May 22, 2015

La Luna by Bert Jansch

One of my mostly fond interests is undoubtly music and yes I'm a selfmade guitar player, one of many in my kind. One of my preferred acoustic guitar players is Bert Jansch.

He wrote a lot of songs and been one of the true fathers of the folk/acoustic scene of the 1960s in UK, had a lot of artists collaborations during his vast career indicating his very welcoming nature of a quite, gentle scotsman. He played the acoustic guitar in a extensive and personal way keeping modest and humble. His modesty was only paired by his exceptional musical expression and kindness.

One of his later songs 'La Luna' appeared on his album Edge of a Dream(2002), to me it depicts and shapes with guitar and words a place we can find inside ourselves sometimes and almost surely in the northern shores of Scotland, on this wonderful small delicate planet. Though I never been in scotland before.

I thought it could be appropriate in a moonwatcher's blog ;-)

La Luna by Bert Jansch

Dirty blood, dripping from a black sky
Onto a barren land
And everywhere there's sorrow, despair and desolation
There is no air nowhere
Dogs bark and it's dark and scary
From the towers to the ocean
Under a Hecatean moon
La Luna

Sister sister Luna, you know who I am, like a star
That flashes and glitters in your eyes in the moonlight
Or the fire on a mountain
Or the light in the heart of a man and the sun that shines
With a glimpse of the light divine
Behind the veil of a rainbow
Just like Perdurabo said
It's gonna be alright
Oooh La Luna, oh she did me good
With a love that loves to love
That loves to love the love that loves to love
Oooh La Luna
And I love to listen to you Lu, and I admire you
For your survival
Sweet poetry and tragedy and comedy and rock'n'roll
Keeping it all in motion
Under a Hecatean moon
La Luna

Oct 31, 2013

Have fun tracking Comet ISON with PyEphem

I'm not an astronomer, but since I was 10 I've had enough curiosity to let me look at night skies and practice the base notions of amateur astronomy. 2013 is a lucky year for comet observations, C/2011 L4 (PANSTARRS), C/2012 F6 (Lemmon) for example and currently transiting C/2012 S1 (ISON).

PyEphem "provides scientific-grade astronomical computations for the Python programming language" and it uses Xephem routines.

Not all sky bodies can be natively computed by PyEphem. A comet must be loaded from external catalog definitions of orbital parameters. PyEphem documentation provides links to various catalogs.

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gianluca:~$ mkvirtualenv astropy --no-site-packages
New python executable in astropy/bin/python
Installing setuptools............done.
Installing pip...............done.
gianluca:~$ workon astropy
(astropy)gianluca:~$ pip install ephem
Downloading/unpacking pyephem
  Downloading pyephem-3.7.5.1.tar.gz (703kB): 703kB downloaded
  Running setup.py egg_info for package pyephem

Installing collected packages: pyephem
  Running setup.py install for pyephem
    building 'ephem._libastro' extension
    gcc -pthread -fno-strict-aliasing -DNDEBUG -g -fwrapv -O2 -Wall -Wstrict-prototypes -fPIC -Ilibastro-3.7.5 -I/usr/include/python2.7 -c extensions/_libastro.c -o build/temp.linux-x86_64-2.7/extensions/_libastro.o
...
...
...
Successfully installed pyephem
Cleaning up...
(astropy)gianluca:~$

After installing virtualenv and virtualenvwrapper I created a virtualenv called astropy and installed PyEphem therein, a simple script shows how fun(and powerful) is to use the PyEphem library.

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import ephem

# load Comet ISON object from catalog http://www.minorplanetcenter.net/iau/Ephemerides/Comets/Soft03Cmt.txt
ison = ephem.readdb("C/2012 S1 (ISON),h,11/28.7747/2013,62.3990,295.6529,345.5644,1.000002,0.012444,2000,7.5,3.2")
date = '2013/10/31'

# compute on date
ison.compute(date)

# define an observer
Rome = ephem.city('Rome')
rome_watcher = ephem.Observer()
rome_watcher.lat = Rome.lat
rome_watcher.lon = Rome.lon
rome_watcher.date = date

# print some useful data computed on the loaded body
print("Tracking object: %s on date: %s from: %s" % (ison.name, date, Rome.name))
print "%s is in constellation: %s with magnitude %s" % (ison.name, ephem.constellation(ison)[1], ison.mag)
print("Rome next rising: %s" % rome_watcher.next_rising(ison))
print("Rome next setting: %s" % rome_watcher.next_setting(ison))
print("Earth distance: %s AUs" % ison.earth_distance)
print("Sun distance: %s AUs" % ison.sun_distance)

Output:

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(astropy)gianluca:~$ python tracking_comet_ison.py 
Tracking object: C/2012 S1 (ISON) on date: 2013/10/31 from: Rome
C/2012 S1 (ISON) is in constellation: Leo with magnitude 8.07
Rome next rising: 2013/10/31 01:12:31
Rome next setting: 2013/10/31 14:07:39
Earth distance: 1.24149298668 AUs
Sun distance: 1.00681865215 AUs

Clear skies to all :) and have fun!

Jan 30, 2013

APOD Full Moon Silhouettes

Couldn't miss this, which I think is quite appropriate here ;) Enjoy this short Video published in today's APOD