4
Eastern Longitudes and Time Zone 12
There●is●an●additional●minor●remaining●issue●with●the●3=Get●Time/Loc●FrMnt●command,●but●it●should●be●of●no●consequence●
to●anyone●that●we●are●aware●of.●●●If●you●happen●to●be●in●time●zone●12●east●and●observe●daylight●savings●time●giving●an●
offset●to●GMT●of●local●time●–●13●hours,●AND●you●are●using●a●GTOCP1●or●2,●you●cannot●use●this●command.●●●Again,●all●data●
sent●to●the●mount●is●fine;●you●just●can’t●have●the●keypad●poll●the●mount●for●your●time●and●location●data.
Eastern Longitude Limit
(see pp. 14-16)
●●●●The●last●issue●will●only●affect●people●in●the●Fiji●Islands●and●in●far●north-eastern●Siberia.●●●Because●of●the●
longitude●issue●outlined●above,●an●eastern●longitude●above●178°●59’●00”●should●not●be●used.●●●At●this●time,●we●know●of●no●
one●who●is●affected.●●●
The International Date Line
The●region●on●either●side●of●the●International●Date●Line●(IDL)●has●the●potential●to●pose●some●problems.●●●●First●of●all,●the●
IDL●is●not●a●straight●line●at●exactly●180°●from●the●Prime●Meridian.●●●There●are●Pacific●Islands●(Tonga,●parts●of●Fiji,●Chatham●
etc.)●whose●longitudes●would●be●measured●as●West,●but●who●are●in●an●eastern●time●zone.●●●Likewise,●many●of●the●western●
Aleutians●are●actually●in●eastern●longitudes,●but●have●western●time●zones.●●●●The●keypad●will●not●allow●a●time●zone●greater●
than●12●or●a●longitude●higher●than●180°●either●east●or●west.●●●●Fortunately,●we●again●know●of●no●customers●in●these●
locations,●but●you●never●know…●●●This●is●where●we●would●have●to●trick●the●system.●●●●
Let’s●say●you●have●taken●your●Mach1GTO●on●a●South●Pacific●Dream●Vacation●in●Tonga●at●175°●08’●West●Longitude,●but●at●
13●hours●east●time●zone.●●(Thank●goodness●there’s●no●DST●in●Tonga!)●●●Since●you●want●to●begin●with●some●solar●observing●
you●decide●to●use●the●Daytime●Polar●Alignment●Routine●which●requires●accurate●time,●date●and●location●information●to●be●
successful.●(The●mount●must●know●the●exact●LST●to●know●the●RA●and●Dec●values●for●the●Park●Positions.●●(See●pp.●23-28)●●●
The●key●to●successfully●tricking●your●mount●is●to●remember●that●your●DATE●must●be●backed●up●by●one●day●if●in●a●western●
longitude●with●an●eastern●time●zone,●and●it●must●advance●by●one●day●if●in●an●eastern●longitude●with●a●western●time●zone.●●●
For●my●Tonga●example,●let’s●assume●it●is●Feb.●15th,●and●local●time●is●3:15pm●(15:15:00).●●●●You●already●entered●the●correct●
longitude●of●175°●08’●15”●W●and●the●correct●latitude●of●21°●10’●47”●S●and●then●entered●the●time●zone●as●24●–●13●=●11●hours●
west.●●(The●keypad●will●assign●the●west●time●zone●because●the●longitude●is●west.)●●You●check●the●GMT●by●pressing●the●
4=Time/LST●button●and●see●that●it●correctly●reads●02:15:00.●●●The●problem●is●that●your●mount●will●be●calculating●LST●one●
day●off●amounting●to●about●●+4●minutes●of●LST●error●or●about●1°●off●(west)●in●your●Daytime●Polar●Alignment●Routine.●●●●To●
correct●this,●just●set●your●keypad’s●date●back●to●Feb.●14th,●wish●everyone●Happy●Valentines●Day●once●again,●and●proceed●
with●polar●aligning●and●observing.●●●
Fractional Time Zones
There●is●no●provision●in●the●keypad●firmware●at●this●time●for●fractional●time●zones●as●are●found●in●Central●Australia,●Iran,●
Afghanistan,●India,●Nepal●and●several●other●locations.●●●To●get●proper●function●from●your●keypad,●you●will●have●to●adjust●
the●keypad’s●clock●to●a●time●value●that●does●not●match●the●clock●on●your●wall.●●●The●important●thing●is●that●the●keypad●
calculates●the●correct●GMT.●●●
COMMAND LANGUAGE / TROUBLESHOOTING UPDATE
The●following●information●relates●to●servocontroller●issues●and●the●Astro-Physics●Command●Language.
Motor Stalls in GTOCP1 and GTOCP2s with the E1 or KE1 Chip
In●the●Troubleshooting●section●of●the●v.4.12●keypad●manual●dated●March●7,●2008,●on●page●69●under●the●“Motor●Stall”●
entry,●please●add●the●following●note●to●the●“Solution”●paragraphs:●●A●problem●was●discovered●in●the●E1●and●KE1●chips●(in●
GTOCP1●and●GTOCP2●control●boxes)●●that●makes●recovery●from●a●motor●stall●a●bit●more●problematic.●●This●ONLY●applies●
to●the●E1●and●KE1●chips.●●Initiating●movements●with●the●direction●buttons●does●not●always●fully●reset●the●stall●condition●
with●these●two●chips.●●If●you●experience●a●motor●stall●with●the●E1●or●KE1●chip,●it●is●recommended●that●you●power-cycle●the●
mount.●●The●mount●will●NOT●be●lost●if●the●scope●has●not●been●moved●by●hand.●
