Astroart Forum

Hi,

Last year I used AA6 SP1 to dophotometry on an image using only one reference star.
I followed this procedure:

Image is a stack of images taken with an unmodded DSLR.

1) Open the stacked image in AA.
2) Split RGB.
3) Close all except G.
4) Platesolve and rotate so that north is up (to make it easier to find stars).
5) Mark the star to measure S_m, the reference star S_r and the check star S_c.
6) Open Tools->Photometry.
7) Press the camera icon (instrumental).
8) Press [OK].
9) Click [P] for S_r to mark it as a reference star.
10) Select the row with S_r.
11) Right-click row with S_r and choose Edit.
12) Type the reference star magnitude in lowe edit in Adu section and press [Ok].
13) Open Tools->Photometry and press [Ok].

After this, the star to be measured, S_m, and the check star, S_c, showed correct magnitudes.
But if I retry this procedure on the same image with AA6 SP2 I do not get the same results...

I do not know if it is changes from SP1 to SP2 or perhaps I have corrupted some vital settings in AA?

How do I "reset Astro Art to defaults"? I hope not a re-install is needed?

/Rudi

Hi,
there are no settings which could cause this, so reinstalling will not solve the problem. (The only thing that you could have changed is S-G-B of stars, but you can verify).
You can solve easily, just try again with SP1 and verify that the ADU of stars is the same before using Photometry.

The procedure you wrote is not optimal, use this instead:

1) Open the stacked image in AA.
2) Split RGB.
3) Close all except G.
4) Platesolve and rotate so that north is up (to make it easier to find stars).
5) Mark the star to measure S_m, the reference star S_r and the check star S_c.
6) Select the row with S_r.
7) Right-click row with S_r and choose Edit.
8) Type the reference star magnitude in lowe edit in Adu section and press [Ok].
9) Click [P] for S_r to mark it as a reference star.
10) Open Tools->Photometry and press [Ok].

in SP2 you can avoid step 6, 7 and 9, just right click over the star in the image, click Edit Star, write the magnitude and enable the option "reference stars". Photometry is not changed in SP2.

If you used the Astroart Demosaic in preprocessing, then you could avoid step 2 and 3 selecting "Green channel 2x2" as Algorithm in Demosaic.

Hi Fabio, after re-installing SP2 I had no problems at all, works like a charm with a single ref star. On 11 measurements on same star, same REF and same check star, check star varied only 0,32% on average
Thanks for the prompt response - as usual.