Filters

A filter is needed for each of the four CCDs. Overall, 124 filters have been built for LAICA, both with a wide and medium wavelength range coverage:

11 wide-band filters (left table, see transmission curves of Johnson- and Sloan filters) and 20 medium-band filters (colored bands overlayed over SDSS bands in black, full optics + atmospheric transmission) designed for the ALHAMBRA cosmological survey.LAICA Alh filterset

Band name λcentral λFWHM Trans.

U_Johnson 

3500 520 Curve
B_Johnson  4200 1400 Curve
V_Johnson 5500 1150 Curve
R_Johnson 6600 1850 Curve
I_Johnson 9000 100 Curve
B2     4300 1480 Curve
u'   SDSS 3500 630 Curve
g'   SDSS 4900 1230 Curve
r'    SDSS 6200 1350 Curve
i'    SDSS 7700 1500 Curve
z'   SDSS 9200 1600

Curve


*** The DLR dewar is being serviced, but other direct imaging camera is currently available for the 1.23: a CCD (iKon XL-230, see this addendum to the DLR manual).
Please get in touch with the support astronomers (coords CHEZ caha.es) for details.

 

The DLR-MKIII CCD is the workhorse instrument at the 1.23-m telescope Cassegrain focus. 

In a nutshell

fotoDRL

Instrument name CCD DLR-MKIII
Observing technique Direct imaging camera for (fast, efficient and accurate) photometry
Shutter Fast (Bonn-type): accuracy <1% with 0.1 s exposures
Wavelength range 330 nm to 890 nm (QE > 50%)
Filters  100 mm: Johnson BVRI, FTmask, GG495, luminance LRGB+Halpha. Any 50 mm.
Detector

e2v CCD231-84-NIMO-BI-DD

Detector size 4096x4096 pixels
Pixel size 15 μm = 0.314" on the sky
Field of view

21.4x21.4 arcmin with 100 mm filters (or ∅11' circular unvignetted with 50 mm)

Readout time

<1 min full frame, <15 s binning 2x2. Parallel readout possible and frame transfer mask available.

 

On loan from the German Aerospace Center (Deutsches Zentrum für Luft- und Raumfahrt e.V.), the DLRMkIII CCD is a fast read-out camera with a high-QE 4k CCD, offering a field of view over 21'x21', for 100 mm round filters. Using 50 mm filters limits the unvignetted field to ca. ∅11'. A filter wheel with 4 filters of 100 mm (frame-transfert mask available) or another one with 8 filters of 50 mm (see complete filter list here) can be mounted.

Since the 1.23-m telecope can be used remotely (based on the rts2 control system), observing runs with the DLR MK-III may be performed from the distance by experienced observers, having a stable internet connection and a casual Windows OS PC. They can control both the telescope, filter wheel, autoguider camera and DLR CCD itself (thru a basic GUI, or extensive scripting). Limited technical support on-site is available in remote mode, night and day, on a best effort basis.

At the moment, the 1.23-m telescope is only offered on a pay-per-night basis to interested groups. They must submit an observing proposal every semester. that will be evaluated by an external TAC. If accepted by this TAC, a MoU has to be signed with the CAHA direction before being authorized to use the 1.23 after finding the best compromise with the other users in terms of scheduling observing runs. See the 1.23 timeline here (right columns).

 

History:

The DLR camera has been extensively used on the 1.23 since 2013. Before that, the 2k SITe#2b CCD was used. For reference, see the old observing manual (nowadays partly obsolete) of the former CCD, used until 2012. 

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