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Saturday, October 30, 2010

 

2003 UV11 Live!

Screen capture of 2003 UV11 from the Virtual Telescope.

While I didn't get my own image of 2003 UV11, over at the Virtual Telescope if you are quick you can catch a live observing session of 2003 UV11.

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Friday, October 29, 2010

 

Well, I got an image from GRAS 14 ...
















...but there wasn't an asteroid in it. Stars and faint galaxies are visible down to below magnitude 14, but there is a complete lack of Asteroid. The SkyMap field for the same time as the exposure is how to the left.

I took 3 x 120 second exposures, which should have been able to pick up a magnitude 14 asteroid. I "blinked" the images so I could see if anything jumped about, but nothing did. Maybe I messed up the times, but even if I'd been out by an hour I should have caught at least two images of the asteroid in this field. [sighs]

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Asteroid 2003 UV11 zips past tonight

The Earth and Moon as seen from asteroid 2003 UV11 at closest approach, simulated in Celestia.

Asteroid 2003 UV11 will flash through our skies tonight and tomorrow morning. Unlike 2010 TD54, 2003 UV11 will be relatively sedate and bright (magnitude 11.9 at its brightest).

Australian observers are best positioned to see the asteroid at its brightest (looks at cloud outside, and GRAS G14 is offline [sob], no back online now), but the relatively low distance above the horizon (32 degrees from Adelaide at the time of brightest approach) will make it a bit hard to follow. You will need a decent telescope to see the asteroid, binoculars won’t pick it up.

I have made spotters maps, which you can see over at my GRAS blog. To make your own, you can download orbital elements for this asteroid from the Minor Planet Ephemeris Center, or hand enter them from here:

Epoch 2010 July 23.0 TT = JDT 2455400.5 MPC
M 278.16307 (2000.0) P Q
n 0.56393601 Peri. 124.79517 -0.91668496 -0.39581712 T = 2455545.61740 JDT
a 1.4509401 Node 31.98952 +0.32434442 -0.81726321 q = 0.3440439
e 0.7628821 Incl. 5.95175 +0.23342962 -0.41881936 Earth MOID = 0.00748 AU
P 1.75 H 19.4 G 0.15 U 2

Location of 2003 UV11 in the sky above Adelaide, at 10:00 ACDST visualized in Stellarium (click to embiggen)

As usual I have made a Stellarium file and a Celestia file for the asteroid. As usual, add the Stellarium elements to the end of the system.ini file and save the Celestia file in extras. The Stellarium file makes the asteroid brighter than it should be, for easy spotting, to be more realistic set the radius to 0.3.



[2003UV11]
name = 2003UV11
parent = Sun
radius = 3
oblateness = 0.0
albedo = 0.15
lighting = true
orbit_visualization_period = 1325.46
halo = true
color = 1.0,1.0,1.0
tex_halo = star16x16.png
tex_map = nomap.png
coord_func = comet_orbit
orbit_Epoch = 2455400.5
orbit_TimeAtPericenter = 2455545.61740
orbit_MeanAnomaly = 278.16307
orbit_SemiMajorAxis = 1.4509401
orbit_Eccentricity = 0.7628821
orbit_ArgOfPericenter = 124.79517
orbit_AscendingNode = 31.98952
orbit_Inclination = 5.95175

======================================2003UV11.ssc=======================================
"2003 UV11" "Sol"
{
Class "asteroid"
Mesh "ky26.cmod"
Texture "asteroid.jpg"
Radius 0.3 # maximum semi-axis
MeshCenter [ -0.000718 -0.000099 0.000556 ]

InfoURL "http://en.wikipedia.org/wiki/2003_UV11"

EllipticalOrbit
{
Epoch 2455400.5 # Epoch 2010 July 23.0
Period 1.75
SemiMajorAxis 1.4509401
Eccentricity 0.7628821
Inclination 5.95175
AscendingNode 31.98952
ArgOfPericenter 124.79517
MeanAnomaly 278.16307
}

RotationPeriod 0.178 #made up

Albedo 0.15 #made up

}
=========================================================================================

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Thursday, October 28, 2010

 

Another Chance to See Jupiter's Moons with the Unaided Eye


Left image, Jupiter at 9:30 pm daylight saving time on Friday 29 October as seen from Australia; Right image, Orientation of the Moons, Callisto and Ganymede will be to the right and below Jupiter.

