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[Chicago Astronomer - Astro Joe]

The second Venus transit of this century

June 5–June 6 2012

It's time to start planning for the 2012 Venusian Transit - the last one we Chicago Astronomers will witness..and the second one some of us have experienced....(I was fortunate to observe and share the last one in 2004... ;D )

We will start to post threads on techniques, equipment and planning on observing this very rare event. Some of us will be travelling for the best views possible, while some of us will set out a telescope outside of our front and back doors.

I will of course will set-up telescopes by the Adler Planetarium and share this beautiful event with all Chicago Astronomer fans, friends and visitors...primarily through solar projection, but white light filters will also be utilized...and some of the C.A. crew may be using electronic means.

Either way, let's start planning together and make the most of this last Venus transit...

[Paulie pchris00]

Four threads on the Venus transit, and I didn't start ANY of them. Good job, Joe!

[Paulie pchris00]

Okay. Depending on the individual observer's goals for the Venus transit, there are a number of ways to prepare for it. Personally, I want to gather scientific data using the DeLisle method of determining solar parallax, even if I don't do anything with that data. The important thing is to get good observations and timings.

There are some difficulties in getting the contact times on a Venus transit, mostly the "black drop" effect due to the Venusian atmosphere distorting the moment of contact with the solar limb (and also because the solar limb is itself nothing but atmosphere). (See the photo at the beginning of this thread, showing either the 2nd or 3rd contact of the 2004 transit for an example of the "black drop"). So, transits of the Galilean Moons- and even their shadows- can be used for practice timings. (Ever notice my preoccupation with Galilean transit timings? Now you know why).

Not quite as useful are lunar occultations of stars. As Curt has informed us, we haven't had many good occultations recently. The idea is the same, though. Get timings of the immersion and emersion of the occulted star. They don't mimic a true transit, but they sharpen the eye.

If recording the Venus transit in any way, I think it's important to run practice sessions on Galilean transits. These will probably be more difficult than the Venus transit, but will hone the techniques you will use for our sister planet next year. We're enjoying Jupiter just past opposition right now. In the months leading up to the Venus transit, time with the Jovian system will be limited, so get your practice sessions in soon.

Obviously, a solar scope will be necessary for the Venus transit. That means you'll need to get practice observing the Sun. For those of us that don't yet have solar filters, this means buying and/or making them. Or perhaps buy a dedicated solar scope, either a cheapie to use for projection, or an H alpha. Personally, I think a white light filter would be best, with projection next. An H alpha scope, to me, would be showing unnecessary, distracting details. That's just my opinion, with only limited H alpha observing to base it on.

Now, all that practice will mean nothing if the Chicago area is clouded out on transit day. I strongly recommend finding a back-up site (or even better, several). I even think it's a good idea to scout your ideal location the week leading up to the transit to get an idea of where the Sun will set, and if there are any obstructions that will limit the view of the sky. If at all possible, do the same scouting with your back-up sites. If you're going to need internet connection, make sure that it will be available. Don't forget about an extra power supply, if needed.

Finally, check out the book The Transits of Venus. It gives a detailed history of the recorded Venus transits. While this historical perspective isn't necessary, I think most of us agree that our observations are more enjoyable when we are informed of it's significance.

If there is one thing that got me interested in astronomy and space science again, it was viewing the 2004 transit at Adler. The possibility of seeing the 2012 transit was on my mind when I bought my Dob in 2008. I have to see this transit, even if it's only the ingress. Unlike a lunar or even solar eclipse, there will be no waiting around for the next one. If the Venus transit is a high priority for you, start planning now. I'll make every effort to assist, both online or maybe even in a practice observation. I wish everybody clear skies in the afternoon and evening of June 5.

[Paulie pchris00]

Two hundred days to go. (Actually, 200 days, 23 hours, 12 minutes, but who's counting?)

There are no scheduled holds in this countdown, so plan wisely.

[erikruud]

Nov 17, 2011 16:52:13 GMT -6 Paulie pchris00 said:

Two hundred days to go. (Actually, 200 days, 23 hours, 12 minutes, but who's counting?)

There are no scheduled holds in this countdown, so plan wisely.

Tell that to the weather gods.

[Paulie pchris00]

Now that I am equipped with a solar filter (http://astronomer.proboards.com/index.cgi?action=display&board=Solar&thread=3496), I'm wondering how to observe Venus before first contact. Being almost entirely backlit, I think it will be far too dim to shine through a solar filter, and too near the Sun to observe without a filter. Anybody know how to observe Venus in the hours and minutes leading up to the transit, or have any ideas?

(Only 190 days until the transit).

[Chicago Astronomer - Astro Joe]

A variable polarizer filter would darken the sky enough to pop out Venus nicely, then when approaching the disk, pop on the film filter.

Depending on the level of filter the solar film has, you may even set the variable polarizer filter to minimum in conjunction with the full aperture one for some interesting views.

