symmetal

To complement Olly's posting, here's my 84 minute ride on the horse, comprising 168 exposures of 30 sec. using the ASI2600MC on a RASA 11v2. As many objects are very bright I opted for shorter exposures. Even these well exceeded the 5x read noise swamping factor on the darkest areas, and I have SQM 21.4 skies on average. No where near the depth of Olly's 4.5 hour effort though. 🙂 Alnitak caused some rather noticeable diffraction effects including a curved arc, which is likely related to the cable routing shape, and I had a go at removing these with the 'Patch' tool in Photoshop. This is similar to the cloning tool but blends the original patch edge colours across the area you're cloning from. Also there were two odd blue tinted patches which I removed fairly well with masked layer blending. The original image is at the end for comparison. I think the default Star Reduction amount in the latext SXT is too high as even with a higher than normal star layer stretch they are still tiny. There are no blue star halos on mine compared to Olly's though. Whether this is due to only 1/6 the individual frame exposure coupled with an Astronomik L-3 filter, I'll have to test. Here's the original image with the diffraction effects around Alnitak, and the circular blue patch near the centre and the blue vertical patch at top centre. I assume they're flares from Alnilam just out of frame top left but why it creates a circular flare seems odd. I took new flats the following day so it's not dust, and the fast scopes don't seem to show dust bunnies anyway. Alan

Over three times the integration would make a difference. As I swap cameras between the ASI2600MC and the ASI6200MM I need the external filter to maintain the correct spacing so forgot about the in built one. The in built filter is fairly narrow anyway, being 400 - 680nm, while the L-3 is 420 - 680nm. Next time I can take a few test images without the filter to see if the L-3 is the reason I have no blue star halos. Alan

Very impressive Olly. 🤗 I just happened to have taken the left half of your image on the last clearish night a few weeks ago, but only got 84 mins worth with the RASA 11 and same camera. I've almost finished processing it and should be able to post it tomorrow. What was the total integration time as it's gone a bit deeper than me? Also, what UV/IR block filter was used? I used the Astronomik L-3 as that was the one I had bought for the FLT-98 and wondered whether an L-2 may be a better choice with the RASA, but I don't have any coloured halos around my stars at the moment so it may be worth sticking with the L-3. 🙂 Alan

Many radioactive elements exist naturally and their decay products are absorbed by living organisms. Caesium-137 (UK spelling) is a problem as it's water soluble and readily taken up by plants. Its primary souce in the environment in recent times is in the fallout of nuclear weapons, and nuclear power accidents like Chernobyl. It has a half life of 30 years so fallout from Chernobyl is the main source currently, though older internal tree rings will have nuclear testing Cs-137 present. Scandanavia was significantly affected by Chernobyl, so wood burned from there will end up having ash with a higher concentration of Cs-137 than wood from other areas. The burning itself doesn't change the quantity of Cs-137 present. Cornwall has large amounts of granite which contains Uranium-238 naturally, and a trace decay product is Cs-137, among others, and so we have one of the highest background levels of radiation in the country. Radioactive radon gas is a concern here too which is a decay product of Radium-226, a decay product of Uranium-238. So beware your granite worktops. 😊 Alan

In air a gamma ray from radioactive decay can travel tens to hundreds of feet depending on its initial energy according to this article. The primary source of gamma radiation in wood is indirectly from Caesium-137, having a photon energy of 0.6617MeV. Not sure how to convert this into air distance. 🤔 From Wikipedia, Caesium-137 decays by beta emmision into an unstable form of Barium-137, which quickly decays into a stable state emitting the gamma rays in question. So your neighbour may be causing your pixel streaks. 🙂 Alan

Here are the results of a couple of detailed studies into radioactivity in wood, and its affect on CMOS sensors. Radiological impact of using forest tree biomass for energy and recycling the ash Using CMOS Sensors in a Cellphone for Gamma Detection and Classification Alan

