Analysis of Observations
Below are the results of the observations made on May 19th 2021
by Dave Gault and Peter Nosworthy. These were the first known
detections of the suspected satellite of (4337) Arecibo.
Peter Nosworthy's light curve
Dave Gault's's light curve
Both Curves on The Same Time Scale
Chord Plot - May 19 2021
The chords from the initial observations on May 19 indicate a main body diameter of 24.5km (assuming a circular fit).
The diameter of the moon is not clear because both chords appear to be very close to the edge of the object.
Excluding the 'Double Star' Hypothesis (Limiting Magnitude Analysis)
If the observations were the result of one body occulting two components of a
double star, it would require that one component of the double be brighter than G-band mag. 14.4.
This possibility can be excluded by confirming that the target star dropped
below mag. 14.4 during both occultation events.
We used dim comparison stars in the field of view to measure the limiting magnitudes of
The limiting magnitudes were 15.4 (Gault) and 15.5 (Nosworthy).
This confirms that the target star dropped below G-band mag. 14.7 during all four recorded events.
The asteroid was mag. 17.0, well below the limiting magnitude of both recordings.
From this we conclude that a single body occulting a double star could not account for the
observations. This makes the case for a 'moon' much more likely.
On June 9, 2021 two observers in California, Kirk Bender and Richard Nolthenius, observed
in which (4337) Arecibo occulted a mag. 12 star in Ophiuchus.
Both observers detected double occultation events consistent with a satellite of Arecibo.
See also Richard's Page describing this event
Kirk Bender's Light Curve
Richard Nolthenius's Light Curve
These observations confirm the existence of the moon beyond reasonable doubt.
Chord Plot - June 9 2021
The chords from the June 9 observations were plotted with assumed circular fits for both objects.
This indicates diameters of 24.4km and 13.5km for the two objects.