Well, as promised based on the information I have gathered from a survey and a question asked over at CloudyNights, First, this is not for experience users. If you've been around for a while, these objects are old friends, kinda of like summer comfort food for amateur or hobbyist astronomers. I do hope the following helps some of you who observe from your backyards, in a range of light polluted skies and are new to the hobby or newer. This is not to say you can't observe these from a dark sky site, you can and should if you have that opportunity. However, I believe that the fast majority of amateur or hobbyist astronomers observe from their backyards as I covered in my last post. So this is my effort to twice a month or so, bring you a post about what you can observe in your backyard.
I will break this up to deep sky objects, DSO's; double stars or DS; Lunar Objects. On the lunar objects I am going to use a couple of sources, but the main one is Moonwalk with Your Eyes; A Pocket Field Guide by Tammy Pletner. She has specific objects for specific days of the lunar cycle so you should try to observe those objects if possible, near the day of the lunar cycle I give. For example, on Day Four of the Lunar cycle, there are two craters, Messier and Messier A that are visible and offer a nice view. That observation should be done around Day Four or Five of the Lunar cycle before the brightness of the moon limits your contrasting view of them. I am hoping after the next couple of days (I am hoping if the weather clears here to get a night in at a dark site before the moon gets too big) to sketch each of these items and include a copy of the sketch in the post. I'll be updating the post when I do that. That should give a novice an example of what you look for. Until then, I will link to a sketch or two to aid in that. So here we go.
1. Messier 22, Globular Cluster in Sagittarius
Facts & Info: From Wikipedia LINK: M22 is an elliptical globular cluster in the constellation Sagittarius, near the Galactic bulge region. It is one of the brightest globulars that is visible in the night sky. M22 was one of the first globulars to be discovered, on August 26, 1665 by Abraham Ihle and it was included in Charles Messier's catalog of comet-like objects on June 5, 1764.
It was one of the first globular clusters to be carefully studied first by Harlow Shapley in 1930. He discovered roughly 70,000 stars and found it had a dense core. M22 is one of the nearer globular clusters to Earth at a distance of about 10,600 light-years away. It spans 32' on the sky which translates to a spatial diameter of 99 ± 9 light-years. 32 variable stars have been recorded in M22. It is projected in front of the galactic bulge and is therefore useful for its microlensing effect on the background stars in the bulge.
M22 is very unusual in that it is one of only four globulars (the others being M15, NGC 6441 and Palomar 6 that are known to contain a planetary nebula. It was discovered using the IRAS satellite by Fred Gillett et al.,in 1986 as a pointlike source (IRAS 18333-2357), and subsequently identified as a planetary nebula in 1989 by Gillett et al. The planetary nebula's central star is a blue star. The planetary nebula (designated GJJC1) is estimated to be a mere ~6,000 years old. I have information on how to observe this planetary nebula.
Two black holes of between 10 and 20 solar masses each have been discovered, initially with the Very Large Array radio telescope in New Mexico, and corroborated by the Chandra X-ray telescope, in 2012. Their detection implies that gravitational ejection of black holes from clusters is not as efficient as was previously thought, and leads to estimates of a total 5 to 100 black holes within M22. Interactions between stars and black holes could explain the unusually large core of the cluster.
To find Messier 22 or M22, you will need to find the constellation of Sagittarius. At the top of the lid for the teapot, is the star Kaus Borealis, and you will need to go there. Here is a wide field view and a zoomed in view with red arrows showing star hops to Messier 22 and to another globular that you may or may not be able to see, depending on how bad your light pollution is, NGC 6626, just above Kaus Borealis.
I know in moderate light polluted skies you will be able to find Messier 22 and hopefull the star charts help. This is a wonderful object and as you observe it, think of a planetary nebula in it, where a star, like our sun, has lived out its life, blew off its outer layer, leaving that layer as a nebula with a white dwarf in the center that is about the size of the earth, extremely hot, and very dense. Perhaps you may want to reflect that in the core, stars and smaller size black holes are dancing as gravity from the black hole tries to grasp the star. Think of what the night sky there would look like if you were on a planet in orbit around one of the thousands of stars there! Remember, this globuar is estimated to be around 12 billion years old!
