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AAVSO Transform Campaign

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hjw's picture
M11 Transform Coeffients

Here are my coeffients for M11 using the whole standard of comps (384) For BVI.

14" f/10 SCT and St-1001e Camera. Quite a load for VPHOT to process!

File upload: 
Newbie looking for feedback on transforms

As stated, I'm pretty new to photometry (but not to imaging).  I'm getting my feet wet by starting with generating my tranformations from images of NGC7790 from last summer, but the first number I'm getting for the color transform seems a bit high (don't really know if its reasonable):  T_bv = 1.308.  I've tried to follow the CCD manual as best as I can, and watched the CCD school video.  Details:

  • SBIG ST8XME on a C8 at f/10, with Chroma B and V filters
  • Stack of 3 images (averaged) in each filter (SNR(B)=88+/-2 (1sd), SNR(V)=132+/-1.5)
  • 35 stars in NGC7790 (uncrowded apertures), elimated outliers, R^2 for trendline = 0.996
  • Photometry using Muniwin, aperture diameter=11.8 pixels (aperture #7), inner annulus=15, outer=25 (average FWHM ~ 3.5 pixels or 3.3")
  • Transformed using a spreadsheet (for now)

Any feedback is appreciated, thanks.  I have more nights to analyze but don't expect a big difference since the plot looks pretty tight.



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