Quality holes in DR2 coverage

The following is a reference note on quality of fields, including hole fields in the DR2 data set.

Each field of DR2 has a quality set. This quality is determined by the seeing of the field, the tracking of the stripe, the cloudiness of the data (photometric or not), and whether or not the photometric pipeline timed out while processing.

The quality is designated by an integer from 0-5, and is stored in the quality parameter of the tsField*.fit file for each field. Here's a key to what that quality means.

 0=UNDETERMINED,   // The data has been obtained, however its
                   // quality has not yet been determined.
 1=BAD,            // Bad data.  Don't bother with it.
 2=ACCEPTABLE,     // The data is acceptable for the survey, but we would
                   // like to improve on it.
 3=GOOD,           // The data is fully acceptable for the survey, and
                   // there is no need to improve it.
 4=MISSING,        // The data is missing, but we include the area of
                   // sky associated with the data as a hole in the
                   // survey.
 5=HOLE            // The data is unacceptable, but we include the area
		   // of sky associated with the data as a hole in the
		   // survey.

Also in the tsField file are more details on exactly why quality was set to what it was.

For instance, if the tsField file has a frames_status value of 3 = FIELD_TOO_LONG, meaning the field timed out during processing, this results in a quality = 5 (HOLE) for the overall field quality.

The psp_status is also available in the tsField file, as are the culled, badmask,acceptablemask,goodmask and holemask masks.

The quality holes are areas of sky where no objects are cataloged, and researchers interested in structure statistics of galaxy or star distributions may wish to mask out these holes from their coverage map. Roughly half of these fields include a very bright star (generally r < 5 or a very large galaxy or globular cluster, causing the object deblending in the photometric pipeline to time out. While no catalog information is available for these fields, the corrected image is available. Data of sufficiently poor quality can also be marked as a hole (where the frames_status is 0): very poor seeing (significantly worse than 2′′ FWHM), glitches in the telescope tracking, and non-photometric data. There are also a few small gaps, also marked as holes, which fall between two adjacent SDSS scans.

We note that there are different holes in the best version of sky than the target version. This is due to the photometric pipeline timing out for a number of fields processed with pipeline version v5_4, where earlier versions did not time out. In other words, if we had let the photometric processing run longer, they may have finished successfully. Future data releases will include these data.

Fields which are marked as hole will show up as holes in the large scale structure masks; objects detected in those fields are not included in the data release. The following table lists the holes in the DR2 fields.

Target skyVersion holes

run rerun camcol fieldstart-end 'quality (5=hole)' 'frames_status (3=timeout,0=ok)'
-------------------------------------------------------------------------

1737 0 6 30 5 3
1739 0 2 31 3 3
1739 0 2 160 3 3
1889 1 4 42 5 3
1895 0 1-6 170-185 5 0
1895 0 1-6 268-285 5 0
1992 0 1 141 5 3
1992 0 1 168 5 0
1992 0 2 130 5 3
2074 0 5 174 5 3
2126 0 4 278 5 3
2126 0 6 341 5 3
2248 0 1-6 186-196 5 2
2328 0 1 77 5 3
2566 0 3 108 2 3
2566 0 4 330 2 3
2566 0 6 64-65 2 3
2566 0 6 220 2 3
2583 0 1 44 3 3
2583 0 2 136 2 3
2662 0 1 38 3 3
2777 0 4 253-254 5 0
2822 0 3 35 3 3
2822 0 6 108 3 3
2825 0 1 44 5 0
2864 0 5 237 2 3
3015 0 1 105-125 5 0
3015 0 1 156 5 0
3015 0 1 159 5 0
3015 0 1 161-162 5 0
3015 0 1 195-215 5 0
3015 0 1 275 5 0
3015 0 1 283 5 0
3015 0 1 287-288 5 0
3180 0 1 72-73 5 0
3180 0 1 78-81 5 0
3180 0 1 85 5 0
3180 0 1 90-91 5 0
3225 20 2 299 5 3
3225 20 3 71 5 3
3225 20 4 264-265 5 3
3225 20 4 310 5 3
3225 20 6 184 5 3
3225 20 6 195 5 3
3226 20 5 127 5 3

Best skyVersion holes

run rerun camcol fieldstart-end 'quality (5=hole)' 'frames_status (3=timeout,0=ok)'
-------------------------------------------------------------------------

