Observational Details
In this page, you'll find:
Field Coordinates
The survey of five 2x2 deg fields, integrates deeply in sub-fields on successive runs. Most runs concentrate on two fields, and the runs come in pairs separated by one month [for SN finding]. Below is a listing of the DLS fields. Star density, extinction, 2-field accessibility, and existing redshifts were factors in their choice.
| RA(J2000) --------- North: F1: 00:53:25.3 F2: 09:19:32.4 South: F3: 05:20:00 F4: 10:52:00 F5: 13:59:20 | DEC -------- +12:33:55 +30:00:00 -49:00:00 -05:00:00 -11:03:00 |
l,b ------- 125,-50 197, 44 255,-35 257,47 328,49 |
ecliptic ------- 17,6 133,14 69,-72 166,-11 212,1 |
E(B-V) ------ 0.06 0.02 0.02 0.025 0.05 |
Here are the centers of each subfield:
| Subfield | RA (J2000) | DEC |
| F1p11 | 00:56:09.7 | +13:13:55 |
| F1p12 | 00:53:25.3 | +13:13:55 |
| F1p13 | 00:50:40.9 | +13:13:55 |
| F1p21 | 00:56:09.2 | +12:33:55 |
| F1p22 | 00:53:25.3 | +12:33:55 |
| F1p23 | 00:50:41.4 | +12:33:55 |
| F1p31 | 00:56:08.8 | +11:53:55 |
| F1p32 | 00:53:25.3 | +11:53:55 |
| F1p33 | 00:50:41.8 | +11:53:55 |
| F2p11 | 09:22:37.1 | +30:40:00 |
| F2p12 | 09:19:32.4 | +30:40:00 |
| F2p13 | 09:16:27.7 | +30:40:00 |
| F2p21 | 09:22:37.1 | +30:00:00 |
| F2p22 | 09:19:32.4 | +30:00:00 |
| F2p23 | 09:16:27.7 | +30:00:00 |
| F2p31 | 09:22:37.1 | +29:20:00 |
| F2p32 | 09:19:32.4 | +29:20:00 |
| F2p33 | 09:16:27.7 | +29:20:00 |
| F3p11 | 05:24:00.7 | -48:20:00 |
| F3p12 | 05:20:00 | -48:20:00 |
| F3p13 | 05:15:59.3 | -48:20:00 |
| F3p21 | 05:24:03.9 | -49:00:00 |
| F3p22 | 05:20:00 | -49:00:00 |
| F3p23 | 05:15:56.1 | -49:00:00 |
| F3p31 | 05:24:07.2 | -49:40:00 |
| F3p32 | 05:20:00 | -49:40:00 |
| F3p33 | 05:15:52.8 | -49:40:00 |
| F4p11 | 10:54:40.5 | -04:20:00 |
| F4p12 | 10:52:00 | -04:20:00 |
| F4p13 | 10:49:19.5 | -04:20:00 |
| F4p21 | 10:54:40.6 | -05:00:00 |
| F4p22 | 10:52:00 | -05:00:00 |
| F4p23 | 10:49:19.4 | -05:00:00 |
| F4p31 | 10:54:40.8 | -05:40:00 |
| F4p32 | 10:52:00 | -05:40:00 |
| F4p33 | 10:49:19.2 | -05:40:00 |
| F5p11 | 14:02:02.7 | -10:23:00 |
| F5p12 | 13:59:20 | -10:23:00 |
| F5p13 | 13:56:37.3 | -10:23:00 |
| F5p21 | 14:02:03.0 | -11:03:00 |
| F5p22 | 13:59:20 | -11:03:00 |
| F5p23 | 13:56:37.0 | -11:03:00 |
| F5p31 | 14:02:03.4 | -11:43:00 |
| F5p32 | 13:59:20 | -11:43:00 |
| F5p33 | 13:56:36.6 | -11:43:00 |
OBSERVING STRATEGY
The individual exposures are 600-900s each, depending on the filter; taken in blocks consisting of five pointings dithered by up to 8 arcminutes to shift all low surface brightness features off themselves (to provide adequate sky-flatfielding) and cover 42'x42' in one "subfield" (9 subfields = one 2x2 degree field). This dither is repeated (with about a one arcminute offset) in each filter -- and then off to another sub-field within one of two fields. The survey observations go deepest in R (to a surface brightness limit of 29 mag/sq.arcsec) and concentrate on R in good seeing in order to obtain the best lensing signal possible. The other bands are imaged less deep (approximately half of the exposure time of R, in order to provide photometric redshift estimates.)