[Paulie pchris00]

I don't have a variable polarizing filter. With Mercury going into inferior(?) conjunction this week, I might try a test observation next weekend, weather permitting. Mercury will be up just before the Sun, a dimly lit crescent. If I do it, I'll post whatever results I come up with. If the weather is an issue, Mercury could still serve as a test observing run near other inferior and superior conjunctions.

Anybody crazy enough to either be up all night, or get up early is welcome to join me. I want no surprises on transit day, and if my experiences help anybody else out with their transit day observations, even better.

[Paulie pchris00]

Well, my plans to time the contacts have been thwarted. I read that first contact is not visible in white light, since Venus will not be visible until it is on the disk. I guess I can now focus on just enjoying the event.

[magic612]

I've already asked for a vacation day on June 5th. Never hurts to ask ahead.

[Centaur]

I've created graphics that preview the transit from different cities, including Chicago at the Adler Planetarium (well serving all Chicagoland observers). The timings vary among locations since parallax is a factor. My diagrams utilize horizontal (alt-az) coordinates which explains the apparent curving of Venus' path due the Earth's rotation. I currently provide previews for eighteen cities, but will add more as the event nears. Here's the link to my webpage for the transit: www.CurtRenz.com/venustransit

[erikruud]

I put in a request to work from home on June 5th. That way I don't need to take a day off, but I will still have time to set up before the transit begins.

I have my solar film and to make filters for my dob and binoculars.

I also acquired a 4" Orion Mak with an Orion glass solar filter to fit.

[Chicago Astronomer - Astro Joe]

Full aperture filtering is the way to go...!

[Centaur]

I've increased the number of cities for my transit previews from 16 to 44: www.CurtRenz.com/venustransit

The one for Chicago is based on the location of the Adler Planetarium. Nevertheless, throughout Chicagoland the timing of transit events should only vary by about one second. However the timing of sunset could vary by several minutes.

[Paulie pchris00]

T- 99 days, 22 hours, 8 minutes and counting.

Yep. Less than 100 days to go.


transitofvenus.nl/wp/2012/02/26/a-hundred-days-to-the-transit/

[Paulie pchris00]

Sixty days and counting until the Venus transit. Don't forget.

[Paulie pchris00]

As of an hour and a half ago, there are only 49 days left. I just e-filed (nothing like waiting until the last minute, huh?), and as soon as my refund lands in my bank, I'll be ordering the rest of the equipment I'll need to pull off my transit plans. I made a wish list over the winter, and should be able to do everything I want to do for the transit, and beyond.

Has anybody ever tried the Baader photo film? I have the visual film, and it doesn't do well for photography. I'm wondering if I shouldn't order a sheet of the photo film just in case.

I also think it would be a good idea to put together a practice observation, to work out the bugs in any new or otherwise untested equipment that will be employed for the transit. Having the crew together could help troubleshoot any problems that come up. Just a thought, and I know I'm not the only one thinking about it.

[Chicago Astronomer - Astro Joe]

Let's do several May Solar sessions...perhaps on Saturdays/Sundays.

[-=CROMAN=-]

Okay... so what is the contingency plan in case of a cloud out over Chicagoland area? How far would you be willing to drive that day. The meteorologist should have a rough estimate the day before which would give us at least 12-18 hours to move somewhere where we can catch it. As of right now I think members of our group have events planned at the Adler, Conway, St. Charles and Elgin.

[erikruud]

I'll have a laptop with a broadband card so we can connect to one of the live feeds if the clouds roll in.

[Chicago Astronomer - Astro Joe]

I have no contingency plan other than being at the Adler locale.

Being a week day, my travel options are limited and I did commit work time at the Adler - wearing both Adler & Chicago Astronomer hats for this event. The CAS will even join me on this.

But, I hope you guys are scoping out sites out west and share with the crew on your experiences.

[Paulie pchris00]

When I got myself appointed Observing Director of CAS, I pretty much tied myself to the observatory for the transit. However, if the weather will almost certainly not cooperate, I might try to weasel my way out of duties, and head for a clear sky. Where, I don't know where yet, but I'm thinking Prairie Grass Observatory near Lafayette, where I went to a star party last summer. It's only two hours away, yet far enough that they might have a different weather pattern that day.

[erikruud]

I just stumbled on this.

transitofvenus.nl/wp/2011/11/26/the-artificial-transit/

www.melbourneobservatory.com/19thCentury.htm

www.museumboerhaave.nl/object/demonstratietoestel-venusovergangen-v13841/

We should have built one too.

[atomant]

Not much practice time left for solar observing at Adler folks.
With NATO party this weekend and Memorial weekend next.
Three weekends left before transit! Yikes!

[Paulie pchris00]

Just when you thought I was done talking about the Transit of Venus...

Based on a rough estimate of Venus's orbital period of 224.7 days, at about 8:52 AM CST this morning, Venus will be back at the point in its orbit where we were lucky enough to observe first contact with the Sun last June. I'm tempted to go have a look for Venus in broad daylight, but I think it's a little too risky, even for me. But I will take note of it, and relive the thrill of watching Venus push into the solar disk.