sdss_specobjid

pydl.pydlutils.sdss.sdss_specobjid(plate, fiber, mjd, run2d, line=None, index=None)[source]

Convert SDSS spectrum identifiers into CAS-style specObjID.

Bits are assigned in specObjID thus:

Bits Name Comment
50-63 Plate ID 14 bits
38-49 Fiber ID 12 bits
24-37 MJD Date plate was observed minus 50000 (14 bits)
10-23 run2d Spectroscopic reduction version
0-9 line/index 0 for use in SpecObj files see below for other uses (10 bits)
Parameters:

plate, fiber, mjd : int or array of int

Plate, fiber ID, and MJD for a spectrum. If arrays are passed, all must have the same length. The MJD value must be greater than 50000.

run2d : int, str or array of int or str

The run2d value must be an integer or a string of the form ‘vN_M_P’. If an array is passed, it must have the same length as the other inputs listed above. If the string form is used, the values are restricted to \(5 \le N \le 6\), \(0 \le M \le 99\), \(0 \le P \le 99\).

line : int, optional

A line index, only used for defining specObjID for SpecLine files. line and index cannot both be non-zero.

index : int, optional

An index measure, only used for defining specObjID for SpecLineIndex files. line and index cannot both be non-zero.
Returns:

numpy.ndarray of numpy.uint64

The specObjIDs of the objects.
Raises:

ValueError

If the sizes of the arrays don’t match or if the array values are out of bounds.

Notes

  • On 32-bit systems, makes sure to explicitly declare all inputs as 64-bit integers.
  • This function defines the SDSS-III/IV version of specObjID, used for SDSS DR8 and subsequent data releases. It is not compatible with SDSS DR7 or earlier.
  • If the string form of run2d is used, the bits are assigned by the formula \((N - 5) \times 10000 + M \times 100 + P\).

Examples

>>> from pydl.pydlutils.sdss import sdss_specobjid
>>> print(sdss_specobjid(4055,408,55359,'v5_7_0'))
[4565636362342690816]