[Aavso-photometry] Transient nebula in Lyra???

[Robin Leadbeater]

Vello Tabur wrote:
>
> This is often caused by chromatic aberation. Miras radiate most of
> their energy in the IR and become bluer when they brighten, thus reaching
> focus. I noticed this several years ago using a camera lens + CCD. To
> test this, I refocused the lens using the IR mark and found that the
> blurry Miras came into focus while the other field stars became
> defocused.

I agree, it does look like that type of effect but if so, it is interesting 
that this has happened despite the use of an APO and IR block filter 
according to the details on the images. The effectiveness of the IR block 
filter used might be questionable I suppose.

Robin