JSeaman

The last fortnight has been spent trying to understand the world of narrowband, I finally got an image I'm happy with although still have much to learn

I've answered some of my own questions now, to update: 1. I'm still not sure Hb is useful 2. When added as RGB channels OIII and SII work a bit even when faint 3. Adding the images as channels to an RGB is what I was missing, layers isn't the way! 4. I'm quite sure the amount of exposures is now holding me back, duration I think may be OK Still not sure why I have stars that are bloated but I found a forum post where someone said it was a feature of the camera

Hi all, Not only did an Atik 314L mono with EFW and 4 Baader filters (Ha/Hb/Sii/Oiii) arrive but we had clear skies too, unheard of! I tentatively set things up over the last couple of days and learnt that the filters have to be focused individually. I developed a script for Nebulosity to control all of this last night and took a few snaps of the Bubble Nebula and North America Nebula, this leaves me with some questions: 1. Hydrogen alpha is incredible. It really is better than I expected and I fully understand why people move to mono imaging now. Hb seems to pick up a very small amount of the Ha but nothing that was missing in the Ha. Is this due to the targets I selected or is Hb really not worth using? 2. Sii and Oiii were very faint, neither picked up much in the way of detail. don't get me wrong I could stretch them and see the target but it was nothing like the Ha, do I need longer exposures for these or is there more to it? 3. The processing. Obviously this is a massive topic but I have been reading a few tutorials and trying to combine my 4 sets of images. I have been creating layers in PS for each of the 4 images and trying to combine them by colourising (Sii Red, Ha/Hb Green and Oiii Blue), layer transparency, layer masks and trying screen/lighten etc. Everything I do to try and pull colour out seems to make something worse than I get with just an Ha image, am I going about this in the right way? 4. Exposures - I have taken 10 minute exposures and gathered 6 for Ha and 3/4 for the others, I'm getting quite a grainy final image. Is this likely to be exposure too short or just too few images at this stage Obviously not a great image but it's a first go, very soft and I had lots of star bloat to deal with too. That said I'm really pleased with the capability of the new kit even if the operator is holding it back! Any help would be greatly appreciated James

