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Home Forums Observing and Imaging Group Solar Observing – International Solar SUNday

This topic contains 22 replies, has 5 voices, and was last updated by  Andy Sawers 3 years ago.

Viewing 8 posts - 16 through 23 (of 23 total)
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  • #6469

    Mike Meynell
    Moderator
    Topics: 119
    Replies: 745

    You cannot be Sirius!

    That deserves one of these, I think… 😉

    Yellow card

    #6471

    Brian Blake
    Participant
    Topics: 187
    Replies: 409

    A red card more like.

    #6475

    Andy Sawers
    Moderator
    Topics: 112
    Replies: 587

    On a, er, ‘serious’ point, I’d be really grateful for details of the different types of gear that people were using on Saturday. I wish I’d the sense to make a couple of notes of peoples’ names and the sort of equipment they were using and what each type is best for. (My memory is like, um, one of those things with lots of holes in it these days.) I remember Tej (and one other guy) was using an H-alpha PST (great for prominences), but was yours an H-Alpha as well Mike (attached to your night scope – I do remember that much!). Who had the camera with the home-made white light filter? And what was the rig at the right side of the group that gave a green tint to the sun but showed up the sunspots well? I recall mention of ceramic heat protection and an X-ray filer… (Must pay more attention in class…) Thanks, anyone!

    #6476

    Astrograph
    Participant
    Topics: 27
    Replies: 101

    Hi Andy,

    What we had were

    2 x Coronado PST’s (the small gold tubed ones) from Tej and ….? These are for H-Alpha and have a bandpass of about 0.8A. This means they will show large Prominence’s but less Chromosphere detail (can’t have it all!). These were dedicated Solarscopes.

    Mikes APM night time scope was using a Daystar Quark ‘eyepiece’ which converted his scope to view H-Alpha. The combination resulted in a magnified, partial disc view of the sun. This had a bandpass of about 0.3~0.4A meaning that Chromosphere detail was high contrast. Prominences were smaller but structure finer. This H-Alpha filter is made for converting a refractor.

    My scope (same as Mikes) had a rear mounted Daystar ION rear filter to convert it to H-Alpha. This was used to show both full and partial discs, with and without binocular viewers. This was 0.5A for detail Chromosphere views. This type of filter can convert both a refractor and a reflector (not Newtonians)

    Both Mikes and my scope had internal energy rejection filters to reflect the UV/IR (hot) light back out of the telescope.

    The camera (I think this was Clives) was fitted with a front mounted White Light filter. White light filters do a similar job to a Herschel Wedge and can be fitted to both refractors and reflectors of any type.

    Martins scope (long black one) – not sure, I did not get round to looking through it. Think this was white light.

    Finally, Grey had a night time scope fitted with a Herschel Wedge for White Light views. The wedge has a prism inside which reduces brightness by about 95%. It reflects some IR/UV light back out the telescope and the rest is diverted to a heatsink. In the case of Greys, some ceramic plates. A couple of filters then reduce the light level further for safe viewing. The ‘Green’ view of the Sun was due to Grey using a Solar Continuum filter. This only passes light at 540nm where the eye is sensitive to contrast. Strictly speaking these filters are intended for Achromats which on a bright object like the sun, show false colour badly. For an APO, Semi-APO like Greys, you don’t need them and can use a polariser instead which tames the light level and increase contrast just the same but gives you a white light view. Personal preference really. Not everyone likes a green sun! Wedges can only be used on refractors.

    Hope this helps

    Rgds

    Rupert

    #6477

    Andy Sawers
    Moderator
    Topics: 112
    Replies: 587

    Hugely appreciated, Rupert. That’s all the detail I was told on Saturday (but forgot) plus stacks more besides. Very many thanks!

    #6479

    Andy Sawers
    Moderator
    Topics: 112
    Replies: 587

    Did you know that Alpha Canis Minoris (or Procyon) is on the flag of Brazil?

    But which country (according to Carl Sagan) has an observatory on its flag? (No Google cheating – though probably Sagan did stretch the definition of ‘observatory’ somewhat.)

    #6484

    Mike Meynell
    Moderator
    Topics: 119
    Replies: 745

    I can only think of one country that has any sort of building on it… and that’s Cambodia:

    Flag of Cambodia

    No idea what that’s got to do with astronomy / observatories, though I suppose that ancient temples were used for observing the heavens. Am I on the right lines?

    #6487

    Andy Sawers
    Moderator
    Topics: 112
    Replies: 587

    Spot on! Good work, Mike! It’s the temple of Angkor Wat in Cambodia.

    Wikipedia seems to downplay its astronomical role, UNESCO makes zero mention of any such function (as far as I could tell on a skim-read), but Nasa is right in there, giving it its own web page.

    I didn’t know any of this till you mentioned about the Brazil flag which reminded me of Cosmos the book in which Sagan lists a lot of countries that have stars, suns, constellations etc on their national flags (page 65 of the plain paperback edition for which I paid £11.99 last year, a week before finding a copy of the illustrated version in a market stall for £1.50).

    • This reply was modified 3 years ago by  Andy Sawers.
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