G400 fastq header description?

[Luke Nguyen]

Hello,

I am doing a comparison of duplicated reads on Illumina NovaSeq vs MGI G400 by checking the distribution of reads on the flowcell. I noticed the fastq header from the G400 is quite different from that of the NovaSeq.

For example, one of the headers is:

@F350009384L1C001R0010008170/1

which I interpret as "flowcell id: F350009384", "lane: L1", "tile column: C001", "tile row: R001", "read: /1" and the remaining part "0008170" is unclear to me. Could this be the X and Y coordinates of the cluster/DNB?

Would love to hear if my interpretation is correct. Thanks!

[EmiTom]

In my opinion, if we assume that F350009384 is the ID of the flow cell, L1 refers to the lane number and indicates that this reading was generated on lane 1, and R001 refers to a row of tiles in the grid, then C001 is probably a column in the tile grid on the flow cell, and /1 indicates that this is the first read in a paired sequencing run (if it is single-ended, it will still be interpreted as the first read).
In that case, the part you're not sure about, 0008170, might actually be the X and Y coordinates of the cluster. In Illumina sequencing, the fastq headers usually contain the X and Y coordinates after the mosaic information, and it is likely that MGI uses similar relationships to determine the exact location of the read on the flow cell.