I upgraded to the latest PI version, released on 3rd Dec and after running it, as usual it needs to reinstall the 3rd party addons which it did. However BXT now only has the AI4 option available. I copied the AI2 version (BlurXTerminator.2.pb) from my other PC to the C:\Program Files\PixInsight\library folder, and the header file with the same name to the C:\Program Files\PixInsight\library\PaxHeader folder. I now have the choice of which AI to choose. 🙂 With AI2 I used to run the PSFImage script to get the image PSF pixel size as that seemed to give better results overall than the BXT Automatic PSF option. With the RASA 11 I generally had sharpen stars at 0 as it tended to create artifacts if used. However I did this with the AI4 version and the result was poor with almost no corner star shape correction. Using the Automatic PSF it did correct the corner stars perfectly as well as sharpening them, (if selected). Possibly AI4 recomputes the PSF for different areas of the image so I'll use that from now on. The AI4 sharpen stars doesn't create the artifacts the AI2 version did either. @ollypenrice If you need the AI2 files send me a PM. 🙂 Alan

I use it at unity gain which is gain 29 and haven't needed to try any other setting. Always had plenty of suitable stars. Zwo uses offset 9 for all their preset gain settings too so I've gone along with that. 🙂 Alan

Particularly with using the fine focus shaft it's important that the helical 'spring' coupler is well aligned to avoid a constant sideways force on it. I noticed on the video you posted not much effort was put into aligning the motor shaft with the focus shaft as there is a noticeable bend in the coupler. Good luck with what you decide to do. 🙂 Alan

Microstepping requires the stepper motor to be continuously powered even when it's stationary so I try to avoid that. I've always tended to use Lakeside stepper motors, with my own arduino based controllers, as they are heavily geared down and so have a lot of torque as well as not needing microstepping. Using the fine focus knob with the Nema 17 would help if the main focus knob has too coarse steps without microstepping. I think the opposition to using the fine focus knob is that it introduces more backlash, but that's not an issue really, as geared backlash is consistant, and if your final focus direction is always the same direction it doesn't matter, if you set sufficient backlash steps in the driver software. Alan

A rubber band likely won't give a repeatable focuser position unless it's possibly very tight as the first few stepper movements will just increase band tension on one side until there is enough force to rotate the focuser. Then when you move in the other direction even more steps are needed as the tension on one side is reduced and the other side is increased. It's non consistant backlash in effect. A toothed belt would be better but needs to match the grooves on the focus knob, or have a toothed pulley wheel which fits the focuser shaft. In line drive would be mechanically simpler but finding a way to mount it is tricky. A base plate that attaches to the two front focuser mounting screws and extends forward to hold the stepper might work but accurate dimensions and the fixing screw angles need to be determined, for it to fit. Alan

I wondered how you were getting on. One of those 3D printer flexible zip-up thermal enclosures may help with your temperature issues. I didn't think about the height of the finder scope either. 🙂 Fitting the bracket on the other side would be easier, but from your initial photos it looked like the manual focus assembly might get in the way, depending on the clearance between it and the fixing plate the 3D printed bracket attaches to. I thought that a thicker base plate, like 4 or 5mm, may also help with any flexure but that will likely need a cutout to clear the manual focuser. Let me know if you want a thicker base plate and whether a cutout is required between the mounting screws. How are you going to set the belt tension from the stepper motor? Do you need some adjustment in stepper distance from the focus knob which may require a separate stepper mounting plate with a slotted screw hole cutout to then fix to the main base plate. Alan

Yes, that would be fine. The plant heater you linked to has a temperature probe which is better as it can control the temperature better. The pet heaters are only two wires going to the pad by the looks of it, so have no remote temperature sensing, relying on the controller power setting to achieve an expected range temperature in normal use. If the pet gets too hot it can get up and walk away. Plants don't have that luxury unless they're triffids. Alan