2. The Grand Summer Tour:
Multiple Objects: Messier 8 or M8 The Lagoon Nebula; Messier 20 or M20 the Trifed Nebula (hard without an OIII or Narrowband Filter in light polluted skies but possible, I did it in my backyard many years ago the first time I saw it): Messier 17 or M17 the Swan Nebula; M16 the Eagle Nebula (again a filter will help you to see this object in light polluted skies) and M11 or Messier 11, the Wild Duck Cluster or as my friend Mat calls it, The Borg Cube from Star Trek.
I am not going to really provide any information on the blog about this objects, just show you how to get to them. If you want the information I will provide the link to Wikipedia for each:
Messier 8 The Lagoon Nebula LINK
Messier 20 The Trifed Nebula LINK
Messier 17 The Swan Nebula or Greek Omega Nebula: LINK
Messier 16 The Eagle Nebula LINK
Messier 11 The Wild Duck Open Cluster or the Borg Cube Cluster: LINK
We are going to start our star hops back at Kaus Borealis, the top star in the teapot's lid. This is where we hopped over to Messier 22 (which can be included in the grand summer tour). I want to let you know from a light polluted back yard, I have seen each of these objects both with and without either a OIII or Narrowband filter. They are faint and difficult. One of those filters will really assist you in seeing the Lagoon Nebula, the Trifed Nebula and the Swan or Omega Nebula and the Eagle Nebula. If you don't have a filter yet, don't give up, give it a try!
The map below shows you how to get to your first to objects, from Kaus Borealis. Your first object is the Lagoon Nebula or Messier 8. It is up and to the right from Kaus Borealis and if your good at sweeping in a wide field eyepiece or a finderscope you can usually pick it up. It is an open cluster of stars mixed with milky nebula.
Messier 20, the Trifed Nebula
This is a very old and poor sketch of Messier 20, so the good news is its time to redo this sketch! It's kinda close to what you'll see. A double star with 3 lanes of darkness separating the nebula. I highly recommend the use of a OIII and/or Narrowband filter. Speaking of which, I have my preferences on filters on objects, but I am going to leave that ambiguous. I want you to use both filters if you have them and decide for yourself which filter works best for you on an particular object.
Above I show two star hops to get to Messier 17, the Swan Nebula or the Omega Nebula. You can go from the Trifed and follow the red arrows or go to Gamma Scuti, the bottom star in the constellation of Scutum and then follow that hope to Messier 17. I think the one from Gamma Scuti is the easiest. Note the Sagittarius Star Cloud marked as the Star Cloud on the map. Scan that with your telescope for fun, and then observe it with your finderscope or binoculars. That is often an overlooked treat!
This is what Messier 17 looks like, but it is usually inverted in a reflector or dobsonian telescope. Some say it looks like a swan, some say it looks like the Greek letter for Omega. You decide when you observe it!
Above is one star hop from Messier 17 or M17 the Swan or Omega Nebula up to the Eagle Nebula or Messier 16 or M16. At a dark site in my 17.5" dob and my 14" I have seen the pillars of creation. Here is a sample of what you may see of M16 which I did at a dark site. Here you can glimpse the pillars of creation. From a light polluted backyard, you will probably get a circle of milky substance or the eagle shape. Using a OIII and a Narrowband filter can help you a lot on this object.
Above is a star hop to Messier 11, an open cluster called the Wild Duck Cluster as some say the star patterns look like wild ducks lifting off the water and away. As I mentioned, my friend Mat says it looks like the Borg Cube Cluster from Star Trek the Next Generation. I tend to agree with him. However, you have to decide what an object looks like to you, that is the fun of this hobby! Well, one of the fun things to do!
A wonderful sketch of Messier 11 is found at this LINK by John Karlsson. I will share the image here since I have provided a link to the original article per fair use guidelines. Sorry I don't see the ducks, well, I kinda of do, but it sure looks like a Borg Cube to me!
