Nightly Observing Plan for MJD 58469 (starting the evening of Dec 16, 2018)


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

CTIO Staff


from kentools ephem

mjd 58469, date 20181216, Site CTIO, UT-offset 3 hr
Current local time 16:29 CLST     UT 19:29     SidTim 20:28
Event      Local-Time  Greenwich  Sidereal-Time
Sunset     20:49 CLST  23:49 UT   00:48   12 deg  
Eve. -10   21:30 CLST  00:30 UT   01:29   22 deg  Zeropoint; standards
Eve. -14   21:53 CLST  00:53 UT   01:52   28 deg  Begin obstac
Eve. -18   22:17 CLST  01:17 UT   02:16   34 deg  Last chance standards
Midpoint   01:39 CLST  04:39 UT   05:38   84 deg  
Moonset    03:00 CLST  06:00 UT   06:59  105 deg  
Morn -18   05:00 CLST  08:00 UT   08:59  135 deg  Begin astronomical twilight
Morn -14   05:24 CLST  08:24 UT   09:23  141 deg  End obstac; begin standards
Morn -10   05:47 CLST  08:47 UT   09:47  147 deg  
Sunrise    06:28 CLST  09:28 UT   10:27  157 deg  
Moon position (deg): RA 14.5, Dec 1.5 Phase: 0.603

Weather Conditions

  • At 17:00 local time, clear, mild (18.2 degrees) with light breeze (6.9 mph), humidity 40%
  • Tonight: Forecast clear, Temp. 14 degrees, light breeze from the west, moderate humidity ~50%.
  • Detailed hourly forecast | Satellite maps

Observing Plan and Goals for the Night

  • DES Half night
  • Evening standards
    UT Date = '2018/12/17 00:30'     Local time = 21:30
    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 = '2018/12/17 04:30'     Local time = 01:30
    SDSSJ0843-0000        ra 08:43:00  dec +00:00:00  secz 1.7

Useful links

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

Notes from 4PM Meeting

Telescope and camera are good, calibrations started at 4:15 local. All data from last night processed by DESDM. All wide field accepted into survey table.

For tonight:

  • standards if clear.
  • photosweep if photometric, OK to start after standards
  • E2 narrow band
  • MACS i_2 if i-band seeing better than 1.1 arcsec; if not, repeat E2 (airmass limit happens at 3:35 UT)
  • ObsTac
  • midpoint 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