As I've previously mentioned, Jupiter's moons are bright enough to be seen with the unaided eye. However, they are so close to bright Jupiter that the intensity of it's light (and the optical imperfections of our eyes), makes it impossible to see them except under special circumstances.

At opposition bright Ganymede (mag 4.6) and Callisto (mag 5.7) can be far enough away from Jupiter to see when they are at their maximum distance from Jupiter in their orbits. Jupiter's light will still probably obscure them for all but those with the most sensitive vision. However, if you use a wall or post to just block out Jupiter's light, you should see them pop into view.

Probably our final opportunity this opposition to see them with the unaided eye is on Friday, October 29 and Saturday October 30. Ganymede will be at its maximum separation from Jupiter at around 9:30 pm daylight saving time, when Ganymede will be at 300 seconds of arc from Jupiter, greater than the 208 arc seconds of epsilon Lyrae, a double star that is just separable by people with good eyesight, and almost as big as the easily separable alpha Capricorni (380 arc seconds).

Orientation of the Moons, on Saturday 30 October at 11:30 pm daylight saving time. The image is the same scale as above, Callisto will be to the right and below Jupiter

You will have to wait until 11:30 pm on Saturday 30 October for Callisto, when it will be 6o0 arc seconds from Jupiter (about 1/3 the diameter of the Moon), but at magnitude 5.7, you will need a dark sky site to see it. If you are willing to wait until 3:30 am Sunday , it will be slightly further away, but this shouldn't make much difference.

You will need a handy wall or post to block Jupiters' light. Stand so that you can hide Jupiter behind the blocking object by just slightly turning your head. When I was doing this back in September, I found I needed a quite distant object. otherwise Jupiter was covered in one eye, but uncovered in the other (lousy parallax), which was quite disconcerting. You may need binoculars to help orient yourself.

Move so that Jupiter just is blocked, then allow your eyes a few moments to adjust from the brightness of Jupiter, and the Moon should "pop out". Ganymede will be easier to see than Callisto, due to its brightness.

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A Meteor Shower from Comet 103P Hartley?

A couple of unusual fireballs have astronomers speculating that there might be a meteor shower from comet 103P Hartley. The comet has come closest to Earth than any other comet fro a long time, and some of its dust trail might cross the Earths orbit. While it's a long shot, look for meteors in the constellation Cygnus on the nights of November 1 and 2. Read the full story here.

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Revisiting the Comet Crash

False colour image of Bo Zhou's Comet in the STEREO COR2A imager on 21 October (compare with the H1A image from 19 October).

Bo Zhou's comet did not survive its encounter with the Sun. The animation below shows it evaporating as it comes close to the Sun. You can download a 4 meg AVI here.

Compare this animation with the low resolution STEREO COR2 animations: very low resolution, low resolution.




video

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Wednesday, October 27, 2010

 

Mira is Brighter!

Image, photo of Cetus taken from my backyard at around 10:45 pm ACDST, the variable star Mira is indicated (Cannon IXUS, 15 seconds at ASA 400). Click to embiggen.

I just went out into the back yard and Mira was quite obvious. In a previous post (here, with spotters maps and a magnitude comparison chart) I reported that very early on in the month Mira was already near the brightest it usually gets, and people were predicting a quite bright maximum this year.

My estimate makes it around magnitude 2.5, it is definitly brighter than magnitude 3, but it may have passed maximum brightness while the full Moon was out. I'll definitely be following this star with interest over the next few weeks.

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Imaging opportunities for comet 10P tempel and asteroid 8 Flora

Up at my GRAS blog I have some posts about challenging imaging opportunities for comet 10P Tempel and asteroid 8 Flora

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Carnival of Space #175 is here.

Carnival of Space #175 is now up at Out Of The Cradle. There's space exploration merit badges, science fairs, space conferences, space art, stunning images and much, much more. Head on over for a read.

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Comet 103P/Hartley near M35

Mosaic of images showing Comet 103P Hartley near M35 (top image near middle), NCGC 2158 (just above M35), CR 89 (hard to see, to the left of the comet) and 1 Geminorum (brightest star). Click to embiggen for open cluster goodness.

The comet appears as multiple images as this is a stack of 3 x 60 second exposures in Global Rent a Scope GRAS 14 and stacked in Image J using Z projection of maximum intensity and a bit of contrast fiddling. Two series of exposures was made, one on the comet and one on M35, the composed images were made into a mosaic using the GIMP, with layers, and using a little bit of rotation to get the star images aligned.

