04 December 2002  Total Solar Eclipse

Sunset Expedition to Fort Grey, Australia

Africa vs. Australian Coast vs. Australian Outback

The path of the total solar eclipse of 04 December 2002spans two continents, Africaand Australia.The maximum duration of the total phase of the eclipse in Africa exceedsthe appx. 1/2 minute one would experience in Australia, a factor of threeon the Mozambique coast as the lunar shadow heads out over the Indian Ocean. And, the maximum elevation of the Sun at mid-eclipse in Australia (at thecoast) is only 9-degrees, and declines as the path progresses inland towardthe outback, compared to a maximum of 45 degrees on the east African coast. If duration and solar elevation were the two principal factors in selectingan eclipse observation site the choice would be obvious.  However,these are not the overriding criteria.

To maximize the probability of seeing an eclipse considerationof the climatology of the target areas, and the need for maintaining mobilityand flexibility, are paramount.  Noting, of course, the caveat that"climate is what you expect, weather is what you get".  The lateris particularly true as localized weather phenomena in regions affectedby the decline of solar insolation during an eclipse are not well representedby statistical examinations of climatalogical (or meteorological) data. None-the-less, it is quite clear that potential for near-sunset clear skiesthe inland regions of Australia at that time of year  exceed thosefound along the track anywhere in Africa .

It has been suggested that in a few isolated spots onthe African continent, such as near Beithbridge in Zimbabwe, that the chanceof "clear skies" might be as high as 60% based upon the normal mid-morning"mixing" model for cloud convection and formation.  During this timeof year, the onset of the rainy season with higher humidity, cold-air advectionbrought on during the eclipse muddies the waters (if I may mix metaphors,if not the atmospheres) and the likelihood of cloud formation would increaseover the nominal and usual scenario.  It would be wise for anyoneconsidering an African observing venue to remain aggressively mobile. But,as many of us learned first-hand in our treks to the 21 June 2001 eclipse,where the path was very similar (in Africa) to that of this years event,mobility is particularly "challenging".  And, given the recently acceleratinginstability in Zimbabwe (in particular) this, sadly,  could make aless than desirable choice for foreign travelers.  In contrast, theinland regions of Australia eastward of the Torrens salt lake bed offervery dry conditions during the austral summer season, with mean cloud coverreaching as low as 20% (and best at the eastern extremedy of the path).On the Australian coast cloud cover may be "expected" at about 50%, thoughhere too convectionally driven cooling of the late afternoon moist seaair would likely increase the likelihood of coastal cloud.  As onemoves eastward along the path of totality in Australia the altitude ofthe sun declines, so the "likelihood" of a cloud along the line-of-siteincreases, which would bias these statistics.  When the low solarelevation is taken into consideration, inland sites are still significantlypreferential to the coastal region.  For these reason, evaluatingthe likelihood of a view of the sun unobscured by intervening cloud, theeastern end of the path of totality in Australia "shines" as the preferentiallocation for an eclipse viewing site.  With the ability to flee westward(i.e., remaining aggressively mobile) to react in situ to local weatherconditions, this is where I will head for the 04 December 2002 eclipse.

Quality, Not Quantity

For some eclipse chasers the mantra is "duration, duration,duration".  For me, like a real estate agent (which I am not)it is "location, location, location".  At this point it wouldbe useful to look at a more detailed MAPOF THE PATH OF TOTALITY OVER AUSTRALIA (2.3Mbytes, patience please).Electing to observe from Australia path means  accepting a durationof totality of approximately half a minute.  From the coast, nearCeduna, the centerline duration of totality is about 33 seconds. At the  (refraction corrected)  sunset point, near Tickalara,it is about 24 seconds.  One can look at this as either a half-empty,or half-full glass, depending upon your philosophy of life.  I.e.,this can be viewed as a "loss" of nine seconds (27% of the duration oftotality at Ceduna), or as a weather-driven opportunity to witness a totalsolar eclipse at (or very near) sunset.  This is something I havealways wanted to experience, purely from the esthetic (some may say ethereal)perspective, but was unwilling to offer up a sacrificial eclipse. Indeed, for all other eclipses I have observed the regions at or near thesunset (or sunrise) points were always contraindicated due to weather (aswell as, secondarily, duration).  To see the totally eclipsed sunjust over the horizon, looming large by the "moon illusion", in a conicalwedge of darkness from the relatively narrow (appx. 25km wide) umbral shadowstretching through a nearly horizontal plane in the atmosphere is a tantalizingthought.  Then, at third contact the "lower" edge of the sun approachesthe horizon near the point where the diamond ring from the soon-to-setvery thin photospheric crescent will appear, and the umbral shadow liftsstraight "up" into space.  Yup, I'll be there.  Any other takers?

