The Observing Logbook
By Paul Markov, June 2000

In this segment I will discuss the benefits of maintaining your own observing logbook. Much of what I suggest below can be applied to any kind of observing, such as deep sky, planetary, lunar, or double stars, however, certain detailed sections apply strictly to deep sky observations.

Unlike astrophotography and CCD imaging, visual observing produces no tangible results that can be shown to other amateurs. All that you see, observe, and enjoy will only be retained in your mind as a memory, unless you take the next logical step and record your observations with pen and paper.

The best way to record what you see through your telescope is to write your observations in an observing logbook. If you do not record your observations on paper, you will never be able to recall everything that you have observed, especially as time goes by and as you view more and more objects. An observing logbook can be used for recalling the details of previous observations, and for comparing past observations with current ones. Also, having to write something about an object, forces you to look for more details, thus sharpening your observing skills. Lastly, a logbook will help you to keep your observing organized and methodical. If you are planning to apply for the RASC’s Messier Certificate, Finest NGC Certificate, or the Astronomical League’s Herschell 400 Certificate, then you should definitely keep a logbook of your observations.

By maintaining your own observing logbook, not only will you be able to share observations with other amateurs, but you will also have something to show for after many years of observing. Simply keeping a list of objects with tick marks next to the observed ones surely does not make for a useful logbook. Instead, think of your logbook as an "observing diary", where you enter dates, times, object descriptions, observing conditions, people that observed with you, and special circumstances. Your logbook should be as scientifically relevant as possible, but should also be used to bring back memories from past observing sessions – it should be something that you can read for enjoyment as well as for reference.

I have been observing since the fall of 1982 and every observing session is recorded in my logbook. Each session describes where I was observing from, who was observing with me (if I had company), what I saw, and what each object looked like. Now I can go back to my logbook and in an instant I can recall all my observing sessions and read about what I viewed. For example, here is my very first deep sky observation: Oct. 4, 1982, backyard (Don Mills area at the time), full moon, 4.25-inch reflector at 15x, the Andromeda Galaxy (M31) – "faint glow, oval shape, disappointing". This type of "observation" is typical of a beginning amateur observer as I was observing with a small telescope, from the city with a full moon, and even though I was looking at the Andromeda Galaxy, I was still disappointed with the view. As you can imagine I was expecting to see something similar to the many pictures I had seen in astronomy books and magazines! To me this logbook entry is a prized possession as it reminds me of my "first steps" in this wonderful hobby.


The format of a logbook is a personal preference. As long as the relevant information is included, you can use any format you want for a logbook. Try to experiment with the various methods and formats suggested below, make your own improvements, then choose the one you like best and the one that is most suited to your observing style. Chances are that over time you will make changes to the format of your logbook, but try to adhere to a similar layout in order to make the logbook more consistent over the years.

The first choice you have to make is whether you want to maintain a chronological or sectional logbook. In a chronological logbook all observations are entered sequentially by date. In a sectional logbook observations are entered according to their type. For example, all globular cluster observations go in one section and all galaxy observations go into another section. My choice is that of a chronological logbook as I am interested in the whole of an observing session.

Next you have to decide what kind of "book" you want to use to record your observations. Typical choices are a simple three-ring binder with standard 8.5 x 11 inch lined paper, spiral bound notebooks, or the more expensive hardcover record/accounting books. The most esthetically pleasing is the hardcover book, but the most practical is the simpler three-ring binder. Using the latter allows you to add all sorts of materials to your logbook with the help of a three-hole punch, and entering observations out of sequence is never an issue because you can easily rearrange the sheets. Also, should you wish to make a copy of your logbook for safekeeping, it’s much simpler with the loose sheets. Initially I started using a hardcover book, but once that was filled I moved to a three-ring binder with lined paper and found it much more practical.

Now you have to decide how to actually record each observation. You can adopt the use of a pre-printed observing form, either of your own design or as found in some observing books, or from the Internet (such as found at There are several benefits of the pre-printed forms; the fill-in-the-blank fields remind you to record the relevant data, they give your book a neat and organized look, they typically encourage observers to make a sketch of the object in the space provided, and make your book easy to read. You will only be able to use pre-printed forms if you choose a three-ring binder as your "book".

