Kuiper Belt Object (KBO) 5000 Quaoar

[Dennis]

After reading a recent post about Quaoar on IIS, I became motivated to obtain a more convincing image of this elusive planetoid than my previous efforts in 2011.

I now believe that I now have a more positive ID for this dim, somewhat obscure magnitude 18.82 TNO (Trans-Neptunian Object) as imaged from Brisbane on Sunday 24th July 2016.

I located the field and grabbed a series of 60 sec frames at a fl of 1932mm and despite some thin cloud and the typical light pollution of dwelling within 7kms of the Brisbane CBD, a good candidate for Quaoar was found on several frames captured between 7:30pm and 9:30pm AEST.

Here are a series of 800x800 pixel crops from the original 1392x1040 original, revealing this shy magnitude 18.82 object lurking between a pair of magnitude 18.99 and 18.93 stars.

800x800 pixel image
Centre:
RA: 17h 49m 51.355s
Dec: -15° 24' 07.378"
Size: 8.67 x 8.67 arcmin
Pixel scale: 0.65 arcsec/pixel

According to various on-line sources, Quaoar was discovered on June 4th, 2002 by astronomers Chad Trujillo and Michael Brown of the California Institute of Technology, using images that were obtained with the Samuel Oschin Telescope at Palomar Observatory.

Using a weighted average of the SST and corrected HST estimates, Quaoar , as of 2010, is now believed to be about 890±70 km in diameter.

Given these dimensions, Quaoar is roughly one-twelfth the diameter of Earth, one third the diameter of the Moon, and half the size of Pluto. And with an estimated mass of 1.4 ± 0.1 × 1021 kg, Quaoar is about as massive as Pluto’s moon Charon, equivalent to 0.12 times the mass of Eris, and approximately 2.5 times as massive as Orcus.

Quaoar orbit around the Sun varies slightly, ranging from 45.114 AU (6.75 x 109 km / 4.19 x 109 mi) at aphelion to 41.695 AU (6.24 x 10 km9/3.88 x 109 mi) at perihelion. Quaoar has an orbital period of 284.5 years, and a sidereal rotation period of about 17.68 hours. Its orbit is also nearly circular and moderately inclined at approximately 8°, which is typical for the population of small classical KBOs, but exceptional among the large KBO. Pluto, Makemake, Haumea, Orcus, Varuna, and Salacia are all on highly inclined, more eccentric orbits.

At 43 AU and with a near-circular orbit, Quaoar is not significantly perturbed by Neptune. As of 2008, Quaoar was only 14 AU from Pluto, which made it the closest large body to the Pluto–Charon system. By Kuiper Belt standards this is very close.

Quaoar has one known satellite, which was discovered on February 22nd, 2007. It orbits its primary at a distance of 14,500 km and has an orbital eccentricity of 0.14. Based on the assumption that the moon has the same albedo and density as Quaoar, the apparent magnitude of the moon indicates that it is 74 km in diameter and has 1/2000 the mass of Quaoar.

While Quaoar is not currently classified as a dwarf planet, it is considered a viable candidate. In the coming years, it may go on to join the ranks of Pluto, Eris, Haumea and Makemake as being officially recognized as such by the IAU and other astronomical bodies.

http://www.universetoday.com/76906/quaoar/

Cheers

Dennis

[AstroJunk (Jonathan)]

Nice one Dennis

I have enormous difficulty getting even near to 19th Mag. Your technique is, as ever, superb!

[RickS (Rick)]

Great work pushing the envelope, as always, Dennis!

[Dennis]

Originally Posted by AstroJunk

Nice one Dennis

I have enormous difficulty getting even near to 19th Mag. Your technique is, as ever, superb!

Originally Posted by RickS

Great work pushing the envelope, as always, Dennis!

Thanks Jonathan and Rick, I appreciate your appraisal and nice words.

When I reviewed my previous efforts, I had exposed sub-frames for between 3 mins and 10 mins and so for this session, I tried something new and ran a series of 110 x 60 sec exposures, which I believe were more effective as I had less star trailing, especially at fl’s of 1900mm.

Here is a (x1.25 up sampled) stack of most of the 110 frames' showing what I believe is the snail like trail of Quaoar during that period. I suspect there are stars down to around mag 20 in there somewhere.

There were a dozen or so frames where Quaoar was shown “tighter”, as a distinct dot, when auto guiding and seeing errors were at a minimum, especially when there were no wispy clouds.

Cheers

Dennis

[andyc (Andy)]

That's an excellent catch Dennis! Makes my imaging of Haumea and Makemake look easy by comparison - this is a good bit fainter and against a very crowded star field. Very impressed you got this, you're inspiring me to have a go

[rally]

Thanks Dennis
Great stuff

[Retrograde (Pete)]

This is a phenomenal pick-up. Well done!

[multiweb (Marc)]

I was looking at this the other night and it's still slowly sinking in. That's a bloody long way from home and the fact you've located and managed to image this is nothing short of amazing. Talk about finding a needle in a haystack.

[Dennis]

Originally Posted by andyc

That's an excellent catch Dennis! Makes my imaging of Haumea and Makemake look easy by comparison - this is a good bit fainter and against a very crowded star field. Very impressed you got this, you're inspiring me to have a go

Originally Posted by rally

Thanks Dennis
Great stuff

Originally Posted by Retrograde

This is a phenomenal pick-up. Well done!

Originally Posted by multiweb

I was looking at this the other night and it's still slowly sinking in. That's a bloody long way from home and the fact you've located and managed to image this is nothing short of amazing. Talk about finding a needle in a haystack.

Thanks Andy, Rally, Pete & Marc, I appreciate your comments.

@Andy – good luck with the hunt, I find these projects to be quite a bit of fun and not too intense.

@Marc – I used both The Sky X Pro and SkyTools 3 Pro to establish the predicted position and a GoTo found the field quite easily, although it was a little busy. As I watched the 60 sec frames being downloaded I could see that some were very tight in terms of clear, round stars, whilst others had seeing/guiding/cloud artefacts that made them slightly less tight than those good frames.

On the good frames the pin prick of Quaoar was quite distinct, whereas on the slightly less perfect frames, it was more of a diffuse clump of photons rather than a distinct point.

On that point, I often find that if the fainter NEO’s move too quickly, their photon trail becomes too diffuse to be recorded as they become spread out over too many pixels, whereas stars that are much fainter are easily captured as their photons accumulate on the same pixels of the imaging chip.

Cheers

Dennis

[strongmanmike (Michael)]

Well that's rather cool Dennis

...but I got a much better image of a Quokka

Mike

[Dennis]

Originally Posted by strongmanmike

Well that's rather cool Dennis

...but I got a much better image of a Quokka

Mike

Ha – thanks Mike, although I was sure that I was pointing towards the meridian and not the islands of WA where these cute creatures are found.

Cheers

Dennis

[Hol_dan (Holly)]

Remarkable that this object can be imaged by armatures!!

[Dennis]

Originally Posted by Hol_dan

Remarkable that this object can be imaged by armatures!!

Hi Holly

The advances in the equipment and software capabilities available to amateur astronomers today is quite breathtaking in its cost and capabilities compared to when I first became fascinated by astronomy.

Cheers

Dennis

[AG Hybrid (Adrian)]

Thank you for sharing that. That's amazing work you've done.

[Dennis]

Originally Posted by AG Hybrid

Thank you for sharing that. That's amazing work you've done.

Hi Adrian

Thanks for your kind words, I appreciate them. I found this quite an enjoyable project so that is a bonus!

Cheers

Dennis