Orpington Astronomical Society

Astronomy => Alerts! Questions? Discussions... => Topic started by: Whitters on Jun 08, 2004, 21:59:00

Title: Transit of Venus
Post by: Whitters on Jun 08, 2004, 21:59:00
06:20:56 first spotted small bite out of the sun
06:28:48 about half way onto the sun's disk
06:33:49 can see atmosphere of Venus
06:37:26 black drop noticeable
06:38:36 Looks like it would be all on the sun now but still a noticeable dark flattening of and can't see the sun
06:38:56 still holding onto the sun
06:39:50 Venus now fully on the Sun's disk
12:04:32 Third contact - using the open2 calculator this gives a value of the AU as 157.8 million kilometres
12:14:00 Can just still see Venus with Eclipse glasses
12:14:30 Can't see it with eclipse glasses any more
Cameras shots around 12:00 250th to 2 seconds then a 500 then another 2 second
12:23:10 Fourth contact, that's it now for eight and 122 years

First and second contact visual, third and fourth using Webcam image

All times BST

[ This Message was edited by: Whitters on 2004-06-08 14:15 ]
Title: Transit of Venus
Post by: Rick on Jun 09, 2004, 01:12:00
I only got two timings:

3rd contact: 11:03:43 UT
4th contact: 11:23:13 UT

Ian called 3rd contact before me, and 4th contact later than me.
Title: Transit of Venus
Post by: Sue on Jun 10, 2004, 04:31:00
1st Contact 5:22:11 UT
2nd Contact 5:39:24 UT
3rd Contact 11:03:19 UT
4th Contact 11:21:21 UT

Tim entered my records onto the University of Lancashire web site with the Lat and Longd. for Sevenoaks and their automatic programme calculated that the distance to the sun from my obs. was 125x10^6 km - a bit low but not bad considering the average on the site at the time was 59x10^6 km! :smile:

[ This Message was edited by: Sue on 2004-06-09 20:33 ]

[ This Message was edited by: Sue on 2004-06-09 20:34 ]
Title: Transit of Venus
Post by: Mike on Jun 10, 2004, 04:34:00
Paul,

You said you could see the black drop and the atmosphere - did you get any images of these ?

I think I may have got a slight black drop effect, but no atmosphere.
Title: Transit of Venus
Post by: Whitters on Jun 10, 2004, 06:13:00
I spent my time at the beginning observing rather than imaging, and I haven't noticed  it on the images I took at 3rd contact, though something I did notice was that my eyeball estimate of 12:04:32 was well out when I looked at the CCD images the image capturing third contact was timed at 12:04:04 BST.

As for the black drop my theory is that the eye is that the eye is trying to make the best of what it sees and the pre-processing section brings out a black drop despearely trying to make a a recognisable shape, result the black drop, or as in my case more a black splat. But the CCD or webcam is not so judgemental, it can also freeze the action, that's why I don't think we will see a black drop on an electronic image.
Title: Transit of Venus
Post by: malcolm on Jun 10, 2004, 15:04:00
I saw the atmospheric refraction of sunlight when venus had moved halfway onto the sun's disc. I was amazed that it was visible through a home made ful aperture baader filter. I didn't make any precise timings rather than watching it all happen.
A great experience.