NICMOS Instrument Handbook for Cycle 11

MULTIACCUM Predefined Sample Sequences
(SAMP-SEQ)

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While it is possible to specify MULTIACCUM observations with nearly any set of up to 25 readout times, such usage requires sending excessive volumes of commanding information up to HST. Accordingly, STScI and the NICMOS IDT defined a set of sequences which should cover nearly all applications of MULTIACCUM. These are defined in  Table 8.3. The observer specifies the name of the sequence and the number of samples to be obtained. The SCAMRR and MCAMRR are to be used when the fastest temporal sampling is desired. The SPARS64 and SPARS256 sequences have relatively few readouts and may be helpful when two or more cameras are operated in parallel (in particular they generally permit a second and third camera to operate in parallel with a minimal impact on the operation of the primary camera). They are also recommended for observations of fields where only faint targets are present. The STEPxX sequences all start with three rapid readouts and then are logarithmically spaced to provide a large dynamic range up to their defined time (e.g., STEP64 has log steps up to 64 seconds) and then revert to linear spacing. The STEPXX sequences are recommended for observations involving both bright and faint targets, where high dynamic range is required. The use of the MIF sequences is not recommended because the multiple initial and final reads induce additional amplifier glow without much advantage over other sequences.

The fastest time to read a single camera is 0.203 seconds, while 0.303 seconds is the fastest time when more than one camera is used. Accordingly, the MULTIACCUM sequences have been set up so that the first read is always the fastest time possible. The second read for all of the sequences, except for the SCAMRR, has a time of 0.606 seconds.

Table 8.3: MULTIACCUM SAMP-SEQs 

Sequence Name	Readout Times					Description
SCAMRR	0.203 1.218 2.233 3.248 4.263	0.406 1.421 2.436 3.451 4.466	0.609 1.624 2.639 3.654 4.669	0.812 1.827 2.842 3.857 4.872	1.015 2.030 3.045 4.060 5.075	Single camera fastest possible operation
MCAMRR	0.303 1.818 3.333 4.848 6.363	0.606 2.121 3.636 5.151 6.666	0.909 2.424 3.939 5.454 6.969	1.212 2.727 4.242 5.757 7.272	1.515 3.030 4.545 6.060 7.575	Fastest possible operation with 2 or 3 cameras used in parallel
STEP1	0.303 3.989 8.979 13.969 18.959	0.606 4.987 9.977 14.967 19.957	0.995 5.985 10.975 15.965 20.955	1.993 6.983 11.973 16.963 21.953	2.991 7.981 12.971 17.961 22.951	Rapid reads up to 1 second then 1 second steps
STEP2	0.303 5.981 15.951 25.921 35.891	0.606 7.975 17.945 27.915 37.885	0.995 9.969 19.939 29.909 39.879	1.993 11.963 21.933 31.903 41.873	3.987 13.957 23.927 33.897 43.867	Rapid reads up to 2 seconds then 2 second steps
STEP8	0.303 7.981 47.951 87.921 127.891	0.606 15.975 55.945 95.915 135.885	0.995 23.969 63.939 103.909 143.879	1.993 31.963 71.933 111.903 151.873	3.987 39.957 79.927 119.897 159.867	Rapid reads up to 8 seconds then 8second steps
STEP16	0.303 7.981 79.951 159.921 239.891	0.606 15.975 95.945 175.915 255.885	0.995 31.969 111.939 191.909 271.879	1.993 47.963 127.933 207.903 287.873	3.987 63.957 143.927 223.897 303.867	Rapid reads up to 16 seconds then 16second steps
STEP32	0.303 7.981 127.969 287.969 447.969	0.606 15.975 159.969 319.969 479.969	0.995 31.969 191.969 351.969 511.969	1.993 63.969 223.969 383.969 543.969	3.987 95.969 255.969 415.969 575.969	Rapid reads up to 32 seconds then 32 second steps
STEP64	0.303 7.981 191.965 511.955 831.945	0.606 15.975 255.963 575.953 895.943	0.995 31.969 319.961 639.951 959.941	1.993 63.969 383.959 703.949 1023.939	3.987 127.967 447.957 767.947 1087.937	Rapid reads up to 64 seconds then 64second steps
STEP128	0.303 7.981 255.961 895.931 1535.901	0.606 15.975 383.955 1023.925 1663.895	0.995 31.969 511.949 1151.919 1791.889	1.993 63.969 639.943 1279.913 1919.883	3.987 127.967 767.937 1407.907 2047.877	Rapid reads up to 128 seconds then 128 second steps
STEP256	0.303 7.981 255.961 1535.961 2815.961	0.606 15.975 511.961 1791.961 3071.961	0.995 31.969 767.961 2047.961 3327.961	1.993 63.969 1023.961 2303.961 3583.961	3.987 127.967 1279.961 2559.961 3839.961	Rapid reads up to 256 seconds then 256 second steps
MIF512	0.303 1.818 127.992 447.982 513.192	0.606 2.121 191.990 511.980 513.495	0.909 2.424 255.988 512.283 513.798	1.212 31.994 319.986 512.586 514.101	1.515 63.994 383.984 512.889 514.404	Eight rapid readout at start and end with 7 evenly spaced readouts over 512 seconds
MIF1024	0.303 1.818 255.991 895.961 1025.167	0.606 2.121 383.985 1023.955 1025.470	0.909 2.424 511.979 1024.258 1025.773	1.212 63.999 639.973 1024.561 1026.076	1.515 127.997 767.967 1024.864 1026.379	Eight rapid readout at start and end with 7 evenly spaced readouts over 1024 seconds
MIF2048	0.303 1.818 511.989 1791.989 2049.201	0.606 2.121 767.989 2047.989 2049.504	0.909 2.424 1023.989 2048.292 2049.807	1.212 127.995 1279.989 2048.595 2050.110	1.515 255.989 1535.989 2048.898 2050.413	Eight rapid readout at start and end with 7 evenly spaced readouts over 2048 seconds
MIF3072	0.303 1.818 639.988 2559.983 3073.193	0.606 2.121 1023.987 3071.981 3073.496	0.909 2.424 1407.986 3072.284 3073.799	1.212 127.995 1791.985 3072.587 3074.102	1.515 255.989 2175.984 3072.890 3074.405	Eight rapid readout at start and end with 7 evenly spaced readouts over 3072 seconds
SPARS64	0.303 255.988 575.978 895.968 1215.958	0.606 319.986 639.976 959.966 1279.956	63.994 383.984 703.974 1023.964 1343.954	127.992 447.982 767.972 1087.962 1407.952	191.990 511.980 831.970 1151.960 1471.950	Similar to STEP64 but without the rapid initial readouts
SPARS256	0.303 1023.996 2303.996 3583.996 4863.996	0.606 1279.996 2559.996 3839.996 5119.996	255.996 1535.996 2815.996 4095.996 5375.996	511.996 1791.996 3071.996 4351.996 5631.996	767.996 2047.996 3327.996 4607.996 5887.996	Similar to STEP256 but without the rapid initial readouts