Large-scale retrospective relative spectro-photometric self-calibration in space

Abstract

We consider the application of relative self-calibration using overlap regions to spectroscopic galaxy surveys that use slit-less spectroscopy. This method is based on that developed for the SDSS by Padmanabhan at al. (2008) in that we consider jointly fitting and marginalising over calibrator brightness, rather than treating these as free parameters. However, we separate the calibration of the detector-to-detector from the full-focal-plane exposure-to-exposure calibration. To demonstrate how the calibration procedure will work, we simulate the procedure for a potential implementation of the spectroscopic component of the wide Euclid survey. We study the change of coverage and the determination of relative multiplicative errors in flux measurements for different dithering configurations. We use the new method to study the case where the flat-field across each exposure or detector is measured precisely and only exposure-to-exposure or detector-to-detector variation in the flux error remains. We consider several base dither patterns and find that they strongly influence the ability to calibrate, using this methodology. To enable self-calibration, it is important that the survey strategy connects different observations with at least a minimum amount of overlap, and we propose an "S"-pattern for dithering that fulfills this requirement. The final survey strategy adopted by Euclid will have to optimise for a number of different science goals and requirements. The large-scale calibration of the spectroscopic galaxy survey is clearly cosmologically crucial, but is not the only one.

23 pages, 19 figures, Accepted for publication in MNRAS, 2017

References in corpus (9)

• Methods for Rapidly Processing Angular Masks of Next-Generation Galaxy Surveys
• Hypercalibration: A Pan-STARRS1-based recalibration of the Sloan Digital Sky Survey
• Toward 1% Photometry: End-to-end Calibration of Astronomical Telescopes and Detectors
• Galaxy clustering, photometric redshifts and diagnosis of systematics in the DES Science Verification data
• Mapping and simulating systematics due to spatially-varying observing conditions in DES Science Verification data
• Unbiased methods for removing systematics from galaxy clustering measurements
• Testing LSST Dither Strategies for Survey Uniformity and Large-Scale Structure Systematics
• Multiplicative errors in the galaxy power spectrum: self-calibration of unknown photometric systematics for precision cosmology
• An Improved Photometric Calibration of the Sloan Digital Sky Survey Imaging Data

Cited by in corpus (6)

• Cosmology with Phase 1 of the Square Kilometre Array; Red Book 2018: Technical specifications and performance forecasts
• The High Latitude Spectroscopic Survey on the Nancy Grace Roman Space Telescope
• Euclid preparation: XVI. Exploring the ultra low-surface brightness Universe with Euclid/VIS
• Euclid preparation: XLVIII. The pre-launch Science Ground Segment simulation framework
• Euclid preparation: VI. Verifying the Performance of Cosmic Shear Experiments
• A proposal for relative in-flight flux self-calibrations for spectro-photometric surveys