used a dry cotton ball to dab the drops of water up to prevent them leaving deposits behind as they evaporate. I also did it to my 130P-DS when I was trying to sell it (sure it didn't NEED it, but if you're trying to move something on it doesn't hurt to make it look its best!)

I do feel a bit detached from my setup these days after robotifying it, but the results I get are a lot better now that it guides and doesn't need to be packed up before I go to bed so I can't complain. It also lets me make the most of the very little clear sky we do get. My visual kit has been gathering dust since at least christmas a mixture of limited clear sky and the heft of my setup and work... I just can't fit a visual trek in. I intend to make a concerted effort to do one this late summer or early autumn when astro dark comes back. Last year I failed to see the NAN from my B4 dark site, but this year I have both a visual OIII and UHC filter to help me out!

Looks good! The only advice I would give here is to pull the green curve down a little, and it should let those blues, yellows and browns in the galaxy shine!

One thing I will add though is that the results at the eyepiece and or camera are the proof that's in the pudding: A flawed star test could help diagnose a problem, but if you are observing or imaging and the views seem good already, then performing a star test is just looking for an itch to scratch!

You could just be seeing the effect of the spiders, which could give the airy disk a slightly boxy look compared to what you'd normally expect. this image from google suggests it could be affected

Aside from the atmosphere attenuating light exceptionally fast as you move through the 400-300nm range, sensor sensitivity falls off too as a double whammy. And for most commercial amateur telescopes you have a triple-nail in the UV observing coffin where most mirrors are dichroic coated (not aluminium) and have very low reflectance outside the visible spectrum, as per this chart from a listing of the GSO 6" RC you can see that the reflectivity to UV light falls off to only 40% by the time you hit 388nm, and seems to fall very rapidly thereafter. These three factors are likely the reason why any UV image is faint. I suspect venus is only possible to image so readily in the near UV is because it is so very bright.

You bringing up negative bananas, null bananas and programming reminds me of a joke. "The developer walks into the bar, orders a beer, orders 10 beers, orders -1 beers, orders fjedfjdiofjiowejfwe, and leaves. The QA tester walks into the bar, asks where the toilets are and the bar catches fire"

Ektachrome 100 seems almost identical to Fuji Velvia when it comes to the spectral response and exposure compensation figures. It does seem they are two of very few films that don't clip out the Halpha line while also staying in a sensible wavelength range for the type of lens you could use (without spending silly money). Black and white films like Ilford SFX200 and Rollei Infrared are sensitive up to 750-800nm+ but they could suffer some focusing and or CA difficulties, potentially... Maybe I am overthinking how precice E6's temp needs to be haha. I was believing even a 1c change could be disastrous but if it's possible in a bath tub then small variations must be somewhat acceptable I guess...

That sounds like some project. You'd need to find an adapter to convert the old lens mount to a telescope thread for one! As for the mirrors, it depends a bit in where the damage is I guess? If it's close enough to the center on either mirror then in theory you can just paint black over the marks without any I'll affect. On the primary you could get away with that anywhere possibily? Else it's a matter of a whole recoat!

E6 process at home seems very complex to me! I have looked into development a little and seen that B&W is supposedly dead easy. C41 is much the same just with two extra steps, and E6 is yet more complex, with the added caveat that it must be performed with all the chemicals at 37.5c! Apparently getting that temp wrong leads to colour shift and all sorts 😬 I haven't looked into Portra yet but i have shot Delta 3200. I took this image as Orion was sinking earlier this year: This was shot on a Canon AE1-Program, Ilford Delta 3200 as said above, using a (crumby) vivitar 35-105mm lens set wide open at f3.5. Exposure time? 26 minutes! This shot was unguided on my star adventurer (original model in the white-green refresh colour). I am surprised there was no drift but as you can see, the film at that ISO is VERY VERY grainy and my wide-open and low quality zoom lens doesn't help matters either. I am still working on film astro, my latest attempt being on Fuji Velvia 100 which claims nearly no reciprocity failure by comparison. However I still underexposed by probably about 2-3 stops (exposure at 6 minutes f5.6 in shot below) so next time I plan on either using a faster lens or taking another set of shots between 20 and 40 minutes long. You have to look out with these films too, check the data sheet always! Most films lose all sensitivity just before 650nm, which cuts out our precious hydrogen line! It's like the infamous DSLR ir blocking filter but it blocks 100% instead of 75%!

I am. The video i posted was for films shot in 2021. It might not be as popular, and is likely reserved for the films with budget to blow on millions of dollars worth of celluloid, but it's still being used. And they wouldn't use it if there wasn't SOME niche for it in filmmaking.

I went to a Saturn when I was in Dusseldorf (big tech chain like Currys in the UK) and they had NEW polaroids in their camera section! Local London Camera Exchange near me stocks polaroid film too. Normal negative and slides are also having a resurgence, but maybe not quite to the same level. I also agree that digital sensors do allow for much more contortion of a scene, they're more scientific, easier to get results from, you get instant results etc etc. But big budget films to this day get shot on celluloid, and there has to be a reason for that! medium-format (60mm) Kodak cine film costs thousands of US dollars per 5 minute roll, the hollywood DPs wouldn't push to buy that equipment if they didn't see value in it!

