Jupiter System I,II,III measurements

[iceman]

Anyone know an easy way to record the System I,II,III measurements on an image of Jupiter, given a date/time in UT?

The Jupiter2 program has System I and System II latitudes, but not System III.

I downloaded WinJupos (http://jupos.org) but I have no idea how to use it!

Any help appreciated.

[[1ponders]]

Welcome to my project for the semester Mike :P You won't be able to use system III Mike as it relates to the rotation of the actual planet and is measured using radio wave or magnetic field fluctuations. Can you be a bit more specific on what you are trying to achieve? There are a number of ways of measuring features against time/date/longitude.


I don't have it with me atm, but when I get home I'll post a grid you can use to measure features (GRS, spots etc) against the Central Meridian and other longitude. Once you have a time of crossing the CM then you use the conversion tables in Astonomy 2006 to convert to Longitude.

I've been using J2 but I'm certainly going to have a good hard look at WinJupos. Thanks for the link.

[iceman]

ah didn't know that about SIII. In that case, the SI and SII details in J2 will be sufficient for what I need.

I think in order to study the images, they need the CM longitudes.



I'm guessing that's the SI and SII longitudes then? Or am I even more confused now?

[davidpretorius]

join the club with winjupos.. i have tried to get my images into the program, but then when trying to orientate, everything is upside down.

I think the only good thing about it is that you can put your own date time timezone and it will give you the I,II,III.

I had uninstalled it, but will give it another go.

It is very hard to understand

[iceman]

Well you did better than me, I couldn't even find where to open my image :)

When one of you figure out how to use it, please post the instructions/tutorial here :)

[davidpretorius]

recording->image measurement

i then loaded my own image, put in the date time, ut etc and up came I,II,III,

on the adjust tab, i tried automatic for outline frame, but got what you see.

i thought south should be up, well thats what damian peach requests i think on the lupos stuff. I could always invert it i spose

Maybe I have to read the data from here and then add to my image in photoshop???

[[1ponders]]

The longitude of the CM changes by 0.6 deg/min. You can work out the longitude of the CM at any given day and date using the tables in Astronomy 2006. Just remember to convert local time to UT.

The Central Meridian is simply an observed division between the eastern and western hemispheres. The same as out meridian. It has no longitude, it's just a north south line.

[[1ponders]]

He's the grid Mike.

To use:
Quote from "The Giant Planet Jupiter" John H. Rogers.
"As the planet's tilt if very small , the distance east or west of the CM can be converted directly into relative longitude. If a spot is X deg from the CM, the distance from CM to spot divided by the distance from CM to limb is Sin X. For speed and simplicity, the author measures photographs using a transparent grid, ruled with lines corresponding to 10 deg intervals of longitude. This is placed over the image with the outmost lines touching the limb at the latitude of the spot to be measured."

I use it by capturing series of avies, a few either side of "Preceding Edge Transit", then either side of what looks like central transit the a few either side of "Following Edge Transit". I process all the avies and check with the grid to find the closest to central GRS transit. I then check by taking the Preceding and Following images and subtracting the times to get the difference. I then divide the difference, add that to the Preceding time to get central GRS transit time. I then check this off on the first guestimate I made. The guestimates are usually pretty accurate using the grid.

Now that the date and time UT of transit is known the longitude can then be worked out using the ephemeris tables. After collecting a series of transits you can then work out any longitude drift of the GRS (or any object you chose as your datum)

You will notice in the second image I've used only the red channel. I found it made it much easier to measure that way, especially on those nights where the seeing is mush.

The third image is the results of a series of measurements showing how the GRS has changed longitude from the 10/4/06 to the 16/5/06

Hope this helps. You know how I like to ramble :P