Zero Points for APO Instrument / Setup Combinations

m = -2.5log(DN/sec) + C - K*(airmass - 1.0) + A*color

Take a look at the system throughput based on the numbers below.

SPIcam:

SDSS Filter Set
g* and i* zero points determined by Eugene Magnier (dec 5, 1997), errors are about 10%.
u*, r*, and z* are very preliminary and may have errors of 20%.

filter	lambda	C	K	A	color
u*	3500A	21.38	0.48	x	none
g*	4700A	24.92	0.19	x	none
r*	6200A	24.93	0.11	x	none
i*	7700A	24.72	0.04	x	none
z*	>8500A	23.43	0.06	x	none

Johnson/Kron-Cousins Filters
UBVI zero points determined by Ted Wyder (fall '97), about 3% internal error.

filter	lambda	C	K	A	color
U	3650A	22.10	0.44	-0.14	U-B
B	4400A	24.43	0.25	0.04	B-V
V	5500A	24.91	0.14	-0.02	B-V
R	7000A	x	x	x	x
I	9000A	24.53	0.06	0.04	V-I

UBVI zero points determined by Dan Zucker (oct 19, 1997), about 3% internal error.

filter	lambda	C	K	A	color
U	3650A	22.30	0.42	0.19	U-I - 0.04(U-I)^2
B	4400A	24.39	0.22	0.01	B-V
V	5500A	24.88	0.12	-0.03	B-V
R	7000A	x	x	x	x
I	9000A	24.84	0.06	-0.04	V-I

Paul Hodge's 2 inch filters

filter	lambda (width)	C
Hbeta	4861A (20A)	20.53
[OIII]	5007A (80A)	21.28
Halpha	6563A (20A)	20.28
[SII]	6731A (80A)	21.73

Narrow-band zero points determined by Brooke Skelton and Eugene Magnier (may '97), errors are about 10%.

DIS:

Gunn Filters

filter	lambda	C	K	A	color
g	4500A?	25.13	0.21	0.14	r-g
r	6500A?	24.20	0.16	0.09	r-g

GRIM:

Standard Photometric Filters
JHK Zero points determined by Eugene Magnier over several runs in 1997.

filter	lambda	C	K	A	color
J	1.25 um	23.11	0.16	x	x
H	1.65 um	23.02	x	x	x
K'	2.20 um	22.26	0.13	x	x

JHK Zero points determined by Eugene Magnier Feb 18, 1999, 0.05 mag accuracy.

filter	lambda	C	K	A	color
J	1.25 um	23.05	0.19	0.10	J-K
K'	2.20 um	22.31	0.10	0.02	J-K