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Error propagation of distance modulus and parallax https://popastro.com/forum/viewtopic.php?f=5&t=15720 
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Author:  muse19 [ Fri Jun 17, 2011 9:50 pm ] 
Post subject:  Error propagation of distance modulus and parallax 
Hi! Here is my problem: there is a star, for which we know the distance, d=21.2 pc, the measurement error is delta_d=1.8 pc. The question is that how far should we put this star, so that the following equation would be true: d/delta_d = 3? The teacher told me to use two formulas: mM=5+5log(d) and pi=1/d (pi=parallax), and then do some error propagation calculations. Of course, I have already tried it using the equations above, but I did not succeed. Does anybody have any idea? Actually, it would be OK as well, if anybody could do it using any other equations. Thank you, and sorry for my english. Cheers, Joe 
Author:  big_kev [ Sun Jul 03, 2011 3:10 pm ] 
Post subject:  
Is it just me or is something missing from this question. 
Author:  Cliff [ Sun Jul 03, 2011 6:58 pm ] 
Post subject:  
Dear Big_Kev No! I do not think it is necessarily you ? One thing that seems to be a possible problem is that the teacher is incompetent, otherwise I would have suggested asking the teacher for advice. Best wishes from Cliff PS "think" added above 6th July 
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