Jim, Robert Burnham was a VERY gifted individual. His handbook was published independantly from the Lowell Observatory (?) where he worked because they were afraid of the data being in error. Yet, history has proven this to not be the casre. His science was exact, and his numbers are still considered today to be some of the most accurate. Burnham's data did not come "out of the blue". Rather than cast dispersion on his monumental and excellent effort, I propose another reason for the disparity you see. You are very aware that no two instruments behave exactly alike in a given situation. Now allow different instruments to be used at vastly different locations, under very dis-similar circumstances and environments, and operated by varying human individuals and you come up with the scatter in the data you are seeing. Look at the data scatter in measurements made by different CCDs for variable star work. Look at data produced for multiple star work for separation and position angle. If you compare all of this you'll see that in astronomy (and all of science) things are not always well quantified. A given individual instrument may be repeatable, but getting agreement in the same lab at the same time with two different instruments is extremely difficult, and many time cannot be done. Please compare numbers aross more than just one catalog. NGC 2000 is not the ultimate bible. Compare with the Yale Catalog of Bright Stars, the Smithsonian Astrophysical Observatory catalog, the Guide Star Catalog, etc. You'll see that no two are alike. I stand by the lion share of data produced by Robert Burnham. He was a far better man than I, and I have enormous respect for the accuracy and consistency he produced. Brent --- Jim Gibson <xajax99@yahoo.com> wrote:
Jim, Kim, and Chuck
Thanks for the response. I have always wondered how magnitudes are derived. Part of my curiosity on the subject stems from my noticing that the magnitudes as stated in Burnham's Celestial Handbook as compared to Sinnett's NGC 2000.0 frequently are at variance. Burnham tends to be more conservative. His magnitudes tend to have higher values than Sinnotts.
Burnhams has a copyright of 1958-1979 and the NGC 2000.0 has a copyright of 1988. Without deeper research, in other words, taking a guess and applying your descriptions of how magnitudes are derived, I would guess that Burnham took his magnitudes out of the blue (pun intended) and Sinnotts may align more closely with the visual.
Jim
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