Heads up: HST passing in front of Moon! - Page 2

citivolus (Ric) · #21 08-08-2008, 01:29 AM

From what I can tell with playing around with Heavens-above a bit more, the line is roughly Kelvin Grove through Murarrie through Wellington Point.

Here is a Google Earth .kml of centre line and parks that it passes through, in case anyone wants to give it a go. Coordinates are based on data from Heavens Above, and I am assuming they are accurate.

Dennis · #22 08-08-2008, 06:54 AM

Thanks for the link and nicely annotated map Ric – this has been a very interesting and educational post for me in using Heavens Above and Google Earth!

Cheers

Dennis

jjjnettie (Jeanette) · #23 08-08-2008, 07:50 AM

Are you going to try to image it Dennis?
While I'm not under the path, I'll take my camera and tripod to work and capture a wide field of the close pass.

Dennis · #24 08-08-2008, 08:13 AM

Hi Jeanette

If I finish unpacking all the gear from the Qld Astrofest I will, otherwise I’ll just enjoy the low tech binocular views!

Good luck to all SE Qld imagers and viewers!

Cheers

Dennis

Sharnbrook (Mike) · #25 08-08-2008, 12:23 PM

G'day all,

From the Google Earth line, I shall be 7.3km away from the direct pass, and Starry Night shows that I shall just miss the transit of the Moon, but I shall try to capture it one way or another.

However, my dilemma is what exposure to use? HST has a magnitude of .22, and the Moon tonight is -11.78, giving a differential magnitude of 12.0. This equates to approximately 64000 times as bright. Presumably, all we are going to get is a black dot as the HST passes in front of the moon, so detail isn't a problem, so expose for the moon, and hope to catch a black dot?

OK. But if HST misses the moon, as I expect it will from my location, what exposure should I give for the HST? I intend using my 40D on an 80mm Celestron ED with a focal length of 600mm. This seems to give a field of view of about 1 deg, or twice the moon's diameter, so if I don't get a transit, I should get HST going past. However, if I expose at say 1 second, the light from the moon will flood the whole view, and I shall miss out on the HST.

Any "Bright" ideas?

sheeny (Al) · #26 08-08-2008, 01:52 PM

Quote:

Originally Posted by Sharnbrook

G'day all,

From the Google Earth line, I shall be 7.3km away from the direct pass, and Starry Night shows that I shall just miss the transit of the Moon, but I shall try to capture it one way or another.

However, my dilemma is what exposure to use? HST has a magnitude of .22, and the Moon tonight is -11.78, giving a differential magnitude of 12.0. This equates to approximately 64000 times as bright. Presumably, all we are going to get is a black dot as the HST passes in front of the moon, so detail isn't a problem, so expose for the moon, and hope to catch a black dot?

OK. But if HST misses the moon, as I expect it will from my location, what exposure should I give for the HST? I intend using my 40D on an 80mm Celestron ED with a focal length of 600mm. This seems to give a field of view of about 1 deg, or twice the moon's diameter, so if I don't get a transit, I should get HST going past. However, if I expose at say 1 second, the light from the moon will flood the whole view, and I shall miss out on the HST.

Any "Bright" ideas?

Mike,

The moon is an extended object so the magnitude is a function of it's size. The actual surface brightness of the moon is equivalent to a house brick. The HST won't be so different from this in terms of surface brightness (maybe some of the reflective foil and solar panels will be brighter

).

So expose for the moon, the surface brightness of both the HST and the Moon will be similar. That in itself is a problem if the HST pass is visible, because the contrast between the light moon surface and the HST will be small

.

It would probably be better if the HST pass was not visible, so you would get a black silouette against the moon...

Al.

Dennis · #27 08-08-2008, 01:59 PM

Hi Mike

For a Lunar near miss, at a FL of 600mm the FOV is around 2 x 1 ½ degrees so the HST should pass through this field in less than 10 secs, so I’d be sure to give an exposure of at least 10 seconds.

But, this would flood the FOV with light from the grossly overexposed Moon, so I’d plan to switch to Jupiter instead and take an image with Jupiter in the FOV, although this too will be grossly overexposed.

