Reading And Formatting CSV in Pandas - Problem with Indexes and Headers

Question

I have this CSV

day        time       dni_tilt  d_tilt    r  g_tilted  dni  dhi  ghi  sky  top  code
                                                                       
2020-08-25 00:15       0.0     0.0  0.0       0.0  0.0  0.0  0.0  0.0  0.0     1
2020-08-25 00:30       0.0     0.0  0.0       0.0  0.0  0.0  0.0  0.0  0.0     1
2020-08-25 00:45       0.0     0.0  0.0       0.0  0.0  0.0  0.0  0.0  0.0     1
2020-08-25 01:00       0.0     0.0  0.0       0.0  0.0  0.0  0.0  0.0  0.0     1
2020-08-25 01:15       0.0     0.0  0.0       0.0  0.0  0.0  0.0  0.0  0.0     1
...                    ...     ...  ...       ...  ...  ...  ...  ...  ...   ...
2020-08-25 23:00       0.0     0.0  0.0       0.0  0.0  0.0  0.0  0.0  0.0     1
2020-08-25 23:15       0.0     0.0  0.0       0.0  0.0  0.0  0.0  0.0  0.0     1
2020-08-25 23:30       0.0     0.0  0.0       0.0  0.0  0.0  0.0  0.0  0.0     1
2020-08-25 23:45       0.0     0.0  0.0       0.0  0.0  0.0  0.0  0.0  0.0     1
2020-08-25 24:00       0.0     0.0  0.0       0.0  0.0  0.0  0.0  0.0  0.0     1

I need to read it back as a DataFrame like this:

                     dni_tilt  d_tilt    r  g_tilted  dni  dhi  ghi  sky  top  code
                                                                       
2020-08-25 00:15       0.0     0.0  0.0       0.0  0.0  0.0  0.0  0.0  0.0     1
2020-08-25 00:30       0.0     0.0  0.0       0.0  0.0  0.0  0.0  0.0  0.0     1
2020-08-25 00:45       0.0     0.0  0.0       0.0  0.0  0.0  0.0  0.0  0.0     1

that is the first column must be a data-time index. I tried with:

 colnames =['day','time','dni_tilt' ,'d_tilt','r','g_tilted', 'dni', 'dhi','ghi','sky','top','code'] 
 out=pd.read_csv(
                response_buffer,                     
                delimiter=' ',
                index_col=0,
                header=None,               
                names=colnames, 
                infer_datetime_format=True,
                parse_dates=[['day','time']])

but the result is strange:

                       dni_tilt  d_tilt    r  g_tilted  dni  dhi  ghi  sky  top  code
day_time                                                                        
2020-08-25 00:15       0.0     0.0  0.0       0.0  0.0  0.0  0.0  0.0  0.0     1
2020-08-25 00:30       0.0     0.0  0.0       0.0  0.0  0.0  0.0  0.0  0.0     1
2020-08-25 00:45       0.0     0.0  0.0       0.0  0.0  0.0  0.0  0.0  0.0     1
2020-08-25 01:00       0.0     0.0  0.0       0.0  0.0  0.0  0.0  0.0  0.0     1
2020-08-25 01:15       0.0     0.0  0.0       0.0  0.0  0.0  0.0  0.0  0.0     1
...                    ...     ...  ...       ...  ...  ...  ...  ...  ...   ...
2020-08-25 23:00       0.0     0.0  0.0       0.0  0.0  0.0  0.0  0.0  0.0     1
2020-08-25 23:15       0.0     0.0  0.0       0.0  0.0  0.0  0.0  0.0  0.0     1
2020-08-25 23:30       0.0     0.0  0.0       0.0  0.0  0.0  0.0  0.0  0.0     1
2020-08-25 23:45       0.0     0.0  0.0       0.0  0.0  0.0  0.0  0.0  0.0     1
2020-08-25 24:00       0.0     0.0  0.0       0.0  0.0  0.0  0.0  0.0  0.0     1