A picture of the chip layout (east up, north to the right) can be found here and then clicking on "The Mosaic CCD's".
The field centers are given here .
We must also take into account the gaps between the chips of the Mosaic. In the north-south direction the gaps are 18 arcsec and in the east-west direction are 10 arcsec. So for the first offset we must go an extra 1.5 times 18 or 27 arcsec in the NS direction and 5 arcsec in the EW direction.
Here is our observing algorithm. Set the 1.5-m telescope at the field center. The center of the northeast-most chip is 2048 pixels = 553 arcsec east (plus that extra 5 arcsec) and 3072 pixels = 829 arcsec north (plus the extra 27 arcsec) with respect to the field center. Offset the telescope to that position, which we will call position A. The next three positions are each 2048 pixels = 553 + 18 = 571 arcsec further south, in sequence. So here are the places to go:
corresponding 4-m mosaic chip A east 558 arcsec, north 856 arcsec of field center im8 B south 571 arcsec of posn A im7 C south 571 arcsec of posn B im6 D south 571 arcsec of posn C im5 Back to field center. Now go to E west 558 arcsec, north 856 arcsec of field center im4 F south 571 arcsec of posn E im3 G south 571 arcsec of posn F im2 H south 571 arcsec of posn G im1We want to calibrate field stars as faint as 19th magnitude. If there is photometric sky, the following exposures are recommended - 360 sec in V and R; 2 exposures of 360 sec in I. One should offset the telescope 10 arcsec east between the two I-band exposures. But then one must remember to offset 571 south and 10 west to the next position.
Here is a log of what has been done so far. For date, for example, 6 November 2002 UT, we abbreviate it as 6nov02. PM = photometric sky. N = non-photometric conditions. The exposure times are given in seconds. If posns = fc, that means we observed at the coordinates of the field center. If posns = SN, that means we pointed at a known active supernova. "X" means airmass in the notes.
Unless otherwise noted, we also obtained images of Landolt fields on photometric nights. Many standards fields were obtained on the night of Nov 8, 2002, but subsequent analysis revealed that it was never really photometric that night.
field UTdate sky posns exposures (sec) notes
V R I
wxa1 6nov02 PM A-H 10 10 15 shallow exps, clear sky
wxa1 6nov02 PM C 60
wxa1 8nov02 N A-H 400 400 800 = 2 X 400 light cirrus, posn to X=2
wxc1 27oct03 PM A 720 720 1440 = 2 X 720 0.9-m stds prove it was photometric
wxc1 27oct03 PM? B 720 720 1440 = 2 X 720 0.9-m some clouds low in SE
wxc1 27oct03 PM? C 720 720 1440 = 2 X 720 0.9-m "
wxc1 27oct03 PM? D 720 720 1440 = 2 X 720 0.9-m probably photometric
