SpecobjID

• DR7 and before

Bits Length (# of bits) Mask Assignment Description

0-15 16 0xFFFF000000000000 plate number of spectroscopic plate

16-31 16 0x0000FFFF00000000 MJD MJD (date) plate was observed

32-41 10 0x00000000FFC00000 fiberID number of spectroscopic fiber on plate (1-640)

42-47 6 0x00000000003F0000 type type of targeted object

48-63 16 0x000000000000FFFF line/redshift/index 0 for SpecObj, else number of spectroscopic line (SpecLine) or index (SpecLineIndex) or redshift (ELRedhsift or XCRedshift)

• DR8 and after

50-63 plate id number (14 bits)

38-49 fiber id number (12 bits)

24-37 MJD (date) plate was observed minus 50000 (14 bits)

10-23 rerun (14 bits)

0-9 line/redshift/index: 0 for SpecObj, else number of spectroscopic line (SpecLine) or index (SpecLineIndex) (10 bits)

SpecobjID和plate,mjd,fiberID的互转参考[sdssidl]中的程序[1]