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Stellarium: FoV vs Mag


DaveS

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I'm confused :confused:

Using Stellarium 0.13 when I zoom in to a scene I see fainter stars than I should given my Bortle number, with fainter stars becoming visible the more I zoom in, some having magnitudes down to 7.5. :confused:  :confused:

So, if I want to match what I see naked eye to what Stellarium shows, what Field of View should I use? On start-up it defaults to 60 deg.

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Well, yes I can set the magnitude limit, and the scroll wheel alters the FoV, but even so, as the FoV gets smaller so dimmer stars come into visibility, to below what should be visible for the Bortle number.

Therefore, at what FoV do the stars you can see on the screen correspond to those you can see in the sky? For instance, if you want to determine your Bortle number by comparing what you can actually see with what Stellarium is showing.

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Yes, I *know* how to limit the magnitude shown, that's not the point. I also know how to vary the FoV shown (Should be obvious from my posts).

By rights, if it says Bortle 9 from the location database, then the naked eye view should be limited to that NELM regardless of FoV, but zooming in shows ever fainter stars, making any attempt to relate what I see in my sky to the Bortle number in Stellarium either meaningless or seriously depressing. Since when does a Bortle 9 sky have mag 5.5 or even (God-help-us) 7.5 which I have seen. Unless, of course narrowing the FoV corresponds to a telescopic view, but that would be dependent on aperture, at least for point sources like stars.

So I dunno anymore, maybe I'll give up trying to determine my Bortle number from Stellarium.

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I have noticed that as you zoom or scroll in then more are displayed immaterial of what you set.

Not sure why, since I would have expected a limit to be exactly that, as in display nothing dimmer the Mag 7, but it does, or appears to.

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The number of stars you see is dependent upon both aperture and magnification. As you up the mag, the sky background darkens but the stars do not so more become visible. I think that is what Stellarium is trying to represent

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Well, I've given up directly trying to match up the views, instead I'm just using Stellarium to check the magnitudes of the stars I can *just* see and the ones that I know are there but *just* below visibility.

When I do that I get NELM of 4.0 though it depends on where I look in the sky, south being worst unfortunately due to a major road, Northholt Aerodrome, the A40 and Heathrow.

This puts me at the boundry of Bortle 8 and 9. Bother, I remember being able to see to mag 5 easily from Acton, which is much further in to London. And I gave up astronomy because of the LP :mad::eek::confused:

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*sigh*

Just updated to ver 0.13.3, and found Ruislip (My nearest location) in its data base, so set that as my default. Oddly when I ask it to set the location from the network it says Enfield  :confused: .

So in Sky and Viewing options I tick "Use data from Location" expecting Bortle 9, or perhaps 8, and it gives me Bortle 5  :mad: . Enfield it says is Bortle 2  :eek:

If Only  :mad:

*cries into his beer*

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  • 1 month later...

Stellarium is quirky isn't it......that's why I like StarCalc.....an old and simple planetarium program.

Hope you solve your problem.

I'll watch for your posting.

Clear Skies ----- Silveradogold :laugh:

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