Sunday, March 16, 2008

Exoplanet blues

You know, I should be setting up the telescope to view the magnificent Moon riding up there in the sky..... If it wasn't 30 deg C out there and any image would be a wibbly-wobbly mish-mash. And the idea of dripping sweat into my optics isn't so cool either.

So instead I'm trying to see if I can tease exoplanet transits out of the STEREO SECCHI data. It would sure help if I was at all competent at this.

Inspired by an article at the STEREO website on analysing variable stars kindly pointed out to me by Comet Al (and some ImageJ tools he pointed me to), I had another go at HD 2638. This time I used an earlier image set (15-02-08) with less potential interference from CME's (no such luck, the entire star field twinkles regardless of CME's as the stars pass across the CCD surface, there must be a way to normalise this). I also used a broader astrometery field, and also did a background field set on an area devoid of stars to counter for background changes.

The results look a little cleaner, but there is still no obvious transit that can be seen above the noise. To get a feel for this look at the graph above comparing an Algol eclipse with HD2638. I processed the Algol data the same way I did HD2638. The Algol data is much more stable, as were the reference stars, but the Algol eclipse depth is enormous compared to HD2638. Oh, where is HD2638's data? Look closely at the zero line, you will see it almost superimposed.

So yeah, HD2638 is a hard ask. But looking at the STEREO article it still looks possible, so I will just have to bite the bullet and learn how to do astrophotometery analysis properly.


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