The "Plan" - from the ground

Last year our small but dedicated band of die-hard Umbraphileshad such successin Zambia, that I advocated something similar for Australia. Again, no touristy "if it's Tuesday it must be Melbourne" and "oh, by theway there is an eclipse" whirl-wind sightseeing trip with a lot of tag-alongsfor whom the eclipse is of secondary import.  No.  Rather, anucleus of us, the enlightened, those who advocate "eclipse or bust" andwill stand by that until the last coronal photon wanes.  Of coursewe would welcome a "first timer" or two, if they are truly motivated bythe eclipse.  Clearly some of us would want to avail ourselves ofthe opportunities to explore "down under" but not at the expense of, oruntil after, the Champaign cork has popped, the egg creams have fizzed,and we are scratching our heads about how we get to Antarctica in 2003. So from hippos to 'roos.  Are you game?  The game is indeed afoot.

The "plan" in detail is still evolving, but inconcept is now relatively mature. Michael Gill and I had been iteratingMichael Gill for quite a while and we were driven (motivated) by a desireto observe totality from very near sunset at centerline.  Recently,we fell in with Joseph Cali, an Aussie some of you may know from the SolarEclipse Mailing List, who has first-hand familiarity with many of the logisticsand transport "issues" which leap to mind.  And, Joel Moskowitz hassaid "count me in", and thus, this is now our small band of die-hards headingfor the hottest place I know of outside of Tucson. By the way by "verynear the horizon", I mean we target for the Sun still being above the horizonat third contact, by about 1-1/4 degrees.  Less than that, well, we'renot absolutely crazy (though some may disagree) - but read on.

Before getting too specific (which I will) it is worthlooking at the above linked map nowif you have not done so. This is a "road map" of the region covering thepath of totality with northern and southern limits overplotted.  Thepath (which has been corrected for atmospheric refraction) "ends" at sunsetjust NE of Tickalara.  You will note a number of blue "+"'sin the path.  These are airfields in the path of totality, more onthat later too.  You probably have noted the paucity of roads andthe sparseness of the road network at the eastern end of the path. Thus, the "basic" plan is that we will converge in Canberra (where JoeCali lives) on November 30th.  There we will pick up (at least) two4WD vehicles.  Joe has his own, and we are gong to rent a camper van,eitherthis model or something similar to travel to our "prime" pre-selectedviewing site, which is on centerline near FortGrey (be sure to click on this link for information on Fort Grey). Two vehicles, of course, is a minimum. One would be downright foolhardy as we cannot risk a vehicle breakdown stranding us outside of thepath of totality.  If more people (within limits!) end up joiningus in this venture we will up the number of vehicles.

Conservatively, we would make our way to and  basein Port Augusta (or Broken Hill) two days before the eclipse.  IFat that time of our  departure to Fort Grey there is a clear and unambiguousreversal in anticipated weather conditions we would head westward towardCeduna. IF not, however, we would take the following route, with drivetimes noted by Joe Cali (who has provided very helpful comments  regarding4WDtravel in the area which should be seen by anyone considering overlandtravel along the path of totality):

a) Port Augusta SE to Peterborough
JC: 120km About 1.5 .- 2 hrs
b) Barrier Highway NE from Peterborough to Broken Hill
JC: Good condition, sealed & fast 270 km 3 - 5 hrs
c) Silver City Highway N from Broken Hill to Tibooburra

Tibooburra is our"gateway to totality".  It is one of (if not the) most remote, andhottest, towns in Australia.  Tibooburra is outside of the path oftotality, but is the logistical "local" staging point for our final assault.

JC: Distance 340km. Time 4- 6 hrs. Condition - pretty good and sealedpart of the way. Conditions get a little worse the further north you go.In a top heavy camper 4wd you probably shouldn't travel over 60-70km perhour once you hit the unsealed roads.

d1) Tibooburra to centerline near FortGrey (about two hours drive time).

{Joe also provides additionaldrive time info for a more direct routing from Canberra.}

FORT GREY.  At Fort Greyis in SturtNational Park. The elevation of the Sun, there,  is 1.3 degreesabove the horizon at mid-eclipse and might offer a bit more comfortable"breathing room" against any horizontal obstructions than sites furtherEast. I have not yet seen a topo myself to see what may lie in the line-of-sitein the direction of the Sun, but Joe Cali now has and reports: "I checkedthe maps. The airstrip and the point where the road crosses the
centerline have low horizons. FG airstrip: 10m high sandridges11 kilometres away @ az = 243deg, Ft Grey: 10m high sandridges 15 kilometresaway @ az = 243deg. There will be similar 10m sand ridges nearby." We could climb them for a bit of extra elevation if necessary. This siteis accessibleby a road and may be seen on a larger arearoad map also showing its location w.r.t. Tickalara.  Note:From centerline, 5' to the north of the Fort Grey landing strip along theroad landing strip along the road, the duration increases by 3 seconds(to 26.2 seconds prior to limb corrections).

