tweakorder limit for astrometry.net API?

[Astro Roe]

Hello,

I'm trying to create a wcs_header with the following python command using astrometry.net API:

wcs_header = ast.solve_from_source_list(sources_df['x_APT'], sources_df['y_APT'], width, height, solve_timeout=360, scale_units='degwidth', scale_type='ul', scale_lower=2, scale_upper=10, downsample_factor=4, tweak_order=4)

randomly I noticed that in the wcs_header provided for tweakorders above 3 all AP_x_y and BP_x_y coefficients are zero which would mean there is no SIP correction present in the calculated wcs.

Tweakorders 2 and 3 work and give non zero coefficients.

is there a limit for maximum tweakorder when using the API?

Thanks for clearification in advance,

Mario Ennes

[Dustin Lang]

Hi,

There is no tweakorder limit in the API (technically I guess 9 is the limit!).  But your image might not have enough stars to support 4th order.  Or the fitting might have failed to find a good 4th-order solution.

cheers,

dustin

--
You received this message because you are subscribed to the Google Groups "astrometry" group.
To unsubscribe from this group and stop receiving emails from it, send an email to astrometry+...@googlegroups.com.
To view this discussion on the web visit https://groups.google.com/d/msgid/astrometry/439a4cfb-500a-46b6-9dfb-4c8a174efd24n%40googlegroups.com.