The Wisconsin Ultraviolet Photo-Polarimeter Experiment (WUPPE) was one of
three ultraviolet telescopes on the ASTRO-1 payload which flew aboard the
space shuttle Columbia during a nine day mission in December 1990 (December
2 through 11). The launch GMT was 1990, day 336/06:49:01. The WUPPE was
designed to measure the polarization of light in the ultraviolet. WUPPE
obtained simultaneous spectra and polarization measurements from 1400 to
3300A. WUPPE consisted of a 0.5m f/10 classical Cassegrain telescope and a
spectropolarimeter. The telescope fed light to a low resolution
spectrometer which was equipped with various polarimetric analyzers. A
magnesium flouride Wollaston polarizing beam-splitter was placed between
the aperture and the relay mirror and split the beam into two
orthogonally-polarized spectra. The two polarized spectra were measured
simultaneously by two parallel 1024-pixel arrays of an intensified Reticon
photodiode array. The cesium telluride photocathode of the microchannel
plate intensifier provided a spectral coverage from 1400 to 3300 Angstroms.
The WUPPE spectrometer was a modified Monk-Gilleson spectrometer: a plane
grating is placed between a spherical relay mirror and the detector. The
focal plane scale was 26 arcsec/mm. The dispersion was 78 A/mm, blaze at
2000 Angstroms. A set of halfwave plates at 6 different angles provided
spectropolarimetric modulation with 5 Angstrom resolution on point sources
through apertures from 6 to 40 arcsec. A "Lyot" analyzer was used to
provide 50-100 Angstrom spectropolarimetric resolution on faint point
targets and diffuse nebulae.
Because of the very high signal/noise required for polarimetry, most
WUPPE targets were in the 0-8 magnitude range: readout integration
times ("frames") were less than 8 seconds, so that a typical
observation was the sum of many short frames. The apertures included
a 40 arcsec diameter acquisition aperture and a 4.2 arcsec diameter
stellar aperture, in addition to a number of aperture shapes for
diffuse source, (e.g. 6x12 and 3x50 arcsec). WUPPE had the ability
to offset from the other two ultraviolet instruments (HUT and UIT) by
as much as 15 arcminutes by use of its articulated secondary mirror.
In spectral mode the field of view was 50 arcsec perpendicular to the
dispersion for a spatial resolution better than 0.7x6 arcsec.
The total system quantum efficiency was about 4 percent,
polarimetric efficiency about 75 percent, polarimetric stability was
better than 0.04 percent, and the instrumental polarization (from in
flight observations of unpolarized standard stars) was less than 0.1
percent. In the Lyot mode the polarimeter measured Stokes Q, U, V with
50-100 A resolution. In the Halfwave plate mode the Stokes Q, U were
supported with 10 A resolution.
Field identification, offsetting, focussing, and pointing trim were
accomplished by relaying the zero-order image of the WUPPE spectrometer
grating to a blue-sensitive Zero-Order Detector (ZOD) camera. The ZOD
was an intensified RCA 320x512 two-dimensional CCD array. The
intensifier was an ITT 18 mm proximity-focussed channel intensifier
with P-20 phosphor, quartz faceplate, and S-20 photocathode for
blue-sensitivity. The array was uncooled and typically read out every
second. The ZOD camera had a 3.4 x 4.4 arcmin field of view, 1 x 5
arcsec resolution, and was sensitive up to 15th magnitude for a 1
second integration. The ZOD made it possible for the experiment team
to acquire and guide upon faint targets and targets in crowded fields.
There were three camera modes: field, zoom and downfield. The field
mode was used for identification and acquisition of the targets. Its
size was 3.3 x 4.4 arcmin, 320 x 256 pixels and used a 1-bit display.
The zoom mode was used for fine pointing and focus. The size of the
zoom image was 24 x 32 arcsec, 30 x 40 pixels and used a 6-bit grey
scale display. The downfield data was similar to the field data
except it used the 6-bit grey scale display and was used to produce a
more detailed picture of the field around the object of interest.
All Astro 1 / WUPPE file names on NDADS begin with "WUPPE1". WUPPE1
file names have one of 4 extensions; .FITS for FITS files, .PS for
PostScript files, .F for Fortran 77 programs, and .DOC for ASCII
document files. WUPPE1 file names are organized in two ways. One
dataset is organized by the Object-ID and the file names contain both
the Object-ID and the 6-digit Pointing-ID (pppppp). A second dataset
is organized by the Mission elapsed time (MET) day number, which is
contained within the file name. All FITS files have the Data-Type
encoded within the file name. In the sample file names below the
following conventions are used:
Notes:
OBJECTID = The Mission Target List name. The names are
common to the HUT, UIT and WUPPE instruments. The number of
characters in OBJECT can vary from 3 to 8 characters. May
be a mix of numbers, alphabetic information, and/or imbedded '-'s.
PPPPPP = The POINTING_ID is a 6 digit number representing the
object identification number which was assigned during the ASTRO1
mission. Each shuttle pointing had a unique POINTING_ID number.
DAYyz = The mission elapsed time (MET) day number times 10
(eg. 00, 05, 10,... 80). Files containing "DAYyz" in the
file name were obtained within a given 12-hour periods. The
launch GMT was 1990, day 336/06:49:01 which is defined to
be MET day00, 00h:00m:00s. For example, MET DAY00 runs from a
MET time of 0 day, 00h:00m:00s to llh:59m:59s; DAY05 runs from
MET time of 0 day, 12h:12m:12s to 23h:59m:59s, etc.