Cheers

Dennis

sheeny (Al) · #28 08-08-2008, 02:24 PM

Quote:

Originally Posted by Dennis

Hi Mike

For a Lunar near miss, at a FL of 600mm the FOV is around 2 x 1 ½ degrees so the HST should pass through this field in less than 10 secs, so I’d be sure to give an exposure of at least 10 seconds.

But, this would flood the FOV with light from the grossly overexposed Moon, so I’d plan to switch to Jupiter instead and take an image with Jupiter in the FOV, although this too will be grossly overexposed.

Cheers

Dennis

Yes... my previous comments were assuming a high resolution attempt to image the HST in front of the moon

... we all know why you shouldn't assume!

A wide field shot showing the path of the HST and the moon is probably best suited to HDR treatment - take a nicely exposed moon shot to superimpose over the blown out moon... you'd still have the glare around the moon to contend with though...

Al.

IanL · #29 08-08-2008, 02:33 PM

I seen the HST pass by last night at about 6:16 and it was as bright as
Venus in the morning sky.

Ian

Dennis · #30 08-08-2008, 03:06 PM

Quote:

Originally Posted by sheeny

Yes... my previous comments were assuming a high resolution attempt to image the HST in front of the moon

... we all know why you shouldn't assume!

A wide field shot showing the path of the HST and the moon is probably best suited to HDR treatment - take a nicely exposed moon shot to superimpose over the blown out moon... you'd still have the glare around the moon to contend with though...

Al.

I just fired up Starry Night Pro and Jupiter is only 43° above the horizon for the scheduled HST near miss – this may be obscured from my usual set up spot as we have a stupendously gianormous gum tree blocking most of that region, up to around 70°.

Oh well, at least I should get to see the HST/Moon pairing.

Cheers

Dennis

citivolus (Ric) · #31 08-08-2008, 04:42 PM

New .kml available, I tracked down a good tool for creating these. That tool can be found here: http://pictures.ed-morana.com/ISSTransits/predictions/

It turns out if you are a few km farther north, you'll get a Jupiter transit on the same pass.

New .kml here.

Regards,
Eric

Dennis · #32 08-08-2008, 05:20 PM

My goodness, Eric – a mighty fine piece of detective work and analysis there!

Cheers

Dennis

Sharnbrook (Mike) · #33 08-08-2008, 05:26 PM

Thanks lads for all the help and suggestions. I'm rushing around getting set up now, and hope to get something. You'll know if I do, or if I don't, either way.

astroron (Ron) · #34 08-08-2008, 06:16 PM

Separation was about 7 degrees apart from my location.
Ron

Omaroo (Chris Malikoff) · #35 08-08-2008, 06:23 PM

So I first see this post at 6:22 Friday...

I even had the little Tak outside pointing at the Moon with a camera on the back.

Arrghh!

IanL · #36 08-08-2008, 06:32 PM

You might see it on the return trip around the world in 90mins.
The wife got some photos of it going by Jupiter. Just waiting on her downloading them to the PC

Ian

Sharnbrook (Mike) · #37 08-08-2008, 06:41 PM

I managed to get 13 quick order shots as it passed the moon, and then the motor drive got stuck in the ON position. By the time I had switched it off, did a goto for Jupiter, I didn't have time to do an adjustment to centre Jupiter, and I missed altogether. However, I managed to get off 196 shots!! most of which are black.

SWMBO has just called to say that dinner is ready, so I must go, and will post something later.

jjjnettie (Jeanette) · #38 08-08-2008, 08:44 PM

I took the binos to work, hoping to catch a glimpse of the close pass.
We were so very busy tonight though that I missed it by about 5 minutes.

citivolus (Ric) · #39 09-08-2008, 09:58 AM

After a bit more digging, I came across calsky.org, which allows you to go nuts with lunar and solar transits of pretty much any satellite. It will even take into consideration things like ISS orbit boosts, and display predicted angular size & transit durations.

Go nuts!

Sharnbrook (Mike) · #40 09-08-2008, 04:15 PM

Here is my attempt at the HST passing close to the moon. This is supposed to be an animated gif file showing the pass, but it doesn't appear to be working on Flickr, and the file is too big for ISS

http://www.flickr.com/photos/sharnbrook/2745363821/

I shall have to try again later, this is getting up my nose!!