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I first made a 6" f/10 telescope back in 2002. It was, as everyone called it here "the minimum size you should make". So I went ahead with it. The f/10 was because some gentleman had ground the glass to f/10 and abandoned it in the local astronomy club and the president of which handed to me.
After having used the scope until 2009 (I went to UK for my Masters and bought my GOTO setup at the Telescope showroom I was working. I am primarily an astrophotographer, but one can never forget ones roots can we?
So, long story short, I am back to grinding a 6' f/8 this time, The FL now stands at 49" (f/8.1). I had finished fine grinding with 1000 grit SiC and moved to 1200 grit SiC but only to realize (after 30mins of grinding) that the seller had incorrectly labelled the powder as 1200 grit. I ended up with large pits all over the mirror and had to resort back to the "actual" 1000 grit SiC. This was yesterday. Now, after about 2 hours of 1000 grit, there are about a dozen pits of varying depth. I think another 30 minutes should get rid of them.
I tried making a polishing tool from White Portland Cement using the mirror as the mold and aluminum foil as separator. Disaster struck as the cement ate away the foil and got stuck to the mirror in the form of a thin layer (thankfully) and I was able to remove all of it by mild scrubbing and later grinding with 1000 grit SiC. The misadventures that I deliberately get into. 😕
Hopefully I can start polishing soon.
Wish me luck folks. I will post al developments here.
I bought two new dew heaters. They are sold to be used on camera lenses and powered from USB. I have modified them to reduce the power from 8 Watt to 2 Watt which will be enough for my demand.
Some photos and documentation from this project:
This will be battery operated and I try to reduce the power consumtion of the equipment.
More than a year has passed since the construction of the Low Spec spectrograph in version 2.0 provided by the author of the project (@Paul Gerlach).
The project provided for the purchase of a ready-made module for illumination of the slit.
From the beginning, I missed a decent calibration module and slit illumination.
But why buy something for almost PLN 100, when you can illuminate the slit while building a spectrum calibration module and add additional functionality.
Everything is great on the "project":
Inside the device:
But the electrical diagram I drew was not correct (I don't know anything about it at the time).
Not everything worked, so the modifications during soldering and compromises started: D, after a few attempts with soldering and desoldering, my calibration module finally works as it should.
It was important for me that the calibration standard should be stationary (not moving), and this of the available components on the market only provides an imaging flip mirror with a tilting mirror.
It is sold under various brands with T2 threads, so it has a lot of possibilities for mounting various accessories and I made the right module for it.
No store in Poland undertook to order it, so I had to buy it on my own (UK).
RELCO 480 starter spectral lamp:
The cylindrical mirror is a piece of aluminum foil stuck to it for packing sandwiches
Slit illumination also works:
Finally, only one LED informing that the slit illumination is on (the RELCO lamp with the diode on doesn't work).
Now it's time to put together the set:
Low Spec with 2 cameras and a calibration module is very big and heavy:
Solar line tests in diffused light on clouds:
RELCO 480 spectral lines have two values, the upper one is measured by calibrating the spectrum with solar lines, and the lower value is taken from
Richard Walker, CH-Rifferswil, 2017, Glow Starter RELCO SC480 Atlas of Emission Lines, available online: https://www.ursusmajor.ch/downloads/sques-relco-sc480-calibration-lines-5.0.pdf
The difference between my measurements and the data from the Echelle spectrograph from the above atlas is basically negligible, everywhere smaller than 0.2 Å, which means that on my scale it is below 1 pixel.
It seems that the construction of the calibration module was successful.
The calibration module will facilitate a sufficiently accurate calibration of the spectra of faint stars without clear metal spectral lines and in regions where there are no atmospheric oxygen and water absorption lines used for accurate spectral calibration.
I had to capture pictures quickly because I have a drift on the diffraction grating holder (the spectra move over time).
Rather, it is loose, there is a micrometer screw and a spring, so the holder isn't very stable.
I would to improve it next.
I've been contemplating making a portable power box so I can take my mount to a dark site, a friend gave me an old lorry battery that no longer turns the engine over but will hold some charge. My intention was to get a nice enclosure and build something that looked professional like a few other members have created on here, unfortunately spare time is limited so I went for a simpler solution and created the following and it works very well.
As a beginner I'm in the process of acquiring all the equipment necessary to start imaging on an EQ3pro.
As we're all experiencing, it's tricky to get your hands on any equipment at the moment due to stock shortage so I've been thinking of ways to keep myself busy in the meantime!
I thought I'd share a project I worked on today that will give me a greater view of the night sky from my covered balcony.
There are some good views from the balcony from East to West but using the tripod severely limits any overhead views.
To bring the setup closer to the edge of the balcony I've built a shelf attached to the sturdy (wall set) balcony itself with a wooden pier for support. The pier itself sits on the balcony floorboards support beam and so there is no noticeable wobble.
I've included an image of the spirit level to show my effort in keeping the mount level.
The mount neatly slides off the feet of the shelf which I'm hoping will reduce setup time (once I have the opportunity to polar align!) The north foot points to magnetic north.
Whilst building I realised I could have saved myself some trouble by using a metal telescopic "chin-up bar", not least from the missis who wasn't too happy I drilled into the decking!
I'm quite happy with the outcome and glad I could get into a hardware store before "tier 4" sets in.