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Observation by Alan Snook: Visual identificaion of Hoag's Object PG...

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Alan Snook


Alan Snook


2021 Apr 18 - 01:00


2021 Apr 22 - 10:24


Hoag's Object (PGC 54559)

  • 50cm f4.1 Dobsonian + 8mm TV Ethos.

East Kent

Target name

Hoag's Object PGC 54559


Visual identificaion of Hoag's Object PGC54559

About this image


I tried for this galaxy every spring from 2014 to 2017 without success. On 2021 April 6 I tried once more and I was confident of sighting it with averted vision. However I wanted to re-perform the observation before being certain of success, and this is it. Hoag’s core is a very difficult, very faint, small spot of light. Seen intermittently with AV say 25% of the time, but held for periods of many seconds. Saw nothing with direct vision. Outer ring not seen at all.

Why success now and not before? What’s changed? The number of aircraft flying through my airspace is much reduced. The sky is visibly cleaner than pre pandemic. Daytime skies are blue, not laced with persistent, spreading contrails.

CAA aircraft movements data during February 2019 and February 2021 (the latest published):   

                                                  2019               2021

Heathrow                                  35,347             8,166

Gatwick                                    19,947                944

Additionally we have been in unseasonal dry artic air for some time now. April has been colder and substantially drier than average. My visual limiting magnitude estimated using the stars in and around the ‘box’ of Ursa Minor was at least 6.5m.

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Paul Leyland
Paul Leyland, 2021 May 01 - 16:08 UTC

The three Q stars, from top to bottom, have Gaia-EDR3 g magnitudes of 16.60, 15.07 and 16.13 respectively. The one labelled 106 is 10.55 in Gaia-EDR3 so the other three are likely to be fairly close to the visual magnitudes too.

Alan Snook
Alan Snook, 2021 May 09 - 09:32 UTC

Thanks Paul, that's good to know. I've got down to 16th mag on rare occasions. My record is Hickson 56D which is 16.8m. JB Sidgwick put the limiting magnitude for 50cm at 16.3m, but EJ Hartung reckons 17.0m, so we're on the limit.

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