wxh1 6nov02 PM A-H 10 10 15 shallow exps, clear sky
wxh1 6nov02 PM SN 120 120 420 = 120+300 b03.wxh1_14 posn
wxh1 7nov02 N A-C 450 450 900 = 2 X 450 losing 0.86 mag in V (clouds)
wxh1 9nov02 PM C-H 360 360 720 = 2 X 360 seeing 1.2 --> 1.5
wxh1 9nov02 PM fc 360 360 720 = 2 X 360 seeing 1.1
wxr1 6nov02 PM fc 420 420 900 = 3 X 300
wyb3 6nov02 PM fc 420 420 900 = 3 X 300
wyd3 6nov02 PM fc 420 420 900 = 3 X 300
wxt2 6nov02 PM fc 420 420 900 = 3 X 300
wxt2 7nov02 N A-C 450 450 900 = 2 X 450
wxt2 7nov02 N D 450 X = 1.8 afterwards, so quit
wxt2 8nov02 N D 400 2X400 800 = 2 X 400 bright airplane through first R-band frame
wxt2 8nov02 N E 400 400 800 = 2 X 400
wxt2 9nov02 PM F 360 360 720 = 2 X 360 X --> 1.8, seeing 1.8
wxb1 7nov02 N A 360 360 720 = 2 X 360
wxb1 7nov02 N B-D 400 400 800 = 2 X 400
wxb1 2dec02 N E-F 400 400 800 = 2 X 400 seeing not so good
wxb1 3dec02 PM G-H 360 360 760 = 360+400 poor seeing
wxn1 23sep03 PM C-E 720 720 1440 = 2 X 720 0.9-m; seeing 1.2-1.6
wxv2 2dec02 N A-C 400 400 800 = 2 X 400
wxv2 3dec02 PM D-H 360 360 720 = 2 X 360 much better seeing at end
wyc3 4dec02 PM fc 360 360 720 = 2 X 360 variable seeing
wyc3 4dec02 PM A-D 360 360 720 = 2 X 360 variable seeing
wyc3 5dec02 PM E-H 360 360 720 = 2 X 360 seeing 1.5-1.8
wxw2 4dec02 PM fc 360 360 720 = 2 X 360 i-band images with X > 1.7
wxw2 5dec02 PM A 360 360 720 poor seeing, ~1.8
wxw2 5dec02 PM B 360 360 360 bad seeing, > 2
wxw2 6dec02 PM B 400 400 400 X = 1.7-1.86 seeing 1.7 (0.9-m)
wxw2 30jan03 PM C 360 360 720 = 2 X 360
wxw2 31jan03 PM D-E 360 360 720 = 2 X 360 bad seeing night
wxw2 1feb03 PM F-H 360 360 720 = 2 X 360 good seeing night, X = 1.35 to 1.96
wxc1 6dec02 PM fc 360 360 720 = 2 X 360 seeing ~1.8 (0.9-m)
wye2 6dec02 PM fc 400 400 800 = 2 X 400 seeing 1.4 (0.9-m)
wye2 6dec02 PM A-C 400 400 800 = 2 X 400 seeing 1.6-1.8 (0.9-m)
wye2 6dec02 PM D 400 400 400 X = 1.7-1.8, seeing 1.8 (0.9-m)
wye2 29jan03 PM E-F 360 360 720 = 2 X 360 about 1.7" seeing
wye2 29jan03 PM G 360 X = 2
wye2 30jan03 PM G 360 720 = 2 X 360
wye2 30jan03 PM H 360 360 720 = 2 X 360
wxu2 27oct03 PM A 720 720 1440 = 2 X 720 0.9-m stds prove it was photometric
In October 2003 we made up another list of fields. Here is a correspondence list:
---- SET A ----
wa11 -> waa1 23:29:52.92 -08:38:59.7
wa12 -> waa2 23:27:27.02 -08:38:59.7
wa13 -> waa3 23:25:01.12 -08:38:59.7
wa22 -> waa5 23:27:27.02 -09:14:59.7
wxa1 -> wa23 -> waa6 23:25:01.12 -09:14:59.7
wxb1 -> wa31 -> waa7 23:30:01.20 -09:44:55.9
wa32 -> waa8 23:27:27.02 -09:50:59.7
wa33 -> waa9 23:25:01.12 -09:50:59.7
---- SET B ----
wb11 -> wbb1 01:14:24.46 +00:51:42.9
xxxxxxx wb12 -> wbb2 01:12:00.46 +00:51:42.9
wb13 -> wbb3 01:09:36.40 +00:46:43.3
wb21 -> wbb4 01:14:24.46 +00:15:42.9
wxq1 -> wb22 -> wbb5 01:12:00.46 +00:15:42.9
