Exoplanets with VaST

[azim7091]

Hi,

I am wondering if any one can help me. Is it possible to use VaST to find exoplanets? I have used VaST to find the light curve of an exoplanet, and I found that the results are good in comparison to AstroImageJ results. But I could not find any thing about the exoplanet with VaST in the VaST paper (and its website). Is there anything which can prevent us from using VaST for exopanet lightcurves generally? If there is, what is/are that/those thing/s? And, can we improve it?

Best Regards Azim

[kirxkirx]

Dear Azim,

I'm sorry for the late reply. In practice, no exoplanet could be found with VaST yet. In principle, there is no reason why VaST could not be used to find exoplanets.

Things to consider:

• An appropriate dataset. As far as I understand, one need a set of many thousand images with tens of thousands of stars on them to have a chance of finding an exoplanet transit candidate.
• Magnitude calibration strategy. By default, VaST uses all stars matched between the reference and the current frame to establish the relation between the instrumental magnitudes measured by Source Extractor at the two frames and approximate this relation with a parabola. This works well for most stars in most cases, but might not be the best choice for the brightest stars in the field (but this is more of a concern for targeted exoplanet transit observations). You may need to experiment with linear magnitude calibration activated by the command line options --type 0 or --type 2.
• One will need to remove residual photometric systematics using SysRem (implemented in VaST as util/sysrem2) or other algorithm.
• The variability search technique based on "variability indexes" that is built in VaST will not be able to identify a transiting exoplanet. Instead, one should rely on periodic eclipse search technique such as the BLS. This and other useful algorithms are implemented in VARTOOLS A set of VaST lightcurves may be processed with VARTOOLS.

I would be very interested to learn if you have any progress/face any issues applying VaST to transiting exoplanet search.

Best wishes, Kirill