brief (or not so) intro and some prelim results from SMEI instrument

John,Thanks very much for the very interesting light curve which seems to be, overall, consistent with our earth bound observations. However, the curve seems to be systematically lower than our V observations. Can you comment on the relationship between your estimates and V estimates?Des Loughney

Hello Dr Clover! Few month ago we discussed SMEI at AAVSO chat room. It would be wonderful to get also other variable stars data. For me are most interesting extrasolar planets transits and bright GML on 2006 October 31st (see http://arxiv.org/abs/0708.1066v3). I tried to make estimates of some variable stars from SMEI jpegs from http://smei.nso.edu/ . Here is lightcurve of Zeta Gem, well known cepheid. Note that I took only few all sky frames and I clicked stars by hand! CS Nikolaj

Hi again,I'm just John, not Dr :) I started working for the SMEI group at UC San Diego as an undergrad and since graduating I have been part of the full time staff while I mull my graduate school options.As far as the magnitudes go, this is an ongoing work with the SMEI instrument. We have compared the SMEI brightness of 17 bright stars to those from LASCO C3 to determine a conversion of SMEI ADUs to surface brightness in S10 units. Unfortunately, I cannot totally vouch for the further conversion to the apparent magnitude in the plot, as it likely still needs work, and I plan to look at the other stars in the citizen sky list to have something more to compare against.We have been dealing with the degradation of the cameras since they have been in orbit for over 6 years (3 years past the expected mission duration) as well as contamination from stray light, bright planets, the moon, high energy particle hits and the south atlantic anomaly and high altitude aurora, the list goes on.Luckily we have plenty of data to work with so despite the noise, the confidence in the measurements is pretty high (once a good calibration can be decided on)I am in the process of moving a new data storage/processing server into place, so work on these stars is paused for a few days as I get the new system up and running, but I'll let you know when I have more results and look forward to any input that will help tune the SMEI calibrations :)As far as the lensing event goes, since the star you are referring to is below 6th magnitude, the SMEI results are probably very unreliable and subject to quite a bit of noise, for reasons stated above as well as many others, but I will have a look. The mirrors in the SMEI imagers are curved and this causes the point spread function for compact sources to be a very asymmetric 'fish' shape which varies with the position in the sky as well as the SMEI orbit and time of year, this as well as 'star crowding' causes a lot of problems for less bright stars when it comes to SMEI light curves.Cheers,John Clover

HiJohn,Thank you for sharing this info - this is a very fine looking light curve and I hope you can continue to accumulate new points as the eclipse progresses.

Hi John!Sorry to address you wrong. But I have some experiences with higher beings ... ;) . Your LC of Eps Aur is in V magnitude, but in Buffington et al. 2005, http://arxiv.org/ftp/astro-ph/papers/0510/0510159.pdf stays: "The aperture area is 1.76 cm2 and the bandpass that of a wide-open CCD detector, thus corresponding roughly to the “R” photometric band, but having a twice wider bandwidth.". So it would be better to calibrate SMEI to R or perhaps R+I or even V+R+I, quite nonstandard.The limiting magnitude for SMEI is R= 10 at 3 sigma, again from Buffington et al. 2005.There are about 70 stars brighter than V= 6 and about 110 brither than V= 7 with planets. Note that probability for planetary transit at 1 AU is around 1%.Clear SkyNikki

Hi Nikki,Yep, the SMEI CCDs are most sensitive to R, but it is not the only contribution which makes comparisons a bit trying, but we are working on it. Cheers,John