Guest zidder Posted January 28, 2015 Share Posted January 28, 2015 In Stellarium It gives Magnitude Absolute Magnitude Surface Brightness Which of these is relevant to the viewing capabilities of a scope ? And how do you know the mag. limit of a scope ? Link to comment Share on other sites More sharing options...
Tweedledee Posted January 28, 2015 Share Posted January 28, 2015 Absolute magnitude is the brightness an object would appear hypothetically if positioned at 10 parsecs = about 33 light years. This allows you to compare the actual brightness of an object relative to another object by theoretically setting them all at the same distance, but this has no relevance to what you see in the scope.Magnitude and surface brightness are relevant to what you see in the scope.All stars are point sources and only have magnitude to express their brightness. Extended objects such as nebulae and galaxies are light sources that are spread out over a wider area so they can be described as having both magnitude and surface brightness. The magnitude can be imagined as though all the light was coming from a point source, the surface brightness is the brightness of a tiny part of that same light which is spread out over the area of the object. Surface brightness is therefore fainter than the magnitude of the object. You will often find a galaxy with a magnitude of 8 but a surface brighness of say 10. If another 8th magnitude galaxy is larger in apparent size, its surface brightness may be something like 13, because the same light is spread over a larger area. So extended objects are usually more difficult to see.There are lots of factors that will limit the faintest magnitude that can be seen in the telescope. Sky quality, light pollution, and your eyes dark adaptation among other things will affect the limiting magnitude that you can see in the scope. In different conditons this limit may vary by 3 or more magnitudes. Here is an online calculator that you can change various parameters in to find the limiting magnitude of your scope...http://www.cruxis.com/scope/limitingmagnitude.htm Perkil8r 1 Link to comment Share on other sites More sharing options...
Perkil8r Posted January 28, 2015 Share Posted January 28, 2015 ^^^ What he said. Link to comment Share on other sites More sharing options...
Tweedledee Posted January 28, 2015 Share Posted January 28, 2015 ^^^ What he said. Well someone had to have a go Preferably leaving out the logarithmic formula and the fifth root of one hundred Link to comment Share on other sites More sharing options...
Perkil8r Posted January 29, 2015 Share Posted January 29, 2015 Well someone had to have a go Preferably leaving out the logarithmic formula and the fifth root of one hundred You beat me to it, and put it rather better too if I'm honest. Link to comment Share on other sites More sharing options...
Guest zidder Posted January 29, 2015 Share Posted January 29, 2015 (edited) Thanks Pete P.S. 14.1 Edited January 29, 2015 by zidder Link to comment Share on other sites More sharing options...
Tweedledee Posted January 29, 2015 Share Posted January 29, 2015 You're welcome. Don't expect 14.1 from anywhere within 50 miles of Nottinghams light pollution Link to comment Share on other sites More sharing options...
Guest zidder Posted January 29, 2015 Share Posted January 29, 2015 You're welcome. Don't expect 14.1 from anywhere within 50 miles of Nottinghams light pollution Therein lies the problem, as a newcomer with a dirty great beast ? and trying to learn your way around not knowing the capabilities of said beast, you could spend ages looking for something that you are never going to see. Is there a recommended viewing list anywhere ? or do you just start with the brightest and work your way down ? what would you say is a realistic dullest ( or whatever the terminology is ) object to try for ? as I am currently mainly stuck in my back yard ( Baz's area) I have found web site listing "M" objects Sorry to be a numpty Link to comment Share on other sites More sharing options...
Tweedledee Posted January 29, 2015 Share Posted January 29, 2015 You might get a really superb night when you can see something of 14th magnitude, but it won't look very spectacular. Start off searching out the brighter, easier stuff first. Messier objects are a great place to start, along with planets and double stars. There are many thousands of interesting things to find before you start looking for 14th magnitude stuff! Link to comment Share on other sites More sharing options...
Tweedledee Posted January 29, 2015 Share Posted January 29, 2015 (edited) Try this observing list generator, it is really good and you can set filters for types of object and faintest magnitude etc. Set your latitude and longitude first and it will only show what is actually above your horizon... http://dso-browser.com/ If you are out tonight or over the next few nights, your must see's are as follows, Messiers 35, 36, 37, 38, 42, 44, 45 and the Double Cluster, Jupiter and the moon. I'm sure others will suggest some more. The moon will make DSO's a little less visible though. Edited January 29, 2015 by Tweedledee Link to comment Share on other sites More sharing options...
Tweedledee Posted January 29, 2015 Share Posted January 29, 2015 Another thing, don't be too disappointed if even the bright DSO's are rather uninspiring at the moment. The moon will wash them out a lot. When the moon is below the horizon and you get a really clear night, you will see some spectacular DSO's with that 10" and if you get it to a dark site even better. Brighter doubles and the planets will still look pretty good despite the moon. Link to comment Share on other sites More sharing options...
Guest zidder Posted January 29, 2015 Share Posted January 29, 2015 Try this observing list generator, it is really good and you can set filters for types of object and faintest magnitude etc. Set your latitude and longitude first and it will only show what is actually above your horizon... http://dso-browser.com/ If you are out tonight or over the next few nights, your must see's are as follows, Messiers 35, 36, 37, 38, 42, 44, 45 and the Double Cluster, Jupiter and the moon. I'm sure others will suggest some more. The moon will make DSO's a little less visible though. Thanks Pete. Appreciate you taking the time. Used the generator threw up 8,000 object, blinking Nora I will be here till I'm 90 Link to comment Share on other sites More sharing options...
Tweedledee Posted January 29, 2015 Share Posted January 29, 2015 Great Told you, there are thousands of objects you will be able to see with your scope. Play around with the filters and fine tune it to show just a few brighter DSO's. Or you might find it simpler initially to have a go at working through the Messiers. You will find a few very difficult Messiers in the list, but you will learn a lot about finding stuff and using your scope. Link to comment Share on other sites More sharing options...
Guest zidder Posted January 29, 2015 Share Posted January 29, 2015 Great Told you, there are thousands of objects you will be able to see with your scope. Play around with the filters and fine tune it to show just a few brighter DSO's. Or you might find it simpler initially to have a go at working through the Messiers. You will find a few very difficult Messiers in the list, but you will learn a lot about finding stuff and using your scope. I set the filter to show up to Mag 6, still 1200 to see Link to comment Share on other sites More sharing options...
tuckstar Posted January 30, 2015 Share Posted January 30, 2015 When I'm in my garden I tend to go for bright objects like clusters as these tend to show through light pollution and you don't get dissapointed wasting lots of time trying to find something that you'll never see from your garden. Double stars are always good for bad conditions as well. Then go for the faint fussies at a darksite. That being said I did find The Crab nebula from my garden one night when the conditions were good just before Xmas. That surprised me from Ilkeston. Link to comment Share on other sites More sharing options...
Tweedledee Posted January 30, 2015 Share Posted January 30, 2015 The Crab Nebula can be very elusive at times. It is only magnitude 8.4 but has a surface brightness of 11, so it is very easily washed out by LP. Tonight the moon will get to about 4 degrees from it, so there is no chance of seeing it for several days. Link to comment Share on other sites More sharing options...
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