88 days since start of observations
13.5 hours of lunar observations
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Brightest Flash - March 1st
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NELIOTA uses a dichroic with two fast-frame sCMOS cameras (Andor Zyla 5.5; USB3.0) attached to the prime focus of the telescope to perform simultaneous imaging of the Moon in two channels (R and I-bands), at 30 frames per second. The cut-off of the dichroic is at 730 nm and the R and I-band filters (Astrodon 50-mm diameter, 3-mm thick) are in the Johnson-Cousins photometric system.

The cameras are used in 2x2 binning and have a pixel scale of 0.8 arcsec/pixel or 1.5 km (of the lunar surface) per pixel. The orientation of the cameras is such that East is up and North is to the left. Their characteristics are listed in the table below.


Sensor type

Front Illuminated Scientific CMOS



Gain settings

Low noise & High well capacity (16 bit)

Gain (e- per A/D count)

0.5 (binning 1x1); 0.4 (binning 2x2)

Read noise (e- RMS)

2.8 (binning 1x1); 5.1 (binning 2x2)

Pixel readout rate (MHz)


Sensor size (mm)

16.6 x 14

Pixel size (μm)


Total pixels

2560 x 2160 (binning 1x1); 1280 x 1080 (binning 2x2)

Field of View (arcmin)

16.64 x 14.04

Pixel scale (arcsec/pixel)

0.4 (binning 1x1); 0.8 (binning 2x2)


The performance of the Prime Focus Instrument (PFI) optical system (dichroic, filters, cameras) is calculated taking into account the Quantum Efficiency (QE; black solid line) of the cameras, the transmittance of the R and I filters (red dotted and grey dotted lines respectively) and the dichroic (brown solid line). The final output is shown by the red and grey solid lines.



Here is the diagram for the linearity of the sCMOS cameras for the NELIOTA configuration (560 MHz, global shutter, low noise & high well capacity). The dark current is essentially zero.