Re: Arp 105

Dan Crowson

Bernard, it’s that 300 feet that makes all the difference. J


We open when it is a bit windier than you can probably deal with. My scope is shroudless and it makes a huge difference if there’s any kind of wind. We also tend to look at the all-sky because there are a lot of times when the forecast says clouds and the sky is clear. Case in point is that the best skies all year (for me) were the night of 7/7 morning of 7/8. CSC showed seeing of something like 2/5.



Dan Crowson                          dcrowson@...
Dardenne Prairie MO     


From: [] On Behalf Of Bernard Miller
Sent: Tuesday, July 09, 2019 5:50 PM
Subject: Re: [DarkSkyNewMexico] Arp 105




Very nice galaxy cluster. The skies must be clearer over your observatory. I have no idea how you find enough clear skies for all these objects.





From: On Behalf Of Dan Crowson
Sent: Saturday, July 6, 2019 2:05 PM
To: 'Dan Crowson' <dcrowson@...>
Subject: [DarkSkyNewMexico] Arp 105


Arp 105 (the Guitar or I’d call it the Geyser) consists of three galaxies in Arp’s ‘E and E-like Galaxies – Connected to Spirals’ class. The top galaxy with the plume is NGC 3561A (NGC 3561N, VV 237c and others). The middle galaxy is NGC 3561 (NGC 3561B, UGC 6224, VV 237a and many others). The bottom galaxy ‘area’ is known as Ambartsumian’s Knot (VV 237b and others). These all appear to be approximately 412 million light-years away in Usra Major.


While not on Arp’s list, NGC 3550 (UGC 6214 and others) appears to be the result of something that was probably really bad in the past. This is the large galaxy near the center top that appears to have three bright cores.


Most, if not all of the galaxies in this image are part of the Abell 1181 Galaxy Cluster.


Luminance – 24x600s – 240 minutes – binned 1x1

RGB – 8x300s – 40 minutes each – binned 2x2


360 minutes total exposure – 6 hours


Imaged March 31st and April 2nd and 3rd, 2019 from Dark Sky New Mexico at Rancho Hidalgo (Animas, New Mexico) with a SBIG STF-8300M on an Astro-Tech AT12RCT at f/8 2432mm.





Dan Crowson                          dcrowson@...
Dardenne Prairie MO     




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