PDS_VERSION_ID = PDS3 LABEL_REVISION_NOTE = "M.K. GORDON, 2003-03-07" RECORD_TYPE = "STREAM" OBJECT = INSTRUMENT INSTRUMENT_HOST_ID = "WHT" INSTRUMENT_ID = "API" OBJECT = INSTRUMENT_INFORMATION INSTRUMENT_NAME = "AUXILIARY PORT IMAGER" INSTRUMENT_TYPE = "CCD CAMERA" INSTRUMENT_DESC = " Instrument Overview =================== The information in this document was taken from the website www.ing.iac.es/ on June 19, 2001. The Auxiliary focus is a facility provided in the Cassegrain Acquisition and Guider unit (A&G box) to allow a direct image to be taken on-axis at the Cassegrain focus, at the expense of an extra (45 degree) reflection. Scientific Objectives ===================== The original idea of the system was that it could be used for short direct images of objects which were part of a mainly spectroscopic program, but it has emerged as the major instrument for a number of projects for which the high throughput in the ultraviolet provided by an all-reflecting optical system, or the 0.1 arcsec pixel size, are a particular advantage. Operational Considerations ========================== Local seeing can be degraded by the presence in the atmosphere of dust from Sahara dust storms, and by the presence of moisture or clouds. Detector ======== Note: Additional information is available in DOCUMENT/U_MAN.PDF Device Identification --------------------- Chip name EEV3 Year of manufacture Unknown Serial number Unknown Technology Unknown Anti reflection coating Metachrome First light on La Palma April 1991 Operational Characteristics --------------------------- Measurements made on ISIS red 3/4/95 Speed Slow Standard Quick Turbo Nonastro Bias(ADU) 3160 5007 4234 3234 3567 Gain(e/ADU) 0.71 0.79 1.10 1.66 3.27 Noise(e) 3.73 3.47 6.00 9.82 20.5 Linear to(ADU) 60k 60k 60k 40k 25k Readout time(s) 193 132 77 63 47 Vertical CTE 0.99999 Horizontal CTE 0.99999 Physical Characteristics ------------------------ X Pixel size 22.5 microns Y Pixel size 22.5 microns X size in pixels of digitized area 1280 Y size in pixels of digitized area 1180 X size of useful imaging area 1242 Y size of useful imaging area 1152 X start of useful imaging area 17 Ystart of useful imaging area 0 LN2 capacity of cryostat 1.5 liters Cryostat window thickness 4 mm Distance from window to CCD ? mm Operational Parameters ---------------------- Flooding type none Operating temperature 147K Anti-blooming available no Measured characteristics ------------------------ Quantum Efficiency @400nm 19% @530nm 38% @650nm 55% Peak non-uniformity in QE across chip Unknown Dark current 8 e/hour Point spread function Unknown Full well bloom limit Unknown Chip flatness Unknown Cosmetics Unknown Filters ======= Note: Additional information is available in DOCUMENT/U_MAN.PDF The Auxiliary focus filter unit is a box mounted at the Auxiliary port, which contains a 6 position filter. The maximum size of the filters to fit in this wheel is 51mm square or 55mm diameter. The filter unit also contains a CCD shutter 25mm in diameter, which is operated as normal by the CCD controllers. The filter wheel is controlled by the Cassegrain A&G box. The standard methane filter was replaced with a filter provided by the Instituto de Astrofisica de Andalucia. It was a narrow band methane filter centered at 8920 Angstroms with Full Width at Half Maximum of 50 Angstroms. This filter was used for all of the API images of the inner Saturnian system. The remaining positions in the filter wheel were occuppied by standard WHT filters which were used to make backup spectral observations of the E-ring as insurance in case the seeing did not prove good enough to use ISIS. The set included a copper sulfide filter (U), three Harris filters (B,V,R) and an I filter which was incorrectly identified as a Harris filter in the observing log, but was most likely the I filter from the RGO filter set. The Harris set of BVR are sandwiches of Schott glass selected to provide CCD analogs of the old Johnson photometric sequence. Until the Schott BG39 was developed, interference filters were required to cut red-leaks that CCDs were sensitive to. But interference filters deteriorate with time, so Harris at USNO found these combinations of very stable glasses that does the job quite well. Name central wavelength FWHM CH4 8920 8895- 8945 B_Harris 4390 3774- 4852 V_Harris 5256 4952- 5944 R_Harris 5920* 5656- 7144 I_RGO 8400** 7500-10500 * - very asymmetric ** - broad, double peak The U_CUSO4 is a copper sulfide filter that has good red blocking. " END_OBJECT = INSTRUMENT_INFORMATION OBJECT = INSTRUMENT_REFERENCE_INFO REFERENCE_KEY_ID = "N/A" END_OBJECT = INSTRUMENT_REFERENCE_INFO END_OBJECT = INSTRUMENT END