For observers who would like to take YJHK spectra of a target,
there is a gui and command line script available to sequence
the observations. Below is an image of the gui used to acquire
the sequence data.
Parameters
Filter-dependent parameters
There are several parameters to change for each filter.
- Exposure time: on source integration time for each
exposure.
- Coadds: number of coadditions per exposure
- Repeats: number of times to repeat the dither
pattern before moving to the next filter. If set to ZERO (0),
the observations for that filter are skipped.
Global parameters
These parameters apply to all filters:
- Pattern: selected dither pattern for observing
sequence:
- stare: performs no telescope nods between
exposures or passbands; target remains at current position
throughout the sequence.
- masknod: uses a two-position (AB) dither
sequence, alternating between two nod positions which are
±nodsize arcsec from the center (starting)
position.
- abba: uses a four-position (ABBA) dither
sequence, employing two nod positions which are
±nodsize arcsec from the center (starting)
position. The advantage to ABBA over masknod is that the
mean airmass of the A pair and the B pair is identical,
which may improve sky subtraction in the absence of
temporal variation in the sky spectrum.
- Nodsize: magnitude of the nod throw relative to
center. Selecting the default value of 1.5 will produce
spectra separated by 3 arcsec between the A and B positions.
- Sampmode: detector sampling mode (CDS or MCDS)
- Nreads: Number of reads for MCDS sampmode only.
Launching the script
You may use either of two methods for launching the script:
- From the desktop menu select MOSFIRE Utilities ->
YJHK Sequencer, or
- From a mosfireserver xterm window, enter the command
yjhk.tcl
You can run multiple instances of the GUI
simultaneously. Observers may find this useful when observing
standards and science targets often. One instance may be
configured for standard star observations while the other is
specific to the science target observations.
Running the script
- Click the GO button to start the sequence of
observations. This will launch an xterm and run the
yjhk_go script with the specified parameters.
- Click the Reset button to restore the default
parameters to the GUI.
- Type Ctrl-C in the xterm running the
script to interrrupt the exposure sequence. The last image will
readout before returning the telescope and instrument to the
starting parameters.
Note
- To minimize motor moves on MOSFIRE, the order of
observation is J, Y, K, H.