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Limbering up for tomorrow... White Light


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Usual "chaos", but slowly getting the MAK150 on air for white light!
Focussing (as ever) is fairly random! But snatched between clouds:

100 evts MAK150 Watec 910HX 1/250s (8.5 mic pixels + ND 2.0!): :D
Plenty of room for improvement, anyway... lol


Trying to work out where "First Contact" might be relative to this (to me) random sunspot! :p
Perhaps more importantly what SIZE will Mercury be compared to the above.
Should I use a focal reducer? 0.7x, 0.5x, 0.3x? Decisions, decisions...

Edited by Macavity
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Good practice run. Nice detail in that AR. Mercury should be about 12-13 arcsec, I think. Should be a fairly easy spot, I remember from last time (2006). Didn't get a chance at imaging then. I am itching to get a good set of piccies this time round. The weather forecast here is looking good, but I'll believe it when I see it.

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I'm almost ready for my own white light trial run although the weather for tomorrow is not looking good at all - however, as a deep sky imager, getting things prepared for this event has been more complex than I imagined so if it all goes south I will at least have a log of what I need to do for a similar event in the future!

Here's the current list:-

1. packing required for filter holder to allow for smaller telescope (it WILL be 100% safe when I have finished)

2. find extension tubes

3. find 2 x Barlow

4. find 2" nosepiece for camera

5. cobble together a piggy back mounting

6. balance DEC axis with second telescope piggy backed in place

7. hunt for and install larger counterbalance weight

Yet to do:-

1. modify dome tracking parameters for new telescope height

2. find correct focus position for Barlow in the light path and reducer

3. find out if mount does solar tracking

4. see if I can remember how to use EOS Movie Record

I love this hobby, so much to do and learn all the time!



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Yes indeed... Good luck everyone! With a bit of application and an occasional
glimpse through clouds! (Watec Video cameras can see through THIN ones!)
I have at least aligned things orthogonal to the polar coordinate system...
I was just being LAZY really! :icon_rolleyes:

Just as an exercise, I am now trying to *calculate* the "size" of Mercury relative
to AR2542. If (still a fairly big if!) I am right (My original image was ~1"/pixel?)
it should indeed be ABOUT the same size as one of the umbra regions... :D


I tried to get the Sunspot within 90-deg of the real coordinates this time. lol
The CENTRAL placement of "Mercury" is entirely arbitrary though! :p

If I am right (Holmes? lol) Mercury should enter the field from the same side
as AR2542 (the left of most SGL images) but below the "solar equator". ;)

But feel free to contradict me... to "ROFL" or whatever? :D

Edited by Macavity
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The size of Mercury against the Sun is only 1/150 of the diameter of the Sun itself.  To put it another way, if you project an image of the Sun 152mm (six inches) across, Mercury will only be 1mm across.

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Y'mean my talents with inverse trig calculator functions were wasted? [teasing] :p

Actually, had my memory been better, I would have made a *Stellarium* chart
with the relevant scope (f=1800) and camera chip (6.4 x 4.8mm) dimensions. ;)


I do a windows "screen capture"...  I tend to "invert" this (Saves on INK!)...  then I print it out!
Hmmm... SUNNY dawn here.  Fair bit of "Alto Cumulus" + mist around. Hoping it'll burn off?
Oh, but wait... Where are my manners? Good Morning (and good luck) Everyone! :D

Edited by Macavity
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Hmmm... N.Wales: Getting really overcast in the SE now. No more sun. :o
All I got was a brief test shot 80/100 events through already thin cloud.


The forecast stills says "Sun", but IR picture shows a large swathe of cloud
stretching from N.Ireland to the "Wash" and moving North Eastwards...

Edited by Macavity
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