The images are a bit rubbish as a) the Moon was pretty close and b) the cloud that I thought had gone away hadn't (the streamers in the comet image isn't a nebula). Later I'll try and match the background better, maybe eliminate an image from the stack to see if can get it better.

UPDATE: Rolando Ligustri does it much much better, his stunning image is here.

Chart of the region identifying objects in the above image, the rectangles show the field of view of the GRAS 14 imager (again, click to embiggen).

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Tuesday, October 26, 2010

 

The Sky This Week - Thursday October 28 to Thursday November 4

The "Blue" Last Quarter Moon is Saturday October 30. Mars is in the head of the Scorpion. Jupiter is easily seen in the evening sky. Comet 103P Hartley climbs higher in the sky. The variable star Mira is bright.

Evening sky looking north as seen from Adelaide at 10:30 pm daylight saving time on Wednesday October 29 showing Jupiter close to Uranus. Jupiter is just past opposition, but is still excellent in telescopes and binoculars. Similar views will be seen elsewhere at the equivalent local time. Click to embiggen.

The "Blue" Last Quarter Moon is Saturday October 30. A "Blue" Moon in modern usage is the second full Moon in a month, and we had a rare occurrence of two "Blue" Full Moons earlier this year. This month we have two Last Quarter Moons in one Month, so I have unilaterally decided to call them "Blue" too, as they are just as rare as the Full Moon type.

Jupiter rises before sunset, and can be readily seen from about 7:00 pm local time. Jupiter now spends most of the evening above the northern horizon.

Jupiter was at opposition well over a month ago, when it was at its biggest and brightest as seen from Earth. However, Jupiter will still be excellent in binoculars and small telescopes for many weeks to come.

Jupiter and Uranus are still close together and can be seen near each other in a pair of binoculars, although by the end of the week they will drift out of binocular range. Uranus is the brightest object within a binocular field north of Jupiter, and is in fact bright enough to be (just) seen with the unaided eye under dark sky conditions. A binocular spotters map is here.

Io and Europa have just exited Jupiter's shadow on October 29 at 23:20 ACDST (23:50 AEDST).

Jupiters' Moons are a easy to see whether you have binoculars or a telescope. Watching their eternal dance is always rewarding. The evening of Friday October 29 has a double eclipse event, with Io and Europa popping out of Jupiter's shadow close together (23:17 and 23:20, 29 Oct ACDST).

This occurs fairly late in the evening, but still early enough to watch and head off to bed without too much loss of sleep.

There are lots of opportunities in the rest of the month to see cool Jupiter Moon events (scroll down until you hit Jupiter).

Evening sky looking west showing the Mars and Mercury at 8:15 pm local daylight saving time on Monday November. Click to embiggen.

Bright white Venus is lost in the twilight.

Mars is distinguishable by its reddish colouring and is the second brightest object above the western horizon, after the red star Antares (which means Rival of Mars). During the week it draws closer to the head of the Scorpion, entering the head on Monday the 1st of November.

Mercury enters the evening sky by the 1st of November, it it is very low on the horizon and you will need something like a sea horizon to see it.

Saturn is now lost in the twilight.

The variable star Mira is very bright. Now that the Moon is waning, you can follow it's changes in brightness.

If you don't have a telescope, now is a good time to visit one of your local astronomical societies open nights or the local planetariums. Jupiter is well worth telescopic observation, and even in binoculars its Galilean moons are easily seen.

Comet 103P Hartley above the northern horizon at 4:30 am ACDST (3:30 non-daylight saving time) as seen from Adelaide on November, similar views will be seen from other places at equivalent local time.

Comet 103P Hartley 2 rises higher in the southern skies this week. It is now well out of the murk on the horizon, but the comet is fading, and will be between magnitude 5-4, seen as a faint fuzzy dot by the unaided eye. And you do have to get up at dark o'clock to see it. Unfortunately, at the beginning of the week, the waning Moon's light will wash out the comet.

The comet will be best seen from dark sky sites. Later in the week it will be easily seen in binoculars, and it races through the sky through some pretty territory.

Click the link for printable maps comet 103P/Hartley.

Printable PDF maps of the Eastern sky at 10 pm ADST, Western sky at 10 pm ADST. For further details and more information on what's up in the sky, see Southern Skywatch. Cloud cover predictions can be found at SkippySky.

