PDS_VERSION_ID = PDS3 LABEL_REVISION_NOTE = "M.K. GORDON, 2003-01-15" RECORD_TYPE = "STREAM" OBJECT = INSTRUMENT INSTRUMENT_HOST_ID = "WHT" INSTRUMENT_ID = "ISIS" OBJECT = INSTRUMENT_INFORMATION INSTRUMENT_NAME = "INTERMEDIATE DISPERSION SPECTROGRAPH AND IMAGING SYSTEM" INSTRUMENT_TYPE = "SPECTROGRAPH" INSTRUMENT_DESC = " Instrument Overview =================== The information in this document was taken from the website www.ing.iac.es/ on June 19, 2001. The Intermediate dispersion Spectrograph and Imaging System (ISIS) was designed and built by the Royal Greenwich Observatory (RGO) and Oxford University in a collaborative effort with the design and construction carried out predominantly at the RGO. Description: This versatile Cassegrain instrument consists of two intermediate dispersion spectrographs which can be operated one at a time or simultaneously, and are separately optimized for the blue and red spectral regions. Scientific Objectives ===================== The main goals are to provide: a range of dispersions between 130 and 16 angstroms/mm in first order, corresponding to a range in resolving power respectively between 800 and 7000 when using a narrow (0.5 arcsecond) slitwidth; maximum possible throughput; high operating efficiency in both the setting-up and observing modes, with the capability of operating the blue and red spectrographs as a single unit; rapid interchange between ISIS and the Faint Object Spectrograph, which share the same slit assembly; long slit (4 arcminute), multi-slit and fibre optic feed capabilities; a cross-dispersed mode capable of recording the wavelength range from 3000 to 1100 nm with a resolving power of about 2000; facilities for spectro-polarimetry; and full capability of being remotely operated. 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. Detectors ========= Note: Additional information is available in DOCUMENT/U_MAN.PDF The detector in each arm for this data set was a TEK CCD (1k*1k). Blue Arm -------- The CCD used on the blue arm of ISIS was the thinned, AR coated chip named TEK1. It is an array of 1024x1024, 24 micron pixels with a pixel scale on the blue arm of 0.33 arcsec/pixel. Operational Characteristics of TEK1 ----------------------------------- Measurements made on ISIS Blue 17/7/95 Speed Slow Standard Quick Turbo Nonastro Bias(ADU) 2379 2289 2250 2220 1787 Gain(e/ADU) 1.16 1.28 1.74 2.73 4.77 Noise(e) 5.02 5.24 5.73 8.38 23.56 Linear to(ADU) 60k 60k 60k 50k 15k Readout time(s) 160 105 70 50 35 Binning - When binning the readout speed will always be TURBO regardless of the readout speed selected. Vertical CTE 0.99999 Horizontal CTE 0.99999 Physical Characteristics ------------------------ Pixel Scale (ISIS) : 0.33 arc/pixel X Pixel size : 24 microns Y Pixel size : 24 microns X size in pixels of digitised area : 1124 Y size in pixels of digitised area : 1124 X size of useful imaging area : 1024 Y size of useful imaging area : 1024 X start of useful imaging area : 50 Y start of useful imaging area : 0 LN2 capacity of cryostat : 2.5 liters Cryostat window thickness : 4 mm Cryostat window size : 40mm x 40mm Operational Parameters ---------------------- Flooding type : none Operating temperature : 173K Preferred amplifier : B Red Arm ------- The CCD used on the red arm of ISIS was the thinned, AR coated chip named TEK2. It is an array of 1024x1024, 24 micron pixels with a pixel scale on the red arm of 0.36 arcsec/pixel. Operational Characteristics --------------------------- Speed Slow Standard Quick Turbo Nonastro Bias(ADU) 996 1088 1231 849 379 Gain(e/ADU) 1.07 1.19 1.62 2.45 4.56 Noise(e) 5.22 4.99 5.77 10.26 22.6 Linear to(ADU) 60k 60k 60k 50k 15k Readout time(s) 164 112 73 58 40 Binning - When binning the readout speed will always be TURBO regardless of the readout speed selected. Vertical CTE 0.99999 Horizontal CTE 0.99999 Physical Characteristics ------------------------ Pixel Scale (ISIS red) : 0.36 arcsec/pixel X Pixel size 24 microns Y Pixel size : 24 microns X size in pixels of digitised area : 1124 Y size in pixels of digitised area : 1124 X size of useful imaging area : 1024 Y size of useful imaging area : 1024 X start of useful imaging area : 50 Y start of useful imaging area : 0 LN2 capacity of cryostat : 2.5 liters Cryostat window thickness : 4 mm Distance from window to CCD : 11.5 mm Cryostat window size : 40 mm x 40 mm Operational Parameters ---------------------- Flooding type : none Operating temperature : 173k Preferred amplifier : A Electronics =========== Unknown Filters ======= No filter was used for the ISIS blue arm. For the ISIS red arm, the GG495 filter was used. The GG495 filter is an order-separation filter designed to filter out second order blue from the first order red in usual applications. In the case of ISIS, where a dichroic splits the beam into red and blue components, it helps define the 'red' channel short wavelength. GG495 is a standard Schott filter which passes long wavelengths and suppresses short wavelengths. According to the Schott catalogue the half-power wavelength is 495 +/- 6 nm with < 1.E-5 for wavelengths less than 450 and > 0.99 for 550 nm with a standard thickness of 3mm. " END_OBJECT = INSTRUMENT_INFORMATION OBJECT = INSTRUMENT_REFERENCE_INFO REFERENCE_KEY_ID = "N/A" END_OBJECT = INSTRUMENT_REFERENCE_INFO END_OBJECT = INSTRUMENT END