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 mangadap.proc.spectralindices.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 |
|
Changing the absorption-line index parameters
The absorption-line indices are measured by
mangadap.proc.spectralindices.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/data/absorption_indices
. There are a few
methods that you can use to change the set of absorption-line index parameters
used by mangadap.proc.spectralindices.SpectralIndices
:
- To use one of the existing parameter databases, you can change
the
absorption_indices
keyword in the
mangadap.proc.spectralindices.SpectralIndices
configuration file. The keyword should be the capitalized root
of the parameter filename. E.g., to use
$MANGADAP_DIR/data/absorption_indices/lickindx.par
, set
the keyword to LICKINDX
.
- To use a new parameter database, write the file and save it in
the
$MANGADAP_DIR/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 mangadap.par.bandheadindexdb.BandheadIndexDB
object,
which is built using an SDSS-style parameter file. The core level
class that calculates the raw bandhead indices is
mangadap.proc.spectralindices.BandheadIndices
.
The columns of the parameter file are:
Parameter |
Format |
Description |
index |
int |
Unique integer identifier of the absorption-line index. Must be
unique. |
name |
str |
Name of the index. Must be unique. |
blueside |
float[2] |
A two-element vector with the starting and ending wavelength for a
passband to the blue of the primary band. |
redside |
float[2] |
A two-element vector with the starting and ending wavelength for a
passband to the red of the primary band. |
waveref |
str |
The reference frame of the wavelengths; must be either ‘air’ for air
or ‘vac’ for vacuum. |
integrand |
str |
Integrand within the passband for the construction of the index,
which must be either ‘fnu’ or ‘flambda’. |
order |
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
mangadap.proc.spectralindices.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/data/bandhead_indices
. There are a few
methods that you can use to change the set of bandhead-index parameters
used by mangadap.proc.spectralindices.SpectralIndices
:
- To use one of the existing parameter databases, you can change
the
bandhead_indices
keyword in the
mangadap.proc.spectralindices.SpectralIndices
configuration file. The keyword should be the capitalized root
of the parameter filename. E.g., to use
$MANGADAP_DIR/data/bandhead_indices/bhbasic.par
, set the
keyword to BHBASIC
.
- To use a new parameter database, write the file and save it in
the
$MANGADAP_DIR/data/bandhead_indices/
directory, and then
change the relevant configuration file in the same way as
described above.