3. Messier 13 Globular Cluster in Hercules.
Facts & Info from Wikipedia LINK: Messier 13 (M13), also designated NGC 6205 and sometimes called the Great Globular Cluster in Hercules or the Hercules Globular Cluster, is a globular cluster of about 300,000 stars in the constellation of Hercules. M13 was discovered by Edmond Halley in 1714, and catalogued by Charles Messier on June 1, 1764. M13 is about 145 light-years in diameter, and it is composed of several hundred thousand stars, the brightest of which is a red giant, the variable star V11, with an apparent visual magnitude of 11.95. M13 is 25,100 light-years away from Earth.
Star hops: Again a more wide angle view followed by a closer zoomed in view on the star charts. Eta Herculis is the top right star in the keystone, and yes, for those new, the keystone is the oft shape square or near trapezoid in the center of the constellation. Messier 13 is about 1/3 the way down from Eta Herculis to the bottom right star of the keystone, Zeta Herculis. Again, you need to find the constellation yourself.
4. Messier 57, The Ring Nebula, a Planetary Nebula in the constellation of Lyra.
Facts & Info: Wikipedia LINK: The Ring Nebula (also catalogued as Messier 57, M57 or NGC 6720) is a planetary nebula in the northern constellation of Lyra. Such objects are formed when a shell of ionized gas is expelled into the surrounding interstellar medium by a red giant star, which was passing through the last stage in its evolution before becoming a white dwarf.
This nebula was discovered by the French astronomer Antoine Darquier de Pellepoix in January 1779, who reported that it was "...as large as Jupiter and resembles a planet which is fading". Later the same month, fellow French astronomer Charles Messier independently found the same nebula while searching for comets. It was then entered into his catalogue as the 57th object. Messier and German-born astronomer William Herschel speculated that the nebula was formed by multiple faint stars that were unresolvable with his telescope.
In 1800, German Count Friedrich von Hahn announced that he had discovered the faint central star at the heart of the nebula a few years earlier. He also noted that the interior of the ring had undergone changes, and said he could no longer find the central star. In 1864, English amateur astronomer William Huggins examined the spectra of multiple nebulae, discovering that some of these objects, including M57, displayed the spectra of bright emission lines characteristic of fluorescing glowing gases. Huggins concluded that most planetary nebulae were not composed of unresolved stars, as had been previously suspected, but were nebulosities. The nebula was first photographed by the Hungarian astronomer Eugene von Gothard in 1886.
Messier 57 can be challenging for some the first time they go for it from the backyard. In the third map I showed two possible star hops. The first is from Sheliak, a multiple star on top (take a look while your there) and coming down to 2 a chain of stairs and then to 3, two stars near each other in this case horizontal (not always, this will change as the constellation moves though the sky, the orientation will, the star will stay next to each other) and then move to M57.
If you come from Sulafat, 1a and to to 1, a triangle shape of stars that points to where you want to go, three stars together, and then up from the last star to M57. Use your own online tools or atlas to find your own way also! An OIII or Narroband filter can help you in light polluted skies to find this object as well.
5. My last object is a double star in the constellation of Cygnus. There are some wonderful objects in Cygnus, and perhaps on another entry I'll share some of the more bright items. At the head of Cygnus the Swan, is a wonderful and colorful double star called Alberio. Most objects in telescopes and binoculars will not show color, they are gray or milky smears. This double star shows color, but I'll leave that color up to you, and won't spoil it by including a sketch or image.
Alberio, Double Star in the Constellation of Cygnus: LINK
The image above shows you one of several ways to get to Alberio. Truly if you have a good eye, a Telrad or red dot finder on your telescope, you can find that end star at the head of Cygnus the Swan, or if you see this as a cross, the bottom of the cross, and go right to it. I am showing a star hope from M57, the Ring Nebula to Alberio. Personally, whether at a dark site or in my backyard, I simply put my Telrad on the star that is Alberio, a double star and I take a look.
Now as I stated in the beginning, if your experience or done astronomy for some time, these objects are probably old and familiar friends to you. Feel free to revisit them! If your newer to this, you may just find this provides one or two interesting nights in the backyard. Remember to always be amazed at the universe in which we have our being! The heavens are truly amazing!
Addendum: No lunar in this post. That is coming up in about a week I would say.