752 40 2 205 5 3
752 40 2 276-277 5 0
752 40 5 692 5 3
752 40 6 660 5 3
756 44 2 587 5 3
756 44 3 338 5 3
1035 40 6 112-113 5 3
1043 40 6 149 5 3
1140 40 6 250-251 5 3
1231 40 6 141-142 5 3
1345 41 2 607 5 3
1359 40 3 60 5 0
1412 40 1 233 5 3
1412 40 3 315 5 3
1458 40 3 646 5 3
1458 40 4 674 5 3
1458 40 6 525 5 3
1462 40 5 88 5 3
1462 40 6 399 5 3
1462 40 6 458 5 3
1729 40 3 195-196 5 3
1729 40 4 387 5 3
1737 40 6 30 5 3
1739 40 2 31 5 3
1739 40 2 160 5 3
1739 40 3 24 5 3
1739 40 5 175 5 3
1740 40 2 95 5 3
1740 40 2 135 5 3
1740 40 6 54 5 3
1889 40 4 42 5 3
1895 41 1-6 270-280 5 0
1904 42 4 172 5 3
1992 40 2 130 5 3
2076 40 1 140-141 5 3
2125 40 1 132 5 3
2126 41 4 126 5 3
2126 41 4 278 5 3
2126 41 6 341 5 3
2131 40 6 25 5 3
2131 40 6 26 5 3
2137 40 2 279-280 5 3
2137 40 3 243 5 3
2137 40 6 183 5 3
2189 40 3 57 5 3
2190 40 1 144 5 3
2243 40 1 130 5 3
2243 40 3 75-77 5 0
2243 40 4 73-77 5 0
2243 40 4 131 5 3
2243 40 5 71-75 5 0
2243 40 6 70-72 5 0
2247 41 6 145 5 3
2299 41 1 300 5 3
2305 40 3 38-39 5 3
2326 41 2 309-310 5 3
2328 40 1 77-78 5 3
2328 40 1 122 5 3
2328 40 2 175 5 3
2328 40 4 38 5 3
2379 40 2 130 5 3
2566 40 2 83 5 3
2566 40 3 108 5 3
2566 40 4 330 5 3
2566 40 6 64-65 5 3
2566 40 6 219-220 5 3
2583 40 1 44 5 3
2583 40 2 136 5 3
2662 40 1 38 5 3
2662 40 2 257 5 3
2662 40 3 130 5 3
2662 40 3 141 5 3
2662 40 4 183 5 3
2662 40 5 84 5 3
2735 40 5 114-115 5 3
2738 40 4 155 5 3
2738 40 4 184 5 3
2738 40 4 280 5 3
2740 40 1 225 5 3
2740 40 4 163 5 3
2777 40 4 53 5 3
2822 40 1 49 5 3
2822 40 3 34 5 3
2822 40 3 35 5 3
2822 40 3 52 5 3
2822 40 6 108 5 3
2825 40 1 45-46 5 3
2825 40 6 208 5 3
2826 40 4 223 5 3
2826 40 4 224 5 3
2830 41 1 68 5 3
2830 41 4 252 5 3
2863 40 6 101 5 3
2864 40 2 40 5 3
2864 40 2 61 5 3
2864 40 5 186 5 3
2864 40 5 237 5 3
2883 40 5 212 5 3
2887 40 6 43 5 3
2888 40 5 45 5 3
2964 40 1 57 5 3
2964 40 6 22 5 3
2986 40 1 173 5 3
3015 40 1 333 5 3
3015 40 4 348 5 3
3015 40 6 121 5 3
3015 40 6 133 5 3
3103 40 1 130-131 5 3
3130 40 6 50 5 3
3177 40 2 229 5 3
3177 40 2 255 5 3
3180 40 4 65 5 3
3180 40 6 42 5 3
3180 40 6 76 5 3
3185 40 1 44 5 3
3225 40 2 299 5 3
3225 40 2 355 5 3
3225 40 2 356 5 3
3225 40 3 71 5 3
3225 40 4 264 5 3
3225 40 4 265 5 3
3225 40 4 310 5 3
3225 40 6 184 5 3
3225 40 6 195 5 3
3226 40 1 88 5 3
3226 40 5 127 5 3
3325 41 1 430 5 3
3325 41 4 99 5 3
3325 41 5 345 5 3
3388 40 3 128-129 5 3
3388 40 4 167 5 3