Instruments & Operations

 

 

News and Updates

January 2012:

LUCI script syntax checker updated to version 4.16. While this is a minor update, we recommend all observers use the latest version to check their LUCI scripts prior to their observing runs. Go to this link for more information and to download the latest version.

November 2011:

ALL scripts should have FLEXURE_COMP = ON. The summer shutdown 2011 servicing of LUCI successfully identified the source(s) of the anomalous flexure seen in over the past year. Thus we expect that flexure compensation can be turned on for all scripts that need it.

Additional repairs were made to LUCI that should eliminate the sources of mechanical errors seen over the past year, as well as the scattered light seen on long, very low background exposures (e.g. z-band spectroscopy).

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Summary Description of LUCIFER

LUCIFER 1 and 2 are a pair of infrared multi-mode instruments for the Large Binocular Telescope. In seeing-limited mode, each will have a 4 arc-minute square field of view and will be capable of long-slit and multi-slit spectroscopy as well as imaging in the near infrared zJHK bands from 0.85 to 2.4 microns. Each instrument also includes diffraction-limited optics covering a 30-arcsecond field of view for use with the adaptive secondary mirrors. LUCIFER1 is now at the LBT and commissioning of the seeing-limited modes is nearing completion.

The LUCIFER team's webpage can be found here. On those pages can be found more detailed descriptions of the optical, mechanical, and electronic design.

Cameras (seeing-limited modes):

Filters:

LUCIFER1 Available Filters (October 2009)
Name
Center WL (microns)

FWHM (microns)

Trans (peak %)

Trans (avg %)
z
0.957
0.195
98.4
94.3
J
1.247
0.305
91.2
83.2
H
1.653
0.301
95.0
90.5
K
2.194
0.408
90.1
85.7
Ks
2.163
0.270
90.7
86.8
OrderSep
1.950
0.981
95.0
86.3
Br_gam
2.170
0.024
79.4
76.5
FeII
1.646
0.018
91.2
89.5
H2
2.124
0.023
87.9
84.9
HeI
1.088
0.015
65.2
64.6
J_high
1.303
0.108
95.9
93.3
J_low
1.199
0.112
95.4
93.3
OH_1060
1.065
0.009
68.6
66.8
OH_1190
1.193
0.010
80.4
78.0
P_beta
1.283
0.012
86.1
85.5
P_gam
1.097
0.010
81.1
80.0
Y1
1.007
0.069
67.3
64.2
Y2
1.074
0.065
94.2
89.5

Longslits:

Gratings:

The resolutions above are all derived using the N1.8 camera and an 0.5-arcsec (2-pixel) wide slit. Resolutions will double, and the wavelength range would be halved, if you use the N3.75 camera with an 0.25-arcsec (2-pixel for this camera) slit. This higher resolution spectroscopy mode has been commissioned, but spectrophotometric calibration is not complete.

The typical spectroscopic configuration will be with the 210_zJHK grating and the N1.8 camera, giving slightly less than a full single (z, J, H, or K) band across the detector. All of the gratings can be tilted over a small range so if your science requires a spectrum at the blue or red ends of the bandpass, this can be accommodated. The 200_H+K grating alows for simultaneous H- and K-band spectroscopy. The 150_Ks grating is blazed closer to the center of the Ks band and thus has a higher overall efficiency across the K band than the 210_zJHK grating.

Detector:

Guiding and Wavefront Sensing:

LUCIFER is connected to an Auto-Guiding and Wavefront sensing (AGw) unit. The guider has a fixed patrol field with respect to the LUCIFER field of view such that both rotate together on sky as the position angle is varied. This must be considered when selecting guide stars and position angles for your observations. There are a few basic constraints to keep in mind:

    1. The guide probe can move on axis, but not past it
    2. The guide probe theta stage limits the X motion of the probe
    3. The focal plane is blocked at >330 arcsec radius
    4. There is vignetting from M3 at field angles above ~4.5 arcmin off axis
    5. To avoid vignetting LUCIFER, keep the probe >1 arcmin from the field edges

Some details:

1. The probe always appears to come down from above the LUCIFER field of view, independent of position angle on sky, because LUCIFER and the AGw are bolted together. Thus, you need to orient the observations such that a guide star is available in the patrol field.

2. The R-theta stage pivot point is 612 mm aove the center of the LUCIFER field. Limits at +/- 18 degrees restricts the motion to just inside the usable focal plane at the left-front bent Gregorian focus. So you need to be careful using guide stars at high field angles and position angles that put them near these limits.

3. The focal plane delivered by the telescope is blocked by parts of the AGw at field angles of more than 330 arcsec radius.

4. The tertiary mirror is a bit undersized and there is some vignetting visible in the wavefront sensor at high field angles (>4.5 arcmin). While the wavefront sensor has been adapted to account for this, selecting guide stars inside a radius of 240 arcsec from the science targert would be better.

5. The probe emits thermal radiation and appears bright in the K band, and at all wavelengths it shadows the LUCIFER entrance aperture when close to on axis. The apparent size of the probe is ~2 arcmin across, or about half the LUCIFER field of view. If this will cause problems for your project, you need to be careful in the selection of your guide star and the orientation of the field for your observations.

The AGw Patrol Field

AGw Patrol Field
A plot of the AGw guide probe patrol field (green) is shown at left, relative to the 4'x4' LUCIFER field of view (gray square) and the delivered focal plane at the left-front bent Gregorian focal station (outer 11 arcmin diameter circle). Click on the image for a full resolution jpeg, or you can download a PDF by clicking here.

During commissioning of the instrument and telescope, guide stars have been used with R-band magnitudes (e.g. "R2" mag from the USNO-B1 catalog) between 12.0 and 16.0. Much brighter than this saturates the guide camera and the system has not been calibrated or demonstrated to work at fainter magnitudes. We strongly recommend selecting guide stars within this range if possible, for maximum usability in varying conditions. However, fainter stars down to R~18.0 should work in good (<0.7 arcsec FWHM) seeing conditions.

Photometric Standards

Zero Points in all filters are available in the User's Manual.