Filters and Throughputs

Calculated filter characteristics and transmission curves are given below. All are based on standard reflectivity or transmission data for various surfaces, unless a part specific curve was provided by the manufacturer. No transmissive optics (ADCs, etc) are currently accounted for.

The atmosphere is included in the numbers presented in the table below. BTRAM was used to calculate the atmospheric transmission for LCO, and the below values assume a zenith distance of 30 degrees and 5.0 mm PWV. A version of each curve is provided without the atmosphere contribution, which can then be combined with the atmosphere of your choice.

None of these values have been verified on sky. They should be used for planning purposes only.

Visible Science Cameras

Filters in the visible science cameras.

camsci1

Filter

WFS B/S

Sci BS

\(\lambda_0\) [µm]

\(w_\mathrm{eff}\) [µm]

\(\mathrm{QE}_\mathrm{max}\)

\(F_0\) [photon / sec]

Files

H-alpha Cont.

H-alpha/IR

H-alpha

0.668

0.009

0.22

\(3.8\times10^{9}\)

atm noatm

ip

65/35

ri

0.764

0.120

0.11

\(2.1\times10^{10}\)

atm noatm

zp

65/35

ri

0.908

0.130

0.08

\(1.3\times10^{10}\)

atm noatm

rp

65/35

open

0.615

0.110

0.23

\(6.1\times10^{10}\)

atm noatm

ip

65/35

open

0.762

0.126

0.11

\(2.2\times10^{10}\)

atm noatm

zp

65/35

open

0.908

0.131

0.09

\(1.3\times10^{10}\)

atm noatm

CH4

65/35

50/50

0.875

0.026

0.04

\(1.3\times10^{9}\)

atm noatm

rp

65/35

50/50

0.615

0.112

0.11

\(2.9\times10^{10}\)

atm noatm

ip

65/35

50/50

0.762

0.126

0.06

\(1.1\times10^{10}\)

atm noatm

zp

65/35

50/50

0.908

0.130

0.04

\(6.3\times10^{9}\)

atm noatm

camsci2

Filter

WFS B/S

Sci BS

\(\lambda_0\) [µm]

\(w_\mathrm{eff}\) [µm]

\(\mathrm{QE}_\mathrm{max}\)

\(F_0\) [photon / sec]

Files

H-alpha

H-alpha/IR

H-alpha

0.656

0.009

0.23

\(3.5\times10^{9}\)

atm noatm

gp

65/35

ri

0.527

0.041

0.24

\(3.1\times10^{10}\)

atm noatm

rp

65/35

ri

0.613

0.106

0.23

\(5.9\times10^{10}\)

atm noatm

CH4 Cont.

65/35

50/50

0.923

0.023

0.04

\(9.6\times10^{8}\)

atm noatm

gp

65/35

50/50

0.525

0.044

0.13

\(1.9\times10^{10}\)

atm noatm

rp

65/35

50/50

0.614

0.109

0.12

\(3.3\times10^{10}\)

atm noatm

ip

65/35

50/50

0.762

0.126

0.06

\(1.1\times10^{10}\)

atm noatm

zp

65/35

50/50

0.909

0.132

0.04

\(6.7\times10^{9}\)

atm noatm

WFS

Filters in the main WFS.

WFS B/S

Filter

\(\lambda_0\) [µm]

\(w_\mathrm{eff}\) [µm]

\(\mathrm{QE}_\mathrm{max}\)

\(F_0\) [photon / sec]

Files

H-alpha/IR

open

0.837

0.205

0.20

\(5.3 \times 10^{10}\)

noatm atm

65/35

open

0.791

0.296

0.08

\(4.2 \times 10^{10}\)

noatm atm

LOWFS

Filters in the low-order WFS.

Atmosphere

Atmospheric transmission curves for Cerro Manqui. These were calculated by Jared using the BTRAM IDL code. Individual files linked below, and the complete set can be downloaded .

ZD

PWV [mm]

PWV [mm]

PWV [mm]

PWV [mm]

PWV [mm]

PWV [mm]

[deg]

0.0

2.5

5.0

7.5

10.0

12.5

0.0

file

file

file

file

file

file

15.0

file

file

file

file

file

file

30.0

file

file

file

file

file

file

45.0

file

file

file

file

file

file

60.0

file

file

file

file

file

file

Specifying Guide Star Magnitude

It is helpful if you have an accurate estimate of the magnitude of your guide star in the MagAO-X WFS bandpass. This is a critical parameter for optimizing the AO loop setup for your science, and being close will save time on sky. For most objects, standard I band will be the closest approximation. Note that we have found that SIMBAD reported magnitudes can be as much as ~1 magnitude bright, especially for redder stars. We find much better agreement using the USNO UCAC4 photometry or DENIS survey I magnitude.

MagAO-X WFS bandpasses with atm model:

WFS bandpasses

Alternately you can use Gaia G band magnitude and correct the color to the WFS bandpasses. These curves give an estimate of the color correction for Gaia G to WFS 65/35 (blue) and WFS Halpha/IR (orange) for main sequence stars (solid) and giants (dotted) by spectral type. Computed using Pickles stellar models and Gaia G-band public filter curves.

Gaia to WFS curves