OSU College of Arts and Sciences Department of Astronomy

MODS Observing Planning Tools

Updated: 2013 May 10

This page provides access to web-based MODS observing planning tools and calculators.

Tools:
MODS1 Instrumental Sensitivity - May 2013 (15k PDF)
Imaging Exposure Time Calculator
Target Visibility Calculator
Differential Atmospheric Refraction Calculators

This is a work in progress, more tools are on the way...


Imaging Exposure Time Calculator

Imaging Exposure Time Calculator

Target u: Point Source (ABmag)
g: Extended Source (ABmag/arcsec²)
r: SNR for ExpTime = sec
i: ExpTime to get SNR =
z:  
Airmass: Seeing: Moon Age: d

Notes

Spectroscopic Sensitivity

MODS1 Instrumental Sensitivity - May 2013 (15k PDF)


Target Visibility

Hourly Visibility Calculator

Object Name:
Right Ascension:
[HH:MM:SS or HH MM SS.S or decimal degrees]
Declination:
[dd:mm:ss or dd mm ss or decimal degrees]
Equinox:
Observing Date:     MST  
For a given date, computes the hourly visibility (hour angle, airmass, parallactic angle, and Moon elevation) of a MODS target from the LBT, including a plot of elevation versus time. Based on John Thorstensen's skycalc program.

John Thorstensen's JSkyCalc program can be very helpful for visualizing your time-and-the-sky constraints; the executable jar file can be downloaded from John's GitHub repository Note that JSkyCalc is also installed on the LBT observing workstations for use on the mountain.


Differential Atmospheric Refraction

MODS does not have an Atmospheric Dispersion Corrector (ADC), so orientation of the slit at or near the parallactic angle is essential in order to mitigate slit losses due to atmospheric dispersion, especially at the UV end of the MODS blue channel.

These tools will help you determine hour-angle restrictions and choice of slit position angle to compensate for atmospheric dispersion for your targets.

Parallactic Angle Calculator

Declination:
[dd:mm:ss or dd mm ss or decimal]
Hour Angle: hr to hr in min steps.
Calculates the parallactic angle, elevation, airmass, and along-parallactic slit position angles of a target for a range of hour angles.

Atmospheric Refraction Calculator

Declination:
[dd:mm:ss or dd mm ss or decimal]
Slit PA: ° (N to E)
Slit Width: arcsec
Hour Angle: hr to hr in min steps.
AGw Filter:

Calculates a table of differential atmospheric refraction for a target for wavelengths of 350-950nm over a range of hour angles and choice of slit position angle, width, and AGw guide camera filter, and generates a plot of the atmospheric dispersion track relative to the slit.
Updated: 2020 Dec 21 [rwp/osu]