Spectral-Index Parameters¶
The spectral indices to be measured by the DAP are divided into two
groups: (1) absorption-line indices that measure the equivalent width
of an absorption feature and (2) bandhead or color indices that
measure the ratio of fluxes is in two passbands. Both sets of indices
are measured using
SpectralIndices
; see
Spectral-Index Measurements.
Absorption-line Index Parameters¶
The table below provides a compilation of absorption-line indices. Recent survey-level runs of the DAP have included all of these measurements.
Name |
Main Passband (Å) |
Blue Sideband (Å) |
Red Sideband (Å) |
Frame |
Units |
Ref |
---|---|---|---|---|---|---|
CN1 |
4142.125 – 4177.125 |
4080.125 – 4117.625 |
4244.125 – 4284.125 |
air |
mag |
|
CN2 |
4142.125 – 4177.125 |
4083.875 – 4096.375 |
4244.125 – 4284.125 |
air |
mag |
|
Ca4227 |
4222.250 – 4234.750 |
4211.000 – 4219.750 |
4241.000 – 4251.000 |
air |
Å |
|
G4300 |
4281.375 – 4316.375 |
4266.375 – 4282.625 |
4318.875 – 4335.125 |
air |
Å |
|
Fe4383 |
4369.125 – 4420.375 |
4359.125 – 4370.375 |
4442.875 – 4455.375 |
air |
Å |
|
Ca4455 |
4452.125 – 4474.625 |
4445.875 – 4454.625 |
4477.125 – 4492.125 |
air |
Å |
|
Fe4531 |
4514.250 – 4559.250 |
4504.250 – 4514.250 |
4560.500 – 4579.250 |
air |
Å |
|
C24668 |
4634.000 – 4720.250 |
4611.500 – 4630.250 |
4742.750 – 4756.500 |
air |
Å |
|
Hb |
4847.875 – 4876.625 |
4827.875 – 4847.875 |
4876.625 – 4891.625 |
air |
Å |
|
Fe5015 |
4977.750 – 5054.000 |
4946.500 – 4977.750 |
5054.000 – 5065.250 |
air |
Å |
|
Mg1 |
5069.125 – 5134.125 |
4895.125 – 4957.625 |
5301.125 – 5366.125 |
air |
mag |
|
Mg2 |
5154.125 – 5196.625 |
4895.125 – 4957.625 |
5301.125 – 5366.125 |
air |
mag |
|
Mgb |
5160.125 – 5192.625 |
5142.625 – 5161.375 |
5191.375 – 5206.375 |
air |
Å |
|
Fe5270 |
5245.650 – 5285.650 |
5233.150 – 5248.150 |
5285.650 – 5318.150 |
air |
Å |
|
Fe5335 |
5312.125 – 5352.125 |
5304.625 – 5315.875 |
5353.375 – 5363.375 |
air |
Å |
|
Fe5406 |
5387.500 – 5415.000 |
5376.250 – 5387.500 |
5415.000 – 5425.000 |
air |
Å |
|
Fe5709 |
5696.625 – 5720.375 |
5672.875 – 5696.625 |
5722.875 – 5736.625 |
air |
Å |
|
Fe5782 |
5776.625 – 5796.625 |
5765.375 – 5775.375 |
5797.875 – 5811.625 |
air |
Å |
|
NaD |
5876.875 – 5909.375 |
5860.625 – 5875.625 |
5922.125 – 5948.125 |
air |
Å |
|
TiO1 |
5936.625 – 5994.125 |
5816.625 – 5849.125 |
6038.625 – 6103.625 |
air |
mag |
|
TiO2 |
6189.625 – 6272.125 |
6066.625 – 6141.625 |
6372.625 – 6415.125 |
air |
mag |
|
HDeltaA |
4083.500 – 4122.250 |
4041.600 – 4079.750 |
4128.500 – 4161.000 |
air |
Å |
|
HGammaA |
4319.750 – 4363.500 |
4283.500 – 4319.750 |
4367.250 – 4419.750 |
air |
Å |
|
HDeltaF |
4091.000 – 4112.250 |
4057.250 – 4088.500 |
4114.750 – 4137.250 |
air |
Å |
|
HGammaF |
4331.250 – 4352.250 |
4283.500 – 4319.750 |
4354.750 – 4384.750 |
air |
Å |
|
CaHK |
3899.5 – 4003.5 |
3806.5 – 3833.8 |
4020.7 – 4052.4 |
air |
Å |
|
CaII1 |
8484.0 – 8513.0 |
8474.0 – 8484.0 |
8563.0 – 8577.0 |
air |
Å |
|
CaII2 |
8522.0 – 8562.0 |
8474.0 – 8484.0 |
8563.0 – 8577.0 |
air |
Å |
