During Evening and Morning Twilight:


1. Evening Twilight: Take twilight flats, then let the telescope operator tune the telescope.
Even if it is cloudy, take at least the first standard star field listed.
If it is photometric, do the 3 standard fields listed, so we can get color terms and extinction.

2. Midnight: If it is really photometric, do the standards, otherwise, skip them.
If you have been closed, and are just starting up in the middle of the night, do one of the midnight fields to be sure everything is working.

3. Morning Twilight: If it is photometric, do all the fields listed. If it is cloudy, do the first one.

Siderial time at Astronomical twilights and midnight

          Evening twi               midnight          morning twi
          ends                                        begins
              LST      local        LST    Local       LST    local          

Jan 15      02:25LST (19:10 local)  07:14 (24:00)      13:17 (06:01)

Feb 15      04:51 (19:35)           09:17              15:04 (05:46)

Mar 15      07:02 (19:56)           11:07              16:23 (05:14)

Apr 15      09:30 (20:20)           13:09              17:42 (04:33)


Evening twilight IN THIS ORDER
start with L95 03:53:11 00:00:00
               1 sec and 2 sec in BVgr
               1, 4, 10 sec in U

PG0231         02:33:40 05:17:41 centered on star A
               1 sec and 3 sec in BVgr
               1, 4, 10 sec in U

L92=SA92       00:54:52 00:40:24    centered on star 253
               1 sec and 5 sec in BVgr
               1 sec 4 sec 10 sec in U

Middle of night

NGC 2419 07:38:07 38:53:39

1 sec and 5 sec in BVgr

there's no U phot that I know of
L98=SA98      06:51:59 -00:21:11  centered on star 642
              1 sec and 3 sec in BVgr
              1 sec 4 sec 10 sec in U

End of night IN THIS ORDER

PG1633        16:35:34 09:46:17  centered on star B
              1 sec and 5 sec in BVgr
              1 sec 4 sec 10 sec in U
PG1323        13:25:50 -08:51:53 centered on star B
              1 sec and 5 sec in BVgr
              1 sec 4 sec 10 sec in U
PG1047        10:50:03 00:00:00  
              1 sec and 5 sec in BVgr
              1 sec 4 sec 10 sec in U

Calibration Field Information, Including OB's and Finding Charts

Note: RA-Decs are chosen to maximize the number of Landolt standards in the LBC FOV.

L92 = SA92 _00:54:52__ 00:40:24______INFORMATION PAGE

PG0231 ____02:33:40 __ 05:17:41______INFORMATION PAGE

L95__________03:53:11 __00:00:00____ *INFORMATION PAGE*

L98 = SA98 ___06:51:59 ____-00:21:11 _____INFORMATION PAGE

PG1047______10:50:03_____00:00:00______INFORMATION PAGE

PG1327______13:25:50_____-08:51:53_____INFORMATION PAGE

PG1633______16:35:34_____09:46:17______INFORMATION PAGE

Where are the OB's for Photometric standards, flats etc.? From Olga:

I wanted to note the locations of some OBs for calibrations in the home 
directory of sdtobs:

   contains OBs to observe photometric standards. These are named by 
standard star field. To allow them to be easily distinguished from 
science target observations in the archive, we set OBSERVER = lbtsdt 
(like science targets) but PROPID = calib. Also, LBCUSER=standard, though 
I am not sure this field (which normally contains the PI Name is 
searchable in the archive interface.

   contains OBs to obtain sets of biases (5bias.ob), extra-focal pupil 
images (*fastextra.ob) where * is the filter (Bfastextra recommended - the 
analysis program takes into account the relative focus offsets for the 
different filters) and focus sequences (*finefoc.ob; rarely used). These 
are not editable by sdtobs and there are only *.ob files. None of these 
have settings for OBSERVER, PROPID or LBCUSER. They'll appear under the 
subdirectory "common" in the archive (vs "lbtsdt" for most other data).


 Contains some afternoon and start of night OBs (end of night too for 
twilight flats):
 Flats: Calibs/ contains a subset of OBs that were used during 
commissioning to obtain 1-sec flats (5 dither positions) - though I think 
that an optimal flat field strategy is not yet well-determined. These are 
simply available here in case they can be of use. Note the exposure time 
can be scaled on-the-fly in the LBC user interface (but not during 
execution of an OB). These assume PA=0 (when not noted) and PA=180 
("Rot180" in the OB name).
  To get a quick measure of sky counts, use the "SkyFlatTest" OBs which 
use only a subregion chip 2 (these have OBSERVER=lbteng). The main OBs use 
the full focal plane array and have OBSERVER=lbtsdt and PROPID=flatcalib.

 Also in this directory I put an OB which takes 25 biases at U
25bias.ob (OBSERVER=lbtsdt, PROPID=biascheck, LBCUSER=bias), and an OB 
which takes a 900s dark, dark900.ob (OBSERVER=lbtsdt, PROPID=darkcheck, 

-- Main.jill - 11 Jan 2007
Topic revision: r6 - 14 Jan 2007, jill
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