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).