Figure 3: A GGO raw image of Gomet Wilson taken through aninterference filter of 10 nm bandwidth centred at 426 nm (GO', Nz',GW). Exposure 30 min, April 29, 1987.

Figure 4: A GGO raw image of Gomet Wilson taken through aninterference filter of 20 nm bandwidth centred at 660 nm {HzO', NHz,GzJ. Exposure 5 min, April 29, 1987.

very successfully with Comet Halley (3).Oespite good transparency of the at­mosphere in this night, we were unableto obtain any useful CO2+images but, toour surprise, we found an N2+ ion tail at391.4 nm. In the third night we used the"red" camera to record images andspectra in the range 420-650 nm. Fig­ure 3 shows a false-colour image in thelight of the CO+ ion at 426 nm. Some N2+or even CW emission may contribute tothe image. In this raw image each newcolour represents a factor of 1.4 in thesignal. The plasma tail is weil visible.The dust continuum is noticeable framthe elongation of the isocontours to­wards west (Iett side of figure). In Fig­ure 4 we present an image of the comet

MIDAS MemoESO Image Processing Group

1. Application Developments

The routines for calculating centres ofstellar images have been impraved byM. Ghigo to take into account the finitepixel size. This gives a significantly bet-

50

taken through an interference filtercentred at 660 nm with a bandwidth of20 nm. Again each new colour repre­sents a factor of 1.4. This image showsthe H20+ tail (0-7-0 band) and a strongdust continuum. In addition, a neutralcoma of NH2 and of the v = 3 band ofthe C2 Swan sequence fall into the filterbandpass (notice the strong intensitygradient araund the nucleus). In the topof the frame a ghost image of the innercoma (scattered back from the CCO andreflected at the interference filter)appears. The spectra, which were takenwith the slit intersecting the tail at rightangles 5 arcmin from the nucleus, showthe C2 Swan band and some H20+ linesagainst the background of an extensive

ter accuracy for undersampled imagessuch as direct EFOSC frames taken witha good seeing. For weil exposed imagesa positional error of less than 0.02 pixelscan be reached.

The first MIOAS version of the

night sky spectrum.We would like to thank S. Oeiries and

S. O'Odorico for the coating of our CCOto make it UV sensitive and O. Hofstadtand his crew for their effort to find apossibility to point to the comet with ourfocal reducer. We appreciate help fromP. Sinclaire concerning our CCOcamera.

References

(1) Jockers, K., Geyer, E.H., Hänel, A.: 1986,The Messenger No. 44, 12.

(2) Cullum, M., Oeiries, S., O'Odorico, S.,Reiß, R.: 1985, A & A 153, L 1.

(3) Jockers, K., Geyer, E. H., Rosenbauer, H.,Hänel, A., 1987, A & A, in press.

ROMAFOT photometry package (ref. R.Buonanno) is foreseen for the 88JAN 15release. Although the user input to thepackage differs in some respect fromthe original version, the MIOAS im­plementation will provide all basic fea-

tures of the original. The first release willstill be based on the internal ROMAFOTdata format; subsequent future releaseswill work on MIDAS images directly andwill use the table file system for thestorage of the extracted parameters.

In the new release the plot packagewill be upgraded by adding the possibili­ty of specifying the formats of the axistick labels. In addition, a commandPLOT/GRAY is now implemented wh ichallows the production of gray scale plotson all graphic devices supported. The88JAN 15 release of MIDAS will use theAGL version 2.1.4.

A new context has been included incollaboration with M. Pierre. The con­text, in this preliminary version, containsthree commands to model interstellarlines.

Work on the reduction and analysis ofIRSPEC data is in progress.

2. Manual

As the MIDAS manual has now out­grown its present folder, it has beendecided to split it into two volumes. Thefirst volume will contain a description of

NTT StatusM. TARENGHI, ESO

Work on the ND telescope is pro­gressing at full speed both in Europeand on its location at La Silla. DuringSeptember and October this year therewas extensive preparation of the groundand roads on La Silla. Civil engineeringWork began on the small hili next to the3.6-m telescope at the place which wasused during the past years for the Gene­va Observatory Telescope. About3000 m3 of earth was removed bymeans of a sequence of minor and finelyControlled dynamite explosions. Fi­gure 1 shows the Chilean workers in theprocess of checking the locations of 28

Figure 1.

the MIDAS system including systemcommands, syntax, data structures andgeneral applications. It will also give thefull help text of all available commands.The second volume will deal with datareduction using MIDAS. There will bechapters describing the general reduc­tion of different types of astronomicaldata and several appendices each de­voted to a specific ESO instrument.

3. Measuring Machines

The upgrade of the OPTRONICSmeasuring machine with a high speedscanning is in progress. The problemsassociated with the reticon array weresolved and it is now possible to digitizeand calibrate its 256 elements in ap­proximately 20 msec. The main limita­tion on the speed is the MC 68010 pro­cessor which does the dark current andflat field corrections. Due to significantdelays in the delivery of disk drives andnetwork equipment it is unfortunatelynot yet possible to offer the scan modeto users. We expect to switch to the newmicroprocessor control system in thespring of 1988 and offer the scanning

explosions. The picture also shows theirprecautions to avoid excessive damageto the surrounding area. Large lorrytyres are placed on the ground and astrong metallic net is used as a protec­tive cover. Figure 2 shows the explosionsome minutes later. The smoke on thetop of the hili indicates the future loca­tion of the ND.

Following the excavation work thetask of ensuring a flat surface began andabulIdozer opened the way for the 3access roads foreseen in the project.Figure 3, taken on 28 October 1987,shows the subsequent preparation of

Figure 2.

mode to visitors in the summer.After reviewing the usage of the

GRANT machine it has been decided todiscontinue its operation as of August1988. After this date, measurement ofcoude spectra must be done on theOPTRONICS machine. Those who wantto use the GRANT machine are stronglyencouraged to arrange for time as soonas possible.

4. MIDAS Hot-Une Service

The following MIDAS Support ser­vices can be used in case of problemsto obtain fast help:

• EARN: MIDAS DGAES051• SPAN: ESOMC1 ::MIDAS• Tlx.: 52828222 eso d, attn.: MIDAS

HOT-UNE• Tel.: +49-89-32006-456

Also, users are invited to send us anysuggestions or comments. Although atelephone service is provided, we preferthat requests are submitted in writtenform through either electronic networksor telex. This makes it easier for us toprocess the requests properly.

the concrete slab upon which the NDwill stand.

The civil engineering work is expectedto be completed in February 1988. In themeantime construction of the rotatingbuilding has been completed in Europeand it will be shipped to Chile during thecourse of the next weeks. The uncon­ventional shape of the building optimallycombines the highest thermo-fluid dy­namic demands resulting in greater pro­tection of the telescope without intro­ducing a dome seeing component.

The rotating building was conceivedby F. Franza and W. Bauersachs at ESO

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