Review of The Cambridge Double StarAtlas and The Cambridge Atlas of Herschel Objects
Well, I am beginning to feel much better (finished my double dose of antibiotics; yep, two at once) but the weather here in northern Utah continues to be very poor. Clouds and rain, well over an inch this weekend from the current storm. There is more water in the snowpack in the higher elevations of the mountains then the reservoirs hold empty, so, we are looking at flooding I fear in June. The good news is the weather looks excellent next weekend and the moon will only be a thin waxing crescent so there will be some observing done!
Today I want to review The Cambridge Double Star Atlas and my latest pick up, The Cambridge Atlas of Herschel Objects that I got back in April. I also picked up about 2 or 3 weeks ago a copy of the Deluxe Office Edition of the Sky Atlas 2000.0 version 2 that is laminated and I'll do another write up on that. Now that I am starting to feel healthy again, I need to swing by and pay Steve for that this week.
THE CAMBRIDGE DOUBLE STAR ATLAS
A couple of years ago I started getting bored with only observing for 2 weeks a month IF the weather holds up during new moon. I admit, I am an observable alcoholic, and during new moon I will observing at my site that is about 45 minutes away even on a work night. I can function relatively well on about 5 hours of sleep and then rest the next evening. However, I began to allow the moon to interfere with my observing and I wanted to expand my horizons. At that time, I decided to do the Astronomical League's Double Star Club list. This provided me with the avenue of giving me something to do during non DSO observing time. I found the list fun and during my time with it, The Cambridge Double Star Atlas came out and I picked one up.
When I first looked at the Double Star Atlas I thought it might server as a replacement for the Sky Pocket Atlas by Sky&Telescope. The Double Star Atlas is larger, spiral bound and is much easier to use in some cases. The problem with it when compared to the Sky Pocket Atlas, is that it is missing some key Deep Sky Objects that many observers want and that are in the Sky Pocket Atlas. For example. In the Double Star Atlas in O'Meara's August list, NGC 6445 a PN in Satitarrius is not included, nor is NGC 6528, NGC 6522, NGC 6540 which are globular clusters and two open clusters, NGC 6583 and NGC 6756. These are all included in the Pocket Sky Atlas.
Evaluation after Field Use
As I stated above, there are DSO's that are missing from the Double Star Atlas that are in the Sky Pocket Atlas. But one MUST remember the purpose of the Double Star Atlas; to guide you to Double Stars. The paper is not laminated, but my atlas copy has never had a problem with dew. The paper is thick and sturdy, and holds up well to being folded on the spine. This is an easy to view Atlas that makes those in their middle forties or above, who are starting to have issues with reading glasses easier to use than the Sky Pocket Atlas.
Review of the Atlas
The Double Star Atlas takes the user to 7.5 magnitude with the stars, while plotting companion stars down to around 10.5 magnitude. So there are fainter stars in the atlas from 7.5. There are a total of 25000 stars visible with the Atlas. Some pairs of stars fainter than 7.5 are also plotted because of their "striking color contrast or other striking backgrounds or difficult component configurations."
In both cases, the Introduction is an outstanding contributor to the Atlas itself. It is one that most observers will want to review, even if your very or highly experienced. Never hurts to have a good reminder of some wonderful tips. One of my favorite quotes from the Introduction is this one:
"It has often been stated that the person behind the eyepiece of a telescope is far more important than the size or type or quality of the instrument itself."
"It was Sir William Herschel, the greatest visual astronomer that ever lived, who said that "seeing" is an art and that as observers we must properly educate our eyes to really see what it is that we are looking at in the eyepiece."
This quotes to me, are the very basis of why this Atlas, and the other in the series are being made. They are to provide an avenue for the observer to get to the object so this type of art, this type of seeing can be made. This section makes three main points on gaining experience. First, the more one observers, the more one sees. Everyone says what great eyes Stephen O'Meara has, and having never met the man (would love to observe with him here in Utah though) I am sure he has fantastic eyes. I would bet though if we truly logged the number of hours he has spent observing, we would know one secret on why he sees so much detail in his observations. I know that based on my own experience.
Next is the area of training the eye/brain combination and using averted vision to do this. I think averted vision is one of the least used and least trained tools of observers and that often we don't ask the public at outreach to do this, because we don't take the time time to teach. I believe that both our own personal observing should be a training session, we need something to be working on to improve ourselves while also in outreach, teaching the public how to see. It is a critical skill when we work with new people in the hobby as well. This section in the atlas is rich with suggestions.
