Astro2020 Science White Paper on "Opportunities in Time-Domain Stellar Astrophysics with NEOCam"

Thematic Areas: Stars and Stellar Evolution (primary); Formation and Evolution of Compact Objects (secondary)

If you, after reading the summary below, are excited about the potential that NEOCam data brings to your corner of stellar research and you're willing to help with the science content of the white paper, please contact me at davy at Thanks!

The NASA Near-Earth Object Camera (NEOCam)

Overview: NEOCam is a NASA Planetary mission, currently in Phase A, whose goal is to discover and characterize asteroids and comets, to assess the hazard to Earth from near-Earth objects, and to study the origin, evolution, and fate of asteroids and comets. NEOCam is a single-instrument, 50cm diameter telescope that will observe in two simultaneous channels, called NC1 and NC2, which cover wavelengths of 4.0-5.2 microns and 6.0-10.0 microns, respectively. There are four Teledyne 2Kx2K HgCdTe arrays per channel with 3.00 arcsec pixels in each. The entire celestial sphere between ecliptic latitudes of +40 deg to -40 deg will continually be mapped over the course of the 5-yr mission, and over 12 yr for the design lifetime.

Cadence: Estimates of on-board overheads and resulting orbit quality are still being refined, but the current data cadence is as follows. The observing pattern consists of a four-peat of a six-position dither (a quick sequence of six images with 28s integration time each) with 2h gaps between each repeat. This four-peat will recur ~13.2d later as long as the 75d visibility window is still open. Afterward, there will be a gap of 215d until the next visibility window opens and the pattern begins again. On average in a typical visibility window, there are ~23 of these six-position dither sequences (a little less than 6 four-peats), ~234 over 5yr, and ~562 over 12yr.

Depth: Each of the six-position dither sequences is expected to have an S/N=5 sensitivity of 65-120 uJy for NC1 and 110-280 uJy for NC2, where the range covers low to high zodiacal backgrounds.

Data Products: NEOCam processing will create images and lists of characterized sources from each individual exposure and each stacked six-dither position sequence. It will also create differenced images by subtracting a static reference image, and a list of the characterized transient detections. Because the goal of NEOCam is to provide and characterize moving objects within the solar system, coaddd and source extractions over longer timescales are not provided, the one exception being yearly builds to create new static images (without any source detection or characterization) of the sky to use in image differencing. No alerting mechanism is provided for astrophysical transient events.

To realize the full potential of the NEOCam data for astrophysical research, additional data products and alerting infrastructure are needed. For a relatively small investment, NASA can leverage the existing NEOCam data to cover a wide range of stellar research.

Last modified: Thu Jan 3 14:03:38 PST 2019