Three observations in my log for NGC3507, one for NGC3501. This pair is Holmberg 224 and KPG 263.

First observation for NGC3507 was in 2009, in my 12" SCT @ 191x / 26' under Dutch skies at a meager SQM 20.19:

A relatively large, round patch, no detail visible. Directly ENE of the middle is a mag. 12 star (TYC1433-01372-1), slightly farther to the SSW (approximately 1/10 FoV) is a mag. 11 star, twice that distance towards the NNE is a mag. 11.5 star.

Second time around was 2015 in the Alps, 14" SCT @ 168x / 29' and a pleasing 21.65 on the SQM. Session notes state: "Clear and a million, second night in a row that conditions are outstanding". As can be expected, the galaxy revealed a lot more detail:

Sharing the FoV with the galaxy NGC3501, almost 1/2 FoV to the SW: A round glow, gradually brighter in the middle. The nucleus is faintly visible with AV. ENE of the middle is a mag. 11 star (TYC1433-01372-1). With AV the outer halo of the galaxy is clearly visible and it is clear that the brighter core is slightly elongated east to west.

Third observation was only 2 years ago, from my light polluted backyard with the SQM meter pegging at a whopping 19.66. Again my 12" SCT @ 191x / 26. This time, I observed little more than the core and the superimposed star even appeared to be detached of (that what was visible of) the galaxy:

A faint, round glow directly west of a mag. 10 star (TYC1433-01372-1). This foreground star appears detached from the galaxy. With AV subtly and gradually brighter in the middle, sometimes the brighter core jumps into view but can not be held. No nucleus visible and no arms can be discerned.

My only observation for elongated NGC3501 was that superb night in the Alps:

Sharing the FoV with the galaxy NGC3507, almost 1/2 FoV to the NE: A clearly NE-SW extremely elongated streak, brighter in a core that is elongated in the same direction and that is slightly SW of the middle, no nucleus visible.

holm224-1.jpg holm224-2.jpg holm224-3.jpg

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