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Messier 102 - the "Spindle Galaxy"

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About this observation
Observer
David Davies
Time of observation
01/06/2019 - 23:00
Object
Messier 102
Observing location
Cambridge, UK
Equipment
8" Ritchey-Chretien at 1660mm focal length
QSI 583 CCD camera with Astrodon filters
Exposure
23 x five-minutes luminance and seven each of five-minutes RGB subs, all binned 1 x 1
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The Spindle Galaxy was discovered by Pierre Méchain on 27th March 1781. Méchain described the object as a “nebula between the stars Omicron Boötis & Iota Draconis,” adding that “it is very faint; near it is a star of the sixth magnitude.”  Méchain probably meant Theta Boötis, not Omicron, which contributed to the subsequent confusion around the identity of M 102. Omicron Boötis is more than 40 degrees away from Iota Draconis, which makes the possibility of an error very likely. Méchain reported the discovery to Messier, who added the object to his catalogue. 

The confusion about the object started two years later, in May 1783, when Méchain wrote to Bernoulli in Berlin saying that the listing of M 102 was a mistake and that the object referred to was a duplicate observation of M 101. One can imagine that M 102 could not be found due to the error in the original observation notes. It was the French astronomer Camille Flammarion who identified NGC 5866 as M 102 in his “List of the Messier Objects,” published in L’Astronomie in November 1917, arguing that the Greek letter Omicron (ο), written down by Messier, was in fact a lowercase Theta (θ).  This was probably correct because the object found at this location corresponds to Messier’s description of M 102.

This galaxy was independently discovered by William Herschel in 1788. Herschel determined the position of the object on May 5, 1788, describing it as “very bright. Considerably large. Extended. Following [east of] 2 stars.”

M 102 is a spindle-type galaxy, seen edge-on and around 41 million light years distant. It is magnitude 10.7 and 6 x 3 arc minutes in extent. In this image David has captured the pearly white glow of the halo around the galaxy, the warp at the eastern (right) edge of the dust lane, something of the blue glow of star-forming regions at the western edge of the dust lane and the orange glow of old stars in the core.

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BAA Observing Sections Comet

C/2017 T2 PANSTARRS

C/2017 T2 (PANSTARRS) was discovered at 20th magnitude in 2017 September when it was it was 9.3 au from the Sun. It is heading for a perihelion at q=1.6 au in early 2020 May. The comet is currently in conjunction but it was apparently brightening rapidly when last seen in April. It should become visible from the UK in mid July very low in the morning sky as it moves slowly NE in Taurus. By then it will be 3.8 au from the Sun and 4.5 au from the Earth. It moves higher in the sky and will be visible throughout the autumn, winter and spring as a circumpolar object and it remains well placed in Ursa Major at perihelion (see this chart). Magnitude estimates through the late summer and autumn should help to constrain the lightcurve.

An analysis by Jonathan Shankin on limited data suggests it could be anywhere between 9th or 2nd magnitude by the end of the year. Definitely a comet to watch when it returns from behind the Sun.

C/2017 T2 imaged by Peter Carson on 2019 January 28.9. At that time it was around 16th magnitude. Further images are available in the section archive.

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Solar diagram 15-5-19_20190516_0001

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About this observation
Observer
Monty Leventhal
Time of observation
15/05/2019 - 22:40
Object
Sun
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SUN HALPHA 20190515 0940-1942UT CFB

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Observer
Carl Bowron
Time of observation
15/05/2019 - 09:40
Object
Sun
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SUN HALPHA 20190515 0923UT AR2741 CFB

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About this observation
Observer
Carl Bowron
Time of observation
15/05/2019 - 09:23
Object
Sun
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SUN HALPHA 20190515 0921UT PROM CFB

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About this observation
Observer
Carl Bowron
Time of observation
15/05/2019 - 09:21
Object
Sun
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SUN HALPHA 20190515 0841UT AR2741 CFB

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About this observation
Observer
Carl Bowron
Time of observation
15/05/2019 - 08:41
Object
Sun
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SUN 20190515 0820-0822 AR2740-2741 CFB

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About this observation
Observer
Carl Bowron
Time of observation
15/05/2019 - 08:20
Object
Sun
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