Skip to main content

Transformation Data

3 posts / 0 new
Last post
sgor's picture
Transformation Data

I would like some advice from the community. I have for years calculated my systems transformation coefficients. After a few false starts (mostly caused by misunderstanding ) with VPHOT I can now regularly generate transformed observations. I usually image in pairs either V and R or V and B. my question is this should I only report thr transformed V results and toss the R or B?  Or should I also report the R or B?  The former seems like a waste of data whereas the latter may be a cluttering of the data base since often there are no other observations at those bands. This is particularly true for those stars that I'm imaging one time a night or once a week.  What do others do.


HTY's picture
I report all the measurements

Hi George,

I wouldn't worry about "cluttering" the database.  That's what computers are for!  I report the measurements in all filters when I transform.  Who knows, you may be the first to find something interesting or a future researcher may be looking for just that data.

The difference in brightness between the two filters (color index) provides astrophysical data that is not as readily available in a single color alone.  Why not record it.


WBY's picture
Transformed Data For All Filters

I agree with Tim. You took the trouble of taking the images in multiple colors. you may have done it primarily to transform your v measurements, but since you have everything you need to submit transformed observations for the other color or colors, I would definitely submit observations for every filter I used. In a number of cases it is necessary to know how the color of the object changes to be able to more properly classify the variable or understand what is going on. If you don't have a spectrograph or the object is too faint to take a spectrum in your telescope, the next best thing is to see how the color indices change. In can be invaluable.  

Log in to post comments
AAVSO 49 Bay State Rd. Cambridge, MA 02138 617-354-0484