February Standards


Below is a table with night-by-night recommendations for standard star fields for observing in evening twilight and just before the middle-of-the-night switchover to the night's Community program.

Currently, we are observing 3 standard star fields in evening twilight -- at least one and preferably more in SDSS Stripe 82 -- and one more just before
switchover. For the 3 standard fields observed during evening twilight, one should be at low airmass (<1.25), one at medium airmass (1.25-1.65), and one at high airmass (1.65-2.10).

If, for some reason, you need to take standards at a different time than the normal times, you can still use the StdStarPicker on observer2:

   source ~/dtucker/bin/setup_StdStarFieldPicker.csh    (or .bash if you are using bash shell) --help --UT=now                   (for standard stars accessible right now) --UT='2013/01/07 00:43'    (for standard stars accessible at 00:43UT on Jan 7, 2013)

And, if you want to generate a json file for a standard field for which we do not already have a json file, you can run script; e.g.: --help -v --stdFieldName="E6-A" --filterList="g,r,i,z,Y" --outputFile=/Users/dtucker/Desktop/DES_sv_e6a_grizY_preswitchover.json

The Table

Table of standard stars to take during normal evening twilight time (i.e., starting about 45 min before Astronomical Twilight)
and just before middle-of-the-night switchover (about 20 min before switchover).

If Evening Twilight or Pre-Switchover standard star fields are not taken at the normal times, you can still use the StdStarPicker 
code on observer2 to choose the fields, if you wish.

The Evening Twilight fields are listed in order of the high-airmass field (hi), the low-airmass field (lo), and the 
medium-airmass field (med).

During Evening Twilight, it is probably best to take the high-airmass field first, followed by the low and medium airmass fields
(i.e., in the order listed).

For Pre-Switchover, a field was chosen which seemed to best complement the fields suggested for Evening Twilight.
Generally, a high-airmass field was chosen, but sometimes a low-airmass field is chosen (or at least chosen as an

Date   |            Eve. Twi (hi,lo,med)                 |   Pre-Switchover                 |  Comments                            |
Jan 29 | SDSSJ0100,SDSSJ0320,SDSSJ0200                   | E2-A (hi)                        |                                      |
Jan 30 | SDSSJ0100,SDSSJ0320,SDSSJ0200                   | E2-A (hi)                        |                                      |
Jan 31 | SDSSJ0100,SDSSJ0320,SDSSJ0200                   | E2-A (hi)                        |                                      |
Feb  1 | SDSSJ0100,SDSSJ0320,SDSSJ0200                   | E2-A (hi) (alternate: E4-A (lo)) |                                      |
Feb  2 | SDSSJ0100,SDSSJ0320,SDSSJ0200                   | E2-A (hi) (alternate: E4-A (lo)) |                                      |
Feb  3 | SDSSJ0100,SDSSJ0320,SDSSJ0200                   | E2-A (hi) (alternate: E4-A (lo)) |                                      |
Feb  4 | SDSSJ0100(alternate: E4-A),SDSSJ0320,SDSSJ0200  | E2-A (hi) (alternate: E4-A (lo)) | E4-A is alt. if 0100 has set too far |
Feb  5 | SDSSJ0100(alternate: E4-A),SDSSJ0320,SDSSJ0200  | E2-A (hi) (alternate: E4-A (lo)) |                                      |
Feb  6 | SDSSJ0100(alternate: E4-A),SDSSJ0320,SDSSJ0200  | E2-A (hi) (alternate: E4-A (lo)) |                                      |
Feb  7 | E4-A,SDSSJ0320,SDSSJ0200                        | E2-A (hi) (alternate: E4-A (lo)) |                                      |
Feb  8 | E4-A,SDSSJ0320,SDSSJ0200                        | E4-A (lo) (alternate: E2-A (hi)) | Note pre-switchover field switch     |
       |                                                 |                                  |                                      |
Feb 17*| SDSSJ0200,E2-A,SDSSJ0320                        | E6-A (hi)                        |                                      |
Feb 18*| SDSSJ0200,E2-A,SDSSJ0320                        | E6-A (hi)                        |                                      |
Feb 19*| SDSSJ0200,E2-A,SDSSJ0320                        | E6-A (hi)                        |                                      |
Feb 20*| SDSSJ0200,E3-A(alternate: E2-A),SDSSJ0320       | E6-A (hi)                        | Note switch from E2-A to E3-A        |
Feb 21*| SDSSJ0200,E3-A(alternate: E2-A),SDSSJ0320       | E6-A (hi)                        |                                      |
Feb 22*| SDSSJ0200,E3-A(alternate: E2-A),SDSSJ0320       | E6-A (hi)                        |                                      |
*For morning twilight standards in the Feb 17-22 period, use E4-A (hi), E6-A (lo), and E5-A (lo/med).