Last update: 2007 July 24

Stellar occultations: Pluto, Jul 31, 2007

overview

There is a potential occultation of the star P495.3 by Pluto on 2007 July 31 UT. The star is bright, about 13.5 mag, making this the brightest occultation star since the Pluto atmosphere discovery in 1988.


P495.3 Plans

Our group (PHOT = Portable High-speed occultation telescope) is
deploying to five locations.  
Auckland, 
 Auckland   0.4 m  Grant Christie, Tim Natusch   
 Mount John 1.0 m  Leslie Young, Bob Howell (two cameras, w/ dichroic) 
 AAT        4.0 m  Cathy Olkin, Kevin Shoemaker
 Mt Canopus 1.0 m  Eliot Young
 Launceston 0.35 m Jeff Regester, Trina Ruhland (portable 14-inch Meade)

P495.3 Predictions

Star Positions

Using the UCAC2 catalog position as our reference psotions, we find the following star positions:

Source         RA            Dec              dra     ddec errx erry
------------  -------------- -------------   ----- ------- ---- ----
UCAC2          17:45:41.9799 -16:29:31.652       0       0   62   62
2MASS          17:45:41.9900 -16:29:31.700     145     -48   60   60
UCAC2-2006     17:45:41.9865 -16:29:31.690      96     -38    5   11
Bruno (Rio)    17:45:41.9850 -16:29:31.647      73       5   
P495.3-AST-1.5 17:45:41.9849 -16:29:31.665      72     -13    9    9
Lowell 31-in   17:45:41.9827 -16:29:31.728      41     -76   22   21
-------------------------------------------------------------------
RA and Dec are epoch of date (where proper motion is know), equinox J2000.
dra and ddec are the offsets from the reference position in mas.
errx and erry are the quoted errors in position (and therefore in dra, ddec) in mas. UCAC2 errors include propogated proper motion error.
UCAC2: the position from the UCAC2 catalog, our reference position. 2MASS: the position from the 2MASS catalog. UCAC2-2006: the position remeasured with the UCAC2 telescope in 2006, provided by Norbert Zacharias. This catalog is available here .

Bruno (Rio) - from http://www.lesia.obspm.fr/~sicardy/31_jul_07/index.html

MIT prediction 1.5 above uses the value as of June 4, 2007. The value has since been updated. See Jim Elliot's group's prediction

Lowell 31-in are from fifteen nights on the 31 inch telescope at Lowell Observatory.

Pluto offsets

Using the DE-413 and PLU-013 ephemerides from JPL as our reference ephemerides, the following offsets are reported

Source           dra    ddec (milliarcsec)
------------     -----  ----
Lowell 31"       -6.7   2.4
MIT 2007-07-12   -42.6  26.0
Bruno Sicardy   -100.0 80.0
------------     -----  ----

Globes

Bruno Sicardy

PHOT Prediction: pred102 posted on 20070629 at 13:48 MDT PHOT (Cathy Olkin)

Jim Elliot's Group

event times

Predictions for 2007 July 31 Occultation of P495.3 by Pluto by Richard G. French, Wellesley College mimas.wellesley.edu:/Volumes/pandora_raid2/Research/PHOT/programs/P495.3_occpred_v4.pro Thu Jul 19 14:01:21 2007

BEGIN OBSERVING 5 MINUTES BEFORE EARLIEST IMMERSION AND CONTINUE UNTIL 5 MINUTES AFTER LATEST EMERSION

--------------------------------------------------------------------------------------------------

P445.3 predictions for Mt. John

                                                                     Distance
                                                             Closest     163 km
                                                             Farthest   1941 km

                                                                               Immersion  Midtime Emersion
                                                                       Earliest 13:43:39 13:45:00 13:46:22
                                                                       Latest   13:46:24 13:47:44 13:49:04
----------------------------------------------------------------------------------------------------------


P445.3 predictions for Auckland
                                                                     Distance
                                                             Closest      71 km
                                                             Farthest   2355 km

                                                                               Immersion  Midtime Emersion
                                                                       Earliest 13:42:57 13:44:18 13:45:39
                                                                       Latest   13:45:51 13:47:01 13:48:11
----------------------------------------------------------------------------------------------------------


P445.3 predictions for Mt. Canopus


                                                                     Distance
                                                             Closest     175 km
                                                             Farthest   2663 km

                                                                               Immersion  Midtime Emersion
                                                                       Earliest 13:44:49 13:46:04 13:47:19
                                                                       Latest   13:47:52 13:48:46 13:49:40
----------------------------------------------------------------------------------------------------------


P445.3 predictions for Launceston


                                                                     Distance
                                                             Closest     304 km
                                                             Farthest   2792 km

                                                                               Immersion  Midtime Emersion
                                                                       Earliest 13:44:46 13:45:59 13:47:10
                                                                       Latest   13:47:57 13:48:41 13:49:25
----------------------------------------------------------------------------------------------------------


P445.3 predictions for AAT


                                                                     Distance
                                                             Closest      59 km
                                                             Farthest   3654 km

                                                                               Immersion  Midtime Emersion
                                                                       Earliest 13:44:38 13:45:16 13:46:08
                                                                       Latest   13:47:02 13:47:58 13:47:41
----------------------------------------------------------------------------------------------------------

P495.3 Finder charts

|   |  Star designation     |RA    (J2000) |Dec (J2000)   |  dra |ddec|  mag |filter|
| A |ucac2 25815762         |17:45:41.9856 |-16:29:31.627 |   0 |   0 | 13.2 | U2R |
| B |USNO-B1.0 0735-0463618 |17:45:42.9100 |-16:29:41.300 |  13 | -10 | 15.2 |  R2 |
| C |USNO-B1.0 0735-0463569 |17:45:42.0900 |-16:29:44.100 |   2 | -12 | 15.2 | R2 |
| D |ucac2 25815751         |17:45:40.9794 |-16:29:35.648 | -14 |  -4 | 15.9 | U2R|
| E |ucac2 25815721         |17:45:35.6675 |-16:29:44.204 | -91 | -13 | 14.8 | U2R|
| F |ucac2 25815705         |17:45:34.0410 |-16:29:52.116 |-114 | -20 | 10.9 | U2R|
| G |ucac2 25815689         |17:45:32.6810 |-16:29:37.314 |-134 |  -6 | 13.6 | U2R|
| H |ucac2 25815791         |17:45:46.0757 |-16:29:30.971 |  59 |   1 | 14.4 | U2R|
| I |ucac2 25815665         |17:45:30.4834 |-16:28:59.006 |-165 |  33 | 10.9 | U2R|
|   |  SAO 160807           |17:46:10.7500 |-16:35:28.000 | 414 |-356 |  8.4 | V  |
U2R = UCAC2 filter, midway between V and R
R2 = the second R mag listed in the USNO B1.0 catalog
V = V mag from the SAO catalog

Finder charts

Narrow field

Narrow field, no labels

Medium field

Medium field, no labels

Wide field

Wide field, no labels


Last updated 2007 July 24 by Leslie Young, layoung@boulder.swri.edu , http://www.boulder.swri.edu/~layoung