With the long Summer nights are in full flow, I decided to update the observatory a little. The conductive fabric was crude and the geometry of the scope position (imaging and guide) didn’t work well to reliably trigger. I decided it was time to use time. I tried to keep things simple looking at triggering a 555 timer board periodically with relays but that ended up being more complicated than accepting an Arduino into my life. I ordered a £20 starter kit which is an incredibly useful package containing all the sensors and bits and bobs to make your first project. I have a software degree so coding it was a doddle but the electronics is where I had to work a bit harder. By the point of completion, the functionality is: 1. I have a configurable timer (in 1 minute increments) and a configurable output (in 10mS increments) to drive some outputs i.e. the dome 2. There is an LCD display which shows me how long it is until the next move and various other things 3. There are three push buttons which can be used to manually drive the dome or navigate a menu system with various settings 4. Two TP122 transistors drive the relays which ultimately make the dome rotate 5. A simple protocol is supported for USB comms to the board but not required in normal operation, this allows different levels of tracing (output text) for debug purposes 6. EEPROM is used to store/load settings (the pulse frequency and duration amongst other things) I have removed the proximity sensors, springs and fabric sheet and made my own little breadboard. I then moved to veroboard for a prototype before the final design as shown in the pictures Spinning the dome one full RPM took about 34 seconds. Based on 86,400 seconds per day this is 1 second of dome rotation for every 42 minutes of time or roughly a 250mS pulse every 10 minutes. I sanity checked this based on how long I know it takes for a typical star to move across the end of the garden and it looked close enough to sidereal to try. Last night I got a clear hour and proved it to be correct. I need to make the LCD turn off after a minute off no buttons being pressed as it is quite bright! Other than that it seems to work very well so I think I’ll call that a solution. Arduino pin outs SCL – No connect SDA – No connect AREF – No connect GND – One side of the push buttons and the transistor emitter Pin 13 – Push button (menu) Pin 12 – LCD Register Select Pin 11 – LCD enable Pin 10 – TIP122 base through a 1k resistor Pin 9 – TIP122 base through a 1k resistor Pin 8 – LCD Data Pin 7 – LCD Data Pin 6 – LCD Data Pin 5 – LCD Data Pin 4 – Speaker (so I can do an old fashioned beep beep startup!) Pin 3 – Push button (anticlockwise) Pin 2 – Push button (clockwise) Pin 1 – Serial comms Pin 0 – Serial comms LCD Pin Out VSS – Ground VDD - +5V V0 – 10K Potentiometer to 5V RS – Pin 12 RW – Ground (always writing) E – Pin 11 D0 – No connect D1 – No connect D2 – No connect D3 – No connect D4 – Arduino Pin 8 D5 – Arduino Pin 7 D6 – Arduino Pin 6 D7 – Arduino Pin 5 A - +5V K – Ground Pot 10KOhm potentiometer was used to provide adjustment to the LCD backlight Pin 1 goes to ground Pin 2 goes to the LCD (V0 pint) Pin 3 goes to +5V rail Adjusting the brightness is necessary, especially when switching between 5V and 12V power sources Transistors/Relays A TIP122 transistor is used to trigger a standard Bosch 5 pin automotive 12V relay. Per the previous posts, this is used to drive the motor forwards/backwards The TIP122 allows the power hungry 12V 5 pin relay to be switched by the output of an Arduino pin Pin 1 (Base) goes to the Arduino pin via a 1K resistor Pin 2 (Collector) goes to the relay ground side of the switching pins (85/86) Pin 3 (Emitter) goes to ground Essentially, when the Arduino pin is set high, the base of the transistor pulls a small current and switches a ground connection to trigger the relay. To avoid a spike when switching, 1N4002 diodes are placed across the relay’s switching pins. My only problem now is that my QHYL5-IIC has stopped talking and the QHY8L seems to be a bit intermittent too. Maybe it's time to go for an Atik ...

Thanks but sadly this is an off the shelf PCB, I only have a pot and an output to work with. It feels like there should be a solution but I can't quite grasp it

Correct, the fabric is OK some of the time but not in all orientations so I want to pulse it periodically which means resetting the timer circuit somehow

No ideas at all?

I have a dome which rotates using conductive fabric hitting springs on the scope. This works OK in some orientations but not all so I'm looking at timers to trigger it and I'm running out of brain power, hopefully someone can come up with something clever. I've got a TA2R1 which is just a timed relay essentially which will switch a couple of contacts after a predetermined amount of time (probably 1-5 minutes). I have a 555 timer board which will switch a COM between a N/O and N/C output after another predetermined amount of time (probably ~1 second) to trigger the dome rotation relay. The bit I'm struggling with is resetting the circuit, once it has triggered I then need to do something to restart it. I feel like it should be possible with a timer board or combination of relays but can't quite land upon the mechanism. Any ideas?!

Just head north, according to this there are plenty of Bortle 1 up towards Mull etc https://www.lightpollutionmap.info/#zoom=7&lat=7688165&lon=-467085&layers=B0FFFFFTFFFF

Yes, if you read the comments this was on a car battery at +12V. It is now running off a power supply at 9V/8A and is much softer on the belt

I was tempted to get a bit more involved with Alexa but settlted myself into some code for running the imaging instead The shutter may follow, it seems to be a popular demand! Thanks for all the feedback

I have two smart plugs, one powers on by default and switches on the vast majority of the kit. The other one is switched off by default for the QHY10 (I only want power to that after USB is switched on and connected to the PC). I can then tell 'her' to turn things off when I'm ready. I also use it to power my PC on and off but I shut down programatically so don't need it at the end of the session. I had to use a wifi extender to get coverage up the garden but otherwise it works very well (and there is a USB port on the plug which is permanently powered and I use this to power my LEDs around the edge all the time)

I wasn't going for steam punk but I guess that fits! I was going to automate the roller door but really would like an excuse to go outside at least once on an evening so will leave it for now. When Summer hits (?!) I'll be taking the door off to re-make this and fibreglass it properly so may have a play then.