wxp1 -> wb23 -> wbb6 01:09:00.16 +00:10:43.3
wb31 -> wbb7 01:14:24.46 -00:20:17.1
wb32 -> wbb8 01:12:00.46 -00:20:17.1
wb33 -> wbb9 01:09:36.40 -00:25:16.7
---- SET C ----
wyd3 -> wc11 -> wcc1 02:10:00.90 -3:45:00.0
wyc3 -> wc12 -> wcc2 02:07:40.60 -3:45:00.0
wyb3 -> wc13 -> wcc3 02:05:20.30 -3:45:00.0
wc21 -> wcc4 02:10:01.20 -4:20:00.0
wc22 -> wcc5 02:07:40.80 -4:20:00.0
xxxxxxx wc23 -> wcc6 02:05:20.40 -4:20:00.0
wc31 -> wcc7 02:10:01.55 -4:55:00.0
wc32 -> wcc8 02:07:41.03 -4:55:00.0
wye2 -> wc33 -> wcc9 02:05:20.52 -4:55:00.0
---- SET D ----
xxxxxxx wd11 -> wdd1 02:33:24.25 -07:43:18.2
wd12 -> wdd2 02:31:00.25 -07:48:17.3
wd13 -> wdd3 02:28:36.25 -07:48:17.3
wxw2 -> wd21 -> wdd4 02:34:30.35 -08:19:18.2
wxv2 -> wd22 -> wdd5 02:31:00.25 -08:24:17.3
wd23 -> wdd6 02:28:36.25 -08:24:17.3
wd31 -> wdd7 02:33:24.25 -08:55:18.2
wd32 -> wdd8 02:31:00.25 -09:00:17.3
wd33 -> wdd9 02:28:36.25 -09:00:17.3
Observations beginning 18 Nov 2003. Position E is 290 north and 566 west of
the nominal field center.
field UTdate sky posns exposures (sec) notes
V R I
waa1 18nov03 N A 720 720 2 X 720 seeing 2.0 + cirrus
waa2 18nov03 PM E 360 360 480 seeing 2.8
wbb1 18nov03 PM E 360 360 480 seeing 2.7
wbb2 18nov03 PM E 360 360 480
wcc1 18nov03 PM E 360 360 480
wdd1 18nov03 PM E 360 360 480
wdd4 18nov03 PM E 360 360 480 seeing 1.9
Here is Nick's list of standards fields. If photometric,
do a standard field every 90 minutes.
RA DEC equinox comment
jl163 00:10:30.00 -50:15:00.00 2000.0 new landolt
T_Phe 00:30:16.00 -46:27:55.00 2000.0 landolt(1992) 5*(B)
92-249 00:54:34.00 +00:41:10.00 2000.0
95-190+3 03:53:16.00 +00:16:45.00 2000.0
lb1735 04:31:38.00 -53:36:59.00 2000.0 new landolt (F)
MCT0550 05:51:54.00 -49:10:48.00 2000.0
SA98-670 06:52:12.00 -00:21:27.00 2000.0 landolt(1992) 10*wide
Rubin149 07:24:16.00 -00:32:17.00 2000.0 landolt(1992) 8*
Rubin152 07:29:56.00 -02:05:39.00 2000.0 landolt(1992) 7*(B)
lss982 08:10:35.00 -40:31:41.00 2000.0 new landolt (A)
#N2437 07:41:36.00 -14:49:00.00 1996.5 stetson calibration 97
#N2818 09:16:06.00 -36:36:32.00 2000.0 stetson calibration 97
#PG0918 09:21:34.00 +02:47:30.00 2000.0 landolt(1992) 5*
PG1047 10:50:09.00 -00:01:08.00 2000.0 Landolt(1992) 4*
G163-50 11:08:03.00 -05:11:35.00 2000.0 Landolt(1992) 2*
PG1323 13:25:49.00 -08:50:22.00 2000.0 landolt(1992) 4*(A)
107-602 15:39:19.00 -00:15:29.00 2000.0 landolt(1992) 5*
PG1633 16:35:34.00 +09:46:22.00 2000.0 landolt(1992) 5*(B)
110-503 18:43:11.00 +00:29:43.00 2000.0 Landolt,stetson 6*
Mark_A 20:43:58.00 -10:46:22.00 2000.0 landolt(1992) 4*
jl82 21:36:06.00 -72:49:00.00 2000.0 new landolt
PG2213 22:16:32.00 -00:21:49.00 2000.0 landolt(1992) 4*(B)
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