Rubin, D.Aldering, G.Amanullah, R.Barbary, K.Dawson, K. S.Deustua, S.Faccioli, L.Fadeyev, V.Fakhouri, H. K.Fruchter, A. S.Gladders, M. D.Jong, R. S.DeKoekemoer, A.Krechmer, E.Lidman, C.Meyers, J.Nordin, J.Perlmutter, S.Ripoche, P.Schlegel, D. J.Spadafora, A.Suzuki, N.2025-06-112025-06-110004-6256http://www.scopus.com/inward/record.url?scp=84946177935&partnerID=8YFLogxKhttps://hdl.handle.net/1885/733758684NICMOS 2 observations are crucial for constraining distances to most of the existing sample of z > 1 SNe Ia. Unlike conventional calibration programs, these observations involve long exposure times and low count rates. Reciprocity failure is known to exist in HgCdTe devices and a correction for this effect has already been implemented for high and medium count rates. However, observations at faint count rates rely on extrapolations. Here instead, we provide a new zero-point calibration directly applicable to faint sources. This is obtained via intercalibration of NIC2 F110W/F160W with the Wide Field Camera 3 (WFC3) in the low count-rate regime using z ∼ 1 elliptical galaxies as tertiary calibrators. These objects have relatively simple near-IR spectral energy distributions, uniform colors, and their extended nature gives a superior signal-to-noise ratio at the same count rate than would stars. The use of extended objects also allows greater tolerances on point-spread function profiles. We find space telescope magnitude zero points (after the installation of the NICMOS cooling system, NCS) of 25.296 ± 0.022 for F110W and 25.803 ± 0.023 for F160W, both in agreement with the calibration extrapolated from count rates ≳1000 times larger (25.262 and 25.799). Before the installation of the NCS, we find 24.843 ± 0.025 for F110W and 25.498 ± 0.021 for F160W, also in agreement with the high-count-rate calibration (24.815 and 25.470). We also check the standard bandpasses of WFC3 and NICMOS 2 using a range of stars and galaxies at different colors and find mild tension for WFC3, limiting the accuracy of the zero points. To avoid human bias, our cross-calibration was 'blinded' in that the fitted zero-point differences were hidden until the analysis was finalized.enPublisher Copyright: © 2015. The American Astronomical Society. All rights reserved.generalphotometricsupernovaetechniques2015-05-0110.1088/0004-6256/149/5/15984946177935