Black-drop - is it real?

Interesting reports on the black-drop from yesterday's transit. Some
saw it while other's didn't. So is it real?

Well, nothing happens to create this effect (the atmosphere of Venus
doesn't know when it's in line with the edge of the Sun and doesn't
have a requirement to suddenly jump out!) but there could be something
that happens when the thin layer of atmosphere surrounding our sister
planet gets very close to the Sun's limb. Or so I was hoping.

I deliberately kept my exposures dark at 2nd and 3rd contact and I did
not, categorically, see the black drop visually or photographically.

Now I could just be a bad photographer but to me if it wasn't visible
in a clear image then it was not occuring outside of the Earth's
atmosphere. If the effect is there, it's being caused somewhere
between the top of our atmosphere and our eyes/cameras.

While processing my dark images and increasing the brightness a tad,
it was clear that the 2nd contact images could be coaxed into a black
drop by boosting the contrast of the image.

http://www.pbl33.fast24.co.uk/black-drop.jpg

So what are the factors that cause it? Do you have an
observation/image that shows it? If so - let me have the
observation/equipment details and I'll try and collate them into some
sort of analysis of the effect.

I believe that the effect was quite well seen by solar projectionists
so these observations would be of interest too.

If you're interested in taking part, drop me an email letting me know
whether you saw it at 2nd or 3rd contacts, your observing method and
whether there is any physical record (image, drawing) of it. For
photos, exposure times and ISO settings will be required. Don't send
any images unless I ask for them yet. I'll put up a website for this
shortly.

Send your details to pete dot lawrence at pbl33 dot co dot uk and put
"black-drop" in the message subject.


--
Pete Lawrence
http://www.pbl33.co.uk
Most recent images http://www.pbl33.fast24.co.uk/recent_images.html

Pete Lawrence wrote:

Interesting reports on the black-drop from yesterday's transit. Some
saw it while other's didn't. So is it real?

Well, nothing happens to create this effect (the atmosphere of Venus
doesn't know when it's in line with the edge of the Sun and doesn't
have a requirement to suddenly jump out!) but there could be something
that happens when the thin layer of atmosphere surrounding our sister
planet gets very close to the Sun's limb. Or so I was hoping.

I deliberately kept my exposures dark at 2nd and 3rd contact and I did
not, categorically, see the black drop visually or photographically.

Now I could just be a bad photographer but to me if it wasn't visible
in a clear image then it was not occuring outside of the Earth's
atmosphere. If the effect is there, it's being caused somewhere
between the top of our atmosphere and our eyes/cameras.

While processing my dark images and increasing the brightness a tad,
it was clear that the 2nd contact images could be coaxed into a black
drop by boosting the contrast of the image.

http://www.pbl33.fast24.co.uk/black-drop.jpg

So what are the factors that cause it? Do you have an
observation/image that shows it? If so - let me have the
observation/equipment details and I'll try and collate them into some
sort of analysis of the effect.

I believe that the effect was quite well seen by solar projectionists
so these observations would be of interest too.

If you're interested in taking part, drop me an email letting me know
whether you saw it at 2nd or 3rd contacts, your observing method and
whether there is any physical record (image, drawing) of it. For
photos, exposure times and ISO settings will be required. Don't send
any images unless I ask for them yet. I'll put up a website for this
shortly.

Send your details to pete dot lawrence at pbl33 dot co dot uk and put
"black-drop" in the message subject.

--
Pete Lawrence
http://www.pbl33.co.uk
Most recent images http://www.pbl33.fast24.co.uk/recent_images.html

I didn't see a hint of it in the first hour of the transit--looking via
web cams and nasa tv. Got clouded out for the direct observation. :-(

On Wed, 09 Jun 2004 14:35:13 GMT, Sam Wormley
wrote:

I didn't see a hint of it in the first hour of the transit--looking via
web cams and nasa tv. Got clouded out for the direct observation. :-(

Bad news Sam - I'm sorry you missed it

A lot of solar projection observations mention the black-drop effect.
Was there anyone out there that saw the transit with a projection
arrangement but didn't see the black-drop?

--
Pete Lawrence
http://www.pbl33.co.uk
Most recent images http://www.pbl33.fast24.co.uk/recent_images.html

On Wed, 09 Jun 2004 15:54:05 +0100, Pete Lawrence wrote:

On Wed, 09 Jun 2004 14:35:13 GMT, Sam Wormley
wrote:

I didn't see a hint of it in the first hour of the transit--looking via
web cams and nasa tv. Got clouded out for the direct observation. :-(

Bad news Sam - I'm sorry you missed it

A lot of solar projection observations mention the black-drop effect.
Was there anyone out there that saw the transit with a projection
arrangement but didn't see the black-drop?


I saw a photo of it yesterday somewhere on the web. I'll wager it's an
atmosphere effect of seeing conditions and what the seeing is like over an
observer's area will determine if they'll see the drop effect.

