![[EXT]](images/offsite.png)
Mask bits for an SDSS spectrum.
Each of these bits is set for each fiber and each pixel. 0-15 indicate something about the fiber; 16-31 indicate something about that particular pixel.
| Bit name | Binary digit | Description |
|---|---|---|
| NOPLUG | 0 | Fiber not listed in plugmap file |
| BADTRACE | 1 | Bad trace from routine TRACE320CRUDE |
| BADFLAT | 2 | Low counts in fiberflat |
| BADARC | 3 | Bad arc solution |
| MANYBADCOLUMNS | 4 | More than 10% of pixels are bad columns |
| MANYREJECTED | 5 | More than 10% of pixels are rejected in extraction |
| LARGESHIFT | 6 | Large spatial shift between flat and object position |
| BADSKYFIBER | 7 | Sky fiber shows extreme residuals |
| NEARWHOPPER | 8 | Within 2 fibers of a whopping fiber (exclusive) |
| WHOPPER | 9 | Whopping fiber, with a very bright source. |
| SMEARIMAGE | 10 | Smear available for red and blue cameras |
| SMEARHIGHSN | 11 | S/N sufficient for full smear fit |
| SMEARMEDSN | 12 | S/N only sufficient for scaled median fit |
| NEARBADPIXEL | 16 | Bad pixel within 3 pixels of trace. |
| LOWFLAT | 17 | Flat field less than 0.5 |
| FULLREJECT | 18 | Pixel fully rejected in extraction (INVVAR=0) |
| PARTIALREJECT | 19 | Some pixels rejected in extraction |
| SCATTEREDLIGHT | 20 | Scattered light significant |
| CROSSTALK | 21 | Cross-talk significant |
| NOSKY | 22 | Sky level unknown at this wavelength (INVVAR=0) |
| BRIGHTSKY | 23 | Sky level > flux + 10*(flux_err) AND sky > 1.25 * median(sky,99 pixels) |
| NODATA | 24 | No data available in combine B-spline (INVVAR=0) |
| COMBINEREJ | 25 | Rejected in combine B-spline |
| BADFLUXFACTOR | 26 | Low flux-calibration or flux-correction factor |
| BADSKYCHI | 27 | Relative χ2 > 3 in sky residuals at this wavelength |
| REDMONSTER | 28 | Contiguous region of bad χ2 in sky residuals (with threshhold of relative χ2 > 3). |