Archive for July, 2010

The 4th Panhellenic Meeting of Amateur Astronomers took place in a magnificent area, at the mountain refugee of the Mountaineering Club of Sparta at Mt. Parnonas. The place is located at ~1400m with a huge field working as the best place to park cars and set up all the necessary equipment. Moreover, the area around is full of trees and a fantastic place for camping. More or less 415 people gathered, more than 100 telescopes, 3 nigths of clear unobstructed dark skies, 6 observational workshops (participating in 2 of them: variable star observations and optical observation methodology of meteors) and some talks, and other activities (great for MTB!!) were enough to satisfy even the most demanding person. The organizing commitee did a great jod and managed to fulfill all the needs (both astrononomical and personal).

More available only in greek but no need of language to see photos.

First observations from Skinakas

Posted July 26, 2010 By grigoris

From 30/6 up to 5/7 I found myself observing from Skinakas Observatory for the first time (doing photometry tests on a number of exoplanet candidates) ! That was really a great experience and I enjoyed much both the procedure of observations and the stay there at the mountaintop. Only the weather could have been a little better the last nights as the humidity was getting very high, halting the observations. Anyway, we cannot predict yet the weather that good!

skinakas2010aSkinakas‘ dome on the left and Capella‘s dome on the right, during the sunset.

skinakas2010bSharing the mountaintop.

Adding scripts in GIMP

Posted July 23, 2010 By grigoris

GIMP is a very powerful image processing program, equivalent to Adobe’s Photoshop, but with the biggest advantage that is totally free (and open source).

Apart from its own capabilities someone can add more scripts (.scm files) in the folder:
local use: ~/.gimp-2.x/scripts
global use: /usr/share/gimp/2.x/scripts

[or for Win
local use: C:\Documents and settings\username\.gimp-2.x\scripts
global use: C:\Program Files\GIMP-2.0\share\gimp\2.x\scripts ]

and then you go to : Filter > Script-Fu > Refresh scripts
to update the script list. The scripts will be obvious at the Script-fu tab.

A good example of how covenient some scripts can be is the following Fake HDR range effect.

How big a star can be?

Posted July 22, 2010 By grigoris

It seems that this question has no final answer yet. Although the recent models were claiming that no star bigger than 100-150 solar masses can exist, there is evidence that a star close to 300 solar masses exists in the Large Magellanic Cloud. One star, R136a1 (from the young cluster RMC 136a or R136), is considered to have a mass ~265 solar masses (with a birthweight close to 320 solar masses).

More on ESO’s announcement (eso1030) & the paper (2010arXiv1007.3284C / Crowther P.A. et al, The R136 star cluster hosts several stars whose individual masses greatly exceed the accepted 150Msolar stellar mass limit, MNRAS, 408, p 731, 2010)

Floating point numbers in bash or csh

Posted July 15, 2010 By grigoris

They just don’t pass through!!

Bash or csh are unable to use floating numbers, as they understand numbers containing decimal point as strings. So, only actions with full numbers can be performed in these shells.

Failing to mount correctly NTFS drive

Posted July 5, 2010 By grigoris

I have seen some times my external drives to fail to mount correctly on Ubuntu giving the message:

“$LogFile indicates unclean shutdown (0, 0)
Failed to mount ‘/dev/disk/by-uuid/FE5C75355C74E9B3’: Operation not supported
Mount is denied because NTFS is marked to be in use … ”

This is frustrating and scary at first. But finally it seems to be a common problem when somebody does not “remove safely” the drive, so the NTFS log of the drive thinks it is still on.

Fortunatelly there is a very easy to use tool:

$sudo ntfsfix /dev/drive_name

where /dev/drive_name can be found by the command: (sudo) fdisk -i.

Many many thanks to this post!