And finally … I made up some steps (which I will get round to painting!) and got a few canvas prints done of my pictures and popped them in the observatory too. I also installed some lights and a camera in the observatory with night vision/motion activation which lets me monitor things from afar and ensure there are no issues. So that’s it, my automation journey to date. Other than opening the shutter and a spot of fibre glassing/gelcoat repairs I don’t think I’ve got much more on my ‘to do’ list All told I guess it has cost around a thousand pounds so not exactly cheap but much more fun and less money than buying from a shop, rough breakdown would be: £450 for the second hand dome £200 in wood to repair it £200 in collection transport £50 in electrical bits and bobs (relays, wire, crimps etc.) £50 in metal bits, brackets, welding, threaded bar etc. £50 on wiper motors and cam belts

My steps are as follows: 1. I ask Alexa (other assistants are available) to turn on a smart plug which controls the mount, heaters, focuser, USB extender and dome power supply 2. Once these are on, I connect USB over cat6 to the QHY8L and tell Alexa to turn on the power to the chiller (they can apparently be fussy about the order of powering up) 3. Then my application will automatically start CDC (Carted Du Ciel) and navigate to the ‘Connect Telescope’ function for me so I can hook into EQMod. This starts ‘dumb’ tracking and I can pick a target to slew to. The change from Synscan to EQMod was very easy and well worth it (much quicker set up times, one less wire for the ST4, easier to pick targets on a sky map, highly recommended) 4. I venture outside and open the dome up then use buttons to jog it to a start position. This is where I align the proxy triggers with the magnets, it takes about 1-2 minutes to do all before I head back in the warm house 5. My application runs EZCap and FocusMax so I can get the QHY8L and Moonlite focuser set up 6. Next, Nebulosity starts up and I select my exposure time, directory and kick off cooling of the camera to -20 7. While the camera is cooling, my application will start PHD2 for me and I select a guide star then start guiding. Note: If you use PHD2 through EQMod you don’t have to align each time, it just does it once then you start guiding immediately on each imaging session, much faster! 8. Once PHD is guiding and Nebulosity has cooled the camera I am good to go with my imaging session. I then do a number of things – I tell CDC to park the telescope at a suitable time when imaging is complete. I tell Alexa to turn off my telescope (and CCD camera) a short while after CDC has parked the scope. I have a shutdown timer in my application which will then close all the applications and switch off the PC So with those few steps I can comfortably be up and running and imaging in about 5-10 minutes from a nice warm living room and then stand in the cold staring at the sky just for the fun of it!

While all this electrical and mechanical work was going on, I also decided to get a better handle on my software and process around imaging. I generally follow the same sequence of steps each time I set up so figured automating it would be good, the screenshot below shows a simple app I made in .net with a list of steps (the green text) which are walked through when you press ‘begin’. This is using the Windows API to spawn processes and SendMessage to pass instructions to them.

The telescope can never hit the dome so my worst case is losing a night’s imaging if it fails to spin but I wanted a failsafe to trigger in case of issues. My wife made an elasticated sleeve for both my scopes with a series of soft springs to make the electrical contact. I then wired each spring together and fed them to the same relay the proxy used. When the springs touch a floating ground sheet, the dome rotates. I used RFI shielding fabric which is conductive but also flexible so the tail of the telescope can push it out the way while the springs will short to the relay when they come into contact. I connected the springs to ground and the RFI sheet to the relevant relay to move right/left accordingly. I also ran a feed to a toggle switch so I can easily move the dome around ‘manually’ if I need to.

