NICMOS to Ground Based Systems Transformations

NICMOS to Ground-Based Systems Transformations

A total of six stars (2 white dwarfs, 2 solar analogs and 2 redden stars; see table) have been observed through the NICMOS JHK system (i.e. F110W, F160W and F222M filters) to help establish transformations between NICMOS and ground-based near-infrared systems.

HST fluxes have been measured for all the HST standards and converted into magnitudes using the fluxes for a zero magnitude star (see column ZP(Vega) in the table of Current Values for NICMOS Photometric Keywords and Zeropoint in VEGAMAG System).

The table below includes the NICMOS HST and ground-based (when available) magnitudes for the standard stars observed with HST. For each star,

NICMOS Standards

"Nov 25, 1998. The Table below is in the process of being updated. We have found a ~0.1 mag discrepancy between the ground-based J, H, K values for the solar analogs and the white dwarf that we used and the corresponding published values (Persson et al. 1998, AJ, 116, 2475."

STAR	Category	F110W	J	F160W	H	F222M	K
G191-B2B	WD	12.49	12.68	12.71	12.72	12.83	---
		0.02	0.02	0.02	0.03	0.02
GD153	WD	14.04	---	14.23	---	14.36	---
		0.02		0.02		0.02
P330E	G star	12.01	11.96	11.57	11.59	11.49	11.51
		0.02	0.02	0.02	0.02	0.02	0.02
P177D	G star	12.47	---	12.02	---	11.93	---
		0.02		0.02		0.02
BRI0021	red	12.45	11.835	11.28	11.086	10.48	10.552
		0.02	0.008	0.02	0.007	0.02	0.010
OPH-S1	red	9.48	8.80	7.44	7.27	6.36	6.33
		0.02	<0.015	0.02	<0.015	0.02	<0.015
CSKD_12	red	12.26	11.585	9.73	9.506	8.61	8.617
		0.02	0.007	0.02	0.005	0.02	0.007

NOTES:

JHK magnitudes for OPHS1 come from Elias et al. 1982, AJ 87, 1029.
JHK magnitudes for P330E, BRI0021 and CSKD21 come from ground-based measurements made by the NICMOS ID team (M. Rieke, private comm.)