Currently I am learning Mishnayot. Bli neder, I hope to finish Seder Moed within the next couple of months. I am currently learning Brachot and I have become quite interested in "time" related halachot, example zman tefilla, international date line, etc. Below are some sources that I have allocated that need to be analysed by anyone interested in the topic:
– My diagrams regarding the Machlokes Gra / Rabbeinu Tam
(http://www.badongo.com/file.php?file=brachot%20notes%20on%20gra%20-%20R%22T__2005-12-22_brachot%20notes.pdf)
– RECITING SHEMA: HOW EARLY? HOW LATE? (http://www.torah.org/advanced/weekly-halacha/5759/vayigash.html)
– On Twilight by Rabbi Gil Student (http://www.aishdas.org/toratemet/en_pamphlet4.html)
– The proper time to Light Chanukah candles by Rabbi Howard Jachter (http://koltorah.org/ravj/channukahlights.htm)
– The International Date Line by Rabbi Howard Jachter (http://koltorah.org/ravj/The%20International%20Date%20Line%20and%20Halacha.htm)
– Twilight, Sunset and Night By Rabbi David Bassous (http://home.earthlink.net/~etzahaim/halakha/twilight.htm)
– When Does One Pray When There Is No Day A Guide to Shabbos Observance and Prayer Times in Alaska and Other Arctic Regions Rabbi Dovid Heber (http://www.star-k.org/kashrus/kk-trav-northpole.htm)
– Gemera Shabbat 34b-35a (http://www.e-daf.com/index.asp?ID=191&size=1)
– Gemera Pesachim 94a (http://www.e-daf.com/index.asp?ID=829&size=1)
Also See Mishna Berura Siman 261 and the Biur Halacha there for great eleboration on the different caclulation for working out the time of day and night
If anyone has some extra notes or anything of interest to add to these sources please leave a comment or email me (If any of the links don’t work please email me as well). Thanks and enjoy.