Forum Replies Created
-
Posts
-
One last post to finish off this thread.
Two more suppliers suggested to me by Terry Pearce and John Nichol. Washington Mills supply Silicon Carbide in bulk and Glassworks Services supply abrasives in any quantity you want.
I went with Glassworks. I phoned them yesterday morning with an order and it arrived Friday morning within 24 hours…very efficient.
Not the most exciting photo but this is what turned up…should last a while! [It is C.80 despite the product code SC220].
Mike.Attachments:
If anyone is interested John Nichol put me on to UKGE as a source of abrasives. They are mainly for rocks and minerals but it’s the same stuff.
See the UKGE web site for details: https://ukge.com/product-category/lapidary-supplies/abrasives/Or another bulk supplier in Germany: https://ots-store.com/ots-store-9070-14-en
Mike.
Update: Just heard from UKGE. Apparently they are winding down their business so won’t be supplying abrasives anymore!
Thanks Callum,
Yes I had a look at Galvoptics but they have clearly moved on from supporting ATMs. They don’t do aluminising anymore either. Vacuum coatings are an option with C.80 at £7.80 for 1Lb so I can use them if I don’t hear from anyone else.
Mike.Thanks Peter,
Both groups are visible through eclipse glasses. 4478 clearly shows two spots while 4479 is smaller and near my ‘naked-eye’ limit. Worth a look…
Mike.Just to note that Kevin McCloud visited the Lovell Telescope as part of his ‘Listed Britain’ series. It will be on channel More4 on Thursday 11th June at 9pm.
Mike.Don’t know if this helps but this is the light curve for the last 300 days taken from the AAVSO ‘Light Curve Generator’: https://www.aavso.org/LCGv2/ .
Any thoughts???
MikeAttachments:
On a related issue, does anyone know what happened to the objective prisms at NLO?
There is a nice BAAJ article from 1982 [1] that mentions three prisms, two for the 300mm refractor and one for the 225mm refractor. They appear to have been used up till 1961 but then no mention of them.
If they were full aperture prisms they would be serious pieces of glass having angles of 15, 20 and 45 degrees. Not items that could be ‘lost’ easily, so they could still be at NLO or deliberately moved somewhere else.
Any historical background on these prisms would be interesting for my own objective prism project.
Thanks.
Mike.
Ref: BAAJ 1982, 93, 1, p25-28. “Sic Itur Ad Astra: A History of the Norman Lockyer Observatory“On a more positive note…If every satellite had an astro camera on it looking out it would be possible to image the entire sky continuously, 24/7. Imagine the possibilities…what would you do with a camera in space?
Time for the astronomical community, amateur and professional, to start working with the constellation builders. How can we use all these camera platforms in space to benefit everyone? It could open up imaging/photometry/spectroscopy in the UV and IR. Exo-planet hunting could be carried out over the entire sky. Anyone could ‘see’ the pristine night sky anywhere, anytime. Good for astronomy, great PR for tech firms. [The dawn of space-based amateur astronomy?].
I can see a headline sometime in the 2030’s…”AI Mega-constellation discovers first exo-planet: Musk-1a”…guaranteed immortality…!
If it’s going to happen why not take advantage of it…I guess it’s evolve or die.
Don’t just think outside the box, think outside the atmosphere…There are a couple of other options for solar viewing.
My favourite is a long focus mirror fed by a driven flat mirror. My version had a 4 inch mirror of 47 feet focal length which gave a solar image 5 inches across…i.e. bigger than the mirror! So although the sun if focussed the surface brightness is less than that of direct sunlight. Sorry I don’t have any images but there was a short piece in Astronomy Now, November 2008 page 75. Not an original idea by me…Hale made a 100 foot solar telescope which was described in detail in volume 1 of the Amateur Telescope Making books.
The other option is to have a heliostat feeding light through a single lens (no need to be achromatic) with the image viewed through an H alpha filter as usual. A nice example is shown in Sky & Telescope, August 1980, page 162. The 24 foot focal length lens gives very detailed views of prominences etc.
These set-ups are obviously much more involved than conventional methods but would make nice projects for astronomy clubs. They have the advantage of having all the optical elements on show so people can see how they work.
Mike.Richard,
Worth giving the Astronomer’s Telegram reference for the image above for additional information: Astronomer’s Telegram #17264Interesting trajectory for this object, almost in the plane of the ecliptic. Odd for an interstellar object given the solar system is tilted about 60 degrees from the galactic equator. How does it compare to the other two known interstellar objects?
Mike
