Object of the Week, April 12th, 2020 – err – Perhaps List of the week!
The Rose Compact Galaxy Catalogue
Constellation, RA and Dec: All are in the main northern spring galaxy region, namely Leo, Ursa Major, Coma, Virgo, Bootes, etc
Size: Ranges from <1’ to about 7’. Most are between 1’ and 3’.
Mag: Dimmest is 17.5 and brightest is 12.9. Most are between 15 and 16
What the heck is the Rose Compact Galaxy Catalogue? It is basically a small list of compact galaxy groups researched by Dr. James Rose back in the 70s during his grad school or his postdoc years. The list comprises of groups of four galaxies and the dimmest member is supposed to be at least mag 17.5. You can read a little more in the intro in my guide, which contains complete finder charts, a couple images and some brief notes. One stop shop. You can fetch it here. Print it out and bring it with you to the eyepiece or display on your favorite tablet or laptop on the field.
There are 33 compact groups easily visible from most of the world and 5 additional groups are added for southern observers. The best part of this OOTW is that at this time of the year, all are visible right now in the spring galaxy season. What list can you complete in just a few observing sessions? But take your time to tease out the details. I intend to re-observe some of the groups as I think I missed some that are probably observable with my 22”.
I’ll feature a few Rose objects. Warning – big telescope objects.
Rose 2 – A “V” shaped group of galaxies. Through my 22” under TSP skies I could not resolve any of the galaxies, but just appears an even glow. However, through Jimi’s 48”, all 4 members were easily resolved.
Rose2.jpg
SSDS image
Rose 13 (Shk 19) – An arc of galaxies with a faint star to the north. Through my 22” at the Texas Star Party, I’ve seen a 2:1 elongated glow that would be perpendicular to the star, which was not seen. Then I went over to someone’s 30”, I saw the same unresolved 2:1 glow, but this time seeing the star. Later that week, I looked through the 48” and saw all 4 members as independent objects. Three were distinct “stellar” cores with one elongated glow with a stellar core. This was one of the objects in Larry’s Advanced Observing List for TSP 2009.
Rose13.jpg
SDSS image
Rose 33 – This group is literally standing next to a mag 7.9 star, at most is 30” away. Yes, arc seconds, not arc minutes. The 4 members range from mag 15.9 to 17.4. Through my 22” and at 821x, only one of the 4 was seen. It was popping in and out, more out then in. The following year, I looked at this object with Jimi with his 48” and we were able to see all 4 pretty easily. The amazing thing object how compact this object is that Jupiter in most cases could “occult” the entire group plus the mag 7.9 star. That is how small this group is.
One note: After looking at the recent SDSS image, one of the labelled components appears as a star, component A. I’m not sure.
Rose33DSS.png
DSS image
Rose33.jpg
SDSS image
Now go grab a copy of The Rose Catalogue of Compact Galaxies and as always, give it a go and let us know.
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