Effective exposure time

We will keep a tally of the achieved depth during the run. Rather than calibrating sequences, we will simply use the weights that come out of the nmbs code in combination with the total exposure time of the sequence. The effective exposure time t_eff is defined as:

t_eff = t_exp <w> / a_λ

with t_exp the exposure time of the sequence in hours, <w> the average weight that comes out of the nmbs program, and a_λ a normalization factor. The values for a_λ are chosen so that the effective exposure times are typically close to the nominal exposure times, for conditions similar to those during the first run. The values are given below.

Filter a_λ

J1 0.026

J2 0.013

J3 0.009

H1 0.0025

H2 0.0017

K 0.0007

Filter	a_λ
J1	0.026
J2	0.013
J3	0.009
H1	0.0025
H2	0.0017
K	0.0007

Depth tracking

The relation between measured 8σ total pointsource depth (from empty apertures) and effective exposure time is shown below (from all data obtained in Run 1).

There is a very good relation between effective exposure time and measured depth. Also, the measured depth in the combined images (colored points) are reasonably consistent with the expected depth based on the individual sequences (broken lines).

The total effective exposure time should be about 45 hrs in each band. The table below lists what we have obtained in the first run and how much we still need to get:

COSMOS-1

Filter t_eff goal t_eff now t_eff to get

J1 45 6.5 38.5

J2 45 6.8 38.2

J3 45 3.8 41.2

H1 45 4.0 41.0

H2 45 7.5 37.5

K 45 6.8 38.2

Filter	t_eff goal	t_eff now	t_eff to get
J1	45	6.5	38.5
J2	45	6.8	38.2
J3	45	3.8	41.2
H1	45	4.0	41.0
H2	45	7.5	37.5
K	45	6.8	38.2

AEGIS-N2

Filter t_eff goal t_eff now t_eff to get

J1 45 11 34

J2 45 12 33

J3 45 7.5 37.5

H1 45 19 26

H2 45 12 33

K 45 9.5 35.5