Alternatively, you can use plain lined paper. The benefits of plain paper are also several; you never have to worry about running out of forms, you record only the required details thus using less paper, you are not restricted to any pre-set format, and you will not need different forms for different types of objects (e.g. deep sky, planetary, etc.)

Personally, I do not like pre-printed logbook forms because many of the blank fields to be filled out are repetitive and do not need to be recorded more than once per observing session. For example, the observer’s name, date, observing site, and telescope typically do not need to be recorded each time you observe an object. Also, many of these forms have a round circle drawn, to represent a field of view, where you can make a sketch of the object viewed, but I doubt many of us will sketch every observed object. Lastly the use of pre-printed forms is not very efficient as most forms allow you to record only one object per sheet, and after a good observing night who wants to have, say, twenty forms?

Recording Observations

In the past I have seen several suggestions on how to keep a logbook. Many of these propose the use of some unbelievably cryptic code to record observations, in essence transforming your logbook into a book full of acronyms and abbreviations, for which you will need a secret decoder ring each time you want to read an observation.

My approach is completely the opposite – I use plain English to make entries in my logbook, such that anyone will be able to read my observations. Of course, you should use abbreviations and acronyms where there is lots of repetition or where these are well known short forms, such as "mag." for magnitude or "OC" for open cluster. You can enter as much or as little data as you want in your logbook, but just make sure you enter enough to make it worthwhile. Here is the information I include in my logbook for each observing session: Date, location, time of arrival and departure (if I have traveled somewhere to observe), names of other people at the observing site, a couple of sentences describing the environmental conditions, such as temperature, dew, wind, sources of light pollution, snow cover, mosquitoes, and sky conditions, such as transparency and seeing. Also record the Moon’s phase, although if you are a deep sky observer, you really should not be observing when the Moon is in the sky!

To simplify your logbook and to make it consistent, you should standardize on a format for recording the time and date right from the start. For the time, choose either military time or the A.M. / P.M. format. If you are accustomed to it, use military time, otherwise using A.M. / P.M. should be fine because even if you forget the A.M. / P.M. designation, it is impossible to confuse a deep sky observation made at 2 A.M. for 2 P.M. For recording observations of static objects, such as deep sky, I suggest the use of local time, not Universal Time (U.T.). U.T. is more useful for timing dynamic events, such as occultations or eclipses, or for meteor shower counts. Lastly, do not forget to record whether the time is Eastern Daylight Time (EDT) or Eastern Standard Time (EST). To avoid confusion when recording the date, I prefer using alpha characters to specify the month rather than numeric characters. My suggestion, for example, would be to use Aug. 5, 2000 instead of 8/5/2000. This ensures that anyone reading your logbook, including yourself, will have no trouble reading the date.

For each object I observe, I record the following information, keeping in mind that I am a deep sky observer: Time of observation, object designation (M, NGC, IC, etc), type (OC, G, PN, etc), constellation, magnification used, type of filter (if any), and visual description. The visual description is typically where some amateurs like to use acronyms and abbreviations, but I prefer using full sentences. The drawback to this method is that it will take a little longer to write your observations while you are at the eyepiece, so you will need a comfortable set up for writing. Alternatively, you can use acronyms and abbreviations while in the field, but make sure to re-write these as full sentences in your final logbook if you want to make your logbook easy to read.

Additional entries should be made if an aurora appears, if you see impressive meteors, if the sky conditions change, etc. You can also draw the objects you observe - even a quick simple sketch is better than none and adds a lot to your logbook, and if you are artistically inclined you can try detailed drawings using a variety of pencils and papers to add reality to your sketches.

Describing Deep Sky Objects

Describing the objects you see in detail will make your observations much more relevant and rewarding. Below are some basic suggestions on what to look for in each of the main deep sky object categories.

Open Cluster: What is its shape? Is there more star concentration in a specific part of the cluster? Is it fully resolved into its component stars, or are there any unresolved stars causing the cluster to appear nebulous? How many stars can you see (only if reasonable to count them)? Are there any bright stars within the cluster? What is your estimated size of the cluster (based on the field of view of your particular eyepieces)?

