1 | $Id: README,v 1.2 2000-09-21 10:08:10 harald Exp $
|
---|
2 |
|
---|
3 | STARFIELD README
|
---|
4 |
|
---|
5 | D. Petry, IFAE, Campus UAB, Spain
|
---|
6 |
|
---|
7 |
|
---|
8 | This is the first useful version of the starfield generator (SG).
|
---|
9 |
|
---|
10 | Purpose:
|
---|
11 |
|
---|
12 | The SG is needed to simulate the non-diffuse part of the night
|
---|
13 | sky background (NSB) in images taken by Cherenkov telescopes.
|
---|
14 | It reads data from star catalogues (presently only SKY2000, see below)
|
---|
15 | and calculated from the given position of the telescopes optical
|
---|
16 | axis (in celestial coordinates), the positional and spectral data
|
---|
17 | for each star from the catalog, how many photons of which wavelength
|
---|
18 | (presently 290 nm - 800 nm are simulated) will hit a circular surface
|
---|
19 | of given radius ("mirror radius") in a given time ("integration time").
|
---|
20 | For each photon the director cosines are calculated.
|
---|
21 | Arrival time, wavelength and ground position are randomized within the
|
---|
22 | integration time, the four wavebands (U, B, V, R) and the mirror area
|
---|
23 | respectively with flat distributions.
|
---|
24 |
|
---|
25 | SG finally writes the generated photons into a binary file of
|
---|
26 | CORSIKA format which can be read by the "Reflector" simulation.
|
---|
27 | The output form the Reflector can then be fed to the camera.
|
---|
28 |
|
---|
29 | The camera will pixelize the photons and calculate the average
|
---|
30 | NSB photon rate for each pixel. From this, the camera can then
|
---|
31 | generate the NSB contribution in each shower image using a Poisson
|
---|
32 | random generator and also taking into account the
|
---|
33 | atmospheric extinction and its dependence on the zenith angle.
|
---|
34 |
|
---|
35 |
|
---|
36 | Installation and first test:
|
---|
37 |
|
---|
38 | 1) Adjust the Makefile to your system and type
|
---|
39 |
|
---|
40 | make depend
|
---|
41 | make
|
---|
42 |
|
---|
43 | The result should be an executable named "starfield"
|
---|
44 |
|
---|
45 | 2) Download the star catalog:
|
---|
46 |
|
---|
47 | ftp cdsarc.u-strasbg.fr
|
---|
48 |
|
---|
49 | (log in as user anonymous)
|
---|
50 |
|
---|
51 | cd pub/cats/V/102
|
---|
52 | prompt
|
---|
53 | hash
|
---|
54 | bin
|
---|
55 | mget sky*.dat.gz
|
---|
56 | bye
|
---|
57 |
|
---|
58 | 3) Unzip the 24 files you have downloaded and put them into some permanent
|
---|
59 | directory e.g. the Data directory of the Monte Carlo source code.
|
---|
60 |
|
---|
61 | 4) Edit the parameter file. The distribution includes an
|
---|
62 | example file named "starfield.par" which looks like this:
|
---|
63 |
|
---|
64 | Starfield Generator Parameters, Date: 21-1-2000, Comment: Example (Crab Nebula)
|
---|
65 | Center of FOV: ira_hours ira_min ira_sec idec_degrees idec_arcmin dec_arcsec:
|
---|
66 | 05 34 32 +22 00 52.1
|
---|
67 | Radius of the FOV for the catalog readout (degrees):
|
---|
68 | 2.0
|
---|
69 | Integration time for the calculation of the number of photons (seconds):
|
---|
70 | 50e-9
|
---|
71 | Mirror radius for the generation of random impact points (meters):
|
---|
72 | 10.0
|
---|
73 | Path inside which the star catalog data can be found:
|
---|
74 | /usr/users/xf/stardata
|
---|
75 | Verbosity level (0 = not verbose, 1 = verbose, 2 = very verbose, 3 = very very ...):
|
---|
76 | 0
|
---|
77 | Output file name, starfiel will generate cerXXXX and staXXXXX
|
---|
78 | CrabNebula
|
---|
79 |
|
---|
80 | Note that the there is a header line followed by pairs of an explanatory
|
---|
81 | line and a data line. You may write in the header line and the explanaroy
|
---|
82 | lines whatever you like, but the data lines matter. The lines may be as long
|
---|
83 | as you like but don't add any carriage returns.
|
---|
84 |
|
---|
85 | For a first test run, you will only have to edit the path for the
|
---|
86 | star data which is the one defined by yourself in step (3).
|
---|
87 |
|
---|
88 |
|
---|
89 | 5) Test run.
|
---|
90 | Run the program by entering
|
---|
91 |
|
---|
92 | starfield
|
---|
93 |
|
---|
94 | The diagnostic output to the screen should be ending with
|
---|
95 |
|
---|
96 | Opened starfield.par for reading ...
|
---|
97 | Starfield Generator Parameters, Date: 21-1-2000, Comment: Example (Crab Nebula)
|
---|
98 | Position RA DEC: 5 34 32 22 0 52.1
|
---|
99 | FOV Radius:2 degrees
|
---|
100 | Integration Time:5e-08 s
|
---|
101 | Mirror Radius:10 m
|
---|
102 | Catalog Data Path: ... your path ...
|
---|
103 | Verbosity: 0
|
---|
104 | SKY2000 - Master Star Catalog - Star Catalog Database, Version 2
|
---|
105 | Sande C.B., Warren W.H.Jr., Tracewell D.A., Home A.T., Miller A.C.