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Monday, October 25, 2010

 

Best Outdoor Chess Set Ever



On Monday nights (when I'm not going to ASCSA meetings), the boys, a couple of their friends, and I head off to the chess group at Sandy's Seachange Cafe in historic Semaphore. Now the chess group has a new addition, there is an outdoor chess set made by form junk artefacts by a local artist.

And wow, is it fantastic. The boys couldn't stop playing with it and we had a small crowd around us as they played. I've played a few artistic big outdoor chess sets before and this beats them all. If your in the local area Monday nights from 7:30 pm, drop on in for a game. I might even start taking the small scope out for some footpath astronomy.

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Saturday, October 23, 2010

 

A Busy Day at Jupiter

Jupiter in the early hours of 21 October, just after Europa has exited the face of the planet. Europa's Shadow can still be seen (click to embiggen)

The night of Wednesday October 20 was a busy one, Chez Reynella went to a meeting were we hear the first about the EPA report that would cause a storm in the media and parliament.

Then when we got home there was a multi-satellite event on Jupiter. With Io passing behind Jupiter, Europa doing a shadow transit of Jupiter and Ganymede coming out from behind Jupiter's shadow.

video In the video you can see all of this happening. I took images at 10 minute intervals so I have a sequence of 16 images. Unfortunately, it was a warm night. Why do I say unfortunately? Because the seeing was terrible with atmospheric turbulence bouncing the image all over the place. Even at midnight it was still wobbly.

Each individual frame was derived from a 20 second AVI taken with my Philips ToUCam webcam, which was subsequently stacked using Registax5 with mild wavelet adjustment. So I got some detail. The Moons are somewhat distorted, but you can clearly see the shadow of Europa and Ganymede popping out of eclipse is quite dramatic. You can download a 14 meg AVI or a 2 meg GIF animation for your viewing pleasure.

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Friday, October 22, 2010

 

...And the Comet goes Crash!

Bo Zhou's Comet in the STEREO H1A imager on 19 October (top right, compare with yesterdays image), substantially brighter than on the 18th.

Bo Zhou's comet did not survive its encounter with the Sun. You can see a movie of its encounter in the SOHO chronograph here (again courtesy of Space Weather). Low resolution STEREO COR2 images show the comet evaporating as well, but I'll have to wait for a few days for the high resolution images.

You can download an MPEG animation of the COR2A images: very low resolution, low resolution.

Animation of the comet in H1A below.

video

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Thursday, October 21, 2010

 

Another Comet Does a Sundive

Bo Zhou's SOHO comet in the STEREO H1A imager, as it heads towards the Sun.

While comet 103P is taking all the limelight at the moment, another comet is about to make a splash.

Chinese comet observer Bo Zhou discovered a comet in images from the SOHO spacecraft. It is headed for a close rendezvous with the Sun, and that inconspicuous dot on the left there will get very much brighter. It may or may not survive it's encounter with the Sun.

An animation of the comet in the SOHO imager is here, courtesy of Spaceweather. And the comet has entered the STEREO COR2 chronograph (see image here), so we could be treated to some great images of the comet over the next day.



video
False coulour nimation of the comet in the H1A imager on 18-10-10 (Hat tip to Comet Al, Michal Kusiak, Karl Battams and the STEREOHUNTER crew)

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Comet 103P/Hartley near Cr62

Left Image, False colour representation of 103P on 19-10-10 to enhance coma and tail structures.

Comet 103P Hartley near open cluster Cr62 (Image below, bottom Left) Click to embiggen for open cluster goodness.

The comet appears as multiple images as this is a stack of 3 x 60 second exposures in Global Rent a Scope GRAS 14 and stacked in Image J using Z projection of maximum intensity and a bit of contrast fiddling.

A chart of the region identifying objects in the image is next to it, the big rectangle is the grame of G14 (again, click to embiggen).

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Carnival of Space #174 is here.

Carnival of Space #174 is now up at Beyond Apollo. There's water on Mars, frost on Pluto, the mysterious disappearing exoplanet, an asteroid smash-up and much, much more. Wnader over on now and have a read.

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Wednesday, October 20, 2010

 

Comet 103P/Hartley near NGC 1664

Comet 103P Hartley near NGC 1664 (top Left) Berk15 (bottom below comet) and epsilon Aurigae (brightest star). Click to embiggen for open cluster goodness.

