Introduction

Several different types of orbit accounting may need to be done at various times. When making recommendations on available orbits to the TAC, slightly different numbers must be provided than when trying to determine the current cycle-end boundary. Below, we will see the difference in action.

First, some definitions:

Previous Cycles

Old cycles. For example, on May 23, 2000, Old Cycles means Cycles 6 & 7.

Current Cycles

The bulk of what is currently executing. For example, on May 23, 2000, Current Cycle is Cycle 8.

New Cycle

Newly assimilated Cycle. For example, on May 23, 2000, New Cycle means Cycle 9.

Next Cycle

Next Cycle. For example, on May 23, 2000, Next Cycle means Cycle 10.

An Example of Orbit Accounting

This link is to a PDF showing the results of the pre-TAC Cycle 11 orbit accounting.

What follows is an example of orbit accounting, with a source of the data, done during the 3rd week of May, 2000.

Nominal Orbit Accounting

Visits With Plan Windows

Type	Total Orbits	MAMA or other Exclusive SAA-free consumer Orbits	Source of Data
Proposals in the LRP
Previous Cycles in LRP	141	58	OPM/Remaining SUs w/ PWs
Current Cycle in LRP	1180	593	OPM/Remaining SUs w/ PWs
New Cycle in LRP	2322	893	OPM/Remaining SUs w/ PWs
Targets of Opportunity
ToO Previous Cycles	0	0	query of ToO props: Orbits executed plus Planned.
ToO Current Cycles	30	??	query of ToO props: Orbits executed plus Planned.
ToO new Cycle	43	??	query of ToO props: Orbits executed plus Planned.

3716 orbits; 1544 orbits MAMA

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Visits Without Plan Windows

Type	Total Orbits	MAMA or other Exclusive SAA-free consumer Orbits	Source of Data
Proposals in the LRP ("In-Plan")
Previous Cycles, in LRP	23	11	OPM/Remaining SUs without PWs, but in LRP.
Current Cycle, in LRP	48	24	OPM/Remaining SUs without PWs, but in LRP.
New Cycle, in LRP	175	25	OPM/Remaining SUs without PWs, but in LRP.
Proposals NOT in the LRP ("Not In-Plan")
Previous Cycles, not in LRP	0	0	OPM/Remaining SUs, not in LRP.
Current Cycle, not in LRP	49	6	OPM/Remaining SUs, not in LRP.
New Cycle, not in LRP	150	16	OPM/Remaining SUs, not in LRP.
DD Time
Current Cycle DDs Expected	0	0	Value in Memorandum from HOD Head minus Executed minus those w/ PWs
New Cycle's DDs Expected	282	140	Value in Memorandum from HOD Head minus Executed minus those w/ PWs
Targets of Opportunity
Current Cycle ToOs	0	0	ToO Props prop_track allocation minus executed minus those with PWs.
New Cycle ToOs	310	158	ToO Props prop_track allocation minus executed minus those with PWs.
Cycle Calibrations, Engineering & pre-SMOV
WFPC Calibrations	67	0	Total from WFPC Team minus those In-Plan
STIS Calibrations	77	31	Total from STIS Team minus those In-Plan
FGS Calibrations	24	0	Total from FGS Team minus those In-Plan
FOC Calibrations	0	0	Total from FOC Team minus those In-Plan
Pre-SMOV and Other Eng	???	???	Head of the SM Team/Office
Other Windowless Items
HOPRs	150	75	3% of the Unexecuted Planned and Unplanned Visits.

1355 orbits; 486 orbits MAMA

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Supplemental Accounting Data

• Accounting needed for determining suggested TAC allocations:

  Type	Total Orbits	MAMA or other Exclusive SAA-free consumer Orbits	Source of Data
  Pre-Allocated Future Cycle Multi-Cycle Proposals	184	???	Memo from HOD Head
  SMOV Estimates	???	???	SMOV Team
  Calibrations	X% of Available Time.	Y% of Available Time.	Similar %ages to previous cycles; Sanity Check with Instrument Leads.
  DD Time	Z% of Available Time	Analysis of DD Time Allocation.	Similar %ages to previous cycles; Sanity Check with DO.
  Future Cycle HOPRs	N% of Available Time.	N% of Available Time.	Analysis of HOPR Rate.

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Items for Consideration

(needs to be reorganized, expanded)
• Why are there two sections (above, Nominal vs. Nominal+Supplemental) on accouting?

  There is a difference between the simple raw accouting and an accounting for the TAC because Management needs to make a recommendation to the TAC of how much GO time is available in the Next Cycle. Nominal orbit accounting is used to track what is expected and existent in the current and New Cycle so that the cycle duration can be projected.

• Execution Rates?

  Needed to

  determine how many orbits can be accomplished within a given period.

  determine how long until the nominal 'end of cycle'.

  determine if there have been changes in the scheduling rates.