2002 MS4 08/08/2020


Observation tips:

- A detailed observation protocol can be obtained here: Obs. Protocol
- Observations are requested from 20:38 to 20:48 Universal Time (main event).
- If possible, observe from 20:20 to 21:20 UT to sound for a putative satellite;
- After observations, please take darks and (if possible) flats.

- Shadow moves from **East to West**;
- The nominal occultation time on the map, corresponds to the big dot, the closest approach.
- Each dot is separated by one minute;
- Dark grey is night and light grey is astronomical twilight (Sun at less than 18 deg below the horizon);
- **Absolute time accuracy is essential** (see important note below);

After the observation, please fill the form available on this link: REPORTING FORM.

Event information: 

Star J2000 coordinates:
RA 18 47 29.9638
DEC -06 16 31.473
Day coordinates of the object:
RA 18 48 36.3396
DEC -06 15 02.891

Star G mag 14.6
Star RP mag 13.6
Star K mag 11.1
Magnitude drop in R 5.7
Maximum duration 38 sec
Moon | 76% illum. @ 94 deg

Important note:

*Absolute time accuracy is essential*

To connect all the observations together after the fact, absolute time accuracy is essential. Check the time of your computer with many sources (ideally with a GPS). It's advised to check the registered time right after and right before the integrations, so if there is a drift, we can correct it by having the difference. Beware of the dead time between the images: if you manage an exposure time of 1 second (for example), but your camera takes 2 sec to read the image, then there is a 67% chance that you miss the dis(re)-appearance of the star [chance of missing = 1 - {1/(1+2)}]. So, it's better to have, for example, 4 sec integration, so you have 67% chance to get the occultation in one of your exposures [chance of getting = 4/(4+2)]. Selecting a window and binning can be very useful (see protocol in obs. tips).

Finding charts from Aladin:

13 x 10 arcmin FOV (North is up, East is left)


Finding charts made with Starry Night:

02 x 01 degree FOV (North is up, East is left)


02 x 01 degree FOV - Magnitudes (North is up, East is left)


02 x 01 degree FOV - Star names (North is up, East is left)


02 x 01 degree FOV - Black Sky (North is up, East is left)


A "zoomable" Finding Chart can be found here:
Interactive Sky Chart


Four occultations by 2002 MS4 were detected in 2019, allowing the calculation of a very good ephemeris. On July 26, 2020, another event was detected confirming the good prediction:


Zoom (red dashed line is the shadow's border error bar):


Link to Lucky Star Prediction

Click for a Open Street Interactive Map or Google Earth kmz