CFHT Information Bulletin, number 39, Second Semester 1998

OASIS Status Report

Pierre Martin, CFHT, Resident Astronomer, martin@cfht.hawaii.edu.

OASIS, the multi-mode spectro imager built by Lyon Observatory, has been extensively used in January (7 nights of engineering and instrument evaluation by external experts) and March (17 nights of engineering, commissionning and normal utilisation by the usual CFHT observers). Despite a bad seeing during most of these nights (sometimes up to 3"!), useful science data have been gathered. The instrument performed extremely well and the user's interface was found to be easy to use and quite robust. On the other hand, XOASIS, the data reduction software developed by Lyon has been used for the first time by normal users. They were generally very impressed by how easy it is to reduce data taken with the TIGER mode of OASIS. Since then, a new version of the software has been produced (development continues) and is available on the Lyon OASIS site at http://www-obs.univ-lyon1.fr/~oasis/home/index.html.

During the engineering nights in March, several important pending issues were addressed:

The f/8 mode, that is, observations with no AO correction at the f/8 direct Cassegrain focus, has been fully implemented and tested. This mode adds a lot of flexibility to the instrument while bad seeing periods prevail. It is STRONGLY recommended to prepared a backup program for your observations which could make use of this mode, in case of poor weather conditions. This mode is also easy to use, except for some complications on telescope focussing which resulted in some mistakes during the observations during this run. The observer's interface has since been modified to avoid these difficulties. Information about the available configurations for this mode is available at the CFHT OASIS web page (http://www.cfht.hawaii.edu/manuals/oasis/oasis.html).
Since the delivery of OASIS at CFHT, some ramdom jumps in the OASIS camera focussing were observed. During the run, the origin of this problem was identified: it was due to a bad connector in the electronic crate of OASIS. The problem has been fixed. To avoid such a problem in the future, all the connections in the crate have been refurbished.
The new AOB beamsplitter for the I-band (i.e. all of the I-band light is transmitted to the instrument, the rest to the AOB) has been received, tested and used during observations. This increases the performance of the instrument in this band by a factor of 2. Future Plans:
In May, five new filters have been ordered to complete a full coverage of the spectral domain (4200 - 10000 Å) in the medium spectral resolution in the TIGER mode. These filters should become available in September.
A new EEV CCD 2k x 4k ("EEV2") has recently been received at CFHT. With its excellent QE all over the spectral domain accessible with OASIS, its 13.5 micron pixel and 250 000 electrons of full well, it is a very well suited detector for OASIS. A new Luppino dewar has been ordered and the CCD adapter of OASIS is being modified so that this detector could be used for the next run in September. However, acceptance tests have first to be done in the lab so at the moment, the availability of this device for OASIS cannot yet be confirmed.
Two other beamsplitters for V and R bands have been ordered from another company (the previous one was not able to deliver splitters according the specifications). They both have been received very recently at CFHT and should be tested in the next few weeks. Again, this should result in an increase in the performance of OASIS by a factor of 2.

Editor: Dr. Timothy M. C. Abbott, tmca@cfht.hawaii.edu