The comet appears as multiple images as this is a stack of 3 x 60 second exposures in Global Rent a Scope GRAS 14 and stacked in Image J using Z projection of maximum intensity and a bit of contrast fiddling.

Here's a false colour animation I made from those stacked images

Chart of the region identifying objects in the above image (again, click to embiggen).

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Tuesday, October 19, 2010

 

Some Movement on Parallax

I've updated my post about measuring the parallax of Iridium satellites, it looks like we are closer to a resolution.

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In Which I Fail to See Comet 103P/ Hartley

Northern horizon as seen from Largs Bay, Adelaide, at 4:30 an ACDST. Capella is the bright star near the bottom,

When I went to bed last night, the clouds had cleared for the first time in ages, so I organised to get up at 4:30 just in case it stayed clear.

I managed to stumble out of bed at the right time and navigated in the dark to the back door, picking up the camera and binoculars on the way.

And completely failed to see comet 03P Hartley.

I wasn't expecting to see much with the unaided eye, a suburban location, with the comet close to the horizon murk didn't give much hop of that. As well, there was a fluoro light just under where the comet was (just near the star forming the tip of the inverted triangle to the left of Capella).

But I didn't see anything in binoculars either, I could see down t at least magnitude 7.5, so I should have picked it up easily, and the camera shot, which picked up stars down to magnitude 7.3, should have shown a faint smudge too.

So it looks like I'll have to wait a couple of days until the comet is higher.

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The Sky This Week - Thursday October 21 to Thursday October 28

The Full Moon is Saturday October 23. Mars near the head of the Scorpion. Venus low on the horizon. Venus's crescent shape is easily seen in small telescopes and good binoculars. Jupiter is easily seen in the evening sky. Comet 103P Hartley at its brightest. Variable star Mira bright.

Evening sky looking East as seen from Adelaide at 9:00 pm daylight saving time on Wednesday October 27 showing Jupiter close to Uranus. Jupiter is just past opposition, but is still excellent in telescopes and binoculars. Similar views will be seen elsewhere at the equivalent local time. Click to embiggen.

The Full Moon is Saturday October 23.

Jupiter rises before sunset, and can be readily seen from about 7:00 pm local time just above the eastern horizon.

Jupiter was at opposition on Tuesday September 21, when it is was its biggest and brightest as seen from Earth. However, Jupiter will still be excellent in binoculars and small telescopes for many weeks to come.

Jupiter and Uranus are close together and can be seen near each other in a pair of binoculars. Uranus is the brightest object within a binocular field north of Jupiter, and is in fact bright enough to be (just) seen with the unaided eye under dark sky conditions. A binocular spotters map is here.

Ganymede has just come out from Jupiter's disk and is about to be eclipsed, Europa is about to enter Jupiter's disk on October 27 at 23:15 ACDST (23:45 AEDST).

Jupiters' Moons are a easy to see whether you have binoculars or a telescope. Watching their eternal dance is always rewarding. The evening of Wednesday October 27 is again particularly busy, with Ganymede coming out from behind Jupiter's disk (23:15, 27 Oct ACDST) then disappearing in Jupiter's shadow (00:28, 28 Oct ACDST), Europa enters Jupiter's disk and later its shadow falls on Jupiter's disk, finally Io disappears behind Jupiter (01:10, 28 Oct ACDST).

This occurs fairly late in the evening, but still early enough to watch and head off to bed without too much loss of sleep.

There are lots of opportunities in the rest of the month to see cool Jupiter Moon events (scroll down until you hit Jupiter).

Evening sky looking North-west showing the Venus and Mars at 8:15 pm local daylight saving time on Friday October 22. Click to embiggen.

Bright white Venus is rapidly heading towards the horizon, and this week it disappears into the twilight. At the begining of the week Venus is visible above the western horizon from half an hour after Sunset, (even before) until just after the end of twilight (about an hour after sunset). By the end of the week Venus is setting just half an hour after Sunset, deep in the twilight.

Venus is in the constellation of Virgo this week. Venus is now well below Mars and draws further away as the week progresses. Venus is visible crescent in small telescopes and 10x50 or stronger binoculars, and becomes dramatically bigger and thinner over the week. Venus's close proximity to the horizon makes telescopic observation extremely difficult, and almost impossible by the 28th.