Finally, the third key in training the eye/brain is that of color perception. Take time next time your observing and see if you can see the tint difference between stars. Can you make out the color differences in various stars at different times of the year and variances even within that star? For me these three areas of the introduction, and touching on dark adaptation are the critical parts of the Introduction. They remind all of us as visual observers, what we should be doing when we go out to observe.
The Introduction now moves on to Sky Conditions and how they impact viewing, and what we can do about it. Next is Resolution and Magnification, a key part for the splitting of Double Stars. This section mentions using the resolving magnification of a telescope, or 25x per inch of aperture. For my 14 inch that is 350x or just around a 5mm eyepiece which puts me at 330x. For the "casual observation of double stars, the rule of thumb is to use the lowest power that just nicely separates the pair."
The next section is that of optical quality and collimation. The focus here is how to test your optics and collimation to ensure that you can get the separation needed to split these double stars. Record Keeping is the next section mentioned, and here I encourage the reader to spend some time here and think about how you want to record your observations of the double stars.
The last section is that of personal considerations. Here posture and having a very good observing seat is mentioned. Proper clothing to maintain warmth is important. It sucks trying to observer when one is cold and it is something I see many new observers make. Often, in the summer, I get weird looks for being layered, but by 11:00p.m. locally, I am no longer being given funny looks but being asked how I layer. This is true in the mountains, but equally true in the deserts of Utah as well. Proper rest and diet are important to observing. Getting a nap can help as can eating light meals, or just eating to keep the energy up and then eating after observing. Ever notice how hungry one is AFTER observing? I tend to get absorbed in my observing, will eat an apple or a piece of fruit, wash my hands off and then observe during the night. When its over and I've loaded up, YES, I am famished!
One of the nicest features in this Atlas is Appendix C: Double star target list that is in the back. It lists the Object/Constellation that the object is in. Next is the RA and Dec. according to the 2000.0. Then comes magnitude and the Separation in arc minutes and any remarks. Here is an image so you can see that. Each object alternates between white and green and is easily usable in the field.
Here is the Virgo, Leo area of the Double Sky Atlas and you can actually see, it does contain a significant amount of DSO material in it. However, remember, this is a Double Star Atlas and as such, it works tremendously well for that.
Here is a second image from the Atlas itself to show what it looks like. In this image you can see the Veil Nebula region and the Double Stars in that area and some of the major DSO's.
Appendix A is a listing of constellations by map
Appendix B lists the Greek letters
Appendix C is a listing of the Double Stars by constellation, RA, Dec., separation etc.
I thoroughly enjoy the Double Star Atlas by Cambridge and find it a wonderful tool put together by James Mullaney and Wil Tiron. It is highly useful for finding Double Stars and for providing some of the better Doubles to go after, both at a dark site or in your own backyard/front yard during those waxing moon phases. I highly recommend it to anyone looking to expand their visual observing. Some think double stars are boring. For me, I find them very interesting since the vast majority of stars in the galaxy are just that, in binary or more groupings.
THE CAMBRIDGE ATLAS OF HERSCHEL OBJECTS
This one I found out about over at CloudyNights on their Stellar forum and since I am enthralled with most things Herschel, and with Star Atlases in general, I knew I had to pick this up. My local Barnes and Noble had this in stock so it was easy to pick up and my 10% discount helped in reducing the cost. I will review this in a similar way to the Double Star Atlas, but will point out the differences mainly, since some of the same points in the introduction of the Herschel Atlas is the same or same/similar point to what was made in the Double Star Atlas.
Much like the Double Star Atlas, this is of the same material and layout. I really like the layout here, and the size is terrific. I really would love to see a Sky Pocket Atlas in this size. Unlike the Double Star Atlas, which is designed to hunt those objects down, this atlas is not missing any of the Herschel 400 that I am currently finishing. Like the Double Star Atlas most stars go down to magnitude 7.5, they do lower since many of the Herschel items go down to 12.5 magnitude. Also, as pointed out in the introduction, in the area of the main object, are often fainter objects that if your telescope will go down to, will be visible in the eyepiece so look for those other objects as well.
Review after Field Use
The only difference between the Double Star Atlas and this atlas is that the DSO's are the focus here. The Herschel items do not have their NGC number next to them in the atlas. Instead they have Sir William Herschel's designation (which is given in the introduction) or a small h if the discovery was made by Sir John Herschel, Sir William's son. If you want/need the NGC number, it is easily located in Appendix B in the back, where all objects are plotted there. It worked well in the field and I had no problem with it, though it took some planning on my list so I knew what object I was going after from Sir William's list. If your working by constellation, I don't think this will be an issue. If your working by Stephen O'Meara's book, you'll want to plot them Herschel number in your observing list. I'll be updating my lists to reflect that number which is in O'Meara's book. That would be a good upgrade in a new edition of O'Meara's book, to include the Herschel ID in his nightly lists so its easier to use this atlas with his list.
