Archive for November, 2013

Comet ISON survives! (or not…)

Posted November 29, 2013 By grigoris

A great gif image[1] of the passage of comet ISON (C/2012 S1) from the Sun, as observed from the SOHO coronagraph!

As the initial image is rather big to upload here (~19MB), I just took some parts of it only, with the most interesting parts.








A systematic campaign has been launched for this comet [2], as it has been believed to be the comet of the century. Although rather disappointing at the beginning it did revived rather unexpectedly before as it was approaching the Sun. Let’s see now what is left and what we will see in the sky. Will it become a naked eye wonder?

[2] NASA Comet ISON Observing Campaign

UPDATED on 2/Dec/2013:
Although it seemed likely that comet ISON survived its close passage from the Sun, it probable transformed into a small cloud of dust which dissolves fast. After almost 2 days there is almost nothing to see in the images of SOHO.
You can find the updated gif image at



Bash scripting: convert float to integer

Posted November 26, 2013 By grigoris

As bash is not able to handle floats the best way is to convert a float number (which is represented as a string, for example an output with awk) into an integer.

To do this [1,2]:

[1] & Linux

Fast note on Wien’s law

Posted November 24, 2013 By grigoris

Just a quick reminder* !

λmax = 2.89776829 x 106 nm K / T

[*] Wien’s displacement law

LaTeX: wide figure or table in a 2 column document

Posted November 15, 2013 By grigoris

Much simpler than I thought, but still I think it deserves a note in order not to forget it!

Simple add the * when using each element (figure/table)[1].
This will place it as wide as the page, but only at the top of the page.

[1]: LaTeX wiki: Floats, Figures and Captions

Where are the stsdas/synphot template spectra?

Posted November 4, 2013 By grigoris

After having looked and searched into the whole IRAF/PyRAF directory to point out the directory that contains the template spectra for the stsdas/synphot package it was just a matter of a quick look at the front page of the package to resolve the issue!

As it is said: “Since the data files used by synphot in its calculations are rather large, they are distributed separately”
and they provide the links to the compressed files containing all the template data.

At the beginning we started looking into which path these files are stored since you can call each template by using the environmental variable crcalspec$template_spectrum. But this variable looks at the path where these templates are stored (outside IRAF), as it is defined (when installed) though the crref variable.