With 12V/5A the dome would rotate smoothly but didn’t have enough torque to start the rotation, using a car battery I had no problem starting the dome rotating but it was faster than I wanted and much more aggressive causing quite a lot of mechanical load on the motor and bracketry (you can see this in the video). I eventually found the sweet spot to be 9 Volts at 8 Amps which gives a nice steady speed when rotating and enough grunt to kick it off from a standstill. The proxy sensors activate approximately 10mm from strong magnets so I bought 5 rare earth bar magnets from China for £10. These were mounted so that whatever position the scope was in it would pass the magnet and trigger the dome to move. I used some 4mm aluminium modelling wire to locate the proxy sensors and position them however to line up with the magnets.

At this stage I had a dome which would rotate finally 75.mp4

I made a fine thread (M11x1.25) on the outside of the 11mm bar from the wiper motor so that I could locate the pulley precisely when in place on the dome. Once lined up, I welded the pulley using a metal plate which I cut to size and bolted through the pulley.

I still needed to overcome a couple of problems: 1. Stressing the wiper motor bearings by pulling it against the dome 2. Allowing some slack in the rotation to control any float I got back to work with the steel and included a 12mm pillow bearing with spring mounts which could take the load. 12mm with grub screws was just right for my 11mm tube and were off the shelf at £4 for a pair Tightening the nuts on the threaded bar allows enough preload on the spring to drive the dome and deal with the undulations during rotation. In terms of spring selection, I went for some fairly stiff off the shelf springs available from RS (Part No: 012-315, free (uncompressed) length: 48.9mm, minimum length: 27.4mm, spring rate of 11.96N/mm), 10 of these cost ~£10 delivered.

This time, however, I wanted to have less lateral load on the motor so I decided to increase move away from the go kart wheel. I had already contacted a belt/gear supplier who someone else used for a dome, and they suggested this was not a good solution and they steered me away from using a belt. The tyre wasn’t able to gain traction on the plywood ring of the dome so I decided to proceed with the belt anyway – the quote for a 25mm wide 7 metre long belt, an eye watering £115 + VAT! I decided to go down a different path and bought six Dayco 94605 belts (Corsa/Astra/Cavalier/Vectra fitment) because they were the cheapest around (all six delivered for £20). This had the 25mm width I wanted to match the dome and was 136 teeth and 1,295mm long meaning I had a 9.5 pitch for the teeth. I matched this to a pulley off a Corsa (I have no Vauxhall affiliation, it was just the cheapest one, honest!), which was part number 94368653 or 97142432. The dome I had purchased was homemade and was far from perfect in terms of run out. I had several centimetres of variance across a rotation. I minimised this with a router before working on my 6 timing belts with a spot of Araldite to hold them in place.

Off we go again and … snap! The motor shaft was being loaded too heavily and gave up so I welded the Transit to the 11mm tube rather than using a roll pin instead

Proof of concept complete, next I made up a bracket to fit this in the dome and made a more permanent mounting

So now I had a motor, a drive wheel and a switching method, so I bought a 12 Volt 10 Amp power supply and tried it out. Pop! The stall current of the motor was too high so just blew the fuse in the power supply when I put any significant load on it. I tested the wiper motor on a power supply and it was pulling 4 Amps at low speed. I ended up changing this from a Vauxhall Corsa (£13) motor to a Transit Van (£20) motor and the current dropped to 1.5 Amps and had plenty more grunt. To wire the motor you will probably find you have 5 pins, one is ground, one is +12V for slow speed and one is +12V for fast speed. The other two are for parking so you can forget them. The slow speed setting has more torque and is a better rate for rotating a dome so I would recommend that. I checked the runout on my wheel and it wasn’t too bad so I held it (hard!) against the dome using a car battery as my power source (no more blown fuses there!) and it spun! Maybe a tiny bit too fast but it spun nonetheless