Skip to main content

M67 Transforms Evaluation

Due to the New England winter storm currently affecting the area, phone coverage at the AAVSO may be much reduced until Wednesday. The staff is still available via email, and we suggest using that method to contact us if you need assistance.
msheald's picture
msheald
Offline
Joined: 2010-10-02

Hello! I imaged M67 on 18-April and 1-May with my 8 inch LX200 classic at f6.3 using BVI filters and an SBIG ST-402 camera.

    After using the photometry wizard in MPO Canopus with the same 15 stars from Mr. Henden's field, I obtained the following transforms: 18-April   B=0.529, V=-0.065, I=-0.006

    01-May  B=0.135 V=-0.051  I=-0.017

    The error plots for each night were very close to zero with small standard deviations.

    The transforms for V and I seem close. B seems quite different on the two nights. How much variation should I expect? Thank you and best regards.

 

Mike

Transform error
TCB168's picture
TCB168
Offline
Joined: 2010-07-26

The first B transform seems much too big. I don't have the same camera but use a ST10XME. My B transform is always less than 0.1.

You need to check that the correct stars were selected for the original analysis. Also make a graph of the raw magnitudes from MPO graphing the B-b over the B-V using excel or something similar. The slope of this graph is the transform coefficient. check that the data looks real and isn't just a noisy graph.

AAVSO 49 Bay State Rd. Cambridge, MA 02138 aavso@aavso.org 617-354-0484