Initial results: Spectral Classes O, B and A

One of the benefits of doing astronomy in late December at this latitude (48 N) is that one can begin observing at 5:00 pm, wrap things up by 9:00 pm and still have an early bedtime. the following observations were made on December 20 and 23, 2023.

Class

Spectral
Type

Name(s)

Obs Date
Time

profile /
reference

O

O9V

10 Lac
HIP_111841
HD214680

12/20/23
5:25 pm

B

B0.5IIIs

Alfirk
bet Cep
HIP_106032
HD205021

12/23/23
7:11 pm

B

B8III

87 Psc
HD7374
HIP_5778

12/23/23
6:10 pm

A

A1IV_sh

HIP_62572
HD112028

12/23/23
6:37 pm

A

A7III

28 And
HD2628
HIP_2355

12/23/23
5:14 pm

Obviously, the best match was for the star Alfirk. I cannot explain the deviations for the other profiles. All profiles were created with the same master flat frame; all used the same instrument response, and all were taken within an hour on the same evening except 10 Lacerta three days earlier.

In addition to trying to improve my workflow, I want to take a look at rectified profiles for these observations (by dividing out the continuum) so I can more readily compare my results with those in Walker’s Atlas. I will save that for another post.

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