M81 Galaxy Group.
I'm moving on now in my project viewing the Spring Milky Way groups of galaxies in a wide field setup. I started with the galaxies at the deep gravitational well of the Virgo Supercluster (~15 Mpc - 50 Mly distance), and before that, I observed the infalling galaxy associations Leo-I (10 Mpc – 33 Mly) and Leo-II (22 Mpc – 73 Mly) in the Leo Spur of galaxies, preceding the Local Sheet on our night sky.
Tonight, I’d like to focus on the nearby galaxy groups in our own Local Supercluster, much closer by (~5 Mpc - 15 Mly), starting from the north with the M81 Group in UMa, then moving south to the M101 and the CVn-I Galaxy Groups in Canes Venatici, and finally ending up deep south with the M83 Group in Hydra. Being ~3x closer to our Milky Way than the Virgo Attractor, the galaxies in these local groups show up more widely scattered on the night sky, but they also offer greater detail in structure as compared to the more distant galaxy groups.
So tonight is 2019-04-01, 23:00 CEST DST UT+2, i.e. the first night in April this year, and we have moved from normal astronomical time to summer time (aka DST: “Daylight Saving Time”). The temp. is a fresh and cool 2⁰C, the humidity is relatively low ~78%, and the DewPt is down at -2⁰C. The 11% - 26dy Moon is buried way down 48⁰ below the N horizon, so the LP is quite good for my suburban backyard (NELM 5.8 - SQM 19.6). We’re still in the wake of a weak high pressure, guiding clear polar air down over Denmark, resulting in another exceptionally transparent (5-6/7) and calm night (seeing 8-9/10). Such perfect DSO nights are rare at our latitudes, but hey! -- here is one
The Great Bear (UMa) is culminating right at this time in the late evening, jumping so to speak over the Lion (Leo) directly towards the South. In fact, Merak (Beta Uma) is passing close to Zenith right now, so observation of the M81 Group does not get better than this for my 56⁰N latitude. (I’m happy though for my 90⁰ Zeiss Amici diagonal, without which observations in UMa tonight would be quite neck straining...). Well then, better get on with it!
I point my 4” refractor with a 41mm ETH eyepiece towards M81, the largest galaxy in the group. The M81 Group counts 41 members, including 4 NGCs: 3031 (M81), 3034 (M82), 3077 and 2976. The two large Messier galaxies (M81-M82) are clearly seen using glass only, and the main structure of both galaxies can be glimpsed with AV. With my image intensifier on top of the 41-ETH, all four mentioned NGC galaxies can now be studied in greater detail (though I can only frame 3 galaxies in the 2⁰ FOV @ 15x magnification).
Edited by AllanDystrup, 04 April 2019 - 07:25 AM.