2022 and 2023 were processed in pixinsight, with small tweaks in RawTherapee afterwards. I use RawTherapee for things like colour noise reduction (it has a good algorithm for it compared to pix) and tweaking certain colours. In the 2023 version for example, the pink hydrogen regions were too intense after the pixinsight colour boost, so I adjusted the image's colour in RawTherapee using the LAB colour mode to bring the nebula saturation down a bit. The big differences here come from the x suite improving the base data and a different approach to editing the image in the first place. I used spectrophotometric colour calibration, I used a fix i found for my overcorrecting flats and that improved DBE performance. I also used curves and stretches more effectively I think too.

I am a fan of the laser collimator, however I also believe they must must must be used *with* the correcting lenses and other accessories on the focuser. All those joints between focuser and camera can have small mis-alignments which you want to take into account when collimating your scope, so just take the camera off and (if possible) screw the collimator on for the best possible result (use collimator with corrector/oag/filter wheel etc) You also will want a v-block or two supported bearings to collimate the laser, as it is unlikely to be perfectly collimated itself from the factory.

When I took this image in 2022 (about 4 hours or so of data if I recall) I thought it was really good, and definitely the best I'd come out with to that point. Having tried the x suite, I went back to older images and figured I'd see what I could do with it on my 2022 M33 attempt. After using blur-x and noise-x and working with the resulting image (all before stretching) I wound up with an image that's almost impossible to believe came from the same data set. So here's my 2023 x suite process of my old triangulum data. Any suggestions and feedback welcome of course, but I am over the moon with the result this time around! And for comparison the original 2022 process:

I can't share the horror at the mast's appearance, albeit I think they could put some effort in to make it look nicer, such as disguising them as trees (or even planting grown trees with the antennas near the top) Super fast phone internet is a bit silly to me, as what customers really want are *usable* speeds and broad coverage, which is typically offered by 4g and 5g in cities but can barely be found at all in more rural areas. Why do we need more than 5g? 5g already supposedly covers a very wide range of uses from insane speeds (millimeter wavelengths that are fast and high capacity but require totally uninterrupted line of sight, all the way to long microwaves that are able to penetrate deep into buildings) I would argue that while many of us are quite happy with our internet, I myself enjoy a cozy 300+mbps download and 25mbps upload, there are many many people who have connections too slow to be considered bearable if you have any use beyond browsing internet forums! I have a friend near Durham, who moved into a new house that was advertised as having fiber internet, only to discover that it is actually a very very BT-neglected ADSL line that can't manage sustained download speeds of more than 1MBps, and it is often slower. Add to that that their freeview TV mast was burned down for 2 years before it was repaired and they were quite unhappy. BT wanted £15'000 to run the fiber cable the next 30 meters down the street to them. Many in even more rural areas lack even ADSL internet, especially in larger countries like the US or australia, or poor/developing countries, or worse countries where internet is restricted like Cuba. For all these people, LEO satellite internet is a godsend even if it's not as cheap as cable in cities. I fully understand and see its importance and yet I despise that it must exist in such a way, and I also am very fearful for China, India, and possibly other countries or even private industries all wanting their own totally unique network! One good internationally supplied and protected LEO sat internet is enough... More networks is just pointless wastes of money, sky ruining, and likely the work of the worst aspects of human society: Regimes and Publicly listed corporations.

I do find my HEQ5 a little variable. Some nights I am pulling RMS at 0.35 seconds, at its worst when there's any wind at all it'll end up around 0.6-0.7. Before tuning it was guiding above 1s. I do agree it punches above its weight class however. Mine is also "overburdened" to the point where the 2 5kg weights provided are nowhere near sufficient to balance it. Yet it still performs well most of the time? I think the big weakness as always is wind. My new refractor has a much smaller wind profile than my old 8-inch which was a lighter setup. Ultimately I think weight is a far less important factor with mounts (unless you're way way overburdening them!) than their rigidity against the wind... Which may correlate with their weight rating but probably won't be exact. Manufacturers probably aren't being super scientific with their method of working out the max weight anyway!

And yet people still partake in horse races and take cart rides as a tourist and holiday activity, sometimes things are not done because they're practical but because we just enjoy them or are interested in the methodology! I personally quite like how tactile the film shots I've done have been, even though my attempts at astro film havent been so successful!

If I've put that reciprocity failure equation into the desmos calculator correctly, the 0.7 reciprocity factor is very extreme! I believe I've set it up so the x axis regards to metered exposure, and y is the corrected exposure for said meter. In theory modern films might be a lot better for reciprocity failure than those of old if 0.7 was typical then. As the worst reciprocity film i've used so far has been Rollei infrared (line chart for such below) and the best one so far is velvia 100 which only has a table (also below) Fuji across II 100 claims only 1/2 stop correction between 120 and 1000 seconds, and no correction up to 120 seconds!