Computing

Tips, tricks, and scripts

Observation planning with Elevation

elevation is an online observation planning tool that runs as a web app. It plots the elevation of comets, asteroids, and fixed targets throughout the night for a specific observatory site:

Lowell Discovery Telescope/LMI dithering

Python script to generate observing macros: lmi-dither

Supports an hexagonal or cross pattern. The scale of the pattern, filter(s), integration time(s), number of positions, and subframe are all configurable. It also provides estimates of the total integration and wall times for 2×2 binning. By default, a short SDSS r' context image is taken at the start and end.

$ lmi-dither --set=OH-long 88P/Howell
#title=true ra=false dec=false exposureTime=true numExposures=false filter=true subframe=false muRA=false muDec=false epoch=false dRA=false dDec=false rotatorPA=false rotatorFrame=false xi=true eta=true comment=true commandOption=false
#
"88P/Howell"   30.0  SL-r       0     2  "Context"
"88P/Howell"  100.0  RC         0   -60  "Position 0"
"88P/Howell"  100.0  RC       -52    30  "Position 1"
"88P/Howell"  100.0  RC        52    30  "Position 2"
"88P/Howell"  300.0  OH         0   -60  "Position 0"
"88P/Howell"  300.0  OH       -52    30  "Position 1"
"88P/Howell"  300.0  OH        52    30  "Position 2"
"88P/Howell"  100.0  BC         0   -60  "Position 0"
"88P/Howell"  100.0  BC       -52    30  "Position 1"
"88P/Howell"  100.0  BC        52    30  "Position 2"
"88P/Howell"  100.0  BC       -52   -30  "Position 3"
"88P/Howell"  100.0  BC         0    60  "Position 4"
"88P/Howell"  100.0  BC        52   -30  "Position 5"
"88P/Howell"  300.0  OH       -52   -30  "Position 3"
"88P/Howell"  300.0  OH         0    60  "Position 4"
"88P/Howell"  300.0  OH        52   -30  "Position 5"
"88P/Howell"  100.0  RC       -52   -30  "Position 3"
"88P/Howell"  100.0  RC         0    60  "Position 4"
"88P/Howell"  100.0  RC        52   -30  "Position 5"
"88P/Howell"   30.0  SL-r      -2     0  "Context"
#
# 20 frames
# 3060.0 s = 51 min integration time
# 3540.0 s = 59 min estimated wall time

$ lmi-dither --help
usage: lmi-dither [-h] [-n N] [-g G] [--scale SCALE] [--offset OFFSET] [--pattern {cross,hex}]
    [--subframe SUBFRAME] [--no-filter] [--filters FILTERS] [--itimes ITIMES] [--no-alternate]
    [--set {OH,OH-CN,OH-long,RC-BC}] [--no-context] [--context-itime CONTEXT_ITIME]
    [title [title ...]]

Generate a DCT/LMI dither macro.

positional arguments:
title                 Image title.

optional arguments:
-h, --help            show this help message and exit
-n N                  Number of dithers; even is best for airmass matching
-g G                  Number of dithers to group before changing filters. Set to 1 to disable.
--scale SCALE         Scale factor for offsets. [arcsec]
--offset OFFSET       Absolute dither pattern offset (xi, eta).
--pattern {cross,hex}
          Dither pattern.
--subframe SUBFRAME   Use this subframe number.
--no-filter           Set to omit filter column.
--filters FILTERS     Comma-separated list of filter names
--itimes ITIMES       Comma-separated list of filter integration times, or one time for all filters. [s]
--no-alternate        Cycle through each step before each filter.
--set {OH,OH-CN,OH-long,RC-BC}
          Use a predefined filter/itime sequence.
--no-context          Do not bracket with a context images.
--context-itime CONTEXT_ITIME
          Integration time to use for context images. [s]