Occultation by Pluto's satellite Hydra 23/09/2014

*See updates at the bottom of the page*

2014-09-23_Hydra/2014-09-23-18.788_IAG12jul_Hydra.jpg





Observation tips:

- Shadow moves from North do South;

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

- Observations are requested:
In Europe: from 18:05 to 18:25 UT.

In Namibia: from 18:35 to 18:55 UT.

See finding charts bellow.


Star J2000 coordinates:
   RA  18 46 06.0183
DEC  -20 36 12.110

Day coordinates:
   RA  18 46 59.18
DEC -20 35 03.2


Star R mag 14.5
Star I mag 13.9
Star K mag 11.4
Magnitude drop in R
 0.6
Magnitude drop in R
(if Pluto is not merged)
6.0
Maximum duration
for a 80 km object. 
27 sec



**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 3 sec integration, so you have 60% chance to get the occultation in one of your exposures.


Finding charts from DSS:
5 x 5 arcmin FOV
2014-09-23_Hydra/field05x05arcmin_20140923_Hydra.jpg

20 x 20 arcmin FOV
2014-09-23_Hydra/field20x20arcmin_20140923_Hydra.jpg
Click here for a fits version of the image.


Astrometric Updates


With WFI original position and offset applied to DE413 ephemeris:
2014-09-23-18.731_WFI_MBuie_Hydra.jpg

Astrometric updates had shown a big offset on the star position, the shadow is displaced to the west (over Europe).

With observations of the star made at Observatorio do Pico dos Dias T 60cm:
[updated 12 Jully 2013] 
2014-09-23_Hydra/2014-09-23-18.788_IAG12jul_Hydra.jpg


With observations of the star made at Observatorio do Pico dos Dias T-60cm:
[updated 04 July 2014]
2014-09-23_Hydra/2014-09-23-18.616_IAG04jul14_Hydra.jpg

With observations of the star made at Observatorio do Pico dos Dias T-60cm:
[updated 29 July 2014]
2014-09-23_Hydra/2014-09-23-18.764_IAG29jul14_Hydra.jpg


With observations of the star made at Observatorio do Pico dos Dias T-60cm:
[updated 30 July 2014]
Preferred!
2014-09-23_Hydra/2014-09-23-18.783_IAG30jul14_Hydra.jpg

Please, see the observation tips at the top!