I have a 60W thermostatically controlled tube heater on the floor of my roll off shed which works very well at keeping everything dry, though they are either fully on or off. When on it's too hot to hold for more than a second or two. They are intended to be used open to the air so would get too hot inside your cover. As mentioned above a pet heater pad like this placed inside the cover would be a better solution as they heat with a preset power setting, and the pad itself is usually 12V or so with short circuit protection if it gets chewed through, not that the scope is likely to do that. Alan

I usually wait until the target is 5 or 10 mins passed the Meridian before flipping. SGP should allow a flip if it's only 1 second passed but the issue here is that after the flip the scope may overshoot slightly and end up back on the other side of the Meridian. Then when it does a target centre the plate solve reports it's on the wrong side of the Meridian and it flips again. 😬 Waiting at least five minutes any slew overshoot when flipping shouldn't cause this issue. It's worth having the Telescope Docking Module visible as shown here. When your slew problem occurred what was the 'time to pier flip' saying. A positive value shows time to the Meridian while a negative value is the time past the Meridian. SGP won't flip if this value is positive. Also check that the reported RA and Dec is close to what your target RA and Dec is. It will be slightly off if you enable dithering but not by much. These reported RA and Dec values are from EQMod and SGP uses these to calculate the time to the Meridian. The Chris Woodhouse videos are several years old and refer to an earlier version of SGP possibly before rotator options were available. I'm fairly sure earlier versions did report the camera angle after each target centreing attempt, which was useful, but the later versions don't if there is no autorotator present. The only way now to get the camera rotation angle I believe, is to do a manual 'Solve and Sync' from the Control Panel's Plate Solve tab. 🤔 Alan

I generally always do a manual Meridian flip anyway and do what you did. After the target's passed the Meridian stop the sequence and select slew to target. Using EQMod it always slowly slewed back to the Meridian and then did the flip correctly. However since I changed to GSS it does ignore the manual slew command when the sequence has passed the Meridian. I have to home the scope, unpark, then manually select slew and it now slews to the target correctly. It's probably a setting in GSS I need to change but I haven't really checked as going via home doesn't add much time. I assume you're still using EQMod. Have you selected 'Dialog mode' as previously mentioned, and did you clear out the EQMod pointing data before your session began. It's worth looking through the SGP log which should say what happened. Looking through the log, at the time you gave the slew command after it passed the Meridian, did SGP acknowledge the slew command and state why it couldn't do it. If your pointing data seemed to have gone off at some point before you gave the slew command it's possible SGP didn't think you had crossed the Meridian yet. After you gave the home command did the scope actually move fully to the home position. It's likely it didn't and ended up some way off. In the SGP Help menu there's a 'View log' option and an 'Open log folder' option if you want to check previous logs. When it failed to slew initially it would be worth doing a manual plate solve and sync. This may fix your problem, or SGP will likely say 'Unable to sync' or similar. It says this when the manual sync data is significantly different from where EQMod reports the scope is currently pointing. Alan

Here it is 🙂 I've used 3mm thick panels. Here are two stl files, one without and one with the cutout in the base. Bracket v1.stl Bracket with cutout v2.stl Any mods like curved edges, chamfers, let me know. 🙂 Alan Edit: I use Cura for slicing and would select 25 or 33% Tri-Hexagon infill. The default infill is not mechanically very strong. Printed with the orientation as shown I'd likely select supports to give a cleaner cutout circle. You could rotate it 90 degrees and print it with the nema face down to give the best circle cutout but the base itself would not be as smooth and also be less rigid.

