Echeclus  11/09/2016

*See updates at the bottom of the page*

Please, see the observation tips!


Observation tips:

- Shadow moves from **East to West**;

- The nominal occultation time on the map, corresponds to the big red dot, the closest approach
- Each red dot is separated by one minute;
- Dark gray is night and light gray is astronomical twilight (Sun at less than 18 deg below the horizon);

Recently Echeclus showed a new outburst, and it's coma seems to be moving N-NE from the main body.
The aim of this observation is to detect any kind of structure around the main body, for example rings or jets.
As the coma has about 2 arcsec in diameter, any telescope at the visible hemisphere can scan Echclus environment and possibly detect the dust around it.
For that, high signal will be necessary, so higher exposure time is needed.
We suggest that images with long exposure times (~ 5 to 20 sec) are obtained up to 30 minutes before and after the event.
During the event, shorter exposures (< 1 sec) should be used, so small structures and the main body may be detected.

Star J2000 coordinates:
   RA   01 24 17.366
DEC  +06 40 32.789

Day coordinates:
RA  01 25 10.6
DEC  +06 45 45.8

Star V mag 14.6
Star R mag 14.4
Star K mag 12.8
Magnitude drop in R  ~1.5
Maximum duration
 7.6 sec

Important note

*Absolute time accuracy is essential**

To connect all the observations
together after the fact. Check the time of your computer with many sources (phone talked hour, different internet sites, ideally with a GPS). Its 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 sec (for example), but have 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. So it's better to have, for example, a 4 sec integration, so you have 67% chance to get the occultation in one of your exposures.

Finding charts from DSS:
5 x 5 arcmin FOV

the retangle has 6.6 x 5 arcmin FOV
[made by Jean Lecacheux]

15x 15 arcmin FOV
Click here for a fits version of the image.

26 x 26 arcmin FOV

Other predictions

Initial prediction, from UCAC4 position.

Astrometric Updates

With measurement of the star position obtained at the 160 cm P&E telescope from Observatorio do Pico dos Dias (OPD).

From average position obtained from observations made with the 1,6m and 60cm telescopes of OPD, on July, September 2015 and July 2016.
An offset to NIMA ephem obtained on July/2016 was applied.

Please, see the observation tips at the top!