Picture For Distance To The Moon

Here's my data:

pic taken approx 04:00 UTC 6/11/14
lat: 32N
long: 110W

Figure 1: My Moon/Saturn Pic Entry (Saturn is above and to the right of the Moon)

And I took a picture of the sky without the moon in the FOV just to see what the camera can do on a nearly full moon evening.  Not bad!

Figure 2: Not too bad for a cheap camera.  Moonglow seeping in at the top.  Very cool that the horizon is red!

Distance To The Moon

Help me measure the distance to the Moon!

On the evening of 10 June 2014, the Moon will appear approximately five degrees away from the planet Saturn.  At that time, I would like to get some help measuring the distance to the Moon.  What I need are pictures of the Moon and Saturn taken at approximately the same time from as many different locations as possible.

• Set your camera up on a tripod for best image quality.
• Make sure that the picture you take has both the Moon and Saturn in it, and that the focus is as good as you can make it.
• Email me the picture along with the time you took it (+/- 5 minutes) and your location (latitude and longitude, +/- 20 miles).

It'd be best if all images could be taken at appoximately the same time.  Let's make this time 04:00 UTC (which would actually make it early morning 11 June in England), which is 21:00 PDT, 22:00 MDT, 23:00 CDT, and 00:00 EDT for the United States.

I did some test images with my little digital camera just set on 'Auto' and got some decent data looking at the Moon and Venus, and the Moon and Jupiter:

Figure 1: Moon and Venus

Figure 2: Moon and Jupiter

Email me your data (pictures) at cosmiclettuce AT yahoo DOT com.

Still Holding

Clouds and wind have conspired to bring this project to a screeching halt.

I'm seriously considering getting more into radio astronomy.

Clear and Windy

Nothing much to update.  It's been mostly clear this past week, but also windy.  Wind bumps the scope around too much which makes for useless data.  I now have an even greater appreciation for domed observatories.

Saturn at opposition yesterday, 177 degrees away from the sun.

It's about time that I start to make the plots of the data I actually want to see: brightness versus orbital phase.  Stay tuned for that.

Seeing Effects

Had a great session last night -- the first night in nearly two weeks!  My prediction that I'd get about half of the nights was very far off.  Sofar, since my Jupiter work started on 12 Feb 2014, I've had 14 observing sessions.  So that means that my "observing efficiency" is at 17.5% (14 / 80).

The surprise this evening was the seeing.  Towards the end of the session, I turned the scope to Saturn to start collecting 300 images of prelim data (I'm still assessing whether I can get "good enough" signal to noise to make the effort worthwhile) when just a little breeze blew through.  The breeze was enough to notice but it was brief and, I thought, uneventful.

However, this little breeze brought with it some nasty air!  The seeing went from really good to really bad in a matter of a couple minutes.  Check these images out of Saturn:

Figure 1: Saturn in good seeing and in bad seeing, minutes apart

Having high-resolution astronomical imaging in my background, I'm curious about these things and would like to understand them better.  I don't recall ever witnessing the seeing deteriorate so quickly.  I'd like to know what exactly causes this and how long it lasts.

I can't make a post to this blog without a nice picture of the Jupiter system from last night:

Figure 2: The Jupiter system 03:09 UTC 03 May 2014

Also some nice Jupiter moon events for May:

5/8     E eclipse R     04:06

        I eclipse R     05:52
5/11    I/E close       04:00
5/17    I/G/C close     04:00
5/18    I/E/C close     05:00
5/24    G eclipse R     03:31
        I eclipse R     04:10
05/26   C eclipse D     04:39

Great Photometry

Looked at the data from 17 March 2014 UTC today and found it to be very clean.  Io and Ganymede were making a close approach to one another, so their light is combined in the plot below:

Figure 1: Photometry for 17 March 2014 UTC

In any case, this data looks really nice and I'm happy with the data collection and calibration process.  This data is now what I'd call "fully calibrated" in that the final "reduction" is now complete with respect to atmospheric extinction.  X-axis is the UTC time, and the y-axis is the brightness, in ADU (corrected such that this would be the brightness at the top of the atmosphere).

Surprise color, Saturn here I come

What does it mean when the atmospheric extinction is different for each moon of Jupiter?

Figure 1: Linear fit to compute Atmospheric Extinction

It means (as far as I can tell) that I'm seeing COLOR DIFFERENCES between the moons.  Very very cool.

