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LS And at minimum


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About this observation
Paul Leyland
Time of observation
28/12/2019 - 22:00
LS And
Observing location
Tacande Observatory, MPC J22
0.4m Dilworth-Relay
SX Trius Pro 814
Johnson-V filter
4860s in 30s subs
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Jeremy Shears and I have recently had an email discussion concerning the ability of amateurs to perform precision photometry of faint objects. Purely for the fun of it, I took 80 minutes worth data on LS And through a Johnson V filter. I'd not usually spend that much time for anything but astrometry and then it would be unfiltered for maximum sensitivity.

LS And is a UGWZ eruptive which spends most of its time at minimum, that is with a B-magnitude around 20.2 according to the AAVSO.  Jeremy mentioned that he had never managed to image it.

The image above shows LS And and the AAVSO sequence stars labelled.  The variable is clearly visible in the image above but, alas, the SNR is such that it can not be measured to the precision (0.15 magnitude) where I would submit it to the VSS database.  Three hours of data through a V filter, or 90 minutes unfiltered, would likely have been sufficient.


Xilman's picture

A more careful selection of the aperture diameters in APT has given a measurement of v=19.068 ±  0.149 so it just squeaks through.

The take-home message is that amateurs can now perform precision photometry down to twentieth magnitude as long as the target is thought worthy of an observation which is several hours long.

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