Images captured

Image taken 29 Jun 2009 05:25UT by Paul Mortfield, Sierra Remote Observatories, Fresno, California using an RC16"f/8.9 and CCD at 60sec binned 2x2. Informal magnitude estimate 16v.  Copyright Paul Mortfield 2009. 

Related messages: 1   2  

 Image taken 2 Jul 2009 22:23UT by Paulo from Portugal using a 4" Tak FS102 and a cooled CCD.  

 Related message: 1

Summary

The best local circumstances for imaging the LCROSS Centaur will be from the southern hemisphere during cruise orbit one between July 22 and July 28 (Figure 4) and during cruise orbit three between September 16 to September 26 (Figure 11).  Cruise orbit two provides sub-optimal imaging opportunities for both hemispheres. Northern hemisphere observers have less than optimal imaging opportunities during all three cruise orbits but are well positioned to view the impact. (Figure 12).

This page provides quick analysis of the best days and hemispheres from which imaging of the LCROSS Centaur spacecraft could be attempted during cruise orbits one to three. Cruise orbit one begins after LCROSS's gravity assist flyby of the Moon on June 23 and continues until LCROSS next passes the ecliptic (approaching from the southern celestial hemisphere on July 31). Imaging is proposed for the LCROSS Centaur during its lunar cruise phase at distances of 500,000km to 700,000km based on an analogous acquisition of amateur images of an Apollo 12 booster in 2002 - minor planet body J002E3. The Apollo S-IVB booster is similar in diameter and length to the Atlas V Centaur booster used in the LCROSS experiment. Amateur images taken of J002E3 in 2002-2003 indicated J002E3 was a magnitude 15 object.  Amateur imaging apertures where 12 to 14 inches.

This quick analysis is based on an observing point at longitude W110 Latitude N41. LCROSS Centaur positions are topocentric senstive. Observing point ephermides need to be run for the reader's geographic location. The NASA JPL Horizon's ephermeris applet at url http://ssd.jpl.nasa.gov/horizons.cgi can be used to generate a topocentric ephemeris for your observing point. Use "LCROSS" as the target body. The current ephemeris data in the Horizon's system presented here is based on the planned flight path, not the actual observed flight path. It is anticipated that the Horizons orbital path data will be updated with the actual flight path after the gravity assist lunar flyby on June 23.

Quick decision analysis plotting charts shown below are based on an observing point at longitude W110 Latitude N41 at 6UT each night for cruise orbits one and two. 10UT is the observing time for planning purposes during cruise orbit three. Analysis is not based on a geocentric observing point. For orbital paths marked in graphics, the green lines represent the LCROSS cruise orbit one path between the last quarter Moon, through the new Moon and on to the First Quarter Moon. The red line represents the LCROSS orbital path between the First Quarter Moon, through the Full Moon and on to the Third Quarter Moon.  Considering the likely target magnitude is 15, imaging is most likely to suceed under dark sky conditions.

Orbital path plots provided below are intended for first-tier quick analysis only. Imagers should perform second-tier detailed analysis to determine if expanded dark-sky imaging opportunities exist around the First and Third Quarter Moon phase dates.

A "favorable" imaging window as discussed in this page means: (1) The Moon is below the horizon at the time of imaging; (2) the object is above about 30 degrees altitude; and, (3) the illuminated fraction of the Centaur booster is predicted to exceed 30 percent.

LCROSS has proven to be an easier object to image under Moon light lighting conditions that previously expected, even with its 16 mag brightness. Attempting imaging during moonlight periods should not be ruled out.

Orbital Elements

Identification USSPACECOM Catalog No.: 35316 ; International Designation Code: 2009-031-B. Heavens Above does not list the orbital elements for the LCROSS spacecraft for use in amateur satellite tracking programs.  This is because the LCROSS orbit is not of a type that is amenable to two-line element computation.  Bill Gray, Pseudo-MPEC for LCROSS, Web doc accessed July 6, 2009. On June 29, two imagers reported acquisition of the LCROSS Centaur booster as a 16 mag object using 16 inches of aperture.  The actual position of the spacecraft closely matches (~ 1 arcminute) the planned orbital path data available through the NASA JPL Horizon's ephermeris applet at url http://ssd.jpl.nasa.gov/horizons.cgi, discussed below.  Imagers should use the Horizons applet to determine pointing coordinates for imaging. 

Bill Gray has computed a table of nightly two-line elements for LCROSS through July. The two-line TLE elements have to be updated in satellite tracking software each night from this table.

