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A few measurements of C/2017 T2

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About this observation
Observer
David Swan
Time of observation
01/12/2019 - 18:04
Object
C/2017 T2
Observing location
Tynemouth, UK
Equipment
200mm SCT
Hyperstar
ASI178MM
Baader UV+IR cut
Maxim DL and Astrometrica
Exposure
52 x 20s
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Comments

djswan2002's picture

My magnitude determination uses the Astrometrica R zeropoint and manual drawing of a region to capture total flux: it takes into account some extra flux not captured by Comphot's circular aperture. With a specified radius of 60 arcsec, Comphot goes for a radius of 62 arcsec and mag = 10.79.

nickjames's picture

What was the area you used for the manual magnitude estimate? The convention is that this should be the coma and not the tail although sometimes it is difficult to distinguish the two!

djswan2002's picture

It'll come out dimmer then. I didn't put 'my' figure on COBS, knowing it may not have been kosher. The Comphot one looks sensible.

* Update. 2019/12/03 morning: Brightness estimate on image reflects flux attributable to coma only.

* Further update. 2019/12/03 evening: new set of images analysed with Comphot - which found coma of diameter 3.4 arcmin and mag 10.4.

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