C/2009 K5 McNaught Near Coathanger

[martinastro]

Over the next three nights comet C/2009 K5 McNaught can be found very close to the the coat hanger asterism in Sagitta during the early morning hours making for a nice visual and photo opp. The comet is brighter than mag +9.5 with a distinct green coma with no tail. Certainly worth a look if it clears later and with the Moon low in the west.

[Roman White]

Hi Martin,
I had a look at this comet tonight, agree with you, it is nice. By the way, I'm very excited because it's my first opportunity to see comet since Sep.2009 
Also tried for 81P/Wild, but it was low in SW, within light pollution. And the Moon will get closer soon, so need to wait again.

Will post a report about C/2009 K5 as soon as possible (need some time for sleep and for our sidewalk astronomy next evening)

[Roman White]

Oops, I forgot to put here a report of Mar.27, so here it is now together with another observation of May.02.
Unfortunately I had very little time for comets this spring, so these 2 observations are the only I have. Had also a few unsuccessful attempts for 81P recently.

I am very glad to see this comet moving towards the Northern pole! 

March 26/27 - observed from 04:00 till 04:24 (UT+2)
2010 Mar.27.10 UT: m1=7.9, dia.=&6', DC=2/?, no tail, 20x90B
[naut. twilight beginning, good transparency, Bortle class 5/6]
Altitude 46°. ML=11.4m
Comet was nicely placed in Sagitta within Milky Way, though I have found it enough easily. Finished my observing session at dawn. ZNELM = 5.6m.
Coma was looking faint (twilight) and diffuse, probably not precise DC estimate.

May 2/3 - observed from 00:30 till 01:18 (UT+3)
2010 May 02.91 UT: m1=8.0, dia.=5', DC=4, no tail, 20x90B
[very good transparency, Bortle class 5/6]
Altitude 45°. ML=11.6m
Have easily located it not far away from beta Cephei. ZNELM = 5.5m. North and NW are least light polluted directions at my observing site, so I was lucky here too.
Comet stood out quite clear from the background, certain brightening towards centre, faint (~11m) nearly-stellar condensation. Underestimated DC if compare with other observers (e.g. S.Yoshida), don't know why. Had significantly moved relative to stars during that time.
In 76mm reflector (35х, 56х) it was almost the same, only with lower surface brightness.
Also tried to photograph it at 1:30 (28x15sec@ISO1600 f/4.5), but despite the magnitude limit was ~10.0m, couldn't see the comet in stacked image.

Sketch


Magnitude estimates are based on 4-6 Tycho-2 stars each time (VSS method). Naked-eye limiting magnitude (ZNELM) was estimated with IMO method (triangles).

In ICQ format:
IIIYYYYMnL YYYY MM DD.DD eM mm.m:r AAA.ATF/xxxx &dd.ddnDC &t.ttmANG ICQ XX*OBSXX
   2009K5  2010 03 27.10  S  7.9 TK  9.0B 5  20 & 6    2/           ICQ XX KOSXX
   2009K5  2010 05 02.91  S  8.0 TK  9.0B 5  20   5   s4            ICQ XX KOSXX

[martinastro]

Well done Roman and congrats on the observations, it feels great to read about comet observing again. Don't worry if your DC estimates contrast with those of others, mine usually do too. The DC value can change with various telescope apertures, those other guys are probably using bigger scopes so DC will be different, especially in the case of the more diffuse comets.

[Roman White]

Thanks Martin

The DC value can change with various telescope apertures, those other guys are probably using bigger scopes so DC will be different

Oh yes, Seiichi Yoshida used 400mm scope