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Astronomical Data Analysis Software and Systems VI ASP Conference Series, Vol. 125, 1997 Gareth Hunt and H. E. Payne, eds.

A User Friendly Planning and Scheduling Tool for SOHO/LASCO-EIT
S. E. Paswaters, D. Wang Interferometrics Inc. 14120 Parke Long Court, Chantil ly, VA 22021, E-mail: scott@argus.nrl.navy.mil R. A. Howard Naval Research Laboratory, 4555 Overlook Ave. SW, Washington DC, 20375 Abstract. The LASCO/EIT instruments ab oard the SOHO satellite (launched Dec. 1995) were develop ed with complicated image processing/acquisition techniques. The Planning and Scheduling Tool was designed allow the user easily to take advantage of all available resources of the four telescop es (LASCO's three coronagraphs and the EIT Telescop e) to maximize the use of the telemetry downlink. The Planning Tool allows users to develop customized observing sequences while monitoring compression factors and on-b oard processing times to realistically work within the limits of the instruments. The Scheduling Tool then graphically displays scheduled sequences and highlights p otential resource conflicts. Sequences are saved in database tables as "as planned observations" and are available to b e retrieved at any later date. Outputs include: database up dates, inputs to the SOHO science activity plan, and the command loads themselves. Statistics are gathered after the images are received so the tool is constantly improving its estimate of processing time and compression factor.

1.

Introduction

The LASCO (Large Angle Sp ectrometric Coronagraph) / EIT (Extreme Ultraviolet Imaging Telescop e) instrument packages having b een op erating continuously since shortly after launch of the SOHO (Solar and Heliospheric Observatory) satellite on Decemb er 2, 1995. SOHO is located at the Lagrangian L1 p oint providing uninterrupted observations of the sun. Commanding and data acquisition are p erformed in real time eight hours of every day with the remaining time provided through solid-state recorder dumps (see Wang et al. 1997, for more on the LASCO data archive). Observation schedules are uplinked daily, consisting of a baseline long-range synoptic program as well as sp ecific observations to take advantage of changing targets on the sun, sp ecial science programs, or joint observations with other observatories. The LASCO/EIT electronics are extremely flexible, offering various image compression techniques which are traded off with consideration of scientific goals. The Planning Tool (Figure 1) allows users to develop customized observing sequences while monitoring compression factors 375

© Copyright 1997 Astronomical Society of the Pacific. All rights reserved.


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Figure 1.

A typical view of the Planning Tool.

and on-b oard processing times to work realistically within the limits of the instruments. The Scheduling Tool (Figure 2) then graphically displays scheduled sequences and highlights p otential resource conflicts. The user can easily add, remove, or modify these sequences.

2.

Implementation

The Planning and Scheduling Tool is written in IDL (12,000 lines of code) with a call to a C routine to generate the binary command strings. The tool is coupled with a relational database (Esfandiari, Paswaters, & Wang 1997) to archive observing sequences and maintain statistics (compression factor, processing time) of science images. Observing sequences are scheduled to maximize the use of LASCO/EIT science telemetry resources (5 kB s-1 /60 MB day-1 compressed science data) while monitoring on-b oard processing time to avoid over-scheduling.


A Planning and Scheduling Tool for SOHO/LASCO-EIT

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Figure 2.

A typical view of the Scheduling Tool.

Table 1. Date Obs 1996/10/31 1996/10/31 1996/10/31 1996/10/31 1996/10/31 1996/10/31 1996/10/31 1996/10/31 1996/10/31 1996/10/31 1996/10/31 16:44 16:46 16:50 16:51 17:00 17:01 17:10 17:11 17:20 17:21 17:21

Sample "As Planned Observations" Summary. Tele Exp Nx Ny Bin Filter Polar Wavelength OS Clear Clear 195A Clear 195A 195A 195A Clear 195A Clear Clear 5302.4224 6376.4419 1984 1985 2020 1694 2020 1762 2020 1709 2020 1943 1943

C1 100 320 288 1в1 Fe XIV C1 48 320 288 1в1 Fe X EI T 9 128 128 1в1 Clear C2 25 1024 576 1в1 Orange EI T 9 128 128 1в1 Clear EI T 9 1024 1024 2в2 Clear EI T 9 128 128 1в1 Clear C3 19 576 1024 1в1 Clear EI T 9 128 128 1в1 Clear C1 100 640 640 1в1 Fe XIV C1 100 640 640 1в1 Fe XIV

5302.4224 5309.2363

3.

Outputs

A summary of "as planned observations" is output as an ASCI I readable file providing a top level view of the schedule (Table 1).


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A SOHO science activity plan file is generated summarizing LASCO's upcoming observations for SOHO-wide planning. Binary formatted commands are output into a single command file. Typical daily command loads consist of 300­ 500 commands. Consistency checks are p erformed on this file, and then the commands are uplinked through a separate piece of software from a LASCO workstation at GSFC to the instrument. 4. Summary

The Planning and Scheduling Tool is currently b eing used almost exclusively for commanding the LASCO and EIT instruments. Integrating user's customized observing sequences with the overall synoptic program typically takes on the order of half an hour, thus reducing the burden on the op erations staff. Through the use of unique observing sequence numb ers, users can correlate their planned observations with the actual data through database queries, and recall sp ecific observations sequences to modify or run in the future. References Esfandiari, A. E., Paswaters, S. E., & Wang, D. 1997, this volume, 353 Wang, D., Howard, R. A., Paswaters, S. E., Esfandiari, A. E., & Rich, N. 1997, this volume, 282