EMIR COMMISSIONING
Commissioning 1:
After the transport and integration of EMIR in the GTC Nasmyth focus, on 12th June 2016 has begun the commissioning phase (scientific and engineering team).
Day 1
This day was the first contact of the scientific team after the integration in GTC.
The first steps were:
- Switch-on of the instrument.
- Check that the instrument rotate freely.
- Check the instrument temperature and pressure.
- Check all the communications, between the components and the new control hardware.
- Check the control commands.
- Check the operation of the CSU and tried several configurations.
- Check the position of the detector: possible tilt and rotations.
- Focus the detector onto the CSU.
- Run some old and new sequences.
Fig. Example of a CSU (55 bars) configuration used for the focus and detector characterization.
Day 2 (first light day)
The morning and afternoon before the first light. Some previous tasks were improved; and the flexures of the detector and its DTU correction were tested and characterized. This behaviour was calibrated during the AIV, but we will repeat that calibration table during all the commissioning phase (possible changes during the travel and GTC integration, using the GTC rotator, etc.).
- Improve the focus in all the wavelengths.
- Check the flexures compensation using the DTU. This calibration table was be improved.
The day 13th June 2016 EMIR has received the first light from the sky. Specifically at 21:38. It was NGC5053, an open cluster with high concentration of stars in the center. The first light was taked in J band, with several exposition times. The pointing and exposure were an absolute success. Since the first attempt we were able to identify the stars in the field using the finding chart. The center of the field was located at the center of EMIR!.
Fig. Open cluster NGC5053 in J band. First EMIR (image with only a basic reduction).
In the following days we will analyze these images using existing catalogs to check the astrometry and limiting magnitudes.
Something also important was taking the initial sky flats on all bands. At first glance and with appropriate analysis tools, they seem to be quite homogeneous and very similar to the AIV flats.
Fig. Flat-field image in K-short
A preliminary check of the EMIR rotation center was done. EMIR is very well centered when GTC rotate. We will repeat this test in this phase.
Fig. EMIR rotation center
Day 3:
After the "fist day light":
- The first spectral calibrations were made using the calibration arcs of GTC (ICM module): Xe, Ne and Ar in J, H, K and Low resolution grisms.
Fig. Spectral calibrations in K-short band using Xe, Ne and Ar arcs.
- The flats were performed and studied in all the bands (Y, J, H, Kshort, Brackett-Gamma, Continuous Brg, FeII, Continuous FeII, H2(1-0), H2(2-1).
- Tested the image mode in several open clusters and extended objects.
- Tested the dithering first time in order to create a superflat.
- Check the center of the DTU.
Day 4:
This day some task were repeated and improved.
- Take flats in all the bands and studied their light distribution.
- Do more flexures test. This is a very critical point and DTU corrections must be very accurate.
- Repeat the spectral calibration with lamps using different CSU configurations.
- Chek the EMIR rotation angle.
- Check the dithering image mode.
Day 5:
- Repeat tasks as: flexures compensation, focus in each filter, quality of the flat-fields, etc.
- Misalignment of the pupil using M2.
- Focus with M2.
- More dithering measures using extended objects (galaxies and nebulae).
- Measures of the detector persistence using a very bright star (Vega).
- First and preliminar zero points in J, H and Kshort.
- Check the ETC using real images of stars.
Day 6:
- Repeat tasks as: focus in each filter, quality of the flat-fields, etc.
- Check different dithering patterns with the final purpose of optimize the observations (several open clusters and nebulae).
- New measures of persistence with Vega.
Day 7:
- Repeat tasks as: focus in each filter, quality of the flat-fields, etc.
- Improve the focus using M2.
- Use a provisional dithering with 9 points with near galaxies and offset sequences.
- Better measures of the detector dark current.
Day 8-10:
- Continue with the MOS spectral calibrations along the fields and with different CSU configurations.
- Aligment of the grism wheel. It has a slight displacement after the integration in GTC.
- Use the dithering mode with some large desing galaxies.
- Measured the sky background in YJHKshort with several configurations.
Images from the first coommisioning (see the gallery here)
After this first commissioning period some useful data and also pretty pictures have been taken.