Further investigation, mixed method v calibration lamp only
The best fit for Z And was when the only frame taken after the meridian flip was used, and it was calibrated using the mixed Balmer and lamp method. The Balmer lines were found from Pi And (also taken after the flip).
The lamp was the one taken for Z And, after the flip. No heliocentric or corrections for radial velocity were made.
The errors were
H alpha -0.4
H beta +0.65
H gamma +1.2
H delta +1.0
H epsilon -1.0
When the same frame was calibrated using its lamp lines only and not the Balmer lines from Pi And
Errors are:
H alpha -0.4
H beta -1.45
H gamma -1.8
H delta -2.5
H epsilon -3.5
So for me it seems the mixed method gave the best results
OK so comparing with the errors you had at the start of the thread it looks like you now have a good calibration across the range, including at H alpha where ISIS only uses lamp lines. We still do not understand why the lamp gives increasing errors towards the blue end but I think we should probably accept this as a win for now !
The best fit for Z And was when the only frame taken after the meridian flip was used, and it was calibrated using the mixed Balmer and lamp method. The Balmer lines were found from Pi And (also taken after the flip).
The lamp was the one taken for Z And, after the flip. No heliocentric or corrections for radial velocity were made.
The errors were
H alpha -0.4
H beta +0.65
H gamma +1.2
H delta +1.0
H epsilon -1.0
When the same frame was calibrated using its lamp lines only and not the Balmer lines from Pi And
Errors are:
H alpha -0.4
H beta -1.45
H gamma -1.8
H delta -2.5
H epsilon -3.5
So for me it seems the mixed method gave the best results
Hi John,
OK so comparing with the errors you had at the start of the thread it looks like you now have a good calibration across the range, including at H alpha where ISIS only uses lamp lines. We still do not understand why the lamp gives increasing errors towards the blue end but I think we should probably accept this as a win for now !
Cheers
Robin
Pages