Standard Star Instructions » History » Version 21

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Douglas Tucker, 08/29/2013 11:16 AM

Standard Star Instructions

  • Standard star fields are to be observed every evening and morning twilight that appear to be clear,
    where "clear" is determined by a quick visual inspection of the RASICAM image, of the TASCA image,
    or (!) of the sky itself.
  • If possible, for each twilight period, 3 standard star fields should be observed: one at low airmass
    (X<1.25), on at medium airmass (X=1.25-1.65), and one at high airmass (X=1.65-2.10). It is generally
    better to observe the high-airmass field first, since its airmass will be changing the most rapidly.
  • For half-nights, 1 or 2 fields -- preferably a low-airmass field and a high-airmass field -- should
    be observed just before switchover. (If only one field, a high-airmass field is preferred.)
  • For evening twilight, use the DES/standard/Yzirg scripts (which start with Y-band and end with g-band);
    for morning twilight or pre-switchover, use the DES/standard/grizY scripts (which start with g-band and
    end with Y-band). (For those rare nights when we also observe in u-band, please use the corresponding
    "DES/standard/Yzirgu" and "DES/standard/ugrizY" scripts.)
  • There are several useful scripts in the StdStarPicker package in the DECamObserver account on observer2,
    including and
  • To check which standard star fields are in a good position to observe (airmass < 2.10, moon separation
    > 15 deg, within Blanco horizon limits), use

  source ~/dtucker/bin/setup_StdStarFieldPicker.csh      (or .bash if you are using bash shell) --help                       (for detailed help) --UT=now                     (for a list accessible right now) --UT='2013/09/17 00:43'      (for a list accessible at 00:43UT on Sept 17, 2013)

  • To get a preferred triad of standard fields -- a low-airmass field, a medium-airmass field, and a
    high-airmass field -- for a given time and date, use

  source ~/dtucker/bin/setup_StdStarFieldPicker.csh      (or .bash if you are using bash shell) --help                   (for detailed help) --UT=now                 (for a triad accessible right now) --UT='2013/09/17 00:43'  (for a triad accessible at 00:43UT on Sept 17, 2013)

  (Warning: will output a default json file, "stdstar.json".  Just ignore it.)

  • For simplicity, a look-up table of preferred triads for the nights of August 30-Sepember 30, 2013,
    listing the preferred triad for each 15-min interval throughout those nights, can be found here:

The Standard Fields

SDSS Equatorial Fields: "Golden Standards"
Field Name RA _.Dec
SDSSJ0000-0000 00:00:00 +00:00:00
SDSSJ0100-0000 01:00:00 +00:00:00
SDSSJ0200-0000 02:00:00 +00:00:00
SDSSJ0320-0000 03:20:00 +00:00:00
SDSSJ0843-0000 08:43:00 +00:00:00
SDSSJ0933-0005 09:33:00 -00:05:00
SDSSJ0958-0010 09:58:00 -00:10:00
SDSSJ1048-0000 10:48:00 +00:00:00
SDSSJ1227-0000 12:27:00 +00:00:00
SDSSJ1442-0005 14:42:00 -00:05:00
SDSSJ2140-0000 21:40:00 +00:00:00
SDSSJ2300-0000 23:00:00 +00:00:00
HST CalSpec/Other Fields: "Silver Standards"
Field Name RA Dec
C26202/HST 03:32:30 -27:46:05
MaxVis 06:30:00 -58:45:00
Graham E-Region Fields (Southern u'g'r'i'z' fields): "Bronze Standards"
Field Name RA Dec
E1-A 01:24:50 -44:33:40
E2-A 04:03:00 -44:41:45
E3-A 06:42:54 -45:05:06
E4-A 09:23:44 -45:21:02
E5-A 12:04:11 -45:24:03
E6-A 14:45:33 -45:15:34
E8-A 20:07:22 -44:37:01
E9-A 22:45:37 -44:22:47