Light Curve Analysis
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Tue 23-Mar-10 2:06 AM
Dear all,
in the last weeks I was pretty much engaged in the Pluto campaign here in Europe, afterwards I was for a week skiing in the alps and now I am back and working again on the analysis of our Jupiter occultation. Because I did not want to spent too much time on the pure extraction of the LCs, I started with the data analysis deriving a profile ob the atmosphere. You may understand this, because getting into the physics is more interesting than working on the lightcurves, but this has to be done also in the near future. I am using for the moment the LCs of Karl-Ludwig and Peter from Namibia, the ones of Tsamis from Greece and the reappearance from Marcelo from the 1.6m in Brazil. I did a pure Baum-Code fit to derive some astrometric parameters and went on to create refractivity profiles from the LCs by the inversion technique. I developed a Fortran program for the inversion technique and at the moment I am playing around with the integration constants for the profiles. Work goes reasonable well, and I hope to present you some ideas about the refractivity profiles in the atmospheres in a few days (hopefully not weeks!). For the beginning I did not include some horizontal refractivity changes in the atmosphere. So, the work has not been forgotten, and I let you know, as soon as more results are available.
With best regards to all from Munich,
Wolfgang Beisker
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Wed 30-Dec-09 12:03 PM
Dear colleagues,
from Munich a happy New Year! I have been on a longer vacation, but I am back and working again on the lightcurves of our important 45 CAP event.
Attached I send you the 2 final lightcurves from Ellinogermaniki Agogi Observatory. the data is the best I can get for the moment....
So, I will send you more lightcurves soon...
Keep also in mind, the 14th of February occultation by Pluto, you can find infos on our homepage http://www.iota-es.de
With best regards from Munich
Wolfgang Beisker
PS: elldis... is the disappearance, ellre... is the reappearance LC
Fri 08-Jan-10 7:24 PM
Dear all,
I send you the final version of the reappearance LC from the 160cm telescopa at Pico dos Dias, Brazil, observed by Marcelo Assafin and Felipe Braga Ribas with a 890nm Methane band filter. Final version (as I always said now) means, that this is a final version before doing some kind of atmospheric calculations. There has been no time correction applied, the x-axis is the time coming from the images recorded (The key-word DATE or DATA-OBS or UT or whatever seems to be in the FITS file. Some correction may be necessary in a final round, when we have first data from a combined analysis of all LCs. Very soon I will start to do a Baum-Code fit, to see, what the approximate situation is, giving some idea of a half light point, which can be used for a first astrometric estimation using WINOCCULT. But before, I have to calculate the LCs for Tenerife and Calar Alto, the last is the most detailed one, but also the most difficult to analyze, because some stellar images are overexposed in some pixels. This has to be corrected, what is not a simple task.
Regards, Wolfgang
Tue 06-Oct-09 6:55 PM
Dear all,
from the recording of Karl Ludwig in Namibia a more or less final lightcurve has been extracted. Comparing to the lightcurve sent before, this one has the following improvements: 1) The x-Axis is now according to the UTC seconds on 3rd of August (this was a big problem, because of some problems in MIDAS system) 2) Using the Horizons ephemeris of Jupiter and Europa, the distance of the Jupiter center and Europa has been used to correct for the movement of Jupiter with respect to Europa. The reduction process has been done as follows: For the images, where 45CAP is without any occultation, Gaussian fits around Europa and the star has been used to determine the positions of the centers of europa and 45 CAP for intensity measurements. From the time of the beginning of the occultation, the aperture has been set onto the Jovian limb at the position, where the star is. The further change in position relative to Europa has been taken from HORIZON ephemeris. 3) Background determination for 45 CAP has been done by two circular apertures on both sides of the true measuring aperture, also fixed onto the Jovian limb. The mean of the two background apertures has been used to calculate the background of the measuring aperture itself. 4) The final result has been divided by the total intensity of EUROPA, in order to compensate for transparancy changes in the Earth atmosphere and has been normalized to 1 fro nonocculted star intensity. 5) No smoothing and nonlinear operations whatsoever have been done. With best regards from Munich, Wolfgang
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