|
---|
106 | <Goddard Space Flight Center, Flight Dynamics Division (1998)>
|
---|
107 | Opened file ...your path.../sky04.dat for reading ...
|
---|
108 | EOF reached; accepted 0 stars from this segment.
|
---|
109 | Opened file ...your path.../sky05.dat for reading ...
|
---|
110 | Warning: star no. 53701440 is bright (Vmag =3, Bmag = 2.85)
|
---|
111 | and has no Umag measurement. Estimated Umag is 2.2395
|
---|
112 | EOF reached; accepted 120 stars from this segment.
|
---|
113 | Opened file ...your path .../sky06.dat for reading ...
|
---|
114 | EOF reached; accepted 0 stars from this segment.
|
---|
115 | Accepted 120 stars in total.
|
---|
116 | Writing binary Cherenkov file ./cerCrabNebula ...
|
---|
117 | Done.
|
---|
118 | Writing binary statistics file ./staCrabNebula ...
|
---|
119 | Done.
|
---|
120 |
|
---|
121 | 6) Using the output.
|
---|
122 | The two output files (in this case cerCrabNebula and staCrabNebula) are
|
---|
123 | of the same format as the file for a single event in the CORSIKA
|
---|
124 | shower simulation. The number in the name is generated from the
|
---|
125 | RA (h) and DEC (deg) of the telescope position in order to allow
|
---|
126 | a distinction.
|
---|
127 |
|
---|
128 | The further processing has to be done with the reflector.
|
---|
129 | A sample parameter file for the reflector is the following:
|
---|
130 |
|
---|
131 | reflector 0.3 -*- sh -*-
|
---|
132 | #
|
---|
133 | # Sample parameters file
|
---|
134 | #
|
---|
135 | verbose_level 2
|
---|
136 | #
|
---|
137 | fixed_target 0. 0.
|
---|
138 | ct_file ../Data/magic.def
|
---|
139 | output_file starfield.rfl
|
---|
140 | atm_model ATM_NOATMOSPHERE
|
---|
141 | data_paths 1
|
---|
142 | ... the diretory in which the output of starfield is found
|
---|
143 | end_file
|
---|
144 |
|
---|
145 | Note that the line "fixed_target 0. 0." is a must.
|
---|
146 | Also the line "atm_model ATM_NOATMOSPHERE" is necessary
|
---|
147 | because the extinction will be simulated in the camera (see above).
|
---|
148 |
|
---|
149 | 7) Notes on the input parameters of starfield
|
---|
150 |
|
---|
151 | a) Center of FOV: ira_hours ira_min ira_sec idec_degrees idec_arcmin dec_arcsec:
|
---|
152 |
|
---|
153 | Here you can put any valid celestial coordinates on the sky.
|
---|
154 | The program doesn't veto invalid coordinates yet, but the result
|
---|
155 | is undefined.
|
---|
156 |
|
---|
157 | b) Radius of the FOV for the catalog readout (degrees):
|
---|
158 |
|
---|
159 | This should be a number larger than the outermost radius of the
|
---|
160 | CT's field of view (FOV), but not too much larger because there
|
---|
161 | is a limit to the number of photons which can be stored by the
|
---|
162 | program and the number of generated photons grows with the number
|
---|
163 | of stars in the FOV. If you hit the limit, try decreasing the
|
---|
164 | integration time.
|
---|
165 |
|
---|
166 | c) Integration time for the calculation of the number of photons (seconds):
|
---|
167 |
|
---|
168 | Since we are dealing with a ray-tracing approach, we need actual
|
---|
169 | individual photons, not just rates. This integration time is needed
|
---|
170 | in order to normalize the numbers of generated photons for each star.
|
---|
171 | The camera program will later calculate the photon rates for each
|
---|
172 | pixel by dividing by this number.
|
---|
173 |
|
---|
174 | Not that this number is given in seconds, but only up to about 100 ns
|
---|
175 | make sense, i.e. you have to write something like 100e-9
|
---|
176 |
|
---|
177 | d) Mirror radius for the generation of random impact points (meters):
|
---|
178 |
|
---|
179 | This number is needed for the flux normalization and the generation
|
---|
180 | of the ground impact points of the photons. Adjust it to the size
|
---|
181 | of the simulated telescope.
|
---|
182 |
|
---|
183 | e) Path inside which the star catalog data can be found:
|
---|
184 |
|
---|
185 | This is the directory containing the SKY2000 data (see point 3)
|
---|
186 |
|
---|
187 | f) Verbosity level (0 = not verbose, 1 = verbose, 2 = very verbose, 3 = very very ...):
|
---|
188 |
|
---|
189 | Set this value to 0 for normal usage. Increase it to discover
|
---|
190 | what is going on in detail.
|
---|
191 |
|
---|
192 | g) Output file name, starfiel will generate cerXXXX and staXXXXX
|
---|
193 |
|
---|
194 | This the key name for the output files
|
---|
195 |
|
---|
196 | 8) parameter file name
|
---|
197 |
|
---|
198 | starfield accepts as its only command line argument the name
|
---|
199 | of the parameter file. Typing
|
---|
200 |
|
---|
201 | starfield my.par
|
---|
202 |
|
---|
203 | will make starfield look for the parameter file "my.par" in
|
---|
204 | the current directory. If no argument is given, it assumes the
|
---|
205 | name of the parameter file is "starfield.par".
|
---|