Worked examples

One would like to observe the z-distribution of the galactic plane at
l=90 degrees. Observations are proposed with P_100 (IRAS 100 micron filter)
with 180" aperture and C_200 (lambda= 200 micron) at b=-10, -5, 0, 5, 10
degrees.

The COBE brightness values at 100 and 200 micron are according to IRSKY:

------------------------
b	I100	I200
degrees	MJy/sr	MJy/sr
------------------------
0	70	150
-5,5	44	84
-10,10	17	30
------------------------

Comparison with the equivalent surface brightness values listed in the table
on page "When to include a dark measurement" the dark signals are for
P_100 and C_200 less than 1% of the sky signal, therefore the default
values should be adequate. For safety a dark measurement is included for
one P_100 and one C_200 pointing. According to the recommendations on page
"When to include a straylight measurement" a straylight measurement
for P_100 is not strictly necessary, but it is for all C_200 observations.
To assess the possible uncertainties due to the P_100 FCS straylight level
it is decided to include 1 straylight measurement at b=0 degrees. For the
sky integration time it is decided to select 256 sec for P_100 and 128 sec
for C_200 (see page "What is the optimum integration time").

-------------------------------------------------------------------------------
OSN	AOT	b	filter	dark	stray	flux	t_int	rms	OTT
		degrees				MJy/sr	sec	MJy/sr	sec
-------------------------------------------------------------------------------
1	PHT05	-10	P_100	N	N	17+-5	256	0.03	707
2	PHT25	-10	C_200	N	Y	30+-5	128	0.3	477
3	PHT05	-5	P_100	N	N	45+-5	256	0.04	707
4	PHT25	-5	C_200	N	Y	85+-10	128	0.3	477
5	PHT05	0	P_100	Y	Y	70+-10	256	0.05	1115
6	PHT25	0	C_100	Y	Y	150+-10	128	0.4	962
7	PHT05	5	P_100	N	N	45+-5	256	0.04	707
8	PHT25	5	C_200	N	Y	85+-10	128	0.3	477
9	PHT05	10	P_100	N	N	17+-5	256	0.03	707
10	PHT25	10	C_200	N	Y	30+-5	128	0.3	477
-------------------------------------------------------------------------------
Notes:
- for C_200 the rms is given per pixel, over the C200 array the rms is a
  factor 2 better
- the "Maximum background" parameter has been set to zero.
- the rms values can be derived from Table 1
  in document "Detection limits and observing strategy for very faint point
  sources".

A pairwise concatenation at each sky position is preferred to have the same
zodiacal background energy distribution in the two filters. The total time
including slew overheads for this set of observations becomes TDT=7813 sec.

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