Orbit One - June 23 to July 30

Lunar phases during curise orbit one favor attempts to image the LCROSS-Centaur spacecraft by observers in the southern hemisphere between July 19 through the First Quarter Moon on July 28. Northern hemisphere observers are disfavored and have only a brief low-altitude imaging window before the First Quarter Moon of June 29 as LCROSS rises of the northwest horizon beginning on June 26.

Major lunar phases through July 30, 2009

Figure1 - LCROSS Cruise Orbit One - Alt-Az view from W110 N41 - Looking Northwest at rising LCROSS beginning June 23, 2009 (Click to enlarge graphic)

Figure 2 - LCROSS Cruise Orbit One - Alt-Az view from W110 N41 - Looking at Zenith beginning June 28, 2009 to July 17 (Click to enlarge graphic)

Figure 3 - LCROSS Cruise Orbit One - Alt-Az view from W110 N41 - Looking at Southeast at setting LCROSS beginning July 8, 2009 to July 17 (Click to enlarge graphic)

Figure 4 - LCROSS Cruise Orbit One - Alt-Az view from W110 N41 - Looking at Southern Zenith beginning July 20, 2009 to July 31 (Click to enlarge graphic)

Orbit one - other detailed local circumstance analyses for individual observing points

Salt Lake City, Utah June 26 to July 2

Orbit Two- July 31 to September 1

Neither the northern or southern hemispheres have favored or favorable imaging opportunities during cruise orbit two. The northern hemisphere has a brief setting imaging window between August 13 to August 14. The southern hemisphere has a brief favorable setting imaging window on August 27 and 28.

Major lunar phases July 28, 2009 to Sept. 4, 2009

Figure 5 - LCROSS Cruise Orbit Two - Alt-Az view from W110 N41 - Looking north beginning July 31, 2009 to August 8 (Click to enlarge graphic)

Figure 6 - LCROSS Cruise Orbit Two - Alt-Az view from W110 N41 - Looking at south beginning Aug. 6, 2009 to Aug. 26 (Click to enlarge graphic)

Figure 7 - LCROSS Cruise Orbit Two - Alt-Az view from W110 N41 - Looking at Southern Zenith beginning Aug. 23, 2009 to Sept. 1 (Click to enlarge graphic)

Orbit Three - September 2 to October 9

The best local circumstances for imaging the LCROSS Centaur will be from the southern hemisphere during cruise orbit three between September 16 to September 26 (Figure 11).  There is an extended period of a rising orbital path around a New Moon with a high illuminated fraction. Southern hemisphere observers will be have several days into which to acquire a LCROSS-Centaur image.  Northern hemisphere observers have less than optimal imaging opportunities but are well positioned to view the impact. (Figure 12). 

During cruise orbit three, the optimal viewing window shifts from local midnight (6UT here) to before dawn (10UT here). At 6UT, in the northern and southern hemispheres, the LCROSS orbital path is low and parallel to the local horizon, but rising in the east. Four hours later, the LCROSS orbital path rises to a a good hour angle relative to the horizon. This condition holds through the impact on October 9.

Major lunar phases between September 2 to October 9

Figure 8 - LCROSS Cruise Orbit Three - Alt-Az view from W110 N41 - Looking at northeast from northern hemisphere beginning September 1 at 10UT - no initial favorable imaging opportunities for the northern hemisphere (Click to enlarge graphic) 

Figure 9 - LCROSS Cruise Orbit Three - Alt-Az view from W110 N41 - Same as Figure 8 at 10UT, but zenithal view (Click to enlarge graphic) 

Figure 10 - LCROSS Cruise Orbit Three - Alt-Az view from W110 N41 - Same as Figure 9, but at 6UT - orbital path is too low for imaging (Click to enlarge graphic) 

Figure 11 - LCROSS Cruise Orbit Three - Alt-Az view from W110 N41 - Looking at Southern Zenith at September 30 10 UT (Click to enlarge graphic) 

Figure 12 - LCROSS Cruise Orbit Three - Alt-Az view from W110 N41 - Looking at south from northern hemisphere from October 4 to October 9 leading to the impact (Click to enlarge graphic) 

LCROSS Cruise Orbit Ephemeris

For OP at W110 N41 Lat from JPL Horizon's System - Planned orbit - not actual - 7-21-2009

Horizon's applet distances in one-way-light-minutes covered to kilometers using 17,987,547.5 km/light-min.