Dive into Ursa Major

Dive into Ursa Major

Postby edward-fraini » Sun Jan 17, 2016 10:25 am

If you don’t get excited about finding a faint fuzzy stop here, but if you are up for a challenge read on.
If asked to name the constellation you associate with galaxies the response usually would be Virgo. That’s because 217 galaxies reside in the borders of Virgo (Burnham’s Celestial Handbook V3). Virgo is thought of not because of this number but because 16 of the galaxies are on the Messier List. The 16 have an average magnitude of 9.4 which puts them in reach of most of our observing gear. We tend to focus our observing sessions on the messier list. Why we see so many in Virgo is in part due to the perspective we view it from. If you assign the line between the sun and the center of the Milky Way as the 0 deg azimuth line then the Messier galaxies in Virgo would be at an azimuth of about 50 deg so you are looking somewhat to the side of the dusty core of the Milky Way. Of more importance is that if you are standing in the plane of the Milky Way the altitude of this Messier group is approximately 80 deg altitude. This is perfect for looking beyond our galaxy. Away from the plane not through it is the best situation for seeing far away objects. Unfortunately the penalty often is the lack of good star fields to hop across.
Let’s push up our expectations one magnitude to 10.5 or two magnitudes to 11.5, which can be possible at the Columbus dark site. Then another constellation that is in the night sky for a good part of the year becomes of interest. That constellation is Ursa Major. Again citing Burnham’s Celestial Handbook we find 114 galaxies within the boundaries of Ursa Major. In this case only five of them are on the Messier List. For the Ursa Major Messier galaxies the average magnitude is 9.0 so collectively they are a bit brighter than those in Virgo. If you apply the same perspective convention as before the galaxies of Ursa Major are at an azimuth of 230 deg and an altitude of 45 deg. So again this helps with the view we have of this part of the universe. From the list of 114 we find 15 galaxies at or less than magnitude 10.5 and another 17 between 10.5 and 11.5. Looking at the location of these 32 objects you will find some loner’s but many are clustered together. Some of the groups should make interesting astrophotography fields. If you star hop across Ursa Major from the lowest RA to the highest it will be easy to move from one object to the next for the most part. That is if you can pick them out and keep track of where you are. Because they are faint and many close together you will have to pay careful attention to the eyepiece field to know you are in the right location.
Most of these galaxies will require your best practiced observing techniques. Protect your dark adaptation, not a good idea to go from laptop monitor to eyepiece. Even with that red Plexiglas. We all tend to have our monitors too bright so we can read the small print of Skytools 3. To work this list star hopping charts are a better approach. If you use a Go To system it will be helpful to know that all 32 of the galaxies selected have NGC or Messier numbers with the exception of one. That exception is IC2574 which is named Coddington’s Nebula after it’s discoverer who cataloged it in 1898 as a nebula. Perhaps a new piece of observing advice is to be patient at the eyepiece. Take the time to move your eye around and give seeing a chance to open up a perfect moment of opportunity. Good things can come from observing a solitary field for three or four minutes.
If you have an interest in spending time observing the Great Bear let me know and we will send you some list files with all the details you will need.
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Re: Dive into Ursa Major

Postby edward-fraini » Mon Feb 08, 2016 7:01 pm

A quick update-
Last Saturday I had the DOB out to Columbus and took a crack at my UM observing list. What I discovered is it is still early to work much on the list. UM is rising right in the sky glow from our neighborly flare and it has the Columbus dome in the background. Off the end of the bowl which is higher above the glow later in the night I was able to pick up a good number of galaxies at Mag 11 to 11.4 but nothing at a higher magnitude. Those that were large were seen as the classical smudge objects, the more compact revealed themselves quite nicely. Next time out I will take some notes to give a better report. It was just too cold to hold a pencil. Sunday morning everything was covered with a heavy layer of frost. My black truck was a good enough radiator of heat to have sheet ice form on the hood and sky facing surfaces. More to come

Ed
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Re: Dive into Ursa Major

Postby rene-gedaly » Sun Jun 19, 2016 3:53 pm

It's the right time for Ursa Major but the weather has been hit or miss. Any update or are you off to the next big list? Or are you like me and have several going at once!
Rene Gedaly, Forum Moderator
Texas 45-Visual, Web Tech Team, Observatory Trainer, Historian, President 2015-2017
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