Keeping a Laboratory (Observing) Notebook

Introduction

While preparing for an observing run and while observing, you will keep a lab notebook. The notebook is a running record of your goals, procedures, observations, measurements, calculations, results, and conclusions. Keeping a good notebook requires a great deal of patience and discipline. It is difficult to stop in the middle of your work and write down comments in your notebook. Keeping an accurate record is essential if you wish to use the scientific method to learn anything from your observations.

Page Header

In order to easily find things in your notebook put the title of the project, the date, and a page number at the top of every page.

Project Write-up

Fundamentally, a notebook is just a running account of what you do as you prepare for and carry out your observations and analysis. The main sections of a good write-up are listed below, but these are just guidelines - use common sense. Strive to include enough information so that you or a fellow student could repeat the experiment at a later date using only your notebook.

Project Title - Provide a descriptive title for the project.

Goals or Purpose - Begin with a brief statement of the goals of the project. This information will help guide you through the observations. One common mistake is to start the project without having a clear idea of exactly what you are trying to do. A project with many small parts should have a goal for each part. In most cases this section will be quite short.

Equipment - If necessary, describe the equipment used for the observations. It is usually useful to include a clear sketch or block diagram. An example of the information contained in this section might be the f-ratio and aperture of the telescope or a description of the photometer. However, you need only include information relevant to your project.

Preliminary Information - This section contains your observing plan and all the information you will need to take and reduce the data. Record the coordinates of the objects you will be observing. Record information about standard stars that you will need to reduce the data. Don't forget to include uncertainties in the data when relevant. Information from a handbook or other source must be referenced properly, including the page number, in case you have to refer to it again. If the project is a long and complicated one, you should include an observing plan. The plan should list what objects you plan to observe in the order you plan to observe them and an estimate of the time required for each observation. This is essentially the work that needs to be done before the night of the lab.

Journal of Observations and Tabulation of Data - This will probably be the longest section of your journal. In this section record what you actually do at the telescope. Use the observing plan as a guide, but don't be afraid to improvise. This section is also where you will record the data you take. Don't forget essential information such as the time of the observation and the filters used. Record uncertainties when appropriate (almost always). Put this in tabular form when possible. Don't forget to put the date on the upper right hand corner of each page.

Data Reduction - This is where your record the procedure you use to reduce the data. Sometimes the data reduction is more work than the observations. It is good to outline the reduction procedure before you begin. If you use a computer for your reduction, don't forget to record the names of the programs used and the algorithm they use to do the calculation. (Don't forget to check your program with a sample calculation. Record the calculation in your notebook.) Record the results from major intermediate steps. Quote all results with estimated uncertainties. Graphs can be printed out an put in the notebook. Don't forget to put the header information on the things you print out too.

Interpretation of Results and Summary - In this section, summarize your major results. Include a discussion of the source, effect and possible methods for reducing observational uncertainty. When appropriate, interpret your result (this is the fun part) and try to determine what your result implies about the object in question. The interpretation leads naturally to new questions, so you might discuss future work that might be done to better understand the object.

Guidelines for Making Entries in the Notebook:

• Don't use scratch paper. Record everything in your notebook. Don't write things on slips of paper to be transcribed later. If you wish, reserve the left-hand pages of the notebook for scratch work.
• Don't erase anything. Neatly draw a line through an incorrect entry and write the correct value nearby. Leave extra space in tables, etc., in case corrections are needed.
• Title all tables and graphs. Record units in the table headings and put them on graphs. Include the uncertainties in your table and error bars on your graphs when this is appropriate.
• Define all symbols used in diagrams, graphs, and equations.
• Take care in drawing graphs. Graph data whenever you can. A graph often allows you to estimate the quality of the data just by looking at it.
• Determine the uncertainties in your data and results (if possible) as you go. These uncertainly estimates are often used to determine the number of measurements needed.
• Record qualitative observations as well as data. For example, if the weather is deteriorating, make a note of it. This kind of information may be useful during data reduction.
• Try to be neat. Remember you (and I) will have to read the notebook. Sloppiness and carelessness can make the best data impossible to decipher.
• Number and date each page of the notebook in the header. If you add something or make a correction on that page later, then box and date the new entry.
• Your notebook is a success if you or a colleague can use it a year later as a guide in repeating or expanding on your work or in writing up a scientific paper.

Scientific Integrity

No one learns in a vacuum. Don't hesitate to consult texts, the instructor, or your lab partners for help. However, it is essential that you give credit where credit is due. When you work in a lab group, be sure to list the members of your group. You may share data but you must not transcribe another student's work without that students permission and without giving him or her proper credit.