|
CaII3 |
8642.0 – 8682.0 |
8619.0 – 8642.0 |
8700.0 – 8725.0 |
air |
Å |
|
Pa17 |
8461.0 – 8474.0 |
8474.0 – 8484.0 |
8563.0 – 8577.0 |
air |
Å |
|
Pa14 |
8577.0 – 8619.0 |
8563.0 – 8577.0 |
8619.0 – 8642.0 |
air |
Å |
|
Pa12 |
8730.0 – 8772.0 |
8700.0 – 8725.0 |
8776.0 – 8792.0 |
air |
Å |
|
MgICvD |
5165.0 – 5220.0 |
5125.0 – 5165.0 |
5220.0 – 5260.0 |
vac |
Å |
|
NaICvD |
8177.0 – 8205.0 |
8170.0 – 8177.0 |
8205.0 – 8215.0 |
vac |
Å |
|
MgIIR |
8801.9 – 8816.9 |
8777.4 – 8789.4 |
8847.4 – 8857.4 |
vac |
Å |
|
FeHCvD |
9905.0 – 9935.0 |
9855.0 – 9880.0 |
9940.0 – 9970.0 |
vac |
Å |
|
NaI |
8168.500 – 8234.125 |
8150.000 – 8168.400 |
8235.250 – 8250.000 |
air |
Å |
|
bTiO |
4758.500 – 4800.000 |
4742.750 – 4756.500 |
4827.875 – 4847.875 |
air |
mag |
|
aTiO |
5445.000 – 5600.000 |
5420.000 – 5442.000 |
5630.000 – 5655.000 |
air |
mag |
|
CaH1 |
6357.500 – 6401.750 |
6342.125 – 6356.500 |
6408.500 – 6429.750 |
air |
mag |
|
CaH2 |
6775.000 – 6900.000 |
6510.000 – 6539.250 |
7017.000 – 7064.000 |
air |
mag |
|
NaISDSS |
8180.0 – 8200.0 |
8143.0 – 8153.0 |
8233.0 – 8244.0 |
air |
Å |
|
TiO2SDSS |
6189.625 – 6272.125 |
6066.625 – 6141.625 |
6422.0 – 6455.0 |
air |
mag |
Input Data Format¶
The parameters that define the absorption-line-index calculations are
provided via the
AbsorptionIndexDB
object,
which is built using an SDSS-style parameter file. The core level
class that calculates the raw absorption-line indices is
AbsorptionLineIndices
.
The columns of the parameter file are:
Parameter |
Format |
Description |
---|---|---|
|
int |
Unique integer identifier of the absorption-line index. Must be unique. |
|
str |
Name of the index. Must be unique. |
|
float[2] |
A two-element vector with the starting and ending wavelength for the primary passband surrounding the absorption feature(s). |
|
float[2] |
A two-element vector with the starting and ending wavelength for a passband to the blue of the primary band. |
|
float[2] |
A two-element vector with the starting and ending wavelength for a passband to the red of the primary band. |
|
str |
The reference frame of the wavelengths; must be either ‘air’ for air or ‘vac’ for vacuum. |
|
str |
Units for the absorption index, which must be either ‘ang’ or ‘mag’. |
|
int |
Never used: Binary flag (0-false,1-true) that the index is a component of a composite index. If true (1), all components with the same NAME are added together to form the composite index. |
and an example file might look like this:
typedef struct {
int index;
char name[9];
double primary[2];
double blueside[2];
double redside[2];
char waveref[3];
char units[3];
int component;
} DAPABI;
DAPABI 1 CN1 { 4142.125 4177.125 } { 4080.125 4117.625 } { 4244.125 4284.125 } air mag 0
DAPABI 2 CN2 { 4142.125 4177.125 } { 4083.875 4096.375 } { 4244.125 4284.125 } air mag 0
Note that the functionality implied by the component
parameter has
been a notional future development for the module, but has never been
implemented. However, unfortunately, it’s still a required element of
the database file.
