Assessing the present status of ALIS

Finding out the present status of ALIS is the inevitable first step in making a plan. As ALIS was closed, the status of the system was reported in [Brändström, 2001b; Brändström, 2001a]. Based on this information, an estimate of the efforts required to restart ALIS will be presented. It is important to note that in order to make a final plan, a thorough technical examination of vital systems is required. Such an investigation is estimated to take about two man-months (preferably two people for one month). However despite this, it should be possible to start immediate measurements with two imagers in parallel as the rest of ALIS is evaluated, the only constraint being staff availability.

The following list summarises anticipated status of the main technical systems (see also Figure A.1 in Appendix A).

The ALIS stations:

In order to save money all stations have been left with electrical power switched off. To avoid equipment damage, heating should be turned on at least two weeks before attempting to turn on any equipment. The GLIPs (Appendix A) are expected to be found in good condition. However the domes will require cleaning, and some stations might require repainting.

Computers:

With few exceptions, all computers should be usable. However, all computers are old, and failures cannot be excluded. As each station computer needs at least two ISA-slots for interface boards (NIPU, CCU), it is important to keep the old computers usable as long as possible as new computers with ISA slots are becoming rare. Although the NIPU must be replaced soon, it is not feasible to replace the CCU within a couple of years at the present funding level. Computer replacements must likely be scheduled within 1-2 years.

The NIPU:

All NIPUs (Section 2.2.2) were working in 2001, and are expected to be used at least initially. It must be stressed, however, that the NIPUs are totally obsolete, they cannot be repaired, nor can any changes to the CPS and FPS be accommodated (for example replacements of angular encoders). As the NIPUs are essential for filter changes, it is important to replace these units as soon as possible. They can be replaced by micro-controllers at a reasonable cost.

Communication systems:

All dial-up telephone lines must be checked. Some modems might require replacement. It should furthermore be investigated if station 5 in Abisko can be connected to Internet via the LAN at the Abisko Research Station. Continued efforts should be made to find cheaper and faster communication to the stations. (see also Section 2.2.3)

Station data storage:

Most external disks used for local data storage (Section 2.2.4) at the stations are well past their safe technical lifetime, due to many hours of operation. They are also small by present standards. As disk-crashes at the stations may lead to large data losses, all disks should be replaced. The cost for procuring 10-12 external disks is relatively low.

Data archiving:

Documentation and backup copying at alternate sites of the ALIS data-base is underway as this is written. It is recommended that the archive media be transferred from CD-R (Recordable CD-ROMs) to DVD-R (Recordable DVD) to keep down the number of discs. (see also Section 2.2.5)

Operating systems:

The operating systems for the control-centre computers must be upgraded to newer versions due to security and compatibility issues. At the stations it is preferable to keep the present operating systems as long as the old station computers are in use.

The control centre:

At least two computers need to be replaced at the ALIS control centre since they are past their technical lifetime. At the operations centre no immediate replacements are required. Some computer screens should be replaced to improve working conditions.

Environmental subsystems:

These systems should be usable for many more years (Section A.2).

Power subsystems:

All stations should be equipped with UPS units for powering the instrumentation. Some stations lack good surge protection devices. A safety check should be carried out for all power subsystems, especially the PDUs.

Housekeeping units:

Although obsolete, all housekeeping units (Section A.4) should be usable for many more years. Replacement will be required eventually as the current housekeeping units are only capable of handling dial-up lines. New housekeeping units can easily be built in the same way as the NIPU replacement micro-controllers.

GPS units:

No changes anticipated, all timing units (Section A.5) should be working.

The mobile station:

The van (mobile station, see Section A.8) is critical for some scientific objectives.

Software:

Most ALIS software (Chapter 5) should be working. At the stations, some bug-fixes and upgrades of mima and aniara would be appropriate. Somewhat larger programming efforts are required in order to get a web-based and user-friendly new user-interface for ALIS. This could be carried out as a student project, but is not crucial to the operation of ALIS in the near future (one year). The NIPU replacement, as well as some other hardware upgrades, will require new control software as well as modifications to existing programs.

After performing these upgrades the block-diagram of a GLIP will change slightly, as indicated in the upgraded block-diagram of Figure D.1.

Figure D.1: In the first stage of the upgrade, the NIPU would be replaced by micro-controllers in the FWC and CPC. Also an UPS and possibly a faster network connection would be added at the stations. The acronyms are explained in Table A.1 and D.1

Table D.1: Explanation of acronyms in Figures D.1-D.2 (See also Figure A.1 and Tables A.1 in Appendix A)

Acronym	Explanation
ICC	Imager Control Computer
LAN	Local Area Network
UPS	Uninterruptable Power Supply
WAN	Wide Area Network (connected to the Internet)
WLI	WAN/LAN Interface consisting of the WAN-Interface, a router, a switch and possibly also a firewall

The ALIS imagers

Since ALIS closed down in 2001, two imagers with supporting systems have participated in observations with good results. All ALIS imagers were taken to Oulu in 2002 for the calibration workshop (see Section 4.2). Although the CCUs are becoming obsolete, the CCDs and camera heads are still state-of-the-art in the field. Therefore prolonging their operational lifetime as long as possible is strongly to be desired. Procuring new imagers is not possible within the current budgetary limits. Two imagers (ccdcam1,6) are immediately usable for observations. Three imagers (ccdcam3,4,5) developed reliability problems during the Oulu visit in 2002. These problems are most likely solvable with moderate efforts. One imager (ccdcam2) had problems with ice-formation on the CCD, probably due to a breach in the hermetically-sealed CCD compartment. Instructions has been received from the manufacturer how to resolve this. However this is a delicate procedure involving a risk of damaging the CCD. Preferably this procedure should be carried out by the camera manufacturer.

A thorough testing of all imagers is required before being able to assess their status. Yet it appears feasible to have 4-6 imagers operational within about six months. On a longer time-scale (about five years) the CCUs at least must somehow be replaced, but this requires additional funding. The remaining subsystems related to the imager are discussed below:

Calibration:

A cleaning of the optical systems, as well as focusing and calibration of each imager, is important to maintain and improve the data quality. This is estimated to take 2-3 nights per imager.

Interference filters:

The change of filter transmittance with time due to aging is at present unknown, as is the filter transmittance as a function of pixel coordinates (Section 4.2.3). Measuring the transmittance could be made locally, but the monochromator system [Vaattovaara and Enback, 1993] must be modernised. For example, this can be done as a student final-year project.

Filter-wheels:

One filter wheel (on ccdcam5) is experiencing mechanical problems. The remaining filter-wheels are operational, but all angular encoders are likely to fail in the near future (due to an aging laser-diode) Therefore these must be replaced, preferably as the NIPUs are replaced. As the filter-wheels are essential for successful measurements, this is a high-priority task.

Camera positioning system:

All CPS units are subject to the same angular encoder problems described above. However replacing these angular encoders is not nearly as high priority as the filter-wheels. It is possible to lock some CPS units in a fixed observing position until new angular encoders can be installed. Furthermore as the filter-wheels are upgraded, spare angular encoders for the CPS are released. A mechanical maintenance and adjustment of all units are also strongly recommended.