Data model: plateGuideOffsets

General description: This file gives the offsets necessary for guiding a plate optimized for the holes drilled for a particular wavelength. The typical use case is that the guide stars are observed near 5400 Angstroms, but the APOGEE holes are drilled and observed near 1.66 microns. This means we want to observe the guides slightly offset from center in cases that we aren't exactly at the design hour angle.

Naming convention: plateGuideOffsets-PLATEID6-pP-lLAMBDA5.par (where P is the pointing number starting with 1, and LAMBDA is the wavelength that the offsets are optimized for)

Approximate size: 200 kbytes.

File type: Yanny

Read by products: platedb, sop?

Written by products: platedesign

Required header keywords: all found in plateHoles files, plus:

• lambda (float32): wavelength optimized for (should be same as LAMBDA in file name), in Angstroms
• pointing (int32): pointing number (1, 2, etc)

Required column names:

• xfocal (float32): X-focal position of hole (mm)
• yfocal (float32): Y-focal position of hole (mm)
• target_ra (float64): right ascension, J2000 deg
• target_dec (float64): declination, J2000 deg
• lambda_eff (float32): design wavelength of hole (Angstroms)
• fiberid (int32): fiber id number of hole
• iguide (int32): guide number of hole
• holetype (string): type of hole ('GUIDE', 'ALIGNMENT', 'APOGEE', etc)
• delha[11] (float32): delta-HA relative to design (deg, positive equals West)
• xfoff[11] (float32): at each DELHA, the X-offset of the image relative to the hole, at LAMBDA_EFF (mm)
• yfoff[11] (float32): at each DELHA, the Y-offset of this hole, at LAMBDA_EFF (mm)