Restarting the research blog.

Brant Robertson bio photo By Brant Robertson

I’ve decided to (re)start the research blog to keep a better record of everything I’ve been up to. Most of these entries will be in bulleted form for convenience.

Continued recovery

I’m still recovering from surgery on March 24. Progress has been correspondingly slow.

JWST NIRCam/NIRSpec GTO proposal

The JWST NIRCam and NIRSpec GTO teams are submitting a joint proposal to execute a ~800h program in the CANDELS regions of GOODS-N and GOODS-S. The team met at 8AM Pacific in their regular telecon to discuss the last few components to the proposal, including the justification of parallel NIRCam/NIRSpec observations.

JEWELS HST Proposal (PI Capak)

I agreed to help with Peter Capak’s HST proposal for WFC3 imaging in the COSMOS field. I offered to create a figure comparing the sizes of the HUDF, CANDELS, and the proposed HST-JEWELS fields.


The figure was created by smoothing a dark matter density field at and then colorizing the density field based on the smoothed overdensity. The scripts for producing this figure sit on gray:~/Desktop/hst_cycle_25/capak/.


The WFIRST Annual Report for the EXPO team was submitted to Jeff Kruk and Dominic Benford. The annual report is available at

WFIRST EXPO Annual Report

The year 2 work plan and monthly report are due in three days.

We are additionally trying to schedule a telecon to frame the big picture for SSR. The WFIRST DRM telecon was delayed until next Tuesday. The WFIRST Simulation WG telecon may be scheduled for the week of April 17, when I am at Evan’s thesis defense.

Disk initial conditions

Evan and I had some correspondence about the disk initial conditions in Cholla. The cold isothermal initial conditions likely were not resolving the pressure scale length, leading to a vertical collapse. With a hotter disk temperature, the disk expands radially. This issue identified a problem with the radial acceleration balance in the ICs generator, which Evan will work to address. More information on the disk ICs can be found here:

3D Disk ICs Hydrostatic Balance Issues


  • Registered for the DGX cloud computing updates.

  • Also, discovered that on a node without an xserver, one can use matplotlib by

import matplotlib as mpl
  • GTC Talk is on May 9th.


Wrote announcement for the prelim exam revision, which drops the elective component. Enrico forwarded it to the department. Revised grades for Astro 5.