Observations of IC504

These are the observations available for IC504. If you have any of your own that you'd like to submit we'd love to put them on the website.

• IC 504 group in Hydra

  I was looking forward to this month’s challenge, because the chosen galaxies were IC galaxies. It is always interesting and a challenge to explore IC galaxies as a change to NGCs. Noting that they are magnitude 13 galaxies meant I would need a decent night. The night 20th March presented a NELM of 5.5 and for GB skies a night with slightly lower humidity levels.

  I headed for IC 504 first as it is the brightest and immediately picked it up – x181. At x470 it clearly had a core, which I describe as a “soft core” – bright central area and gradually fading further out. IC 504 sits at the end of a delightful curve of mag 11/12 stars – useful to locate the galaxy as well as a “pretty sight”.

  Putting the 13 ethos back in I was able to just locate IC 505 and IC 506 using AV, but it required a magnification of x294 to be certain of their position. At x470 I could detect a small, tight core in IC 505. Lying between these two galaxies is a delightful collection of mag 14 stars.

  Just for interest I wondered if the 3 PGC galaxies would be detectable (all magnitude 15+). PGC 23509 is at the other end of the star curve from IC 505 and with concentrated viewing I spotted a faint patch of fuzz. Next up I was able to locate PGC 23493, using averted vision (AV2). Finally after much squinting I kept getting hints of PGC 23510 (AV3).

  

  The following night, under similar conditions I was observing with Andrew Robertson, using his driven 600mm Dob. The observation went something like this: Andrew at the eyepiece, myself on the ground.

  Mike: see the line of curved stars at the top of the fov

  Andrew: yep.

  Mike: look to the left of the curve.

  Andrew: got it.

  Mike: look to the right of the curve.

  Andrew: got it.

  Mike: now look to the far right of the fov.

  Andrew: got them both.

  Mike: see the brighter star in the centre of the fov and look a little below..., Yep got it before I finished my sentence.

  Mike: now look below 504 and..., Yep got it was heard again before I finished my sentence.

  So in the space of 5 minutes Andrew saw all 6 galaxies, whereas it had taken me the best part of 30 minutes teasing them out in my 500mm Dob. It just goes to show the considerable greater light gathering of a 600mm Dob over a 500mm Dob.

  After this enjoyable adventure, we wandered off to the Twin Quasers in Ursa major – now that did take a bit more effort, including using AV but wonderful to see an object 8.7 billion light years away.

  Mike Wood (and Andrew Robertson) - 23 March 2017