Mars is distinguishable by its reddish colouring and is the brightest object above Venus. During the week it draws closer to the head of the Scorpion.

Saturn is now lost in the twilight.

The variable star Mira is very bright.

Venus is a distinct crescent, and grows measurably bigger during the week. In my 10x50 binoculars on a tripod mounting Venus is very small but the crescent shape is easily visible. If your binoculars don’t have decent anti-glare coatings, you may have to observe in the early twilight in order to see Venus’s shape without internal reflections from the binocular lenses getting in the way.

If you don't have a telescope, now is a good time to visit one of your local astronomical societies open nights or the local planetariums. Jupiter is well worth telescopic observation, and even in binoculars its Galilean moons are easily seen.






Comet 103P Hartley above the northern horizon at 4:30 am ACDST (3:30 non-daylight saving time) as seen from Adelaide on October 22, similar views will be seen from other places at equivalent local time.

Comet 103P Hartley 2 rises higher in the southern skies this week. The comet will be at its brightest on October 22, but will still be faint, between magnitude 5-4, and will be seen as a faint fuzzy dot by the unaided eye. And you do have to get up

The comet will be best seen from dark sky sites. It will be easily seen in binoculars, and it races through the sky through some pretty territory (lots of binocular friendly open clusters).

Unfortunately Moonlight will significantly interfere after the 22nd. Although the comet will still be readily visible in binoculars, it will be difficult to spot with the unaided eye until the Moon wanes. Click the link for Printable maps comet 103P/Hartley.

Printable PDF maps of the Eastern sky at 10 pm ADST, Western sky at 10 pm ADST. For further details and more information on what's up in the sky, see Southern Skywatch. Cloud cover predictions can be found at SkippySky.

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Monday, October 18, 2010

 

Venus and the Scorpion

Venus glows underneath Scorpius, the constellation of the Scorpion. Click to embiggen, it's well worth it.

Back on September 28, Tony Travaglia sent me these stunning images of Venus below Scorpius taken from Oamaru, New Zealand. Of course, I was out and about, far form any internet connection at the time, and when I came back his email was buried uder a pile of others, so I only just found it to share with you.

Sorry Tony.










Venus and the Milky way.

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Sunday, October 17, 2010

 

Using Iridium Flares for Parallax Measurements

Iridium flare captured simultaneously at a) Largs North, SA and b) Black wood SA. You may need to click on the image to embiggen and see that the flare trail is shifted with regard to the stars.

Back on October 8 I and some other people were fortunate to witness a bright Iridium flare near Jupiter. I got a nice shot from my camera (mounted on my telescope with the drive going to stop star trailing), and Dean Male from Blackwood kindly sent me his image captured at the same time.

One thing that I noticed was that the image of the flare was slightly shifted with regard to the background stars. This represented a great opportunity to measure parallax in these images and do ... something.

Parallax is the slight shift in a nearer object against a simultaneously viewed distant background object. Parallax is used to measure the distance to the Moon, the planets and the stars. Amateur photographers have used their images of the Moon and nearby stars to measure the distance of the Moon to within 3%. So could I use the parallax shift in the images of the flare to measure the height of the satellite?

Highly sophisticated parallax measuring system.

Well, I measured the separation of the trails, using the sophisticated method of scaling SkyMap charts to the same scale as the images at full resolution, and using a bit of paper to plot the flare location.

I came up with 36' 57"
separation, or 0.6158 degrees (about a Lunar Diameter). Using the formula used for Lunar parallax:
\mathrm{distance}_{\textrm{moon}} = \frac {\mathrm{distance}_{\mathrm{observerbase}}} {\tan (\mathrm{angle})}
and estimating that Largs and Blackwood are roughly 25 km apart as the crow flies I get .... the iridium satellite was 2,326 Km up.

Which, as they orbit around 800 Km up, is a 300% error. I tried the formula out on the lunar separation measured here, and got the right result. Using the more complex formula:
Where D is the distance to the object, b is the separation between observers and Theta is the angular separation between the two images with respect to the background stars gives the same result.

Either Dean and I were 8 Km apart or the flare images separation was 3 times larger than I measured (not likely) or I'm doing something very wrong, or the formula is not appropriate for small separations of observers (The amateur Moon calculation was done from observers over 2000 Km apart, this won't work fro iridium flares which are only observed in a small area).

