Spotting the star HD 81474 in Ursa Major

[remcot]

I will try to find the star HD 81474 in Ursa Major. It has a visible magnitude of 8.14. And i have some questions. 1 is it visible with the unaided eyes? 2 Can i see it with a field glass? 3 Can i see it with a small or medium telescope? 4 Where can i find the (complete) HD (online) star catalog? Can somebody answer this 4 questions? Thank you. remcot

 

[petepan]

<font color="yellow">1 is it visible with the unaided eyes?</font><br /><br />no, you can only see down to mag 6 in dark skies and if you have really good vision<br /><br /><font color="yellow">2 Can i see it with a field glass? </font><br /><br />yes, or at least i should think so.<br /><br /><font color="yellow">3 Can i see it with a small or medium telescope?</font><br /><br />yes<br /><br /><font color="yellow">4 Where can i find the (complete) HD (online) star catalog? </font><br /><br />Sorry, don't know that one<br /><br />cheers

 

[doubletruncation]

You can find the HD catalogue on SIMBAD at:<br />http://cdsweb.u-strasbg.fr/viz-bin/Cat?III/135A<br /><br />In general, SIMBAD is an excellent tool for finding any astronomical data that you may desire, http://simbad.u-strasbg.fr/ particularly the query by identifier/coordinates is very useful.<br /><br />By the way, why are you interested in HD 81474? It seems like just a random star as far as I can tell. <div class="Discussion_UserSignature"> </div>

 

[remcot]

Because many stars are interesting for me ,also the random stars.

 

[doubletruncation]

Fair enough <img src="/images/icons/smile.gif" />. <div class="Discussion_UserSignature"> </div>

 

[remcot]

Some more (interesting) questions: 1 What will be the magnitude limit of stars that you can see when you are standing on the nightside on the moon whit (no) Earth in the sky? 2 How will it look outside (hypothetical) if we can see stars down with the (unaided) eye to magnitude 8.75? And question 3 What will be the magnitude limit of stars that you can see with (unaided) eyes at the clearest nights on the top of Mauna Kea Hawaii?

 

[doubletruncation]

<font color="yellow">1 What will be the magnitude limit of stars that you can see when you are standing on the nightside on the moon whit (no) Earth in the sky?</font><br /><br />Unfortunately, I think it would be pretty much the same value. With a very dark sky on Earth I don't believe your visual limit is determined by the sky background since a 6.5 magnitude star is still significantly brighter than the sky background (I believe the sky background should be something like 9 mags/square arcminute, where an arcminute is roughly the resolution of the human eye.). I could be wrong, but my impression is that the 6.5 mag limit is roughly set by the size of your eye and the effective integration time in your retina. So without a bigger eyeball (which is really what a telescope provides when you look through the eyepiece), I don't think you'll be able to see down to 8.75 anywhere.<br /><br /><font color="yellow">2 How will it look outside (hypothetical) if we can see stars down with the (unaided) eye to magnitude 8.75?</font><br /><br />For humans I don't think this is possible. Nonetheless, you can imagine what it would look like - if you used a sky simulator like starrynight or xephem (the latter is free, but not as user friendly) you can switch the faint magnitude limit between 6.5 and 8.5. Using the HD catalogue though, there are about 15,000 stars with photographic magnitude less than 6.5 and about 55,000 with photographic magnitude less than 8.5 - so you'd see something like 3-4 times as many stars in the sky if you could see down to 8.5. I suspect that the milky way would also be a lot more pronounced.<br /><br /><font color="yellow">3 What will be the magnitude limit of stars that you can see with (unaided) eyes at the clearest nights on the top of Mauna Kea Hawaii?</font><br /><br />As per above, I believe it's roughly the same as down here near sea-level. Though the chances of having a clear night on Mauna Kea are much better than <div class="Discussion_UserSignature"> </div>

 

[doubletruncation]

<font color="yellow">Because many stars are interesting for me ,also the random stars.</font><br /><br />In case you're interested - a particularly fun star to find right about now is R Virginis in the constellation Virgo. If you're able to see HD 81474, I think you should be able to see R Virginis as well (which is about magnitude 7 - so you'll need a field glass or telescope to find it). If you keep an eye on it over a few weeks, and perhaps draw a picture of how it looks compared to the stars around it, I think you'll find it quite interesting. There is a finding chart for this star at: http://www.aavso.org/cgi-bin/shrinkwrap.pl?path=/charts/VIR/R_VIR/RVIR-B.GIF<br />Note that the scale is about 1 degree by 1 degree (which is twice the diameter of the full moon on the sky). <div class="Discussion_UserSignature"> </div>

 

[rhodan]

remcot,<br /><br />I get an error message when I tried to approve your picture. You may want to resize it or save it with a different extension (jpeg for example).

 

[remcot]

Some last questions:<br />1 What kind of experience will it be when i go outside now and i can see stars with a magnitude limit of 8.79? How strange and beautifull will it look then?<br />2 Are there programs on the internet where i can simulate and create a kind of starcharts including constellations where you can set the magnitude limit? Cen somebody help me to answer this questions? Thank you.

 

[doubletruncation]

<font color="yellow">1 What kind of experience will it be when i go outside now and i can see stars with a magnitude limit of 8.79? How strange and beautifull will it look then?</font><br /><br />Sorry remcot, I'm not sure exactly what you mean here. Do you mean if we could see things down to 8.79 with our naked eye, or do you mean if you looked with a telescope at objects that are 8.79 in magnitude? If you could see to 8.79 with your naked eye you would be able to see about 70000 stars in the sky.<br /><br /><font color="yellow">2 Are there programs on the internet where i can simulate and create a kind of starcharts including constellations where you can set the magnitude limit?</font><br /><br />One that seems pretty good is:<br />http://www.fourmilab.ch/yoursky/<br /><br />just set your latitude and longitude and click "Make Sky Map"<br />then under "Display Options" you can change the "show stars brighter than magnitude" value. <div class="Discussion_UserSignature"> </div>

 

[remcot]

Yes i mean how it will be when you (hypothetical) can see the stars with a magnitude limit of 8.79 with the naked eye. I think that will look much more impressive than the limit of magnitude 6 that i can see here in my country when i have (very) clear skies.

 

[remcot]

That is a great site ,and WOW! i have seen Ursa Major with a limit of magnitude 8.79 Beautifull! What a great difference with the limit of magnitude 6. <br />I have 2 questions for you ,to wat kind of magnitude can i set the program? I mean what will be the faintest magnitude i can change this superb program?<br />2 I have also found the fantastic program Celestia ,is it true that you can with Celestia also set a specified magnitude on the part of the sky that is on your screen? remcot

 

[remcot]

Can you answer mij 2 last questions doubletruncation? Great! thank you very much.

 

[doubletruncation]

I don't know, I think you could probably find out by trying different values and seeing at what point the number of stars no longer appears to increase. If it uses the HD catalogue for its stars then it probably goes down to about 13 or 14, probably wouldn't be complete that faint though. I don't use celestia so I can't offer you any help with that. <div class="Discussion_UserSignature"> </div>