zline

Contents: Copyright | Download | Installation | Examples

zline is a trivial program to calculate a redshift given a line name and observed wavelength. It also outputs a table of redshifted galaxy lines at that redshift.

Copyright

No copyright. Entirely free.

Download

You can download the source code: zline.c

Installation

zline is written in C, so you'll need an appropriate compiler (gcc, cc, etc.). To compile, simply type:

	gcc zline.c -o zline

NOTE: if you use a C compiler other than gcc, replace 'gcc' in the line above with your compiler name.

This will output an executable file named zline. Typing 'zline' at a terminal prompt will print the syntax.

> zline
 Usage: zline redshift (e.g.: zline 0.46)
    OR  zline line_name observed_wavelength (e.g.: zline OII 4355)

 Available lines: type 'zline 0.' for a list of line names
                  and rest wavelengths (in Angstroms)

 NOTE: a warning is issued if a redshifted galaxy line
       is within   20.0 Angstroms of a sky feature

To display the names of available lines (and their rest wavelengths), type 'zline 0.' at a terminal prompt:

> zline 0.

   !!! NOTE: BEWARE OF SKY LINES !!!

 emission:   O I  @ 5577, 6300, and 6364
 absorption: O II @ 6880 (B-band center)
             O II @ 7620 (A-band center)

Typical galaxy lines, redshifted to z = 0.000

# Line      Rest       Observed
#              wavelength (A)
======>    EMISSION    <======
 Ly_alpha1  1215.70    1215.70
 Ly_alpha2  1240.00    1240.00
 SiIV       1400.00    1400.00
 CIV        1549.00    1549.00
 CIII       1909.00    1909.00
 MgII       2798.00    2798.00
 NeV        3425.86    3425.86
 OII        3727.30    3727.30
 NeIII      3868.75    3868.75
 H_epsilon  3970.10    3970.10
 H_delta    4101.70    4101.70
 H_gamma    4340.50    4340.50
 H_beta     4861.33    4861.33
 OIIIa      4958.91    4958.91
 OIIIb      5006.84    5006.84
 NIIa       6548.06    6548.06
 H_alpha    6562.83    6562.83
 NIIb       6583.57    6583.57
 SIIa       6716.44    6716.44
 SIIb       6730.82    6730.82
======>   ABSORPTION   <======
 CaIIK      3933.70    3933.70
 CaIIH      3968.50    3968.50
 H_delta    4101.70    4101.70
 CaIG       4304.40    4304.40
 H_beta     4861.33    4861.33
 Mg         5175.36    5175.36
 CaFe       5268.98    5268.98
 NaID       5892.50    5892.50

Examples

Example 1. Suppose you see [O II] at 4355 Angstroms:

> zline OII 4355

 Line OII (3727.3 A) observed at 4355.0 A => z =  0.168

   !!! NOTE: BEWARE OF SKY LINES !!!

 emission:   O I  @ 5577, 6300, and 6364
 absorption: O II @ 6880 (B-band center)
             O II @ 7620 (A-band center)

Typical galaxy lines, redshifted to z = 0.168

# Line      Rest       Observed
#              wavelength (A)
======>    EMISSION    <======
 Ly_alpha1  1215.70    1420.43
 Ly_alpha2  1240.00    1448.82
 SiIV       1400.00    1635.77
 CIV        1549.00    1809.86
 CIII       1909.00    2230.49
 MgII       2798.00    3269.20
 NeV        3425.86    4002.80
 OII        3727.30    4355.00
 NeIII      3868.75    4520.27
 H_epsilon  3970.10    4638.69
 H_delta    4101.70    4792.45
 H_gamma    4340.50    5071.47
 H_beta     4861.33    5680.01
 OIIIa      4958.91    5794.02
 OIIIb      5006.84    5850.02
 NIIa       6548.06    7650.79
 H_alpha    6562.83    7668.05
 NIIb       6583.57    7692.28
 SIIa       6716.44    7847.53
 SIIb       6730.82    7864.33
======>   ABSORPTION   <======
 CaIIK      3933.70    4596.16
 CaIIH      3968.50    4636.82
 H_delta    4101.70    4792.45
 CaIG       4304.40    5029.29
 H_beta     4861.33    5680.01
 Mg         5175.36    6046.92
 CaFe       5268.98    6156.31
 NaID       5892.50    6884.83
 WARNING! Above line within   20.0 A of telluric feature: OII_B (6880.00)

So the corresponding redshift is 0.168 (=4355/3727.3 - 1). The first column gives the line name, while the second and third columns give the rest and observed wavelength, respectively. There is also a WARNING! issued because the redshifted NaID absorption line is within 20 Angstroms of the OIIB telluric feature.

Example 2. If you know the redshift and would simply like to see where other typical galaxy lines would fall, you can skip the redshift calculation. E.g., suppose you know the redshift is 0.46:

> zline 0.46

   !!! NOTE: BEWARE OF SKY LINES !!!

 emission:   O I  @ 5577, 6300, and 6364
 absorption: O II @ 6880 (B-band center)
             O II @ 7620 (A-band center)

Typical galaxy lines, redshifted to z = 0.460

# Line      Rest       Observed
#              wavelength (A)
======>    EMISSION    <======
 Ly_alpha1  1215.70    1774.92
 Ly_alpha2  1240.00    1810.40
 SiIV       1400.00    2044.00
 CIV        1549.00    2261.54
 CIII       1909.00    2787.14
 MgII       2798.00    4085.08
 NeV        3425.86    5001.76
 OII        3727.30    5441.86
 NeIII      3868.75    5648.38
 H_epsilon  3970.10    5796.35
 H_delta    4101.70    5988.48
 H_gamma    4340.50    6337.13
 H_beta     4861.33    7097.54
 OIIIa      4958.91    7240.01
 OIIIb      5006.84    7309.99
 NIIa       6548.06    9560.17
 H_alpha    6562.83    9581.73
 NIIb       6583.57    9612.01
 SIIa       6716.44    9806.00
 SIIb       6730.82    9827.00
======>   ABSORPTION   <======
 CaIIK      3933.70    5743.20
 CaIIH      3968.50    5794.01
 H_delta    4101.70    5988.48
 CaIG       4304.40    6284.42
 WARNING! Above line within   20.0 A of sky emission line: OI (6300.23)
 H_beta     4861.33    7097.54
 Mg         5175.36    7556.03
 CaFe       5268.98    7692.71
 NaID       5892.50    8603.05

Again, a warning is issued because the redshifted CaIG absorption line is within 20 Angstroms of the OI sky emission line.