Photometry in version 2023-05-31

[Jerry Philpot]

Hello;
I notice that ASTAP photometry now has a tab "Transformation (auto)". I don't understand how the new function works. Are transforms applied to the data to be sent to the AAVSO? This would be absolutely fantastic
if automatic transform data could be calculated and applied.
I don't see any documentation explaining how to use, and the AAVSO data still has "NO" in the transform column.
When the AAVSO report is generated, what values go in the (b-v) box? I see the value for the slope and assume that value goes in the box for slope (makes sense).
Thanks

[han.k]

Hi Jerry,

It is all experimental but your setup transformation factor can be measured using the button most right. See screenshot.

Calculating the reference Johnson B magnitude from the Gaia database is also difficult and I have to use a two step transformation since it is not documented in the Gaia documentation. In fact I use the documented transformation from Gaia to V and Tycho Vt and Bt and then the Tycho documented transformation from (V, Bt, Vt) to Johnson-B. How good that is I don't know. Gaia documentation did not provide transformation directly to Johnson-B so that indicates it could be some error in.

I will update the documentation very soon. A part I will do today. More thoroughly testing is required. Any help would be nice.

Han

[han.k]

The transformation button has been improved. Download the ASTAP version from today.

Currently Windows only:
https://sourceforge.net/projects/astap-program/files/windows_installer/astap_setup.exe/download

This is now in the manual:
http://www.hnsky.org/astap.htm#transformation

Han

[Darren L Hill]

Hi Han;
Like Jerry, I was excited to see this new feature since I have a new prime lens and the standard fields do not rise much above 30 degrees where I live right now, and we have very little darkness. When trying this feature, it gave me an absolute correction of .462 which bought my result a little closer to the V filter reported values than previous. This is for the supernova in M101 which appears to be slowly dimming from ~11 to 12 visual and Johnson V.

Only thing that confused me, it appears to work when designating the Var, check and 3 star position, or leaving those annotations at default position. If I perform the scrolling function first where the magnitudes are calculated I get a divide by zero error and the program needs to be shut down.

That was not clear to me when reading the instructions.

Maybe that can be of use to someone trying it out.

[han.k]

Hi Darren,

If the Var and Check star are not selected it should show a ? in these columns once you activeta the >| button . The default position for the measuring position is at position 1.1 , so typical the left bottom corner. A runtime should not occur. If the runtime error occurs every time, send me a link to two of your files for testing.

I'm still busy improving things. A new development version will be released tonight or tomorrow here:
http://www.hnsky.org/astap.htm#beta_version

Han