Asteroid 2012 DA14 (T940 tel. and new spectro.)

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Asteroid 2012 DA14 (T940 tel. and new spectro.)

Postby Christian Buil » Tue Feb 19, 2013 2:20 am

[english]

An observation of 2012 DA14 with Saint-Caprais "geant" telescope (D = 0,94 m)
by Pixel and Cassoulet team (the telescope is located near Toulouse,
south of France, see http://www.astrosurf.com/buil/saintcaprais/first.htm):

Image

The spectrum reveal a nearly grey object for the hour of observation.

I have used a new spectrograph from Shelyak instrument (the very first production
model in the world!). The spectrograph is compact, very easy to use, and efficient.
It is possible to add optionals powerful guiding module and calibration module.
The spectral resolution is near R = 600, little lower than LISA, but higher than
a Star Analyser. The spectrum is very sharp from 370 nm to 800 nm and the instrument
can accept f/5 beam

A must!

-------------------------:

[français]

Une observation de 2012 DA14 avec le télescope "géant" de Saint-Caprais (D = 0,94 m)
par l'équipe Pixel et Cassoulet team (pour plus détails sur le télescope, voir
http://www.astrosurf.com/buil/saintcaprais/first.htm).

Le spectre de réflectance révèle un objet assez gris au moment de l'observation.

J'ai utilisé à cette occasion un nouveau spectrographe qui va
être poposé par Shelyak Instrument dans peu de temps (j'ai la chance de tester le
tout premier exemplaire de série disponible au monde !). Le spectrographe
est compact, très simple a utiliser et efficace. Il est possible d'ajouter en option
un puissant module de guidage ou encore un module d'étalonnage. Le pouvoir de résolution
est voisin de 600, plus faible qu'un LISA, mais plus élévé qu'un Star Analyser. Le spectre est très fin
de 370 nm à 800 nm au moins et l'instrument peut accepter un faisceau à f/5.

Un must !

Christian B
Christian Buil
 
Posts: 920
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Re: Asteroid 2012 DA14 (T940 tel. and new spectro.)

Postby Robin Leadbeater » Tue Feb 19, 2013 11:37 am

Hello Christian,

Interesting. I am still reducing my spectra (I have about 50) but your spectrum slopes the opposite way to mine. (See attached, taken with a Star Analyser and a 0.28mm aperture,divided by G2v star HD107582) My result is consistent with it being a spectral type L asteroid as published.
http://echo.jpl.nasa.gov/asteroids/2012 ... nning.html
Thanks to Paolo for the link

Cheers
Robin
Attachments
2012_da14_all_divg2v.png
2012_da14_all_divg2v.png (13.82 KiB) Viewed 7116 times
LHIRES III #29 ATIK314 ALPY 600/200 ATIK428 Star Analyser 100/200 C11 EQ6
http://www.threehillsobservatory.co.uk
Robin Leadbeater
 
Posts: 802
Joined: Mon Sep 26, 2011 4:41 pm

Re: Asteroid 2012 DA14 (T940 tel. and new spectro.)

Postby Christian Buil » Tue Feb 19, 2013 2:50 pm

Robin,

I have reprocessed the data and I confirm my first conclusion.

Here comparison of ateroid and star HD76151 used for reference:

Image

The acquisition conditions are not ideal (relatively short expsoure time + guiding
problems + faint magnitude for the date), but the data are consistant.

and the recomputed reflectance spectrum (differential atmospheric absorption is taken into account (13 deg. elevation difference)):

Image

Perhaps a reddining by Earth atmopshere in your situation ??
(during my observation the asteroid is far of the Earth).

Christian
Christian Buil
 
Posts: 920
Joined: Mon Sep 26, 2011 6:59 pm

Re: Asteroid 2012 DA14 (T940 tel. and new spectro.)

Postby Robin Leadbeater » Tue Feb 19, 2013 3:37 pm

Hello Christian,

I see the same effect even when the asteroid and reference star are both > 50deg elevation so there should not be a big atmospheric effect. Perhaps our reference stars do not not have exactly the same spectrum. I will complete all my processing and then we can make a full comparison. I also have an A star reference which I used for wavelength calibration so I can measure the instrument response and produce flux calibrated spectra to compare directly with yours.


Cheers
Robin
LHIRES III #29 ATIK314 ALPY 600/200 ATIK428 Star Analyser 100/200 C11 EQ6
http://www.threehillsobservatory.co.uk
Robin Leadbeater
 
Posts: 802
Joined: Mon Sep 26, 2011 4:41 pm

Re: Asteroid 2012 DA14 (T940 tel. and new spectro.)

Postby Christian Buil » Tue Feb 19, 2013 6:21 pm

Hello,

The differential atmospheric transmission is moderate (about 13 deg. difference elevation).
The effect is low, but it is considered (see plot). Of course meterological
evolution can be also a classical problem (30 minutes between asteroid observation and reference
star...). And your spectrum i not so red Robin for a L-type asteroid (to be confirmer)...

Christian B
Christian Buil
 
Posts: 920
Joined: Mon Sep 26, 2011 6:59 pm


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