Tom

I saw a photo of it yesterday somewhere on the web. I'll wager it's an
atmosphere effect of seeing conditions and what the seeing is like over an
observer's area will determine if they'll see the drop effect.

Tom


I think that this may be the cause. However,

Tom Randy wrote:

I saw a photo of it yesterday somewhere on the web. I'll wager it's an
atmosphere effect of seeing conditions and what the seeing is like over an
observer's area will determine if they'll see the drop effect.

Tom

That's what I'm beginning to think too. It may be a very localized
event.


-----= Posted via Newsfeeds.Com, Uncensored Usenet News =-----
http://www.newsfeeds.com - The #1 Newsgroup Service in the World!
-----== Over 100,000 Newsgroups - 19 Different Servers! =-----

"Pete Lawrence" wrote in message
...
On Wed, 09 Jun 2004 14:35:13 GMT, Sam Wormley
wrote:

I didn't see a hint of it in the first hour of the transit--looking via
web cams and nasa tv. Got clouded out for the direct observation. :-(

Bad news Sam - I'm sorry you missed it

A lot of solar projection observations mention the black-drop effect.
Was there anyone out there that saw the transit with a projection
arrangement but didn't see the black-drop?

I used an 8'' Newt projected on to a piece of paper. I am a newbie so my
quality is not great. In this pic,
http://www.darofamily.com/jeff/files...s/p1010065.jpg, I believe
there is some black drop.

BV.

On Thu, 10 Jun 2004 13:03:34 -0400, "Benign Vanilla"
wrote:


"Pete Lawrence" wrote in message
.. .
On Wed, 09 Jun 2004 14:35:13 GMT, Sam Wormley
wrote:

I didn't see a hint of it in the first hour of the transit--looking via
web cams and nasa tv. Got clouded out for the direct observation. :-(

Bad news Sam - I'm sorry you missed it

A lot of solar projection observations mention the black-drop effect.
Was there anyone out there that saw the transit with a projection
arrangement but didn't see the black-drop?

I used an 8'' Newt projected on to a piece of paper. I am a newbie so my
quality is not great. In this pic,
http://www.darofamily.com/jeff/files...s/p1010065.jpg, I believe
there is some black drop.

That's a really nice pic, and for a newbie, ou should be pretty proud
of it!

Like a number of other pics I've had, the black-drop appears to be
'stimulated' in pics like this from a degree of chromatic fringing
around the dark edges. What eyepiece (fl + type) were you using?
What were your sky conditions like?


--
Pete Lawrence
http://www.pbl33.co.uk
Most recent images http://www.pbl33.fast24.co.uk/recent_images.html

"Pete Lawrence" wrote in message
news snip
I used an 8'' Newt projected on to a piece of paper. I am a newbie so my
quality is not great. In this pic,
http://www.darofamily.com/jeff/files...s/p1010065.jpg, I believe
there is some black drop.

That's a really nice pic, and for a newbie, ou should be pretty proud
of it!

Like a number of other pics I've had, the black-drop appears to be
'stimulated' in pics like this from a degree of chromatic fringing
around the dark edges. What eyepiece (fl + type) were you using?
What were your sky conditions like?
snip

Forgive my ignorance, but the best answer I can give is that it was the
lower powered plossel that came with the scope. I think it may be a 25mm, at
48x mag I guess? Sorry. Still amazed at what I can see with the scope, so I
have not focused on "how" it is letting me do it yet. It's a Hardin Optical
8'' Dob.

On to my next area of ignorance. I do not know how to report on my seeing
and clarity in the area. I can say, I was shooting just off the edge of my
neighbors house, but I don't think the roof heat was a problem as it was
early in the morning. We had some light haze and lots of moisture in the
air. No clouds at all, and the disc of the sun was clearly visible. Just as
the sun crested the trees, I briefly looked over and was able to see venus
naked eye but just for a second. So I think seeing was a close to perfect as
it could have been.

BTW, thanks for the compliments. I appreciate. The pics most of you post
astonish me. I have to say my favorite pic that I took that day (and I have
no idea why) is the one showing the trees. I stepped partially in front of
the scope and that image got reflected from the primary on to my arm. It
looked cool, so I refocused it on some paper and took that snap.

http://www.darofamily.com/jeff/files...s/p1010035.jpg

Now on to the black drop. I have no knowledge of why or if this happens, but
I believ that I can see it in the picture I mentioned in the original post.
To me, it looks like that old illusion of the white lines criss crossing on
the black background. The intersections all look grey.

BV.

On Wed, 09 Jun 2004 14:35:13 +0000, Sam Wormley wrote:

I didn't see a hint of it in the first hour of the transit--looking via
web cams and nasa tv. Got clouded out for the direct observation. :-(

My damn mouse wheel broke. Please trim quotes for context.