SkySafari | star magnitude changes with FOV

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    Originally from ticket #24420.

    Hello, 
    I was using your outstanding sky safari 4 pro software last night, on my android S3 (V4.1.2).  I experienced an issue wherein the star magnitude would change on me. I put the limiting magnitude to 8.2 (to reflect what I was seeing in my binos), then I would add an observation to a list, or look at star information, and when I would go back to the star map, the limiting magnitude had changed, sometimes way too high (like 14.5) and sometimes way too low (like 3.2, though it was always random).
    Restarting the software and then my phone did not fix the problem. I've never experienced this before. Can you help? A Google search did not yield much for me.
    Thank you!

     

    Bill Tschumy replies:

    Mike,

    SkySafari automatically adjusts the mag limit as you zoom in and out. So if you set a star mag limit of 6.0 at 90º and then zoomed into (say) 10º, the star mag limit will have changed to 9.8. Is this what you are seeing? If so, it is working as designed. There is no way to set a magnitude limit and have it remain fixed for all fields of view. SkySafari has worked this way for 6 years.

    Bill Tschumy
    SkySafari Developer

     

    Ticket update:

    Great! I guess I had just never noticed it change. I'll keep that in mind the next time I am observing. I guess that means I'll have to switch it more frequently if I'm zooming in and out. Thanks for the response! I love the app.

     

    Bill Tschumy replies:

    You really shouldn't have to switch it manually. SkySafari does a pretty decent job of scaling the magnitude with FOV. When you are zoomed into a telescopic FOV, you will see faint stars you can see in a scope.

    If you find you really need to tweak the magnitude a lot, please let me know.

    Bill Tschumy
    SkySafari Developer

     

    Ticket update:

    I see. What I was experiencing was, I would zoom in to, say 35 Pegasi, then set the mag limit to match the star field I was seeing in my binoculars (around 8.2 at the time). Then after I found my object and observed it, I would zoom out to look for another object, only to see barely any stars, which made me think the app was messing up, because the mag limit would be something like 3.9 once I zoomed out. I'm sorry to take up your time with such a rudimentary misunderstanding of how the app works. 
    I'm trying to figure out a way to go through that scenario without having to change the mag limit back and forth, but whenever I see enough stars in the zoomed out sky to identify the constellation and star, it turns out to be way too many stars in the field when I zoom in to star-hop through the smaller fov.
    I'm thinking that arises from the fact that I'm using binoculars and not a telescope (at the moment). In a scope that had the same fov  as my binos (that would be nice!), I would see many more stars in the scope eyepiece than the binos because of the larger objective. Makes sense. 
    Does it sound to you like I just have to switch the limiting mag back and forth? Or I guess I could just try to get used to star-hopping while ignoring the fainter stars in the field.
    At any rate, thanks for helping me out. I thought my phone or the app was going wonky.

     

    Bill Tschumy replies:

    Mike,

    Yeah, it may be that wide binocular fields of view end up showing more stars on screen than you will see. This is due to the low power. I can see that case you may need to readjust when you zoom out again. Alternatively you might just try to get used to seeing more stars on-screen than you are seeing in the binos.

    At least now you know what is going on.

    Bill Tschumy
    SkySafari Developer

     

    Ticket update:

    Thank you, Bill. I appreciate your time! I'd like you to know, whenever someone asks me what astronomy apps I like, I always have great things to say about sky safari (however, they usually just download something free, like Google sky, and it makes me a little sad :(
    Anyway, thanks and clear skies! 
    Mike

     

    Bill Tschumy replies:

    Thanks Mike.

    Bill Tschumy
    SkySafari Developer

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