[BAA Comets] C/2018 Y1 Iwamoto

[Juan Jose Gonzalez]

Nick, and friends,


Your interesting CCD image shows a ~ 4' coma diameter; the related 
photometry giving 10.7 integrated magnitude for 152 arcsec radius ( ~ 
2.5' ).

But the actual visual coma is larger ...

 From my recent observation :

2019 Jan. 7.26 UT: m1=8.9, Dia.=8', DC=2/, 20 cm SCT (77x).
[ Altitude: 22 deg. Sidgwick method. Tycho-2 comparison stars.
SQM : 20.7; 21.6 at zenith.].
( Alto del Castro, Leon, Spain; Alt. 1720 m ).

An updated visual brightness formula is :

m1 =  7.0 + 5 log Delta + 10.0 log r ( Nakano ).

providing m1 ~ 5.5 at perihelion.


Let's hope for a bright lightcurve ...


Best regards and clear skies,


J. J. Gonzalez Suarez


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On 09/01/2019 Nick James wrote :

> The latest astrometry means that we can now be fairly confident about 
> the path that this comet will take across the sky. The one-sigma 
> uncertainty around the time of closest approach on February 12 is now 
> only 10 arc minutes. I've posted some updated charts here:
>
> https://www.britastro.org/node/16796
>
> Note the close approach to the nice barred spiral galaxy, M95, on the 
> morning of February 11. It is still to early to say how bright the 
> comet will be since there is a very large scatter on the magnitudes 
> reported so far but if we are lucky it might reach magnitude 6 at 
> closest approach although it will be around a quarter of a degree 
> across. It is currently around mag 10.5. The attached image was 
> obtained from Siding Spring yesterday.
>
> Nick.
>
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