Page 1 PROPOSAL FOR HUBBLE SPACE TELESCOPE OBSERVATIONS ST ScI Use Only ID 2774c Report Date: 09-May-96:17:20 Version: ********** Check-in Date: ********** 1.Proposal Title: DISCRIMINATOR TEST ------------------------------------------------------------------------------------ 2. Scientific Category 3. Proposal For 4. Proposal Type 5. Continuation ID OV/FOS Sub Category ------------------------------------------------------------------------------------ 6. Principal Investigator Institution Country Telephone Ross Cohen U.C., SAN DIEGO U.S.A. (619) 534-2664 ------------------------------------------------------------------------------------ 7. Abstract Observations will be made with the internal Flat Field lamp of the FOS to determine to correct discriminator settings for both sides. The high voltage will be set to 12750 KV for the measurements. Revised by o.Lupie ------------------------------------------------------------------------------------ ------------------------------------------------------------------------------------ 9. Est obs time (hours) pri: 0 par: 0 10. Num targs pri: 0 par: 0 ------------------------------------------------------------------------------------ 11. Instruments requested: FOS ------------------------------------------------------------------------------------ ------------------------------------------------------------------------------------ Page 2 I. GENERAL FORM Proposal 2774c PI: Ross Cohen Proposal Title: DISCRIMINATOR TEST ------------------------------------------------------------------------------------ 1. Proposers: Proposers Institution Country ESA ------------------------------------------------------------------------------------ George Hartig SPACE TELESCOPE SCIENCE U.S.A. INSTITUTE Ross Cohen U.C., SAN DIEGO U.S.A. ------------------------------------------------------------------------------------ 2. Scientific Justification. In order to get the best scientific results from the FOS, we must optimize both the quantum efficiency and noise characteristics of the individual detectors. The primary means of doing so is to properly set the discriminator for each channel to reject noise pulses while accepting all pulses due to real, detected photons. Currently, the only discriminator/noise test that is included in the OV/SV plans is a crude scan, at 5s per DAC setting, with DAC increments of 5, and with detector high voltage OFF. While this is marginally adequate for detecting channels with a high degree of pre-amp noise, it is useful for nothing else. The optimal discriminator threshold settings were last determined in ambient testing in March, 1988. Because both the noise and gain of the characteristics are known to be temperature sensitive, it is plausible and likely that a significant fraction of the channels will experience some change in their optimal discriminator threshold settings on orbit. We note that the last test did show systematic changes from previous tests and also that none of the testing prior to March 1988 is really relevant as many of the pre-amps and one entire detector were changed at that time. ------------------------------------------------------------------------------------ 3. Description of proposed observations. The FOS high voltage will be brought to approximately one-half the nominal operating voltage (12750 KV), with the REFDAC=250 and the trim focus current at 0. A 60S wait will allow the high voltage to stabilize. The command block YTDN will be run, with the INTFLAT as the source, for the following parameters: FOS/RD FOS/BL DAC values 100-255 DAC values 100-255 1 unit per step 1 unit per step 10s exposure time 30s exposure time 26M total exposure time 78M total exposure time 13M total overhead 13M total overhead The exposure time in lines 1.0 and 10.0 is based on running command blocks YSHDLV (8:37) and YSHVON (1:41). ------------------------------------------------------------------------------------ 5. Description of special scheduling requirements. This program may be performed anytime after the HV has been successfully turned on (OV Prop 2163). It also must be performed at lest 2 weeks prior to the first external calibrations in SV. According to the most recent timelines (as of May 1989), this means the test could occur late in OV/1, anytime in OV/2, and within the first 20 days of SV. Note that the detector high voltage is 12750 KV (HVDAC=1000), which is not the nominal value. It is advisable that this test be run intermittently throughout the mission. Disable overlight protection. ------------------------------------------------------------------------------------ 6. Description of special calibration exposures. All observations are internal. ------------------------------------------------------------------------------------ 7. Data reduction and analysis plans. Data reduction will be performed at the ST ScI, and the analysis will be performed using FOS IDT computer facilities. This is a verification of ground- based analysis, so no data will need to be added to the PODPS pipeline. However, it is likely that new values for some of the discriminator settings will need to be uplinked. Page 3 ------------------------------------------------------------------------------------ 10. Resources to be supplied by investigator's institution(s). Data analysis, research assistant support, and funding will be provided under NASA's FOS GTO contract(s). ------------------------------------------------------------------------------------ 11. Address Information Name: ROS COHEN Category: PI Institution: U.C., SAN DIEGO Address: CASS DEPARTMENT, C-011 City: LA JOLLA State: CA