The prominent, large dust lanes on the disk of M31 are NOT meant here, of course.
This article talks about the filaments that are seen very close (10') to the M31 core on photographs. Can those bulge filaments be seen visually by DSOs ? How ? Amazingly this turns out to be an observation feasible under middle-/low-class skies (21.25mag/sq.arcsec) as well, probably also with much smaller telescopes than 20"... I know M31 is a bit ON the beaten track, but so what !?
FYI: you may have noticed another thread of mine on the more general topic of experience w/field sweeping as well.
Thanks for comments.
Last edited by petersurma; May 17th, 2023 at 08:32 PM.
If you look at my drawing of M31 with a 30 inch f2.7, you'll see that I saw some of these in-tight dust lanes. Difficult to draw in an ultra-wide angle sketch.
Per your other posting, yes, indeed, I see more when my eye vs the field moves every few seconds. I do this consciously (otherwise my eye does it unconsciously and not as efficiently); I also move the scope manually not only to 'shake lose' detail but also to enlarge the field that I see in my mind. One reason why I do not add tracking to my scopes anymore.
Yes, seems like you sketched a fair indication of them, great ! Position (from M31 core) roughly halfway out to HIP3447 = SAO36609 is correct. Your sketch focus was on larger scales, sure (impressing anyway, wow !). I guess anyone else is just waiting for M31 to come up 'behind' (in alpha) the milky way, after the summer (or at least very late in the night), finally verifying (or falsifying) what a crazy German said once on the forum... :-)
Wrt the 'theory' of field sweeping I have not heard a lot on the 'subjective' background of it to observers - that's why I asked (decoupled thread). I would have guessed that especially those guys in the sketching biz have their special opinion on this technique.
As you say, yes, enlargement of the field of view (in your mind, i.e. you remember the other parts you already have swept over + patch them into a joint impression/picture) is also one clear objective, of course. I remember using FS e.g. on California regularily. This neb is so big, you can't get it well (in reasonably big scopes i.e. small fields) without sweeping over.
But still, I was always amazed on HOW effective this technique really is. Seems our visual system is very much trained on enhancing perception during movements... I wonder if there is some more scientific work on it !?
And of course, there must be more experience on this topic in the field of DSObserving.
Last edited by petersurma; May 22nd, 2023 at 01:24 PM.
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