Changing the absorption-line index parameters¶
The absorption-line indices are measured by
SpectralIndices
; see
Spectral-Index Measurements. A set of parameter files that
define a list of absorption-line index sets are provided with the DAP
source distribution and located at
$MANGADAP_DIR/mangadap/data/absorption_indices
. There are a few
methods that you can use to change the set of absorption-line index parameters
used by SpectralIndices
:
To use one of the existing parameter databases, you can change the
absorption_indices
keyword in theSpectralIndices
configuration file. The keyword should be the capitalized root of the parameter filename. E.g., to use$MANGADAP_DIR/mangadap/data/absorption_indices/lickindx.par
, set the keyword toLICKINDX
.To use a new parameter database, write the file and save it in the
$MANGADAP_DIR/mangadap/data/absorption_indices/
directory, and then change the relevant configuration file in the same way as described above.
Bandhead or Color Index Parameters¶
The table below provides a compilation of bandhead and color indices. Recent survey-level runs of the DAP have included all of these measurements.
Name |
Blue Sideband (Å) |
Red Sideband (Å) |
Frame |
Integrand |
Order |
Ref |
---|---|---|---|---|---|---|
D4000 |
3750 – 3950 |
4050 – 4250 |
air |
\(F_\nu\) |
R/B |
|
Dn4000 |
3850 – 3950 |
4000 – 4100 |
air |
\(F_\nu\) |
R/B |
|
TiOCvD |
8835 – 8855 |
8870 – 8890 |
vac |
\(F_\lambda\) |
B/R |
Input Data Format¶
The parameters that define the bandhead index calculations are provided
via the BandheadIndexDB
object,
which is built using an SDSS-style parameter file. The core level
class that calculates the raw bandhead indices is
BandheadIndices
.
The columns of the parameter file are:
Parameter |
Format |
Description |
---|---|---|
|
int |
Unique integer identifier of the absorption-line index. Must be unique. |
|
str |
Name of the index. Must be unique. |
|
float[2] |
A two-element vector with the starting and ending wavelength for a passband to the blue of the primary band. |
|
float[2] |
A two-element vector with the starting and ending wavelength for a passband to the red of the primary band. |
|
str |
The reference frame of the wavelengths; must be either ‘air’ for air or ‘vac’ for vacuum. |
|
str |
Integrand within the passband for the construction of the index, which must be either ‘fnu’ or ‘flambda’. |
|
str |
Define the order to use when constructing the index. The options are either a ratio of red-to-blue or blue-to-red, which are respectively selected using ‘r_b’ or ‘b_r’. |
and an example file might look like this:
typedef struct {
int index;
char name[9];
double blueside[2];
double redside[2];
char waveref[3];
char integrand[7];
char order[3];
} DAPBHI;
DAPBHI 1 D4000 { 3750.000 3950.000 } { 4050.000 4250.000 } air fnu r_b
DAPBHI 2 Dn4000 { 3850.000 3950.000 } { 4000.000 4100.000 } air fnu r_b
DAPBHI 3 TiOCvD { 8835.000 8855.000 } { 8870.000 8890.000 } vac flambda b_r
Changing the bandhead index parameters¶
The bandhead and color indices are measured by
SpectralIndices
; see
Spectral-Index Measurements. A set of parameter files that
define a list of bandhead index sets are provided with the DAP source
distribution and located at
$MANGADAP_DIR/mangadap/data/bandhead_indices
. There are a few
methods that you can use to change the set of bandhead-index
parameters used by
SpectralIndices
:
To use one of the existing parameter databases, you can change the
bandhead_indices
keyword in theSpectralIndices
configuration file. The keyword should be the capitalized root of the parameter filename. E.g., to use$MANGADAP_DIR/mangadap/data/bandhead_indices/bhbasic.par
, set the keyword toBHBASIC
.To use a new parameter database, write the file and save it in the
$MANGADAP_DIR/mangadap/data/bandhead_indices/
directory, and then change the relevant configuration file in the same way as described above.