Comet 103P Hartley

[russ]

Liking that shot Russ!

Thanks Nick

It's been a great comet this one, really enjoyed it visually too.

[NickH]

Yeah, it was nice in the 12" Dob before that went off down to the costa-del-sol, but as I am tracking with a 4" refractor now, and with the Moon, the view has been a bit "underwhelming", imaging though, the narrowband set just punches through the Moon like butter, and it's lit up like xmas in OIII. The CLS filter is good too

[S.A.M]

Just read you reply Nick, in four goes I have not been able to spot the comet from Swindon. Next time I go out I will try with either the CLS or OIII filter and see how that makes out. Of course it could be just my eyes playing up! Thought I had seen the comet at the beginnig of the month but that turned out to be M31.

[NickH]

Just got the official IAU CBAT on the rotation rate...to say I am chuffed would be an understatement, just gotta go with first calculations and gut instinct in future and not be swayed by others who are more experienced than me...as in this case,...well Just see the image...from my FB profile on Oct 16th... and then read this (which came out today Oct 21st)

>>

COMET 103P/HARTLEY

M. F. A'Hearn and L. M. Feaga, on behalf of the DIXI/EPOXI science team,

report that routine sampling with the Deep Impact Medium Resolution Imager

(MRI) enabled the discovery of an unusual cometary phenomenon on comet 103P

(sometimes known by its old name, "Hartley 2") that may recur. Between Sept.

9 and 17, the outgassing of CN, as acquired with the CN filter (sensitive to

both the dust continuum and CN gas), increased by a factor of five and then

slowly decreased, returning to its prior trend line by Sept. 24. There was

no apparent change in the reflected continuum, acquired with a clear filter,

other than a small, gradual increase consistent with the increases before

and after this period in both CN and dust due to the decreasing range from

the spacecraft to the comet and the increasing activity of the nucleus as it

approaches the sun. This long-duration, gradual increase and decrease of

gaseous emission without any increase in the dust is very unlike typical

cometary outbursts, which have sudden onsets and are usually accompanied by

considerable dust. It is dissimilar to the activity observed at comet 9P

(old-style name "Tempel 1") and not apparently associated with the dust-free

CN jets observed in this and other comets. Thus it is not like anything

that the authors are aware of in any other comet. Observers should be aware

of this type of activity when planning observations and interpreting their

data. In addition, H_2O and CO_2 have been unambiguously detected in the

coma using the High Resolution Instrument infrared spectrometer (HRI-IR) on

Oct. 16.

N. H. Samarasinha and B. E. A. Mueller, Planetary Science Institute; and

M. F. A'Hearn and T. L. Farnham, University of Maryland, obtained CN

narrowband images at the Kitt Peak National Observatory 2.1-m telescope from

Sept. 30 to Oct. 4 UT. The enhanced images clearly indicate the rotation of

a jet feature centered around a position angle near 30 deg. This is

presumably the same feature reported by Knight et al. (IAUC 9163). This

feature moves from the northwest towards the earth's direction, almost towards

the line of sight, and then moves to the east-northeast and finally to the

far side before starting the cycle again; while on the far side from the

earth, its level of activity decreases significantly before starting to

increase again. The repeatability of the CN morphology is consistent with a

periodicity around 17.6 hours. Small differences in the morphology during

some cycles suggest that there may be a slight rotational excitation, probably

a low-excitation short-axis mode. The CN coma morphology is compatible with

a nucleus having a high obliquity and a retrograde rotation and suggests a

low-to-mid-latitude active region in the negative hemisphere. A preliminary

estimate for the rotational angular momentum vector is R.A. = 345 deg, Decl.

= -15 deg, and the uncertainty is as large as 20 deg in some directions. The

continuum images from the same observing run show the dust tail, but no clear

jet features are discernible.

M. Knight and D. Schleicher, Lowell Observatory, report new narrowband

imaging of comet 103P using the Hall 1.1-m telescope at Lowell Observatory.

Further to Knight et al. (IAUC 9163), the CN gas feature was centered at

a position angle near 355 deg on 2010 Aug. 13-17, near 350 deg on Sept. 9-13,

and near 350 deg on Oct. 16, 17, and 19. Numerical modeling of these position

angles and the sense of rotation yields a rotation axis having an obliquity of

about 15 deg in the comet's orbital frame, corresponding to R.A. = 310 deg,

Decl. = +80 deg, assuming principal axis rotation. Preliminary modeling

suggests that the CN jet originates at a latitude of +50 to +60 deg. An

additional, fainter CN feature was seen towards the southeast in the October

1.1-m-telescope images and in additional images obtained Oct. 12-14 on the

0.8-m telescope at Lowell Observatory. For this pole solution, the comet's

maximum sub-Earth latitude is attained in early October, resulting in an

overlap of the two CN features towards the east, as was observed in the Oct.

