On 12,  november   1999  UAI Lunar Section reported a short note   concerning a suspect event in Mare Serenitatis that covered a significant area of the  surface.
The GLR group on 16, november 1999 reported the interpretation  that the spot is clearly an external/internal reflex for the size. Furthermore no anomalies were recorded by GLR observers in the same day and time. OUR report is presented in TLP section (see link).
The UAI page was update on 3 april 2000 with the same  consideration obtained by GLR group.
Furthermore the Dr. Albino Carbognani reported his consideration according to the GLR interpretation.

On  3 april 2000  UAI Lunar section reported also  a new  observation by Luca Vazzoler with the use of a refractor of 60 mm.

In this communication is reported that the observer recorded the presence of a white area near the craters Landsberg and Reinhold  . The white spot was estimated to have  the same size of Landsberg (about 39 Km).

The visual observation was carried out on 24 february 2000 at 1 UT (seeing good).
No other data or confirmation were available.
Our interpretation is that the spot is probably  a  reflex due to the presence of  an area having  high albedo.
Futhermore the most curious thing about this anomaly is its size. Several features near the two craters have these sizes.

We have not any estimemated value of the several albedo features in this region and it is very difficult to do any specific work or to suggest that the spot was a real event.
We admit that GLR members  have trouble accepting the communication  uncritically because of this alone.
 

From the reported data the parameters were:
colongitude was 138.9 °, longitude and latitude selenographic was 5.6 and -6.7 ° respectively. The solar altitude on Lansberg  was 67.7°.
The Moon's age was corresponding to 18,49 days (% frac. Illuminated 0.788).

Several observation and CCD images were analyzed.
 
 
CCD image obtained by Badalotti on june, 24, 1999  at 18.10 UT (SCT 250 mm f/10).
On the left is shown the area of interest.

The interested region   shows the presence of  extended  ejecta, ridges and high albedo features.

Reinhold and Landsberg. Image from Atlante fotografico della Luna (Nuovo Orione)
 
 In our images there are several features having high albebo (f.e to the NW of Reinhold,  SW of Reinhold, E of Landsberg).
 

 Albedo values (using the Elger scale) versus the time  have not been  reported by the observer. It is important  to have  standardized procedures in order to establish a normal or suspect bahavior of lunar areas under specific conditions of illumination.

Our data show that  the spot is not an suspect event but more probably it is a reflex or an high albedo feature.