nova.astrometry.net works, astrotortilla daesnt....

[uhb1966]

I cant get AT to solve my plates, while astrometry solves IN 1 SEC!

Astromety.net says:

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25 reference sources within the image.
RoR: 315408
Test stars in RoR: 1137 of 1137
Good bins: 117 / 117; effA 1.79799e+07 of 1.79799e+07
Ref stars in RoR: 25 of 25
Logodds: 216.994
24 matches, 15 distractors, 0 conflicts (at best log-odds); 1137 field sources, 25 index sources
24 matches, 1113 distractors, 0 conflicts (all sources)
Hit/miss: ++-++++++++++-++++++----++-+--------+++(best)-------------------------------------------------------------
Tweak2: final WCS:
Found tag-along columns from field: FLUX BACKGROUND
Field 1: solved with index index-4109.fits.
Field 1: tried 192 quads, matched 3977 codes.
Spent 0.96406 s user, 0.012 s system, 0.97606 s total, 0.979876 s wall time.
Writing 24 rows (of 1137 field and 25 index objects) to correspondence file.
cx<=dx constraints: 55
meanx constraints: 807
RA,Dec constraints: 0
AB scale constraints: 25
Spent 0.996413 seconds on this field.

+++

Has anybody Any ideas (( ?

[uhb1966]

Solved!

For those with similar problems: In my case, the following helped:

1.- Let the picture be solved by nova.astrometry.net

2.- Note the index that solved it (in my case index-4109.fits.)

3.- Get exactly that index and put it inAT's working folder, move all other indexes to a safe place.

4.- !!!! REMOVE THE SIGMA OPTION FROM THE "CUSTOM" DEFAULT SETTINGS!!!

my working settings are:

Everytrhing in default, EXCEPT:

Custom options:  --no-plots -N none

5.- The actual solving now runs in 1 sec!

[frugal]

Astrotortilla sets a maximum time to attempt before it times out. So if you have all of the index files, and you are trying to scan teh whole sky, it might well time out.

There is a link to a good tutorial on how to set up AT for use, including how to work out what index files you need to use: http://stargazerslounge.com/topic/193470-my-tutorial-for-installing-setting-up-and-using-astrotortilla/

[Thalestris24]

Hi

In general you'll need a set of index files determined by your fov and to cover the whole sky. The sigma value allows for a certain amount of background noise so you normally need a value of around 30-70 (more or less) depending on whether you are lucky enough to have dark skies... Obviously if you've already determined the needed index file for a particular image then it will solve very quickly when you only have that index in the folder! Normally, it will need to iterate through the set of index files before it might find the one it needs or before it might fail to solve.

Louise

[uhb1966]

Dear Thalestris,

thanks a lot! However, the 41xx indexes are "widefield" indexes, and each of them covers the complete sky . Principially, for a given  scope/camera pair with fixed fov and fixed focal length, there should be only one of the 41xx indexes necessary as long as your  focal length is short enough for the 41xx indexes...

regarding sigma and background noise: i can only say that the installation default for sigma of "1" does not work with my setup, while removing the parameter works - possibly because some default value is used that fits my setup better (?). I will put up a message to the developers

Thanks again!!

[Thalestris24]

Hi

I confess I'm not au fait with the 4100 indexes and don't know what fov they cover.

My AT is set up to use the 4200 indexes http://astrometry.net/doc/readme.html#getting-index-files

That's what I've always used and they work for me! Are you saying I don't need them?

In reply to a question about index files, one of the AT authors says:

"Yes. As long as you know you have the index files needed, you're good to go. In general, if you have the 4200 index files, there's no need for the 4100 index files, as they cover the same FOV ranges with better accuracy and more stars than 4100 index files.

-Antti"

But if the 4100 work for you then that's fine

Louise

[uhb1966]

Well, to be honest the 42xx did not work for me! I only got hits after i swapped the 42xx with the 41xx.

But if you have a working config with the 41xx indexes, i would stick with them. Never touch a running system

Kind regards, U.

[Thalestris24]

Hiya

The AT FAQ is a useful resource, especially the part at the bottom about failing to solve:

http://sourceforge.net/p/astrotortilla/home/FAQ/

All the best

Louise