🚀 go-pugleaf

Hi there,
I got a data set from Siemens CCD for an inorganic molecule and the
background (F^2(sigma)) is very small. There is only one reflections
goes negative for a set of 60,000 reflections to a 47x47x23 P3 cell. 

This lead to serveral problems:
1) I am not very sure if I pick the right space group. Because the
systemic absent are not very clear. The space group suggestion list 
16 possible trigonal/hexagonal space group from P-3 (CFOM 4.38) to 
P6mm (CFOM 111.94).
2) The best R1 is as high as .18 (with shelxl93 in one of the space
group
P6cc(actually not in the suggesting list). And the best R1 used other
trigonal/hexagonal space groups is about .25 to .40 and above.

when I tried a wild suggestion to multiply the sigma by 10 to all my
reflections to see what happen. I did. The R1 drop from 0.18(wR2 0.39)
to 0.10(wR2 0.31) and the suggested space group drop from 16 to 2(

My question:
Can I change the parameters in the WGHT or  HKLF or other cards to get
to the same result but a wild guessed 10xsigma?
Should I ask the person who ran the structure for me to modify the
background from the frames and give me a new set of hkl?
If the sigma from a CCD is really that low?

Your help will be very appreciate.

Sean (Xiang Ouyang)
P.S.You may reply me by e-mail