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  #21  
Old 09-02-2013, 03:43 PM
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Position - 10th Feb 2013, 0400 hrs EST (1800 hrs UT)

If your an early riser and your skies are clear, you might be able to catch three comets. Comets Lemmon (C/2012 F6), Panstarrs (C/2011 L4) and if your scope is large enough, Linear (C/2011 F1).

You will have to be quick, as morning twilight will start to wash out the faint objects around 0415 hrs EST (1815 hrs UT).
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  #22  
Old 09-02-2013, 05:08 PM
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instead it looks a little like a difuse globular cluster with a bright core.
Tried last night but saw nothing where Stellarium (with comet data downloaded) said it should be - using a 10" SCT. However, nearly a degree away in Dec, and with pretty similar RA, I saw an unidentified "diffuse' object with bright core, but no distinguishable tail. Colour seemed about right going by people's images.

Does anyone know if Stellarium's data is accurate?

Tonight (sky permitting) I'll try using Stu's chart.
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  #23  
Old 09-02-2013, 06:01 PM
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Does anyone know if Stellarium's data is accurate?
Well, I'll answer my own question.

I rolled Stellarium forward to 09-02-2013 2030 EST and lo-and-behold, it put Lemon in a different location compared to Starry Night: similar RA but out by ~45' in Dec - Stellarium puts Lemon almost on top of HIP 112911, but Stu's chart from Starry Night puts it half way between HIP 112911 and Beta Octans.

Time and timezone are correct, so that's not it.
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  #24  
Old 09-02-2013, 07:44 PM
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Does anyone know if Stellarium's data is accurate?
I can't comment on Stellarium, even though it is loaded on my machine. I find Starry Night easier to use. For what it's worth, I can vouch for Starry Night's accuracy in this case. Every clear night, I have relied on SN to find Lemmon in my light polluted urban location and it has been spot on.

Starry Night is not always right. It is not accurate when dealing with predicted positions for NEO Asteroid 2012 DA14. It goes against their own policy of not adding NEO's to their database, but this time they did and users who trust it will miss out on seeing this asteroid. It's the only time that Starry Night has been left wanting. Instead I am using the data from JPL for my location and have plotted it onto a paper star chart.
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  #25  
Old 09-02-2013, 08:06 PM
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Stu, thanks for the updates, you're doing a brilliant job!
I find Starry Nights easier to use than Stellarium too and their comets have seemed spot on so far.

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Suzy, I am not into facebook but have had a look at the IIS public page and I love your work.
Thank you

Glen, tail visible now in binoculars hey? I'll look extra hard for it, tho I don't know if it'll show up in 10x60's and light pollution.
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  #26  
Old 09-02-2013, 09:32 PM
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Originally Posted by Astro_Bot View Post
Well, I'll answer my own question.

I rolled Stellarium forward to 09-02-2013 2030 EST and lo-and-behold, it put Lemon in a different location compared to Starry Night: similar RA but out by ~45' in Dec - Stellarium puts Lemon almost on top of HIP 112911, but Stu's chart from Starry Night puts it half way between HIP 112911 and Beta Octans.

Time and timezone are correct, so that's not it.
Hi, I took photos of the comet last night with a 300mm lens. I just compared the starfield in Stellarium to the same actual time of the photo and the position matches very closely with the surrounding stars.
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  #27  
Old 09-02-2013, 11:01 PM
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Quote:
Originally Posted by Astro_Bot View Post
Well, I'll answer my own question.

I rolled Stellarium forward to 09-02-2013 2030 EST and lo-and-behold, it put Lemon in a different location compared to Starry Night: similar RA but out by ~45' in Dec - Stellarium puts Lemon almost on top of HIP 112911, but Stu's chart from Starry Night puts it half way between HIP 112911 and Beta Octans.

Time and timezone are correct, so that's not it.
RG, CdC with the latest elements puts C/2012 F6 half way between HD215587 (HIP112911) and HD214846 (HIP112405, Beta Oct) at that time. Stellarium does too.
When did you last update the solar system data?
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  #28  
Old 09-02-2013, 11:04 PM
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Thanks Suzy, with your guidance, I just picked it up in 12x60s last Thursday night around midnight. Bit of a challenge since I was looking through kms of Sydney light pollution including the entire CBD!
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  #29  
Old 10-02-2013, 01:41 AM
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When did you last update the solar system data?
Friday arvo - fresh download from the Minor Planet Centre - for use that evening.

