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Dwarf Planet Quaoar
#1
Dwarf Planet Quaoar

Here is an image of the Dwarf Planet Quaoar (mag 18.88) taken from our back yard in Brisbane on 19th July. (90x30 sec).

Quaoar is a planetoid that lies beyond Pluto's orbit in the solar system. 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. The discovery was announced on October 7th, 2002, at a meeting of the American Astronomical Society. At the time, the object was designated as 2002 LM60, but would soon be renamed by Brown and Caltech his team.

Quaoar lurks in the Kuiper Belt, a group of icy objects beyond Neptune. It is about 42 astronomical units, or Earth-sun distances, away. That's about 4 billion miles (6 billion km) — a billion kilometres more distant than Neptune. It takes about 288 years for Quaoar to go once around the sun in a roughly circular orbit.

Quaoar has only one moon, called Weywot. it orbits around Quaoar at an approximate 9000 mile distance.

Some SkyTools Data:
(50000) Quaoar
Minor Planet, Dwarf Planet
Magnitude: 18.88
Orbit Period:  288.3 years
Diameter: 590 - 1900 km
Current Status:
Earth Distance:  41.9 AU
Total motion: 2.66 "/hr PA 264.0°


Cheers

Dennis

   

   

   
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#2
Congratulations! That's impressive.

Phil S.
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#3
Cool
Clear skies,
Greg
Head Dude at Skyhound
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#4
Thanks for the comments Phil and Greg, I appreciate them.

I managed to get out on 24th July, albeit with the insult of a Full Moon nearby, and record the position of Quaoar again. Here is a composite showing the movement between the 2 sessions.

Cheers

Dennis

Composite of 19th and 24th July
   

Annotated
   
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#5
Awesome work. It would be educational to know from where (Brisbane, Australia?) and what time (UT) the images were taken. I'm not familiar with AEST. My assumption is the 19th image was around ~9 UT and the 24th image was ~11 UT. I think I can see westward trailing on both dates. Really an amazing feat. Thanks for sharing.
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#6
On 19th July I started collecting images at 7:50pm local time AEST (0950 UT) and completed the run at 8:30pm (1030 UT) and I was recording 30 sec exposures through LRGB Filters.

On 24th July I started collecting images at 7:00pm local time AEST (0900 UT) and completed the run at 10:00pm (1200 UT) and I was recording through LRGB Filters.

Although I purposely selected Quaoar for both sessions, I actually wasn’t confidently expecting to be able to record it, but as I was testing some new equipment, I figured why not pick an interesting target. Smile

As with Nereid (moon of Neptune) I have found these mag 18-19 objects very tricky to capture due to their movement against the BG stars. With the fixed stars the photons all arrive at the same location but with these moving objects, their light is spread out over an extended trail and so is much less distinct and does not reinforce across all frames like the fixed stars.

For faster moving NEO’s I can generally record a trail down to around mag 16.5 but any fainter, or faster moving, they don’t leave enough photons on my sensor to record their passage, even though I can obtain fixed stars down to mag 20 from my Bortle 6 skies in Brisbane.

I use PixInsight for the calibration and processing of the sub-frames and with these faint moving objects, the signal is usually just a few counts above background. Some of the processing tools artificially “lift” the edges of the data to increase micro contrast and this can also produce an artificially textured BG where random “noise” might well look like an object.

So, these faint objects are a real test and when I can find a sprinkling of photos above the BG levels and confirm its position with say SkyTools, then I consider it to be a good candidate, but there always remains some doubt due to the very low levels of signal above the BG.

In a clear patch of sky, I am generally more confident of an object but when it is closer to other stars, then I am less confident, as I often see spurious signals around these stars due to the effects of unstable atmospherics and imperfect auto guiding.

But it remains a fun activity and becomes especially rewarding when apps like SkyTools make it relatively easy to find, track and hopefully confirm these objects. Smile

We are going through another CV-19 lockdown in Brisbane right now, so it is therapeutic to have a hobby like astronomy where you can gather data by night and process by day – no time to get bored. Smile

Cheers

Dennis
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#7
Dennis,

I must admit that your message pains me. You talk about SkyTools doing mundane things that other software can do, such as confirming a position. But you make no mention at all of the calculations that SkyTools does to estimate which of these objects you can detect and help you choose exposure times to do it. I know that it works very well for this, because I use it myself for these very same things. SkyTools should be able to give you a very good idea of whether or not a minor planet can be detected. That's what its for.

So I am baffled as you why you aren't using SkyTools 4 fully. This is basic stuff that plays to SkyTools strengths. A minor planet has a well determined magnitude and color. Its not like a diffuse emission line object with poor data for the line strengths, which vary over the extent of object. What on earth has gone wrong that you aren't using it?
Clear skies,
Greg
Head Dude at Skyhound
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#8
Thanks for sharing all your data. It's really good to be able to enjoy the hobby and actually "do stuff". Expose and detect away and good finding!
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#9
(2021-08-02, 02:51 PM)theskyhound Wrote: Dennis,

I must admit that your message pains me. You talk about SkyTools doing mundane things that other software can do, such as confirming a position. But you make no mention at all of the calculations that SkyTools does to estimate which of these objects you can detect and help you choose exposure times to do it. I know that it works very well for this, because I use it myself for these very same things. SkyTools should be able to give you a very good idea of whether or not a minor planet can be detected. That's what its for.

So I am baffled as you why you aren't using SkyTools 4 fully. This is basic stuff that plays to SkyTools strengths. A minor planet has a well determined magnitude and color. Its not like a diffuse emission line object with poor data for the line strengths, which vary over the extent of object. What on earth has gone wrong that you aren't using it?

Hi Greg

Thanks for your feedback as the developer of SkyTools and your attempt to encourage me to take a deeper dive, I do appreciate it. Smile

I guess the short answer is that as I have moved from ST2 to ST3 and now ST4, the way I have traditionally used the earlier versions of the program has continued to meet (actually exceed) my needs.

The long answer is that a lot of my imaging is very ad hoc in nature, ill-defined and generally not planned in terms of dates, times, equipment configurations and targets. When an opportunity to set up the scope arises, I just select a target and off I go. I don’t really have Projects or Programs, so I haven’t done a deep dive into that functionality.

I think how I operate is more like a home DIY enthusiast who goes into his shed to grab a few materials he has lying around, to then knock up an ad hoc piece of furniture, versus a manufacturing plant that has a large inventory store with all the components codified which allows them to assemble a repeatable, standard product efficiently and effectively.

So far this has worked for me and meets my requirements based on my observing patterns and needs throughout the year. But, I am always open to being re-educated.

However, please don’t despair at my simplistic usage, I really enjoy what I do and how SkyTools enables me to achieve my objectives and have fun. Smile

Cheers

Dennis
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#10
Hello Dennis,

I get that you might not want to use the entire observing system (although you should consider it). But this is a really basic calculation. The Target Selection tool and the Exposure Calculator should be able to tell you which minor planets you have a chance to image. No reason to be guessing about that.
Clear skies,
Greg
Head Dude at Skyhound
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