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By Michele Scotti
i'd like to share with you the design, making and progress of a project my astro club endeavoring to. I'll post here relevant info in a run-up to where we got to so far.
Here is the mission: 800mm in diameter. That's it. A lot of inspiration out there but it needs to be able to do science. So it's a relatively fast Newtonian capable of tracking for tens of minutes.
So we realized that we were facing 2 projects in one. The mirror on one side and the mount on the other. Shall we start with the mount? What's the best compromise in terms of ease to build and cheap components and the chance to have a stiff yet light structure. An alt-az, like the biggest telescope! - or rather a glorified dobsonian in this case.
Any comment/suggestion is welcome!
As my GoTo is successfully finished (some cosmetic issues remain) I shoud focus my attention on planets' positions. I have proper source of information: fantastic book "Astronomical Algorithms" by Jean Meeus, thus I will sort the planets soon. But planets are not a challenge for me at this moment, they are just something obvious to do in my list.
I have another idea and ambitious plan for next project within the year: locating and tracking the ISS to be able to make a video of its fly, not only transition.
Similarly to other objects, I need some equations. I'm pretty sure they are available somewhere, because plenty websites or apps offer showing current position of the ISS.
I will use this topic for sharing a progress ot the project.
By Cosmic Geoff
I have had an issue with the mount of my CPC800. I have noted that sometimes when slewing through a large angle in azimuth the note of the gear noise changes. Also once or twice the target image has taken off to the left while I was preparing to image and even motor speed 3 would not hold it on screen. Also I have once or twice left it unattended for several minutes and returned to discover that I needed to use the optical finder to recover the target. This makes me wonder if something is binding.
It still works far better than the 6/8 SE mount, so I am reluctant to send it for repair or open it up without a clear pointer to the nature of the problem and likely fix. It would be a more serious issue for long exposures/deep space imaging.
I have an EQ5 telescope mount which i use for astrophotography. I have modified it with a motorised RA axis using a bipolar stepper motor - my thread for the build is here .
I want to expand the mount's tracking ability by motorising the DEC axis and using a guide scope/camera. I generally use the mount in fairly remote locations so would like to use a raspberry Pi for portability.
I understand that I'll need to use a Raspberry Pi Camera Module for the guide camera.
The capability I want is:
1. guide the mount along RA and DEC axes using a guide star as feedback
2. track the mount using the RA axis only, and if possible continuously take 20-30 second exposures on the guide camera (this functionality is optional, but would assist in polar alignment of the mount)
I don't want any GOTO capability. I am very new to RPi and need some help:
- do I need to write code for this, or is there existing programming available for what I want to do?
- is it possible to avoid the use of screens (in the field)? My preferred option would be to flick a switch to start and stop the guiding, with another switch for alignment mode (or something simple like this).
- do I need to use any particular stepper motors/drivers for raspberry Pi? I'm using a bipolar stepper motor running quarter steps, with an A4988 stepper driver
- is the RPi 3 Model B+ the unit I should buy?