Nightly Observing Plan for MJD 58468 (starting the evening of Dec 15, 2018)


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

CTIO Staff


from kentools ephem

mjd 58468, date 20181215, Site CTIO, UT-offset 3 hr
Current local time 17:04 CLST     UT 20:04     SidTim 21:00
Event      Local-Time  Greenwich  Sidereal-Time
Sunset     20:48 CLST  23:48 UT   00:44   11 deg  
Eve. -10   21:29 CLST  00:29 UT   01:24   21 deg  Zeropoint; standards
Eve. -14   21:52 CLST  00:52 UT   01:48   27 deg  Begin obstac
Eve. -18   22:17 CLST  01:17 UT   02:12   33 deg  Last chance standards
Midpoint   01:38 CLST  04:38 UT   05:33   83 deg  
Moonset    02:27 CLST  05:27 UT   06:22   96 deg  
Morn -18   05:00 CLST  08:00 UT   08:55  134 deg  Begin astronomical twilight
Morn -14   05:24 CLST  08:24 UT   09:19  140 deg  End obstac; begin standards
Morn -10   05:47 CLST  08:47 UT   09:42  146 deg  
Sunrise    06:28 CLST  09:28 UT   10:23  156 deg  
Moon position (deg): RA 2.9, Dec -3.1 Phase: 0.544

Weather Conditions

  • At 17:00 local time, clear, mild (17 degrees) with light breeze (11 mph), humidity 42%
  • Tonight: Forecast clear, Temp. 12 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 = "12/16/2018 00:19:00"    Local time = 21:19
    SDSSJ2140-0000        ra 21:40:00  dec +00:00:00  secz 1.9
    SDSSJ0320-0000        ra 03:20:00  dec +00:00:00  secz 1.4

    * Midpoint standards
    UT Date = '2018/12/16 04:30'     Local time = 01:30
    SDSSJ0200-0000        ra 02:00:00  dec +00:00:00  secz 1.9

    h3. 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 about to start. All data from last night processed by DESDM, all but two declared good, and accepted into survey table.

For tonight:

  • Do standards if clear.
  • At start of night, remaining survey fields likely still at airmass above 1.4, so instead of starting with Obstac, the decision tree is as follows:

1. If seeing <1.1" in i-band and sky is clear, execute MACSJ0416_z_2 script in /usr/remote/user/DECamObserver/ExposureScripts/DES_script/MACSJ0416_z_2.json. This is a deep field with good spectroscopy for photo-z calibration. Estimate this will take about 1 hour.

2. If seeing is still <1.1" in i-band, execute MACSJ0416_z_1 script; if seeing < 1.3" and sky is clear, execute up to 2 photosweep (about 1 hour each). Instructions on creating photosweep scripts are below.

3. If seeing >1.3" and sky is not clear, excute E2 narrowband script up to an hour.

4. Execute Obstac starting after 02:01 UT (23:01 PM local time), expecting to do the 6 remaining z-band exposures.


5. If seeing is <1.1" in i-band and sky is clear, excute the MACSJ0416_i_1 script for about an hour.

6. If seeing is <1.3" in i-band and sky is clear, excute photosweeps if more than 30 minutes left; if less than 30 minutes left, continue with OBSTAC.

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