(meteorobs) Advice for capturing daytime visual fireballs?

[Jay Salsburg]

In the vernacular of Astronomy, use an artificial Eclipse. Having
refurbished large Telescopes and their Domes, I was interested in observing
Planets in the daytime. I learned to use an artificial Eclipse to assist
viewing the Planets in full sunlight, even Mercury near the sun. When I say
"Artificial Eclipse" I mean a shield to block out the sun. I used a black
tube extension over the Telescope inside the Telescope Dome and a black
umbrella on a Jib, however, this technique would scale well and not yield a
view of the entire Sky minus the Sun for an All-Sky Observatory. One thing
about an eclipse is that it works better when the object blocking the Sun is
far away from the Telescope or Camera. Both Newton and Galileo used towers
and trees to block out the Sun for daytime viewing and block The Moon at
night. Also I am sure the Atmosphere was more transparent then than now. I
can often see Venus and Jupiter at Noon with my unaided eye. On a rare
occasion at Noon, while in the Desert, I could see Venus, Mars, Jupiter, and
the Moon with my unaided eye. It would be quit a trick of modern innovation
to make a Controller/Mechatronic device to hover and orbit near an All-Sky
Observatory which puts a constant shadow on the Dome to block out the
unwanted effects of the Sun together with intelligent adjustment of the
Camera Iris to equalize the Video's dark Curve, but who am I to suggest such
a thing?

Jay Salsburg


-----Original Message-----
From: meteorobs-bounces at meteorobs.org
[mailto:meteorobs-bounces at meteorobs.org] On Behalf Of Chris Peterson
Sent: Wednesday, October 17, 2012 11:10 AM
To: Meteor science and meteor observing
Subject: Re: (meteorobs) Advice for capturing daytime visual fireballs?

In general, detecting daytime fireballs is problematic. Fireballs have a low
IR output, so you definitely don't want an IR filter. Fireballs bright
enough to be seen against the daytime sky are pretty rare (mag -8 or
brighter), of course. I think the only filter that is likely to be helpful
is a polarizer, which will increase contrast against the sky (but only in
certain areas). Overall, however, you're probably better off with no filters
at all. I've observed Iridium flares with my video allsky camera, and they
are most easily seen without any filtering. This also required using a
manual iris and finding a narrow balance between saturation and detection.

Chris

*******************************
Chris L Peterson
Cloudbait Observatory
http://www.cloudbait.com

On 10/17/2012 10:00 AM, Thomas Ashcraft wrote:
> Some years ago I acquired a dark reddish colored plastic dome for my 
> all-sky camera. I am not sure if it had infrared filtering qualities 
> but at least it made more contrast in the sunlit sky.  Using 
> continuous video recording I conducted an all-sky visual search for 
> daylight fireballs in conjunction with my radio array. When there was 
> a large radio meteor reflection on my charts I would go my video 
> recording and check for any sort of meteor flash or streak.  After a 
> few months of daily observing I never detected any visual daytime 
> meteors so I ended that experiment.
>
> I may try again for daytime visual meteors.
>
> Does anyone have any suggestions?
>
> For example:  Is it possible to use something like a HOYA #72 red 
> filter on an all sky lens using a camera such as a Watec 902H2?
>
> Thank you in advance for any replies.
>
> Thomas Ashcraft  -  Heliotown  -  New Mexico

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