Globular Cluster: What is the degree of the cluster star concentration (high, medium, low)? How much of it can be resolved in its component stars (none, outer edges, middle, down to the core)? What is your estimated size of the cluster (based on the field of view of your particular eyepieces)?

Galaxy: What is the shape of the galaxy? Does it have a bright nucleus? Is the galaxy uniform in brightness? It is diffuse or stellar? Can any details or mottling be seen? Can it be seen with direct vision or is averted vision required?

Emission or Reflection Nebula: What is the shape of the nebula? Is its brightness even or are there brighter/darker areas? Are the edges of the nebula well defined? Are there any stars within the nebula?

Planetary Nebula: What is the shape of the nebula? Can you see any colour? Is it stellar in appearance or can a disk be seen? Are the edges well defined or diffuse? Are there any brighter/darker areas? Can a central star be seen?

If you are well beyond the Messier Catalogue and well into the New General Catalogue you will soon reach a point where most objects you view are at the limit of our telescope’s light grasp ability, and just about every deep sky object will look like a "very faint fuzz with little detail". When you reach this point you may think recording your observations is pointless due to the lack of detail, however, as your observing skills improve, you will be able to write something about even the faintest object.

Hard or Soft Copy

With the advent of computers and deep sky databases many years ago, it became possible to use a computer to record, log, and track your observations. I have partially adopted the use of a computer database to track my observations, however my paper logbook is still my main tool.

The primary reason I still use a paper logbook is that when I am at the eyepiece, it is much easier to write what I see on paper, rather than into a computer. Besides, you can only draw a deep sky object on paper! If you are really keen on maintaining your observations in "soft" format, you can transcribe your paper observations into your database, however that takes additional time which most of us do not have. So what I write on paper at the eyepiece, remains on paper and becomes part of my permanent logbook. This also lessens the chances of transcribing errors.

Several years ago I started using a computer database to track deep sky objects I have observed. I use the Saguaro Astronomy Club database (download for free at and I simply added four fields to it: Seen (Y/N), Date, Telescope, and Location. Now in a matter of seconds I can find out which objects I have observed, and if I need to read my own observations for an object, the "Date" field directs me to the correct page on my paper logbook. My database is also extremely useful for generating up-to-date observing lists in a matter of minutes (see my previous article "The Observing List" in Scope, Dec. 1999). You can also determine interesting facts, albeit trivial, such as at which observing location you observed the most objects, which telescope produced the most observations, or the magnitude of the faintest object you have ever seen.

Recently I have taken my logbook a step further; it is now available for everyone to see on-line at This huge effort is certainly mostly for my benefit as I doubt too many people will be interested in reading my logbook. The purpose of recreating my logbook in HTML format is the ability to combine text with actual photos, thus giving it the look and feel of a magazine layout. I can then print the on-line logbook on a colour printer and have a beautiful and useful logbook complete with pictures. The other useful aspect of the on-line logbook is that my astronomy friends and acquaintances will be able to read and see what I have been up to on a regular basis. My on-line logbook lists only some of the observing details mentioned earlier. I chose to only list the objects’ designation numbers for each session, rather than include the detailed observations for each object. It would have taken me much too long to enter observations for each of the nearly 800 deep sky objects I have seen, and also it would have made for pretty "dry" reading material. Instead I chose to include only details on the observing site, other observers at the site, and any special circumstances (aurora, meteors, unusual observations, etc), as well as adding some relevant photographs. Take a look at it as I think you will enjoy it and may like the concept.

Remember that visual observations are quite abstract, so if you decide to maintain your logbook primarily in soft format, make sure to print out a paper version so as to make your efforts as tangible as possible, and remember to backup your data files often!

Long Term Benefits

My logbook now spans over 18 years. By leafing through it I can see how my observing skills have improved over the years, I can read how the same objects appeared through the different telescopes I have owned, and I can see how various observing sites have become more light polluted. In the next few decades I may notice how my observing acuity has diminished as my eyesight deteriorates with age, and hopefully I will be able to include my son, now just two years old, in my logbook as one of my observing buddies.

I strongly urge you to start, or to continue updating, your own observing logbook. For visual observers it is the only way to show others, and remind yourself, what this hobby is all about. If you have your own tips and hints on maintaining a logbook, I would like to hear from you at


Copyright (C) 2000 by Paul Markov

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