Hawaii Two-0 Observing Plan


2018A — NEP

  • 4 nights HSC (4 nights lost to earthquakes)

2018B — CDF-S

  • 5 nights HSC (3 nights lost to earthquakes, 2 successful nights)

2019A — NEP

  • 4 nights HSC (observations TBD)

2019B — CDF-S

  • 4  nights HSC
  • 3 nights DEIMOS
  • Proposal under IfA TAC review

2020A — CDF-S + NEP

  • 5 nights HSC
  • 2 nights DEIMOS
  • 2 nights MOSFIRE

2020B — CDF-S + NEP

  • 5 nights Subaru HSC
  • 2 nights Keck MOSFIRE

Data Reduction


  • The HSC Data Reduction Pipeline has been successfully installed and tested on the UH Cray supercomputer
  • Co-I Chambers will ensure the team has access to the latest Pan-STARRS data for astrometric and flux calibration.
  • Generation of HSC mosaic will be done by Co-Is Repp & McPartland
  • The IRAC image mosaic pipeline of Co-I Capak has recently been optimized for cluster/supercomputer environments. The runtime of the pipeline analysis is now only a few hours, rather than a few weeks with the original version.
  • IRAC photometry will be measured using IRClean (Co-I Capak lead) that was successfully applied in COSMOS and SPLASH Laigle et al. (2016).
Extraction of Data from the Archives
  • We have discovered a significant amount of HSC data in the Subaru archive covering the two H20 fields:
    • NEP: HEROES and AKARI-NEP programs (~50% of total data needed)
    • CDF-S: various small programs (~10% of total data needed)
  • With these data in hand, we have nearly made up for the HSC time lost in 2018. See Archival Data on the Progress Page for more details.
Preliminary Tests
Purchase of Data Storage/Reduction Server
  • We have recently purchased a dedicated server for H20 data storage and reduction. This will allow us to streamline the data reduction process by minimizing latency due to data transfer.
  • 60+ TB hard drive, 24 CPU cores, 512 Gb RAM

Hawaii Two-0 Survey Footprint

The 10 deg footprint for each of the H20 fields comprised of seven HSC pointings arranged in a flower petal pattern.

*** Note: We will continue to request classical time until Subaru can develop a more robust and widely used queue system. Furthermore, due to the RA/elevation constraints of our fields, it is much more efficient to execute the observations in classical mode. ***

Limiting Magnitudes / Exposure Times for Final Survey

g r i z Y JHK ch1 ch2
Limiting mag 27.5 27.5 27 26.5 26 26 24.8 24.7
HSC exposure time 1.1h 2.5h 4.1h 4.8h 9h

☆ From Euclid Deep (operations start in 2021). WFIRST will also cover this area at 26 mag 10σ (operations start mid-2020s).
† From the Euclid/WFIRST Spitzer Legacy Survey (ADS)

High-z Dropout Selection 

To confirm the ability of the Hawaii Two-0 (20 sq. deg.) survey (as designed) to robustly identify high-redshift galaxies (z≳4) using our H20 dropout selection technique, we used the UH+SSP HSC data in the COSMOS (2 sq. deg.) field to select high redshift galaxy candidates. See Dropout Selection Section of the Science Page for more details.

H20 Predictions

Dropout Band Redshift Expected Sources in
H20 20 sq. deg
g 4 ~720,000
r 5 ~40,000
i 6 ~3000
z 7 ~500

 Photo-z selected sources

Redshift Expected Sources in
H20 20 sq. deg
2 ~3,000,000
3 ~2,000,000

Note that r-band dropouts are sources that “just begin to appear” in the r-band, are clearly absent in the g-band, and robustly detected in the i-band. The above figure clearly illustrates the potential for H20 observations to detect high-redshift dropout galaxies.

Exposure Time Calculations for

DEIMOS Spectroscopy

***High level summary***

Density of High-Redshift Dropout Targets in a DEIMOS FOV

In each DEIMOS mask (16’x4′, yellow box), we expect to collect spectra for:

60+ g-band droupouts

40 r-band droupouts

10 i-band droupouts

For comparison, we indicate the smaller LRIS FOV (6’x7.8′, red dashed box).

Expected Magnitude Distributions for the gri-band Dropouts

DEIMOS Instrument Configuration & Exposure Times

The optimal configuration for our DEIMOS spectroscopy is the 600ZD grating with the OG550 order blocking filter (green dot-dashed line below). This configuration maximizes efficiency over the wavelength range where we expect to dectect Ly-α emission in the gri-band dropout galaxies at z = 4, 5, & 6. The galaxy templates were generated using FSPS assuming a 10^10 Msun galaxy with a delayed-exponential SFH with τ = 2 Gyr and age of 1 Gyr. The signal to noise estimates are based on an exposure time of 3.5hrs with a 1 arcsec slit, 1 arcsec seeing, and an airmass of 1.3.

Institute for Astronomy

Manoa  808 956-8312
Hilo       808 932-2300
Maui     808 573-9500