Instrument Apertures and Foci

Instrument Apertures and Foci

NOTE: Details on how to measure the UIST apertures and Focii are given on the main QA-night web page.
IMPORTANT: the array was inverted back to where it usually is in Summer 2007; so the parameters below should be back to where they were BEFORE the summer 07B cass block..

Apertures (in arcseconds)
(Last update of this table – 4 December ’08)
All apertures to be measured on QA night, please
NOTE: Some of aperture pixels on array shifted to cleaner locations in Spring 08

Mode4 Dec ’07 – 20 June ’08
Spec and Im-pol
in TOP of array
20 June ’08 – Sep ’08
Spec and Im-pol
in TOP of array
4 Dec ’08 – present
Imaging 0.12+1.97, +3.74+2.50, +2.61+3.10, +5.61
Imaging 0.06+2.32, +2.74+3.02, +1.39+3.52, +4.49
Spectroscopy+2.69, +6.40+8.51, -0.43+9.10, +2.61
IFU-3.66, -15.19+3.66, +1.11+4.60, +2.11
Polarimetry+19.84, -16.19+27.32,-2.37+27.80,+1.11
Coronograph-26.66, +15.81-19.06,30.69-18.20, +34.11

Notes: 1. POLARIMETRY: Using the same aperture for imaging-polarimetry and spectro-polarimetry; the former is measured and entered in the system. This means that with spec-pol during acquisition the star will always be slightly off (posn angles of more than -90 will make things progressively worse!); UPICK at the scope will fix this, moving the target onto the slit..
2. CORONAGRAPH: Again, using the same aperture for pol and non-pol. Aperture should be measured (with all the other apertures), using the non-pol reference pixel listed below.
3. UNITS: The arcsec values are simply the mm values times by -1.524
4. ORIENTATION: The first value is E-W, the second N-S, so in the rotated UIST frame the first value is along the slit (up and down, or in Y in pixels – see below)

Reference Pixel on array
Use these numbers when measuring apertures

(Last updated/checked – 04 Dec ’07 – Moved Spec and Im-Pol to TOP)
Apertures highlighted in red to be measured on QA night, please

ModeReference Pixel on array, (x,y)
Spectroscopy, 1 pix slit507.8580
Spectroscopy, 2 pix slit506.7580
Spectroscopy, 4 pix slit503.5580
Spectroscopy, 5 pix slit503.0580
Spectroscopy, 7 pix slit509.0580
Spectroscopy, 2 pix slit with spacer505.5580
Spectroscopy, 4 pix slit with spacer503.8580
Coronagraphic 6-pix wire764.5349.0
Coronagraphic 6-pix wire (pol)764.0264.0
Spec-Pol, 2 pix slit511.6740
Spect-Pol, 5 pix slit512.5740
Imaging, 1024×1024 (0.12″)530530
Imaging, 1024×1024 (0.06″)530530
Imaging, 512×512 (0.12″)280280
Imaging Polarimetry490737

Notes on locating these pixels (daytime eng): 1. POLARIMETRY: The reference pixels for imaging-pol and spec-pol are measured WITHOUT the waveplate and wollaston prism in the beam. This is because we do imaging acquisition with spec-pol WITHOUT the prism in the beam. However…
2. CORONAGRAPH: The reference pixel for coronographic imaging POLARIMETRY is measured WITH the wollaston prism in the beam. This is because we have to do imaging acquisition with the wollaston in the beam (can’t use the acquisition eyeball in the OT because this isn’t spectroscopy!). NB: Should UPICK on the LOWER pol beam.

Additional offsets during source acquisition
(Last update/check – 27 May ’07)

GrismFilter usedAdditional offset
(applied by UPICK)
Short_KB2right 0.2 arcsec
Long_KB2left 0.90 arcsec
KLB2left 0.90 arcsec
Short_L3.4contleft 0.10 arcsec
Long_LBrAright 0.17 arcsec
MBrAleft 0.15 arcsec

TTTs PLEASE NOTE: UPICK automatically applies the above offsets. TSSs do not have to adjust the source position after imaging acquisition for these grisms (this is why upick puts the star on a slightly different pixel than is listed earlier on this page).

The acquisition pixels and additional offsets listed above are read by the telescope from: /jac_sw/itsroot/src/oracda_new/uist/uocs.cfg (file at the summit, not in Hilo – updated/maintained by Russell). This file also includes the plate scale, array rotation, etc.

UIST Focii

The plot below shows fine-focus measurements taken on QA nights. Note that not all focii are measured on a given day (so some values are missing). The dates marked “UIST off scope” indicate when the instrument was physically taken off the telescope for a period of time. Thus, after one of these periods values might be expected to change…

IMPORTANT: Note that in August 2006, to accomodate FF values for IJ and JH spectroscopy, all values displayed on the autofocus.dl screen have had 1.0 mm (1000 micron) added to the values listed below. This also affects the values we enter into the bec.cfg configuration file.


Last update to Plot: 4 Dec ’08

Pink – 0.12 imaging focii; Blue – Spectroscopy focii; Yellow – 0.06JHK focii; Light Blue – 0.06LM focii; Purple – IFU focii; Brown – Pol focii.
NOTE: 0.12″ imaging and spectroscopy focii should be the same.

Mean Telescope FF values
(Last update of this table – 4 Dec 2008)

ModeMean Focus, mmValue relative
to 0.012″ Im
Imaging, 0.12″0.75
Spectroscopy IJ-0.2-0.95
Spectroscopy JH0.39-0.36
Imaging, 0.06″JHK0.97+0.22
Imaging, 0.06″LM0.72-0.03

Earlier apertures and focii are available on previous versions of this web page. The date corresponds to when an update was made:
20080701 20080620
20070621 20070508
20060925 20060808 20060210
20040622 | 20040522 | 20040402
20031220 | 20031124 | 20031003 | 20030903 | 20030731 | 20030424 | 20030403 | 20030131 | 20030106