Review of the Atlas
The Introduction is again, very, VERY rich in information. It begins with a wonderful introduction of Sir William, his sister Caroline, and Sir William's son, Sir John and their experiences and the telescopes they used, especially the 20 and then the 40 foot telescope. The Introduction the moves into the Herschel designations, so one can learn those, since they are used in the atlas itself. At first I didn't like this, but it has forced me to learn Herschel's designation and it makes sense to me, that since I am chasing his objects, I should know his designations. I can use and write down the NGC number, that is easy. This seems to connect me to Sir William, Caroline and Sir John and I like that. The Introduction then moves into nonexistent objects and the miscalculated objects. These are two important sections and I invite the owner to read them carefully since I think it is important to know these. Finally, the Introduction moves into the overlooked objects that the Herschel three missed. These include the Helix Nebula, the Flaming Star Nebula, Stephan's/Webb's Protoplanetary Nebula in Cygnus, Barnard's Dwarf Galaxy, Hind's Variable Nebula. The author also mentions they missed his one of his favorite objects, NGC 6791 in Lyra, an open cluster that resembles a globular because of its 300 members.
The next section reviews the map parameters and what was selected and why. A good read to understanding the rationale behind the choices made. The Herschel 400 as used by the Astronomical League are all included in the Atlas.
After this, the book gets into Instrumental and Personal factors, just like the Double Star Atlas does. In this section I like the portion where the recommend what power to use based on the Herschel Object being used. Like the Double Star Atlas, they mention "resolving magnification" as 25 x the aperture of the telescope, but then modify that by explaining what low, medium and high power is. "Big scattered open clusters or extensive nebulosities (and eve a few of the largest galaxies), the lowest possible power and widest field of view give . . . the most pleasing results. The same applies in the initial sweeping for objects to find them. In the case of rich, compact open clusters and tight globulars, medium magnifications typically give the best view. The same goes for the smaller diffuse nebulae and most planetaries, and also for galaxies in general. Unless the atmosphere is steady, high powers can give a 'washed-out' appearances to the image and typically restrict the field of view. But they are still worth trying on all but the very largest of objects to see if any additional details are revealed."
Great advice that most observers know. Low magnification, wide field for scanning or well spread out objects. Medium power next for details and then high power if conditions allow.
They also talk about the star test to test optics to see how well the optics and collimation is.
Under Training the Eye, they again emphasize the need to train the eye and the brain to use averted vision. They do a good job as they did in the Double Star Atlas in explaining this. Next they focus on Dark Adaptation focusing on the dilation of the eye and the chemical changes that occur in the eye in the dark. They add here visual acuity, "the ability to see or resolve fine detail in an image or in splitting close double stars." This is gained by spending time at the eyepiece, with experience. They do share an excellent way though to improve visual acuity, and I'll leave that as a tease for getting the atlases. They also touch on color perception again.
The rest of the Introduction is almost verbatim to the Double Star Atlas, where they discuss sky conditions, record keeping, personal considerations. They close the Introduction, and I left this out in my review of the Double Star Atlas above, with a recommendation list of Herschel Showpieces (in the Double Star Atlas they have 133 Double Star Showpieces). There are 215 Herschel show pieces based on James Mullaney's thousands of observations of Herschel items.
Appendix A in the back is a listing of Constellations and which maps correspond to them. You'll use this if you hunt by constellations or are looking for objects in various constellations.
Appendix B is the Cambridge Atlas of Herschel Objects target list. This is the 2500 + clusters, nebulae and galaxies arranged by right ascension. This list the item by its Herschel designation and by its NGC number. Provides RA and Dec information, Constellation, Size, Type etc.
Here is the northern hemisphere by map and constellation:
Here is what the Atlas looks like in the Veil Nebula region.
Here is M31 and M33 areas.
If you are doing the Herschel 400, or a want to do what I am going to expand to, to do all 2500 objects in this atlas, then I recommend the atlas. It may not go as deep as you need it to in some areas, but for the most part it will work nicely. When added to a computer chart, it is a very helpful item. These are fine products to own. Disclaimer: I receive no financial compensation from anyone associated with either atlas.