Prominences a bit subdued this morning.
This is the last solar post for a while as we are off to Scotland for 2 1/2 weeks.
This post (http://spaceweathergallery.com/indiv_upload.php?upload_id=148025&PHPSESSID=ufu9aq45u6ht3gl4rhuesc8jj2)
is entitled “Ionize Calcium / Better Than H-alpha?”
Not sure I’m convinced!
Compare with this a day earlier – http://spaceweathergallery.com/indiv_upload.php?upload_id=147977&PHPSESSID=ufu9aq45u6ht3gl4rhuesc8jj2
(same as this: https://roslistonastronomy.uk/nice-prominences-this-morning-13-09-2018)
Need to see Ha and Ca-K at the same time. Pete? Andy?
Interestingly, although we have no sunspots, prominences are fairly abundant.
To all (both?) of you with Ca-K filters, this says you can see prominences in Ca-K.
I have wondered about the resolution I get with my solar scope, so here are some fag-packet calculations:
Telescope diffraction limit (in radians)= 1.22 X wavelength in cm/scope dia. in cm
Telescope diffraction limit (in arcseconds)= 206265 X 1.22 X wavelength in cm/scope dia. in cm
Ha light wavelength = 6562 angstroms = 6562 X 10^-8 cm
Lunt LS35 THa is 3.5 cm dia
Diffraction limit = (206265 X 1.22 X 6562 X 10^-8)/3.5
= 4.7 seconds, or about 5
Solar diameter is around 30 arcminutes, or about 1800 arcseconds
In this image the distance between the 2 spots is around 0.135 X the solar diameter, or around 250 arcseconds
The lines or striations around spot 2620 at their thinnest, are around 1/50th of this distance, or around 5 arcseconds.
So. my Lunt LS35THa images could, in fact be diffraction limited!
The GONG cameras have an aperture of 2.8cm, so they are similar.
Conclusion, to get images like this one (http://spaceweathergallery.com/indiv_upload.php?upload_id=147458)
Of course, a Quark fitted to a 80mm scope should be pretty good! (Andy)