12-14 images and possibly explaining the morphology described by Samarasinha

et al. (above). With this pole solution, the sub-earth latitude should be

near the comet's equator at the time of the EPOXI spacecraft encounter,

yielding side-on corkscrews.

[firefiten]

Russ, where are you to get such a stunning shot...I thought I could see alot of stars, you've put me to shame...lol

[russ]

Outskirts of a town Took some processing to loose the LP.

[CaptPaul]

It's in Auriga at the moment or at least it was Wednesday morning. This is the image i took yesterday morning. It was on its way towards the open clusters.

Thanks! im gonna try spot it this weekend.

Great picture!! I bet there will be some other great ones if it passes by the clusters and can be all in the same view.

[russ]

I may have read the chart wrong, but it appears Hartley will be near M37 on the 23rd October. Great photo op

At the moment it is not far from M36. I wonder if a 135mm lens will frame Hartley, M36 and M38?

[SirFoo]

Found M37 which is quite faint itself but could not find the comet. Too much moonlight methinks.

[Star child]

I think i got my first glimpse of tjhe comet last night, well i saw a faint fuzzy object which was in roughtly the right area, i thogut that might be it but there was something else that caught my eye, below and to the right was a even fainter more diffuse object, i kept thinking my eyes were playing up so i looked away then back again and it was still there, i did this a few times to make sure! then i checked a few finder charts and i think the first thing io saw was M37 and the fainter blur could have been the comet, it seems to tally with the charts, at least i found one thing, my new binouclars must be good if i can see M37 with a full moon illuminating the sky!

Im going to try again tonight as i think its going top be near K Aurigae which should make a handy guide star.

[Star child]

Woo hoo, I got the comet at last! I looked at K Auriga, and noticed another star above it and to the right (which is HIP 28930) inbetween these stars i noticed a faint triangle of stars made of HIP 29435A which im calling the top left star in the triangle, the top right is HIP 29224A and the one at the bottom in the middle is 29352 below that is a even fainter star which has no name or number, its a mag 8 star and the comet was just below that, infact i think it may have obscured that star earlier, having checked stellarium there are no fuzzy blobs in that area so it can only have been the comet, plus thats where the finder charts showed it would be! (although i find finder charts hard to read becuase they never seem to be orientated how im seeing things with my eyes) I also managed to spot M37 and M36 which were prtty much in a strait line above the comet, and i didnt realise if i went up just a bit further i would have seen M38 as well!

[Andrew*]

I too saw it last night. Looked for ages, and finally showed up a very small, pretty faint, nebulous blob, between Auriga and Gemini. There are no bright nebulae in the area, so it can only have been the comet. I could see no particular details, and no colour. I think if it was the comet, only the nucleus was visible.

I was viewing with my 12", but the almost full moon was not so far away and it was very low in altitude, right in Aberdeen's skyglow.

Does this sound about right to others?

Andrew

[QldLiz]

Checked it out after midnight this am, and was looking brighter than when I saw it 2 weeks ago. Then it was faint, large, round and nebulous, but now was smaller, brighter and more condensed.

View improved with a comet filter, and thought I could ..... maybe see a fan shaped tail with averted vision .... or could have been wishful thinking.

[cathalferris]

I was coming home from dinner and drinks at a friends house on Saturday night/Sunday morning and I saw it was clear out. I brought out the 15x70 binoculars, propped them on a fencepost, and I could quite clearly see the comet, probably between 10'-15' wide of a coma, with a nice condensation to a clear nucleus. No indication of any colour, and no real inidications of a tail, though I may have seen hints of a tail in the expected direction with averted imagination.

[Star child]

I think my eyesight is not good, or its my bino's, but I managed to find the comet last night to, weather conditions were not great for observation, there was a lot of cloud around but it was blowing over fast and there was the occasional clear spell, thats when i managed to see the comet but, it was visible but i certainly could not see any evidnece of tails or condensed comas, it was just a very faint fuzzy blur.

Maybe from a dark sky sight it would have been better, I was observing from urban area.

Still it was nice to see it again (only observed it once before)

Is the magnitude right on heavens above? it looked fainter than the given magnitude (5.4) but probably becuase its more diffuse.