Anyone have any ideas? UPDATE: There is at least a partial solution to the Puzzle. In my original posting I had estimated that Dean and I were 25 Km apart, based on my rough measurements from Google maps. But that was from points that Google decided were Largs North and Blackwood. Dean sent me the flare information from his site, and from that I could calculate that we were 13 Km apart, not 25.

This gives a distance of 1209 Km, within 20% of the distance to the satellite from my site (1022 Km given by CalSky), still not the orbital distance (790 Km) but a heck of a lot better than 200%. JupiterIsBig (see comments) sent me the following diagram:














which illustrates the sorts of correction we need to fix our calculations. I'm waiting for JIB to give this math's challenged biologist explicit instruction on how convert Altitude and Azimuthal data into correction factors.

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Saturday, October 16, 2010

 

Comet 103P/Hartley near NGC 1528

Comet 103P Hartley mosaic showing the nebula NGC 1491 , open cluster King 7, and open clusters NGC 1528 , 1513 and 1545 . This was shot from Global Rent a Scope GRAS 14 (stack of 5 black and white images at 60 seconds each for top image and one 60 second image for the bottom image with the comet). You, really, really need to click to embiggen (it's worth it).

Yes, I deliberately made this mosaic, really I did. I didn't mess up my imaging co-ordinates and take 6 images of a completely comet free area before realizing my mistake, no siree.

If you want to see how it is really done, this stunning mosaic from Rolando Ligustri is the way to go.

Chart showing area where images were taken, the field of view of the G14 imager is shown as the large rectangle at the bottom.

The individual FIT images were stacked in Image J using Max Z projection, saved as half scale png's then assembled in the Gimp using layers and difference features.

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Comet 103P/Hartley Enters the Southen Skies

Comet 103P Hartley above the northern horizon at 4:30 am ACDST (3:30 non-daylight saving time) as seen from Adelaide on October 18, similar views will be seen from other places at equivalent local time. For the next few days it will be easy to spot near the bright star Capella.

Comet 103P Hartley 2 has now entered the southern skies. The comet has been reported by northern observers to be visible to the unaided eye as a faint fuzzy dot under dark sky conditions. In the southern hemisphere, with the comet closer to the horizon, it will be difficult to spot until later in the week (and of course the horrible weather means we have had little opportunity to see it).

Unfortunately you need to get up around 4 am (local daylight saving time, 3 am local standard time). Also unfortunately, Moonlight will begin to interfere by the end of the week.

The comet should become brighter, leading up to its closest approach on October 20, but will never get brighter than between magnitude 4-5.

Naturally the comet will be best seen from dark sky sites. It will be easily seen in binoculars, and it races through the sky through some pretty territory (lots of binocular friendly open clusters).


Spotters map of 103P Hartley in black and white, suitable for printing out (you need to click to embiggen and print the embiggened map) .

Alternatively you can download this printable back and white PDF Map.

If you want to add 103P Hartley to Stellarium or Celestia, the elements for those programs are here.

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Friday, October 15, 2010

 

Comet 103P/Hartley near NGC 1491

Comet 103P Hartley is getting very bright now (for astronomical values of "bright", it's just a dim fuzzy dot to the unaided eye).

Last night I got some images of the comet near the nebula NGC 1491 and the Open cluster King 7. To the immediate left is a cropped wide-field shot from Global Rent a Scope GRAS 14 (stack of 3 black and white images at 60 seconds each). Click to embiggen (it's worth it). Due to stacking the images on the stars the comet is smeared.






This image is an RGB composed image of single 90 second RBG frames taken with GRAS 05. Again click to embiggen. I used the RGB composer module of Image J, I think I'm doing it wrong, maybe I should read the manual :-0

I have have been taking images of 103P for nearly 2 weeks. I really should post them.

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Wednesday, October 13, 2010

 

Comet 103P in Stellarium, a cautionary tale















Left image, 103P as imaged with the GRAS 14 telescope in New Mexico; Right Image, predicted position of 103P as visualized in Stellarium at the same time.

Stellarium is a pretty handy program. Realistic planetary visualization, customizable, I can run as a planetarium as well as control telescopes, and above all, it's free! You can also add objects to it. However, a reader (Wojtec) has posted a problem with Stellarium's implementation of 103P Hartley.