In Figure 1, the x-axis is the sec(Z) value, and the y-axis is the photometric value (in ADUs).  The relationship between these two values is linear with a negative slope (objects get fainter as they get closer to the horizon).  But the fact that there are differences between the slopes for the different moons can only mean that I'm seeing color differences in those moons.

My system is looking through a 'green' filter:

Figure 2: The filter set I use

So what do the differences in color mean?  Well, I can say that moon A is "redder" or "bluer" than moon B.  But what does a larger or smaller slope mean in terms of color?

The atmosphere absorbs blue light more than red light.  So as the object gets lower and lower to the horizon, more blue is lost, which makes the object appear fainter.  What this tells me is that Ganymede is "bluer" than Europa and Io, and Io is slightly "bluer" than Europa.

The larger the negative slope, the "bluer" the object is.  This is a hard one to visualize, so I may have to correct this statement later.

I noticed all of this in some data I was looking at from 01 April 2014 and noticed these differences.  Since I have to go back and run all my data reduction software again on all the data, I figured I'd stop and take a look at this (and other things) to try to work out how I want to proceed with yet another surprise.

There have now been three surprises:

1. Watching targets move in and out of Jupiter's shadow
2. Watching targets occult or near-miss (I've seen the latter) each other and (I think) seeing a dimming event caused by targets' "atmosphere".
3. Seeing the color differences between the targets

What else is in store for me?  I'm open for more suggestions, Mr. Jupiter.

I am GO for Saturn

I'm very excited to start my Saturn observations.  For starters, there are SEVEN moons to monitor, with orbital periods between 22.6 hours (Mimas) and 1903.7 hours (Iapetus).  They are all tidally locked, so I'll get the same sort of "full disk" view every orbit.  But in this case, the entire system is tilted at an angle of 26.73 degrees to the ecliptic (very similar to ours) which means I'm seeing more of one pole at a time.  Very photometrically dynamic, I would think.  We'll see.

Saturn opposition is 10 May 2014 - 16 days.  I found this interesting article about Saturn and most interesting is this:

Another interesting phenomenon to watch out for near opposition is known as the Seeliger effect. Also sometimes referred to as the “opposition surge,” this sudden brightening of the disk and rings is a subtle effect, as the globe of Saturn and all of those tiny little ice crystals reach 100% illumination. This effect can be noted to the naked eye on successive nights around opposition, and will get more prominent towards 2017. Coherent-backscattering of light has also been proposed as a possible explanation of this phenomenon. Perhaps a video sequence capturing this effect is in order for skilled astro-imagers in 2014.

According to the Wikipedia entry on 'Opposition Surge', the variation can be quite noticeable.

Just the distances involved are pretty awesome.  Jupiter is about 700 million km away.  Saturn is 1340 million km away -- nearly twice as far!

Approximate maximum elongations for the moons:

Mim: 28.6 arcsec (11 pixels)
Enc: 36.6 arcsec (14 pixels)
Tet: 45.4 arcsec (17 pixels)
Dio: 58.1 arcsec (22 pixels)
Rhe: 81.2 arcsec (31 pixels)
Tit: 188.2 arcsec (72 pixels)
Iap: 548.5 arcsec (210 pixels)

Some of those might be tough, but we'll see.  I should see the same "surprises" with the Saturn system as I do with Jupiter.

PLUS, there is the planet itself and those nice rings.  Since I'm not saturating, I should be able to track the lightcurve of these, also.

I think the signal-to-noise is going to be ok with a 0.2 second exposure.  I think any longer exposure will ruin my chances of getting photometry on Saturn itself.  So I'll suffer a bit with the S/N.

Here's a plot showing the signal from Iapetus -- one of the fainter ones for sure:

Figure 3: Signal from Iapetus

And here's another plor showing the signal from Titan:

Figure 4: Signal from Titan

Both of these plots, as you can see, are on the same scale.

I've calculated that the S/N for Iapetus and Titan are 14.7 and 41.5 respectively.  Anything over 10 is good enough for me, but it will be challenging and I'm anxious to see how noisy this data is.

All of this is very preliminary as I collect more data.  I only took 100 images the other evening, and many of those will be garbage.  So at this point I'd guess that I've got maybe 50 data points on this stuff.  More data required to see how it's going to all work out.  As usual, I'll let the data guide me.