Useful astronomical numbers
Just some useful numbers and units to remember and to have an easy access to! [last updated: 29 Dec 2011] >> Distance 1 AU = 150 x 106 km 1 pc = 3.09 × 1013 km = 206260 AU = 3.26 ly 1 ly = 9.4 x 1012 km = …
About full Moon and Moon illusion
The size of a Full Moon depends on the position of the Moon in its orbit (~ 0.5 degrees). Thus the biggest Full Moon is when the Moon is closest to Earth (i.e. at perigee). from spaceweather.com (28 Jan 2010) “… a “perigee Moon” some 14% wider and 30% brighter …
A great image of star sizes
A magnificent picture comparing star sizes !!! (from Wikipedia / Star – Diameter)
Moon (Lunar) phases
Just a quick note for moon (or lunar) phases. From Wikipedia / Lunar Phases (moon phases). Phase Northern Hemisphere Southern Hemisphere Visibility New moon Not visible, traditionally Moon’s first visible crescent after sunset Waxing crescent moon . Right 1-49% visible Left 1-49% visible afternoon and post-dusk First quarter moon Right …
40 characters limit in Starlink
When you install Starlink you have to determine the directory of the program (set env starlink_dir /path/to/software/star, in the ~/.tcshrc file). Then, any application runs under this directory. But, there is a limit in the number of characters used (only 40). This can cause some programs not to run at …
While loop in C-shell scripts
When using the while loop in C-shell scripting the usual stucture is: while (expression)commands…end BUT, you need to add an empty line or a comment after end in order for the loop to work!
Period04 and .sh files
If you have any difficulty to find it just go here: Period04 “Period04 is a computer program especially dedicated to the statistical analysis of large astronomical time series containing gaps. The program offers tools to extract the individual frequencies from the multiperiodic content of time series and provides a flexible …
Lost sticky notes in Ubuntu!
Just happened on Ubuntu 8.10 (intrepid ibex)… 🙁 “If disk usage reaches 100%, when you exit your gnome session, all your sticky notes will be erased. Next time you log in, they’re all gone.” link source
Welcome…
… to an online notebook about anything related to Astronomy through my experience (from theory to computers, from hints to tutorials, from etc to etc!). Enjoy!