UPDATE: Reader Dagger stab writes:
If you are using the MPC's Minor Planet & Comet Ephemeris Service as a source, there's an error in your Stellarium data: it should be "orbit_PericenterDistance = 1.058686". (There should be an 8 after the 5.) It's correct in the Celestia script. :)
(Thanks RD. Strangely, I used both the JPL horizons data as well a the MPC data, why SkyMap gets it right with the MPC data is a mystery, I will check back)

UPDATED UPDATE: I ended up completely rebuilding the Hartley add-on with fresh MPES data to match SkyMap, and with the rebuilt add-on 103P is within 5' of the CCD position, good performance and about as accurate as SkyMap. I've posted the revised figures on the original post and at the end of this post. The JPL horizons data was older than the MPES data, so it gave wacky results. Makes sense that it was the add-on elements rather than Stellarium being weird.

Wojtec found the Stellarium position was off by over 20 minutes of arc, I've confirmed this, actually, I found a 37 minute of arc discrepancy, and that was using a 103P definition file with the latest MPC parameters. Now this isn't much, for visual location or using binoculars and low power telescopes it will be just fine. But if you are using CCD imaging, then this is a significant discrepancy, if say, you were using the GRAS G14 imager the comet would be significantly displaced (see above images, and the image below which makes it clearer), and with the GRAS G5 imager the comet could be out of frame.

Stellarium location of 103P compared to the SkyMap prediction, and the actual measured position from the G14 CCD image (click to embiggen)

I've tired two separate definition files for 103P, and there is still the same discrepancy, in the image to the left I've used the same parameters for SkyMap and Stellarium. So it's not the values. I've also been careful to check that the times were correct (imaging run vs Stellarium prediction) so the apparent differences were not due to timing errors.

Curiously, it only is happening with 103p Hartley (and to some extent 2010 TD54). For Comet Enke, Comet 10P Temple, and Vesta the Stellarium prediction is within 5 minutes of arc of the actual object, which is quite tolerable. It can't be a topocentric vs geocentric problem, the discrepancy for 2010 TD54, which has a huge parallax, was only 18' compare to 103P's 37' difference (and with only a short observation time you would expect a large uncertainty in the 2010 TD54 position).

So, I'm baffled, I'll put up a query at the Stellarium forums [answered rapidly, see above, thanks DS], but for now, just be aware that if you are using Stellarium to guide your telescopic CCD imaging, 103P's position will be off. [Now Fixed, see below]

=======================================
[Hartley]
name = 103P/Hartley
parent = Sun
radius = 24
oblateness = 0.0
halo = true
color = 1.0,1.0,1.0
tex_halo = star16x16.png
tex_map = nomap.png
coord_func = comet_orbit
orbit_TimeAtPericenter = 2455497.76729
orbit_PericenterDistance = 1.058678
orbit_Eccentricity = 0.695113
orbit_ArgOfPericenter = 181.1969
orbit_AscendingNode = 219.7661
orbit_Inclination = 13.6168
lighting = false
albedo = 0.5
orbit_visualization_period = 365.25
===========================================

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Mira is Bright!

Left hand image, eastern horizon as seen from Adelaide around 10:00 pm ACDST, similar views will be seen elsewhere in Australia at the same local time.

Right hand image, photo of Cetus taken from my backyard at around 10:00 pm ACDST, Mira is indicated (Cannon IXUS, 15 seconds at ASA 400). Click to embiggen both.around

Mira is a pulsating Red Giant star that ranges in brightness from under unaided eye visibility to
around magnitude 3-4 in just under a year. This year we were expecting Mira to be around Magnitude 3.7 in late October, but Sky and telescope is reporting that people have been seeing it as bright as magnitude 3.1 already! Mira is fairly low in the sky at reasonable hours, but a few days ago I could confirm that it was bright, at least brighter than magnitude 3.5, but better estimates weren't possible because of light pollution. You can find Mira yourself using the spoter chart above, it's in the smae part of the sky Jupiter, so locating it should be easy.

Magnitude chart for estimating the brightness of Mira.

You can have a go at working out how bright Mira is yourself. On this chart I've indicated the magnitude of several comparison stars. You will have to wait until Mira is high enough above the horizon for horizon murk not to interfere (around 11 pm at the moment). Then compare Mira to the reference stars. If it is brighter than the 3.8 star, but dimmer than the 3.5 star, it's magnitude is around 3.6-3.7.

Practice a bit, and keep a record as it nears maximum in late October, then dims again.

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