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3/09/2011

Sites to Help in Observing the Virgo Cluster; Observing the Jet in M 87














The Jet from the Black Hole in Messier 87 in the Virgo Cluster.














Hubble Space Telescope view of the Jet in Messier 87 (NASA Image).

One of the things on blogging when I am not reporting my own observations, is trying to come up with material that I think is interesting. Some is, some isn't. However, with Daylight Savings Time coming up on Sunday (YUCK, BOO, etc.) here in the U.S. (wish they would leave it alone or put it back to the first of April and October when the clocks change at minimum) and spring coming on or around the 21st of March, the thoughts of many lads and lasses aren't turning towards each other, but upward to the Virgo Cluster of galaxies. Yes, spring is galaxy time as Virgo, Ursa Major and many other wonderful constellations that contain great galaxies to view also (actually, I've found fall to be pretty enjoyable also).

So this post will focus on the Virgo Cluster of galaxies while later posts near full moon will focus on other constellations. My goal here is not to reinvent the wheel here, as there are some wonderful observers who are far more skilled than I who have shared their thoughts. So I will be presenting links to their websites with a summary of their web page.

The first link comes from SEDS and has some terrific links built into it. It has been five years (2006) since the information has been updated, but it is still quite useful for the visual amateur. There is a nice map that Charles Messier put together as seen here:




















The site briefly discusses Messier's and Messier's peer ,Pierre Méchain who said he had seen more nebulae than Messier had in a 1783 letter, though what Pierre Méchain saw has been lost to history, at least for now.

The site has an image of the galaxies around M87 which is large and bright in the center, and then a list of top links that you can use and investigate if your wanting to get into this area or look at fainter objects.

If your new or find this area confusing, then SEDS site Observing the Virgo Cluster is a welcome site. The offer four different routes to exploring this region as offered by four authors, each who has their own unique way of navigating, which is true of each of us for the most part.

In this link you will see Scott Davis' sketch of the galaxies in the region and labeled (at the bottom, the top image is inverted).

Focus on Downtown Virgo is a great site for a this area also. It has an image again with the galaxies labeled. It begins with all the Messier galaxies, and then has a map for galaxies brighter than the 12th magnitude for larger scopes. It finally describes how to see the jet in M87 and states that a 10 inch with great seeing, quoting Jay Reynolds Freeman on this. I feel that my 14 inch can give it a good go and I know in the right conditions my 20 inch will show me the jet.

The Virgo Mainline by Steve Gottlieb (one of the great visual observers of our day in my opinion) offers a written description of navigating this area. Steve's observations are used in the NGC/IC Project, a site I highly recommend you use if your not.

This map by Jan Wisniewski gives an excellent overview of galaxies in the Virgo cluster. I must point out that Jan recommends using this map to identify individual galaxies. The easiest way, click on the galaxy and it will take you to a new page with a finder chart that is zoomed in more. This is just such a fantastic link and I highly recommend you use it.

Now for observing the jet in M 87. Steve Gottlieb and his friends have a site called Adventures in Deep Space, a site that should be your top site or in your top 3 for observing. In the site is a wonderful description of what it takes to see the jet in M 87 (this is the galactic material being spewed out by the enormous Black Hole at the center of M 87; see Astrobites as they have some interesting reviews of papers on these jets in large galaxies). Dave Healy saw it with a 16 inch Meade visually, and states "If I could see the jet in a 16-inch, it probably won't require someone with Steve O'Meara's eyesight to see it in a 14-inch or even a 12-inch, given a dark site."

Also at the link at the bottom, Roger Clark states at the link what it took for him to see the jet:

"12.5 inch f/6.1 Dob from the Colorado Rockies (about 9000 feet), very dark site.
Magnifications: 70, 98, 158, 280, 408x
Faintest star (in NGC7031): 16.3 > 50% time at 280x.

I did not know the direction of the jet (I did this on purpose so I would not have any bias).

The jet was visible at 280x 20% of the time. At 408x, it was visible 50% of the time. I made a drawing and later checked it against photos and the orientation was right on. The length observed was about 0.5 arc-minute long and only a few arc-seconds wide."

This web site by Reiner Vogel (it is in German, so use Google Translator; I do read French and some German so I follow some blogs on astronomy from Europe and then I test if my translation and thinking in that language are up to speed. So if it is in another language you may need to use Google Translator or another translation program to read it). Anyway Mr. Vogel reports this about seeing the jet using his 22 inch dob:

"After upping the magnification to 400x, the jet could be discerned with surprising ease as a small appendix to the nucleus of the galaxy. Its length was about 20 arc seconds, in agreement with the references in the literature. I had tried to get a feeling for the size of 20 arc seconds by observing Saturn ahead of M87. For comparison, the length of the jet in the image to the left corresponds approximately to the line width of the lettering of M87. As expected, I could not discern structures, such as the knots shown above, in the jet. Using the small galaxies in M87's immediate vicinity, the observed position of the jet was found to be in agreement with the photographs. These small galaxies might be helpful to direct your way to the jet under less optimal conditions where the observation is borderline.

I guess that good seeing is the most important condition for a successful observation of the jet, as the structure is very small and of low contrast, such that it blends into the background of M87's central part under suboptimal seeing. On the other hand, you will not need exceptionally dark sky, precisely because of the bright background of M87. This was confirmed in later observations under less than optimal seeing, which were not successful. In summary, an observation of the jet is really exciting, that's astrophysics at its best, live at the eyepiece!"

So, I do think with the right conditions based on these men's experience, and if the observer is an experience observer and has a dob or SCT say of 12.5 inches or better (the bigger increases the chance of seeing it) can see the jet in M 87. It takes good to very good skies, a dark site, an high magnification to get a glimpse. I am excited to try this in both my 14 inch and in my 20 inch this spring. Nice challenge for an evening. So if you have seen this wonderful object (the jet) in your scope leave a comment and let us all know the instrument, magnification and any tips you may have.

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