Oh. I need 60mm to fit the Nema 17 as shown. I'll make a 20mm cutout which should give plenty of room. I'll post version 1 shortly. I could make the Nema 17 flush with the left hand edge of the base plate but that would mean the Nema would obscure the base mounting hole and would need the Nema fitting after the base plate is mounted on the focuser. I'd also need to raise the Nema up a few mm to clear the screw head. This means the base plate would be 48mm wide. I can post one of these after if you wish. Alan

Yes, those measurements are very useful. Also, the maximum possible width of the base plate as shown in'red' would be handy too, ie. where it would touch the finder scope 'riser' when the plate is screwed in place. If this isn't wide enough to fit the stepper mounting I'll need to make a cutout in the plate to fit around the finder scope. I'll post a quick image and stl file later to see if it's basically ok and can then modify it later as required. 🙂 Alan

The 'ethernet' connection is actually the ST4 guide port ( 6 pin RJ12 connector) which is used for direct guiding control of the mount from the camera. As you will be using the ASIair software to do the guiding, the ST4 port is left unconnected. Ethernet uses 8 pin RJ45 connectors. 🙂 You can use any USB2 socket in your system which has a connection back to the ASIair, so the connected ASI294 camera USB2 socket is fine to use with the ASI120. You can also use any spare USB3 socket for a USB2 cable as USB3 is backwards compatible with USB2. Alan

Hi ofranzen, Is this the kind of bracket you're looking for with your belt drive? It can use the two focuser mounting holes if you replace them with longer screws, and the bracket plate just sits flush with the face the screws go through. If the plate is thick enough it shouldn't flex too much. The bracket vertical end plate with the Nema 17 mounting holes will add some stiffness anyway. Can you give the spacing between the two focuser screws and what size hole will be needed in the plate for them, M4 or M5? The length of the focuser mounting plate would be useful too, so the bracket sits flush with the ends. Also the distance available between the focuser cylinder and the stem of the finder bracket assuming it's just a flat plate parallel to the focuser screws mounting face. I may need to make cutouts to clear the finder bracket if the Nema 17 is too wide to fit the available plate width as it's shown. I have Nema 17 steppers so have their dimensions already. I use Blender to create my 3D printer STL files. Alan

As long as the print bed is cleaned before use (IPA spray bottle and box of lint free cloths) and the bed is maintained at 60C while printing, it sticks to the bed very well, even with only 2mm thick walls and no brim. It's a PEI coated flexible steel magnetic bed which helps with print adhesion, and release afterwards. Turning the bed heater off it generally releases the print automatically when it's cooled, as the metal bed contracts more than the print. I could have printed faster by increasing print speed and using 0.4mm layer height rather than the default 0.2mm but I like the prints to look their best as well. 🙂 I upgraded the software to use Linear Advance, so could have possibly gone up to 120mm/s print speed without losing quality but didn't risk it and stayed at 80mm/s. Alan

Thanks. 😁 They take quite a while to print. The dew shield takes 4 days to print and uses a whole 1kg reel of filament at £20 a reel. On the last one I had a five second power cut after three days so had to print a separate extension tube to complete it. 😟 I've now bought a UPS for the printer so it will handle up to about 15 mins loss of power which should cope with more than 90% of the kind of power cuts I get here. The rings are about 1.5 days each to print. If you're interested in obtaining some rings and/or dew shield, (with or without end cap), drop me a PM. The dew shield in particular is a large item to post. 🙂 As you say there probably arn't that many possible RASA 11 customers. Wonder if FLO would like to stock them? 😁 Alan

Forgot to mention I have two of the WO 50mm guide scopes as well and use them with the ASI120mm. The nosepiece extension is recommended with this scope. I couldn't remember whether the extension tube came with the camera, but it looks like it does. 🙂 The ASI220 is newer and higher spec but is significantly more expensive. I've never found the 120 to be short on sensitivity and the sensor size is plenty big enough. One thing I found useful with the nosepiece cameras is attaching a 1.25" eyepiece parfocal ring on it. With a helical focuser, adjust it to get focus, then tighten up the parfocal ring and you can then rotate the camera for orientation without it losing focus. Alan

I have three ASI120MM used as guide cameras, two of them are the mini version and they have all do the job well. The USB2-C connector on the mini gives a good reliable connection too. Depending on the guide scope you may need an 1.25 inch extension, as when in focus not much of the camera nosepiece is inside the scope. Alan