Nightly Observing Plan for MJD 58470 (starting the evening of Dec 17, 2018)


  • Qiqi Wang (Observer 1)
  • Richard Kron (Observer 2, Run Manager)

CTIO Staff


from kentools ephem

mjd 58470, date 20181217, Site CTIO, UT-offset 3 hr
Current local time 19:29 CLST     UT 22:29     SidTim 23:32
Event      Local-Time  Greenwich  Sidereal-Time
Sunset     20:50 CLST  23:50 UT   00:53   13 deg  
Eve. -10   21:31 CLST  00:31 UT   01:34   24 deg  Zeropoint; standards
Eve. -14   21:54 CLST  00:54 UT   01:57   29 deg  Begin obstac
Eve. -18   22:18 CLST  01:18 UT   02:21   35 deg  Last chance standards
Midpoint   01:39 CLST  04:39 UT   05:42   86 deg  
Moonset    03:34 CLST  06:34 UT   07:37  114 deg  
Morn -18   05:01 CLST  08:01 UT   09:03  136 deg  Begin astronomical twilight
Morn -14   05:25 CLST  08:25 UT   09:28  142 deg  End obstac; begin standards
Morn -10   05:48 CLST  08:48 UT   09:51  148 deg  
Sunrise    06:29 CLST  09:29 UT   10:32  158 deg  
Moon position (deg): RA 26.5, Dec 6.1 Phase: 0.663

Weather Conditions

  • At 19:30 local time, 60% covered with light clouds, 17.4 degrees with light breeze (6.8 mph), humidity 38%
  • Tonight: Forecast clouds, Temp. 12 degrees, light breeze
  • Detailed hourly forecast | Satellite maps

Observing Plan and Goals for h1. 12172018the Night

  • DES Half night
  • Evening standards
    UT Date = '2018/12/18 00:31'     Local time = 21:31
    MaxVis                ra 06:30:00  dec -58:45:00  secz 1.8
    SDSSJ2300-0000        ra 23:00:00  dec +00:00:00  secz 1.5
    C26202/HST            ra 03:32:30  dec -27:46:05  secz 1.1
  • Midpoint standards
    UT Date = '2018/12/18 04:39'     Local time = 01:39
    SDSSJ0843-0000        ra 08:43:00  dec +00:00:00  secz 1.6
    C26202/HST            ra 03:32:30  dec -27:46:05  secz 1.1

Useful links

Nightsum | CTIO Night Report | DECam Logbook
Tololo Environmental Web Page | Detailed hourly forecast | Satellite maps

h2.Today's instructions for tonight:

  • if cloudy: ObsTac
  • if clear: standards, E2 narrow-band, star flats, standard

Clear for photosweeps means no clouds. Rasicam, or going outside and looking at the sky.
Clear for MACS field is clear or nearly so.
If you have "Bad Seeing" and photometric and not worse than 2.0", do
Photosweep. Instructions can be found here:

Do not bother with this program if clouds are visible on Rasicam or if
seeing is highly variable, for the varying aperture corrections make
it difficult to get to mmag accuracy.

One needs to run a script at CTIO to generate the jsons (see the
instructions wiki page). Having done that the Photosweep scripts can
be found in
with names like: photosweep20180914-2200Z.json

Select the one with timestamp closest to the next top of hour, now in
UT (we got the z added). Do not bother with this is there's < 30
minutes left in the night. A script probably takes an hour.

If "Bad Seeing" and not photometric, or if "Bad Seeing" and everything
else if done, then do Narrowband. Instructions and a description can be found here:

Narrowband scripts are in the same directory as Photosweep, and have names like SN-C3X-N964.json

They are on the SN fields, so select the field that is closest to transit. Transit time for SN fields can be found on this page:

These are expected to be about an hour long. If the clouds are only moderate, we could do these.

Priorities (highest to lowest)

Other Notes

1. Be prepared for a GW follow-up interruption. No alert at time of 4pm Meeting, but it is still a possibility