Data-Types:
HW = Halfwave filter data,
L2 = Medium resolution Lyot filter (Not available)
L4 = Low resolution Lyot filter (Not available)
SN = SCAN data
ZM = ZOOM data
FD = FIELD data
DN = DOWNFIELD data
EG = Engineering data
4.1 Level 1 Spectropolarimeter data:
WUPPE1_OBJECTID_PPPPPP_HW.FITS
WUPPE1_OBJECTID_PPPPPP_HW.PS
WUPPE1_OBJECTID_PPPPPP_HW.DUMP
Samples:
WUPPE1_ALF-CAM_210720_HW.FITS
WUPPE1_HD25443_065823_HW.PS
4.2 Level 0 SCAN Spectrometer data:
WUPPE1_DAYyz_SN_nnnn.FITS
WUPPE1_OBJECTID_PPPPPP_SN_nnnn.FITS
Samples:
WUPPE1_BD284211_001014_SN_0001.FITS
WUPPE1_DAY05_SN_0001.FITS
nnnn = 4 digit starting SCAN number
4.3 Level 0 Zero Order Detector (ZOD) ZOOM Data:
WUPPE1_DAYyz_ZM_nnnn.FITS
WUPPE1_OBJECTID_PPPPPP_ZM_nnnn.FITS
Sample Files:
WUPPE1_DAY05_ZM_0001.FITS
WUPPE1_BD284211_001014_ZM_nnnn.FITS
WUPPE1_C-LEVY_111230_ZM_0001.FITS
nnnn = 4 digit starting ZOOM Image number
4.4 Level 0 ZOD DOWNFIELD Data:
WUPPE1_DAYyz_DN_n.FITS
WUPPE1_OBJECTID_PPPPPP_DN_n.FITS
Sample Files:
WUPPE1_NGC1068_820333_DN_1.FITS
n = 1 digit DOWNFIELD Image Number
4.5 Level 0 ZOD FIELD data:
WUPPE1_DAYyz_FD_nnnnn.FITS
WUPPE1_OBJECTID_PPPPPP_FD_nnnnn.FITS
Sample Files:
WUPPE1_DAY55_FD_00081.FITS
WUPPE1_NGC4151_FD_00081.FITS
nnnnn = 5 digit FIELD Starting Image Number
4.6.0 Level 0 Engineering Data:
WUPPE1 Level 0 Engineering data consist of General Measurement Loop
(GML) data and Image Motion Compensation System (IMCS) data.
4.6.1 GML Engineering data:
WUPPE1_DAYyz_EG_cnn.PS
WUPPE1_OBJECTID_PPPPPP_EG_cnn.PS
Sample Files:
WUPPE1_DAY70_EG_A01.PS -> WUPPE1_DAY70_EG_A40.PS
WUPPE1_DAY70_EG_M01.PS -> WUPPE1_DAY70_EG_M40.PS
WUPPE1_DAY70_EG_D01.PS -> WUPPE1_DAY70_EG_D46.PS
WUPPE1_G70D8247_260911_EG_A01.PS -> WUPPE1_G70D8247_260911_EG_A40.PS
cnn = 1 character + 2 digit number indicating which engineering
value is contained in the file. Analog data = A01 -> A32;
Serial Message data = M01 ->M40; Digital Data = D01 -> D46.
4.6.2 Image Motion Compensation System (IMCS) data:
WUPPE1_DAYyz_ISTATUS.PS (Only available ordered by DAYyz)
4.6.3 Documentation:
All documentation is in plain ASCII format.
WUPPE1_GENINFO.DOC
WUPPE1_OBSLOG.DOC
WUPPE1_HALFWAVE.DOC
WUPPE1_SCAN.DOC
WUPPE1_ZOOM.DOC
WUPPE1_DOWNFIELD.DOC
WUPPE1_FIELD.DOC
WUPPE1_ENGINEERING.DOC
4.6.4 Software:
All software is Fortran and uses FITSIO 3.2. It was written with
DEC fortran for ULTRIX RISC Systems (Ultrix 4.2) and is F77.
Software files are available from NDADS.
SPECFITSREAD.F - Read FITS header and primary data array
of the Level 0 spectrometer (SCAN) data.
ZOOMFITSREAD.F - Read FITS header and primary data array
of the Level 0 ZOD Zoom camera data.
HWFITSREAD.F - Read FITS header, primary data array (flux),
and Binary table extension (%P, and P.A.)
of the Level 1 Halfwave Filter
Spectropolarimetry data
FLUXFITSREAD.F - Read FITS header and primary data array (flux)
of the Level 1 Halfwave Filter
Spectropolarimetry data
DFLDFITSREAD.F - Read FITS header and primary data array
of the Level 0 ZOD Downfield camera data.
FLDFITSREAD.F - Read FITS header and primary data array
of the Level 0 ZOD Field camera data.
NOTES:
(a) Launch stow position
(b) Rochon prism, mounted with plane of splitting at PA 22.5
(c) Apertures 10 and 11 have occulting disks in the center of their slits
of 3 and 12 arc-sec, respectively.
(d) PA measured clockwise from radius vector of wheel to optic axis.