Edit: Just updated again, with overwrite enabled, and saw C/2012 F6 jump significantly toward Beta Octans. Was I being naive in thinking that Solar System (Comet, Asteroid) data contains velocity data? That is, it's not just a single static point that's only updated for Earth's rotation? They wouldn't do that, would they?

Last edited by Astro_Bot; 10-02-2013 at 01:52 AM.
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  #30  
Old 10-02-2013, 03:06 AM
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1.5 degree tail

The tail on Comet Lemmon was about 1.5 degrees long at 3am DST (16 UT) this morning.
I looked at it with a 102mm refractor and a 9mm EP (55x).
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  #31  
Old 10-02-2013, 08:24 AM
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Position -10th Feb 2013, 2030 hrs EST (1030 hrs UT)

Some more star charts for tonight.

If you are new to Astronomy, it might be easier to locate globular cluster 47 Tucanae and move your bino's / scope until you pick up star Beta Octantis.

If you are observing using bino's from light polluted skies, ignore the tail. It will look like a smaller version of 47 Tuc.
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  #32  
Old 10-02-2013, 10:44 AM
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I updated MPC comet data again a few minutes ago and again watched Lemmon jump, but not as much as last night. Either the MPC data is a bit out and needs constant updates to correct errors, or the way Stellarium uses the data allows errors to creep into the system quite quickly. I watched the comet move in a ~100x timelapse and it moved smoothly relative to the star background.

Anyway, with a fresh comet data update and rolling time forward to 2030 this evening, Stellarium now agrees closely with Starry Night. Thanks to those offering advice and feedback, and thanks, Stu, for those charts.


(PS: I'm using Stellarium 0.11.3 in Linux - 0.11.4 isn't compiled for my distro yet).
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  #33  
Old 10-02-2013, 11:05 AM
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Here's a great binocular map, thanks to Ian Musgrave who posted it on facebook from his Astro Blog site today. He also writes the Southern Sky Watch page and is also part of this forum. Lol it's a shameless plug for a brilliant astronomy event page!


BINOCULAR MAP FOR COMET LEMMON.

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  #34  
Old 11-02-2013, 05:25 PM
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Position -11th Feb 2013, 2100 hrs EST (1100 hrs UT)

Charts for tonight taken from Starry Night v6.4.3
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  #35  
Old 12-02-2013, 02:16 PM
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Position -12th Feb 2013, 2100 hrs EST (1100 hrs UT)

Charts for tonight taken from Starry Night v6.4.3
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  #36  
Old 12-02-2013, 02:31 PM
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Charts for tonight taken from Starry Night v6.4.3
Stu, you can get SN to draw the orbit, or at least my version will. That makes comets and asteroids easier to spot.
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  #37  
Old 12-02-2013, 03:42 PM
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Stu, you can get SN to draw the orbit, or at least my version will. That makes comets and asteroids easier to spot.
The orbit line's not much good as a predictive tool in Starry Night because (naturally) it doesn't take account of precession - ie while the orbit is fixed, the background stars appear to shift in position night-to-night (see attached).

Cheers -
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  #38  
Old 12-02-2013, 04:09 PM
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Stu, you can get SN to draw the orbit, or at least my version will. That makes comets and asteroids easier to spot.
Starry Night Enthusiast v6.4.3 does not provide an option to support viewing of multiple comet locations over a set period of time. Maybe they will provide this option when they release v7.


I really like Starry Night, but I now have two items that could be improved when they release their next major upgrade:
  1. Accurate handling of NEO orbital elements (eg Asteroid 2012 DA14)
  2. The ability to do what your planetarium software does for object positions over multiple days.
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  #39  
Old 13-02-2013, 04:21 PM
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Position -13th Feb 2013, 2100 hrs EST (1100 hrs UT)

Charts for tonight taken from Starry Night v6.4.3

I hope your skies are clearer than those in Brisbane.
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  #40  
Old 14-02-2013, 06:36 PM
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Position -14th Feb 2013, 2100 hrs EST (1100 hrs UT)

Charts for tonight taken from Starry Night v6.4.3
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