re spikey things

[jg <jg@jgws.freeisp.co.uk>]

aah@nofs.navy.mil wrote:

>   Along those lines, has anyone looked at the really bright
> stars in the field to see how well blooming is being handled?
> Often starfinders will have several 'hits' down the spike,
> and there is a chance that both V&I will be matched and you
> will have false stars.
> Arne

A quick look at the fields around Bellatrix and Procyon _suggests_ that
the converse is more likely to be the case.

That is, there may be a dearth of fainter stars detected at these
locations, as also often happens, for instance, with catalogues based on
survey plates due to the overexposure of these bright objects.

Procyon is at the edge of a field though, so that could be a reason for
fewer stars, and I don't know if Bellatrix's reflection nebulosity would
cause any bother re faint stars.  Their could just be fewer stars here
anyway.

Then again, it depends what you mean by bright, seeing TASS CD 23 has an
upper cut off about V = 8.  Gomeisa (beta CMi) looks okay, neither
obvious spikes nor dearth, but there isn't a great density of TASS
objects (maybe even stars in general) around it from which to say for
sure.

nu Virginis looks okay spikes-wise, but too few field stars to say
anything else.

[All from cursory visual inspection of plotted TASS objects and GSC
objects each examined at various field depths to full GSC mag limit].

Over all, though, I reckon Tom couldn't've picked a much better
declination strip in the winter to spring night sky for avoiding bright
stars, except possibly +85 ;)

Cheers

John G.