Zip Code: 92093 Country: U.S.A. Telephone: 619-534-2664 Telex (or e-mail): ------------------------------------------------------------------------------------ EXPOSURE LOGSHEET ID = 2774c [ 4] ------------------------------------------------------------------------------------------------------------------------------------ 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 |10 | 11 | 12 |13 |14| 15 ------------------------------------------------------------------------------------------------------------------------------------ Line | Seq | Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | S/N |Flx|Pr| Special Number | Name | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| |Rel. Time|Ref| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 1 DARK S/C POINTIN V1 1 2.5M 1 SEQ 1-3 NON-INT G Comments: SET THE HV DAC TO 512(DECIMAL), DISC. REFDAC=250, TRIM FOCUS CURRENT=0. WAIT 60S FOR HV STABILIZATION. EXECUTE DUBMY HOLD FOR ENABLING ALL CHANNELS. ------------------------------------------------------------------------------------------------------------------------------------ 3 INTFLAT FOS/RD IMAGE 4.3 MIRROR SUB-STEP=1 1 13.0M 1 COMB=NO Y-SIZE=1 Y-SPACE=0 Comments: TURN OFF OVERLIGHT; PERFORM DISCRIMINATOR OBSERVATIONS AT ONLY ODD VALUED THRESHOLDS. START AT DISC 101. ------------------------------------------------------------------------------------------------------------------------------------ 3.1 DARK S/C POINTIN V1 1 2.5M 1 SEQ 3.1-3.3 NON- G INT AFTER 3.0 BY 24H+/ -12H Comments: SET THE HV DAC TO 512(DECIMAL), DISC. REFDAC=250, TRIM FOCUS CURRENT=0. WAIT 60S FOR HV STABILIZATION. EXECUTE DUMMY HOLD FOR ENABLING ALL CHANNELS. ------------------------------------------------------------------------------------------------------------------------------------ 3.3 INTFLAT FOS/RD IMAGE 4.3 MIRROR SUB-STEP=1 1 13.0M 1 COMB=NO Y-SIZE=1 Y-SPACE=0 Comments: TURN OFF OVERLIGHT; PERFORM DISCRIMINATOR OBSERVATIONS AT ONLY EVEN VALUED THRESHOLDS. START AT DISC 100. ------------------------------------------------------------------------------------------------------------------------------------ 10 DARK S/C POINTIN V1 1 2.5M 1 SEQ 10-12 NON-INT G Comments: SET THE HV DAC TO 512(DECIMAL), DISC. REFDAC=250, TRIM FOCUS CURRENT=0. WAIT 60S FOR HV STABILIZATION. EXECUTE DUMMY HOLD FOR ENABLING ALL CHANNELS. ------------------------------------------------------------------------------------------------------------------------------------ 12 INTFLAT FOS/BL IMAGE 4.3 MIRROR SUB-STEP=1 1 78.0M 1 COMB=NO Y-SIZE=1 Y-SPACE=0 Comments: TURN OFF OVERLIGHT; PERFORM DISCRIMINATOR OBSERVATIONS AT ONLY ODD VALUED THRESHOLDS. START AT DISC 101. ------------------------------------------------------------------------------------------------------------------------------------ EXPOSURE LOGSHEET ID = 2774c [ 5] ------------------------------------------------------------------------------------------------------------------------------------ 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 |10 | 11 | 12 |13 |14| 15 ------------------------------------------------------------------------------------------------------------------------------------ Line | Seq | Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | S/N |Flx|Pr| Special Number | Name | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| |Rel. Time|Ref| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 12.1 DARK S/C POINTIN V1 1 2.5M 1 SEQ 12.1-12.3 NON- G INT AFTER 12.0 BY 24H+ /-12H Comments: SET THE HV DAC TO 512(DECIMAL), DISC. REFDAC=250, TRIM FOCUS CURRENT=0. WAIT 60S FOR HV STABILIZATION. EXECUTE DUMMY HOLD FOR ENABLING ALL CHANNELS. ------------------------------------------------------------------------------------------------------------------------------------ 12.3 INTFLAT FOS/BL IMAGE 4.3 MIRROR SUB-STEP=1 1 78.0M 1 COMB=NO Y-SIZE=1 Y-SPACE=0 Comments: TURN OFF OVERLIGHT; PERFORM DISCRIMINATOR OBSERVATIONS AT ONLY EVEN VALUED THRESHOLDS. START AT DISC 100. ------------------------------------------------------------------------------------------------------------------------------------ Summary Form for Proposal 2774c [ 6] Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Configurations S/C FOS/RD FOS/BL ------------------------------------------------------------------------------------------------------------------------------------ Opmodes POINTING IMAGE ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters SUB-STEP=1 COMB=NO Y-SIZE=1 Y-SPACE=0 ------------------------------------------------------------------------------------------------------------------------------------ Proposal for OV/FOS ------------------------------------------------------------------------------------------------------------------------------------ S/C Hours ------------------------------------------------------------------------------------------------------------------------------------ Scientific Category ------------------------------------------------------------------------------------------------------------------------------------ Scientific Sub-category ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements SEQ 1-3 NON-INT; SEQ 3.1-3.3 NON-INT; AFTER 3.0 BY 24H+/-12H; SEQ 10-12 NON-INT; SEQ 12.1-12.3 NON-INT; AFTER 12.0 BY 24H+/-12H ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements MIRROR ------------------------------------------------------------------------------------------------------------------------------------ Target Names ------------------------------------------------------------------------------------------------------------------------------------