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IRIS2 Observing Sequences

Foreword

Infrared observing tends to be fairly repetitive by nature, involving numerous short exposures, telescope offsets, filter changes, etc. Although particular IRIS2 configurations and exposures can be commanded from the User interface GUI, it is recommended that the bulk of your observing program be carried out using pre-defined observing sequences. In the vast majority of cases, there will almost certainly be an Observing Sequence template available for whatever it is that you want to do; all you need to do is to make your own copy, set the object name and exposure parameters, then save and execute it. Your Support Astronomer can advise you on the most appropriate sequence template for your needs.

If you wish to do something a little more complicated (an unusual mosaic pattern for instance), then it may still be possible to hack an existing template for your purposes. However, be aware that these sequences are written in tcl, which is not the most trivial of languages to understand. Some examples, together with a description of the available IRIS2 commands can be found in the Sequencer documentation. If you don't see a standard sequence listed below that you think will meet your purposes, then please consult your support astronomer well before your run, so that arrangements can be made to construct and test a new sequence using the IRIS2 and telescope software simulators in Epping.

>Also bear in mind that many of the standard sequences provided are written to suit a particular recipe of the data reduction pipeline ORAC-DR. While it is not our intention to force observers into observing only in a manner that makes the data reduction automatic, you should bear in mind that writing a new recipe to match your particular observing sequence may be more complicated than writing the sequence itself, and you may therefore have to forego the convenience of having pipeline-reduced data available in "real time". In any event, ORAC-DR recipes already exist to suit a wide range of observing modes, and it is rare that you will find yourself without a suitable combination of observing sequence and matching ORAC-DR recipe.

Standard Imaging Sequences

Sequence Name Purpose Action ORAC-DR Recipe
AAO_Array_Tests Verify nominal detector performance. Take 3 short dark frames, followed by 1 long dark. The difference of two short darks gives the array read noise, while the last frame gives the dark current. Warns observer if either read noise or dark current are outside nominal range, and writes the output to a log file. Repeat for all 4 combinations of read mode and read speed (DRM/NORMAL, DRM/FAST, MRM/NORMAL, and MRM/SLOW). ARRAY_TESTS
AAO_JHKKs_Std Multi-colour imaging of bright point source (e.g., photometric standard star). Takes a dark frame (if requested) to match the object exposure parameters. For each broad-band filter, do a 5-point jitter observation. JITTER_SELF_FLAT
JITTER_SELF_FLAT_BASIC
AAO_Jitter Imaging faint point sources in an uncrowded field. Takes a dark frame (if requested) to match the object exposure parameters. For a series of filters, do a N-point jitter observation, and repeat a specified number of times. Offsets can be either a fixed pattern (3<N<9), or randomised amounts in each axis (with checking to avoid repeating any previous dithers) up to a specified size. JITTER_SELF_FLAT
JITTER_SELF_FLAT_BASIC
AAO_Quadrant_Jitter Imaging extended sources up to ~3.5 arcminutes in size. Takes a dark frame (if requested) to match the object exposure parameters. Places the object in the centre of each array quadrant in turn, allowing the other 3 quadrants to be used for flatfield construction. Repeat a specified number of times, in a specified range of filters. Most time-efficient, as no times is spent on blank sky, but object-masking residuals can be significant. QUADRANT_JITTER
QUADRANT_JITTER_BASIC
AAO_Chop_to_Sky Imaging extended sources between 3.5 and up to 7 arcminutes in size. Takes a dark frame (if requested) to match the object exposure parameters. Alternates between object, and sky 10 arcminutes north, while doing a N-point jitter on both the object, and the sky position. Offsets can be either a fixed pattern (3<N<9), or randomised amounts in each axis (with checking to avoid repeating any previous dithers) up to a specified size. Repeat a specified number of times, in a specified range of filters. Begins and ends on a sky position. CHOP_SKY_JITTER
CHOP_SKY_JITTER_BASIC
AAO_Extended_3x3 Imaging extended sources between 7 and 10 arcminutes in size. Takes a dark frame (if requested) to match the object exposure parameters. Alternates between object and sky, while doing a 3 x 3 mosaic of the object, with (typically) 50% overlap between images. Begins and ends on a sky position. EXTENDED_3X3
EXTENDED_3X3_BASIC
AAO_LargeAreaNew Wide-field mosaicing of NxM IRIS2 pointings. Takes a dark frame (if requested) to match the object exposure parameters. Makes an NxM mosaic of the object, with 10-20% overlap between pointings. Can be restarted at any point in the sequence. Repeat for a specified range of filters. JITTER_SELF_FLAT
JITTER_SELF_FLAT_BASIC