Localcircumstances (left) for the Airstrip at FortGrey, which has two 900 x 30 runways, heading 8/26 and 3/21, (informationgraciously provided by: Bill Harvey, Public Affairs, Department of Transport& Regional Services, (02) 6274 7860, Bill.Harvey@dotrs.gov.au, andGary Oldman, Information Technology Manager, Royal Flying Doctor Service(SE Section), Ph  08 8080 1718, Fax 08 8088 4536, gary.oldman@rfds.gov.au).The somewhat off-centerline airstrip is in the path of totality and locatedat: Longitude = 141° 10' 24"E, Latitude = 29° 06' 48"S, with theadvisory "sand hills in vicinity of strip".

d2) Continue North (unimproved?) road to centerline justeast of Old Nariyilko

OLD NARIYLKO. "Bottom NarrabappaTank", on centerline near Old Nariylko and is  is a possible viewingsite.  However, with the sun only 1/2 degree above the astronomicalhorizon , and < appx. 1/5 degree above the local topographic horizon,at mid eclipse. That was a bit too close for us, and we vetoed this sitein favor of the slightly more westerly Ft. Grey.  Do see the informationon this, the Tickalara/Old Nariyilko/BottomNaranappa site, though.  And, also, a 250:000,1 topographicmap of the sunset end of the path of totalitynear Tickalara.
 
 

The Backup - The Escape (Plane)

Once at a specific site in the path of totality, particularlyfurther toward the east, an overland "escape" to avoid unexpected cloudson eclipse day would be difficult.  The rate which one could back-trackto the west by going overland off-road (with a 4WD of course) is likely < appx. 10km/hr.  Indeed, fleeing even a "modest" distancefrom Fort Grey, off-road could take much too long.  We could backtrackthrough Tibooburra (see this MAPtoo) to reach another centerline (or at least in-the-path site, but wereally would want to be able to move further faster.  Hence: the escapeplane -  a light aircraft standing by at, or very near,  ourPRIME observing site capable of transporting us from there to another in-the-pathsite on very short notice.  Of course this would mean leaving ourvehicles at the prime site (or airstrip close to it) and observing froman airstrip where would would land as we would have no local transportationthere.  This would include the possibility of flying as far as Cedunaif necessary (and hence loosing the "sunset" aspect of the eclipse). The "alternate" air accessible sites in the path are limited.  Atthe moment, I have found only four which I have looked into.  Theremay be others, but this is under investigation - and further input fromany local pilots would be appreciated.  The four sites with airstripsunder consideration, along with local circumstances of totality at thoselocations are:
 

NOTES:

Additionally,there is an airstrip at Lake Everard, right at at the southern limit oftotality.  The approximate coordinates of this site (estimated froma large scale map, so an [for now]uncertainty of a couple of miles) are 135deg 10minE, 31deg 44mS for whichI compute a partial eclipse of magnitude 0.9995.  However, if onewere to walk two miles to the north one would see a 10 second total eclipse. Clearly, we need the actual airstrip coordinates (which I should have inhand soon. If everywhere else is cloudy, as a last ditch effort (no punintended) we could land here and go walk-about into totality.

Finally, very near sunset, there are twoairstrips at Naryilco just north of northern limit. Naryilco (a),Lon = 141deg 53.5minE, Lat = 28deg 34.5minS; Narylco (b), Lon = 141deg55.0minE, Lat = 28deg 32.5minS.  From the more southern one (a), a1 mile walk will bring you into the path of totality.

In the even of low-level obscuring cloud over the entirepath, or "last-minute" cloud on the horizon at the prime site, the "escape"aircraft could be used to observe the eclipse from the air.  We arenot talking a high altitude jet as we used in in 1986or 1992,but here a small prop could save the day.

Ready, Set...

So, now our Sunset Expedition is a band of fourhardy Umbraphiles.  I suspect not too many eclipse chasers would planan observation only with the sun only 1.3 degrees above the horizon. Butgiven the weather prospects, the weather contingencies we have put in place(and, if the weather dictates we could end up in Ceduna anyway where thevast majority seem to be headed), and this is something I have always wantedto do, it really could be glorious.  So my 23rd total solar eclipsemay indeed be the "low point" of my eclipse-chasing endeavors.  Ihope so, and I'll savor every of the 25 seconds of it.  If you aresimilarly inclined do let me know.  We are very seriously into theplanning and arranges stages regarding resources, transportation, infrastructure,local contacts, etc. It would be wonderful to watch the umbra disappearat 09:11:48 UT "straight up" into space, and kiss it goodbye until we rendezvouswith it again in the Antarctic.

Glenn Schneider
18 January 2002