Sitelle has three new filters (SN4, SN5 and SN6)! Their transmission curves are available here. A report by Benoit Epinat on their capabilities is available here.

Sitelle has a new field corrector ! A report by Marc Baril is available here.

First article on SV data submitted ! Available here. SV processed data are publicly available here.

The document outlining the latest on the instrument performance is now available here.

The Science Verification phase of SITELLE was a big success! Mahalo to all the team involved in the achivement! Several objects were observed and are now being analyzed to provide PIs a current update of the instrument. Stay tuned!

SITELLE had another successful run on the telescope! Besides some wonderful spectral cubes that we will show very soon, important milestones have been reached. First, the Exposure Time Calculator (ETC) has been validated thanks to the observations of standard stars (GD248, G24-9). The ETC predicts counts within 5-10% of the observations for all filters except SN1, though we know the reflectivity of the mirrors changes quickly with time on the blue. Second, using amazing observations of M57, we tested some large Optical Path Difference (OPD), i.e. resolution. At the position of the H?? line, FWHM of 5.54 cm-1 were expected and we measured a width only 3-4% larger. This means that SITELLE meets the expectation at least up to a resolving power of about 2800. Third, the noise levels of the ETC were also validated using observations of NGC628 with the SN3 filter. Predicted levels at 3?? are very close to those observed using a binning of 1x1 (20% difference), 2x2 (less than 10% difference), and 3x3 (no difference). SITELLE will be offered for the upcoming call for proposals (semester 2016A) with the possibility to ask for "shared-risk" time during 2015B. SITELLE is also offered in the call for the Large Programs 2017-2019.

SITELLE has seen its first photons from the skies of Maunakea! For the past three nights, SITELLE has been mounted on the CFH telescope, going through a first series of tests. While a few minor adjustments are necessary, all lights are green for a second run on the telescope at the beginning of August.

SITELLE mounted on the CFHT

A part of the Veil Nebula NGC6992 as seen with SITELLE

SITELLE is at CFHT! It was shipped to Hilo via Honolulu by plane, and then carefully driven to the summit of Maunakea, where it was unpacked by the crew like children unpack their birthday gifts. A video that summarizes the events of the day can be found on our Vimeo channel.

A happy project manager, Marc Baril, with SITELLE on the fifth floor at CFHT

SITELLE has been moved from ABB to U Laval for the cold tests, which are part of the acceptance tests. Marc Baril from CFHT will be there for at least a couple of weeks.

The ME in the near UV appears to be excellent. SITELLE's efficiency (modulated power/total power, which takes into account the two output ports) is around 70% at 370 nm. The UV source used for the measurements is very weak and the small amount of parasitic light in the lab caused problems, however the filter was a great help. There was some contamination on the filter (fingerprint? dirty tissue?) when it was installed in the clean room, though nothing was seen on the images. Two other LEDs are being purchased to obtain more flux (and better quality measurements).

The instrument has undergone much testing since March and is essentially materially complete with all of its electronics boxes populated and cables fabricated. Testing in March and April focused on verifying the effect of vibrations on instrument performance as determined by looking at the modulation efficiency (ME) near the zero-path-difference (ZPD) position of the interferometer. The ME measured at 534 nm reaches over 85% with the cryo-coolers powered on. This closely meets the goal desired for the instrument and is well above the requirement at 534 nm of 73% ME. The modifications made to the beam splitter mount had a significant effect on the optical path difference (OPD) stability, allowing the ME goal to be reached. However, the ME at 370 nm, the short wavelength extreme of the instrument, has yet to be measured. If the ME is good at this wavelength it will almost certainly meet requirement at all other wavelengths given what is known about the spectral reflectance (R) and transmission (T) of the beam-splitter (i.e. a factor of 4RT contributes to the ME).

Marc Baril travelled to ABB for ten days of work at the beginning of April (see previous News entry); at this time repairs were made to one leaking camera cryostat and the sensitivity of the instrument to vibrations was investigated. Implementation of the control software for the instrument by Jim Thomas was done in May, firstly working at CFHT and then at ABB for one week. Marc returned to ABB for another ten days to work on testing instrument performance and develop scripts and reduction tools required for the final testing.

Early in this week of work it was noticed that the ME was degrading as the distance of the scanning mirror from ZPD increased much more rapidly than expected. The effect is worse on one camera, with the ME dropping to 30% for a 1 mm OPD on that camera. Furthermore, there is a noticeable drop in the ME across the field of view, with the ME being lower where the fringes are more closely spaced. Note that the spatial frequency of the fringes on the detector was well below the regime where the modulation transfer function of the combined optics and detector would affect the ME. Stopping down the input pupil of the output camera lenses improved the differential ME drop between the cameras, however it did not improve the overall ME degradation, using the more well-behaved camera as reference.

Rotation of one of the cameras led to an improvement in the ME suggesting that a tilt was present somewhere in the output optics. There is also likely to be a strong effect to the overall ME function with OPD due to the manner in which the instrument is being illuminated during the tests (the pupil is over-filled by the integrating sphere at the instrument input). ABB is working with Denis Brousseau at Laval to resolve these issues while personnel at CFHT provide feedback and suggestions. Until this problem is resolved, testing cannot continue and we anticipate that testing in the cold will not commence until late August at the earliest.

The preferred option for cold testing of the instrument is for ABB to install a cold room at their facility that they would rent to Laval for its use as a way to recuperate some of the capital costs for its construction. Testing at ABB holds several advantages; cleanliness of the room, ready availability of personnel and test equipment, access to the instrument is completely under ABB???s control and the instrument does not have to be crated up for shipping to Laval (a very time consuming process). The second option is to use the civil engineering cold testing facility at Laval.

If testing happens in September, the earliest shipping of the instrument to CFHT would be in October.

Marc Baril travelled to ABB for ten days of work at the beginning of April. This trip was very useful in providing a more clear understanding of the functioning of the instrument, it???s sensitivity to vibrations and acoustic noise, and to settle details of what will be required for the acceptance testing.

One problem that has arisen with the delayed schedule is that the cold room originally identified for testing and final tuning of the instrument is no longer available on a time-scale that is acceptable to the project team. ABB is re-evaluating the possible options to find a solution that gets SITELLE to CFHT by the end of the summer.

Several infrastructure (hardware and software) items remain to be implemented at CFHT prior to SITELLE???s arrival, however it is not anticipated that the schedule for these items will impede commissioning readiness of the instrument.

The first two SITELLE filters received at CFHT (668nm center 34 nm wide, and the 593.6 center 63 nm wide). A third filter (H-alpha) was received in April at Laval by Laurent Drissen

532 nm laser fringe image, 80 metrology fringes away from ZPD (lab image used to determine ME). Taken with the SITELLE science cameras (channel 1 at left, channel 2 at right).

Julie Mandar checking for light leaks prior to ME measurements. View of the lower optical output. Metrology laser pickup fibers can be seen directly above her right hand. CCD cryostat is the gold structure near the bottom ??? cryo lines heading upward toward the right.

View of the instrument showing both output ports.

Instrument on its handling gantry - the relatively large size of the instrument (for CFHT) is more fully grasped in this image.