The Lake County Astronomical Society

Record What You See

Jack Kramer

After you observe an object, do you have just a pleasant memory or do you have something additional to show for it? Can you compare observations of the same object that were done over a period of time? When you hear how an object looked to a different observer, do you have some means to refresh your memory as to how that object appeared to you? Could your observations be scientifically useful?

If you've replied "yes" to all those questions, then you've probably kept good observing notes. If you'd like to start maintaining an observing log or improve the one you're now using, there are some items to consider. First of all, records can be maintained in any format or medium that's convenient for you. Many observers make rough notes in the field, then transcribe them to a neater format later. (But not too much later so you forget some of the nuances that might later prove interesting.) Your records could also be transcribed to a computer database which will make searches and sorts much easier.

There are a number of items that are generally considered necessary in order to realize the maximum value from an observing log. You might opt to record only the essentials, but I suggest that if you do so, include spaces for additional items so that you'll be prepared if you decide to be more precise in the future. The following list is usable for all types of observing -- both deep sky and solar system.

Some things in the above list are pretty obvious, while others merit a bit of explanation.

Constellation isn't applicable to something like a planet, but it's often handy for yourself in keeping track of deep sky objects. It can also be important in verifying the identity of an object.

Date is obvious for solar system objects which are constantly changing, but it's also important for deep sky objects because once in a while transient phenomena do appear (e.g.: a star at the edge of a galaxy could be a supernova).

Filters very much affect the detail visible on all different types of objects. Rather than record this as a separate line item, any filters used could instead be included in your descriptive notes.

Description is how the object appeared to you. Next to recording which object you observed, this is the most important part of your record. Simply recording that you saw an object accomplishes zilch! Note as many features as possible, but don't be influenced by photographs or anyone else's description of the object. This may also be an appropriate place to record subsequent observations that reveal additional details missed the first time.

Observing Site is (obviously) the place from which you conducted the observation. A surprising number of published record forms don't include the location, but it's an important item insofar as it tells you a lot about the prevailing conditions. Light pollution, altitude, humidity, and air flow are different at each site -- they all contribute to what you're able to see qualitatively.

Other Names means any other designation that an object may carry. For example, most Messier objects are also Herschel objects. If you later decide to work on a "Herschel 400" list, you'll want to know whether you've already recorded the object in both of its incarnations.

Coordinates are right ascension and declination. That's more in the nature of a convenience if you use setting circles and refer back to your records for re-observation. I've included them as a field in my computer database, but have not populated it. (I'm a star-hopper, after all!) The one situation where coordinates are a necessity is if you come upon an object that isn't recorded on an atlas - this could be a comet, nova, asteroid, etc.

Time is important for noting anything transient, which obviously includes all solar system objects or when noting anything you feel is unusual. Use a consistent format and be precise; it's probably a good idea to use Universal Time (UTC), rather than local (civil) time.

Seeing refers to the steadiness of the image. It's usually rated on a 10 point scale, with 10 being the steadiest. For example, if you're observing a bright planet that has a rock solid image that only quivers a little now and then, you might rate that as a 7, and you'd record it as 7/10.

Transparency, like seeing, affects how well you're able to see details of an object. But it's of more importance for deep sky observation where you need as much light as possible to pass through the atmosphere. You'll probably find that a night that is very transparent has poor seeing, and vice versa. Transparency may also be recorded on a 10 point scale, although many record it as the magnitude of the faintest star visible to the naked eye.

Temperature is just another indicator of seeing and/or transparency conditions, obviously linked with the date. If you've recorded the seeing/transparency conditions, then you probably don't need temperature.

Size and Magnitude may be actual and/or your own estimate. I record both the actual size and magnitude, then note whether the object appeared larger/smaller and brighter/fainter than the stated figures. As you check the different reference works, you'll find that they often don't agree with one another.

Drawing is your picture on paper of how the object looked to you. You don't have to be an artist; the important thing is to capture the outstanding features. However, in order to be of real value, you must include some indication of field size, along with the orientation of the object, via a north/south indicator, plus an east/west or preceding/following direction. Remember that each telescope design puts its own unique twist to the view, reversing it top-to-bottom and/or left-to-right. The simplest style of drawing uses a soft lead pencil on white paper, then using your finger to "smear" the lead slightly to portray nebulosity, spiral arms, cloud belts, etc. Creating a drawing is the most time-consuming part of the process; however, it can't be beat for improving your powers of observation. I don't do it nearly enough!

The ideal observing record will include all or most of the preceding items. The philosophy is that you want to record exactly what you saw on a particular date and indicate the conditions that affected how you saw the object. This will then provide a meaningful basis of comparison with your other observations of the same object or with those of other observers. This also helps in analyzing or comparing the observing quality at various sites.

There are some groups which welcome reports of your observations; these include the Association of Lunar and Planetary Observers (ALPO) and American Association of Variable Star Observers (AAVSO). If you find what you believe to be something totally new -- a previously undiscovered comet or nova -- then after having your observation confirmed by other observers, you'd want to contact the Central Bureau for Astronomical Telegrams in Cambridge, Massachusetts (cbat@cfa.harvard.edu). These groups maintain very precise standards for what is considered useful data, and your observing records are useful to them only in proportion to the level of detail you've recorded.