Standard Spectroscopy Sequences


Sequence Name Purpose Action ORAC-DR Recipe
AAO_Array_Tests_Long Verify nominal detector performance. Take 3 x 5 sec dark frames, followed by 1 x 600 sec dark. The difference of two short darks gives the array read noise, while the last frame gives the dark current. Warns observer if either read noise or dark current are outside nominal range, and writes the output to a log file. Repeat for all 4 combinations of read mode and read speed (DRM/NORMAL, DRM/FAST, MRM/NORMAL, and MRM/SLOW). ARRAY_TESTS
AAO_Arc_Flat Obtain dome flats and Xe arcs in all spectral bands. Align dome and windscreen, and open mirror covers. For each filter, begin with a dark exposure, then take a 1.5sec x 21 reads x 3 cycles exposure with the quartz lamp on. Position Xe arc lamp on Guide Probe 2 for the appropriate slit, and observe for 1 sec x 5 cycles, again preceded by a dark frame. REDUCE_DARK
REDUCE_FLAT
REDUCE_ARC
AAO_Atm_Std Observe an atmospheric/telluric (smooth spectrum) star in the selected band at two slit positions. Observe star at one slit position A, then nod to a second slit position B and observe (usually these are pre-set to be Axes A and B, corresponding to rows 580 and 640 on the array). Take another exposure at B, then nod back to A and observe. This defines one "quad". STANDARD_STAR
STANDARD_STAR_NOFLAT
AAO_Nod_Along_Slit Observe a point source in the selected band at two slit positions. Observe object at one slit position A, then nod to a second slit position B and observe (usually these are pre-set to be Axes A and B, corresponding to rows 580 and 640 on the array). Take another exposure at B, then nod back to A and observe. Repeat this "quad" a specified number of times. The "FAINT" recipes don't attempt to trace the object spectrum; instead, they use the same optimal extraction parameters as the most recent standard star. POINT_SOURCE
POINT_SOURCE_NOFLAT
POINT_SOURCE_NOSTD
POINT_SOURCE_NOFLAT_NOSTD
FAINT_POINT_SOURCE
FAINT_POINT_SOURCE_NOFLAT
FAINT_POINT_SOURCE_NOSTD
FAINT_POINT_SOURCE_NOFLAT_NOSTD
AAO_Std_ES Observe an atmospheric/telluric (smooth spectrum) star in the selected band at two slit positions to match those for an extended source. Observe star at one slit position A, then nod to a second slit position B and observe (usually these are pre-set to be Axes A and B, corresponding to rows 185 and 670 on the array). Take another exposure at B, then nod back to A and observe. This defines one "quad". STANDARD_STAR_ES
AAO_Extended_Source Observe an extended source in the selected band at two slit positions. Observe object at one slit position A, then nod to a second slit position B and observe (usually these are pre-set to be Axes A and B, corresponding to rows 185 and 670 on the array). Take another exposure at B, then nod back to A and observe. Repeat this "quad" a specified number of times. Object extraction is done using the same optimal extraction parameters as the most recent standard star. EXTENDED_SOURCE_IRIS2


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These pages contain information on the functionality of the IRIS2 Infrared Imager and Spectrograph. Pages maintained by Stuart Ryder (sdr -@- aao.gov.au) and Paul Dobbie (pdd -@- aao.gov.au). Page last modified by Stuart Ryder.